In Vivo Dosimetry in Brachytherapy (1)

8/10/2019 In Vivo Dosimetry in Brachytherapy (1)

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In vivo dosimetry in brachytherapyKari Tanderup , Sam Beddar , Claus E. Andersen , Gustavo Kertzscher , and Joanna E. Cygler

Citation: Medical Physics 40 , 070902 (2013); doi: 10.1118/1.4810943 View online: http://dx.doi.org/10.1118/1.4810943 View Table of Contents: http://scitation.aip.org/content/aapm/journal/medphys/40/7?ver=pdfcov Published by the American Association of Physicists in Medicine
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In vivo dosimetry in brachytherapyKari Tanderup a) Department of Oncology, Aarhus University Hospital, Aarhus 8000, Denmark and Department of Clinical Medicine, Aarhus University, Aarhus 8000, Denmark

Sam Beddar Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston,Texas 77030

Claus E. Andersen and Gustavo KertzscherCenter of Nuclear Technologies, Technical University of Denmark, Roskilde 4000, Denmark

Joanna E. Cygler Department of Physics, The Ottawa Hospital Cancer Centre, Ottawa, Ontario K1H 8L6, Canada

(Received 15 January 2013; revised 12 April 2013; accepted for publication 16 April 2013;published 25 June 2013)

In vivo dosimetry (IVD) has been used in brachytherapy (BT) for decades with a number of differentdetectors and measurement technologies. However, IVD in BT has been subject to certain difcultiesand complexities, in particular due to challenges of the high-gradient BT dose distribution and thelarge range of dose and dose rate. Due to these challenges, the sensitivity and specicity toward errordetection has been limited, and IVD has mainly been restricted to detection of gross errors. Giventhese factors, routine use of IVD is currently limited in many departments. Although the impact of

potential errors may be detrimental since treatments are typically administered in large fractions andwith high-gradient-dose-distributions, BT is usually delivered without independent verication of thetreatment delivery. This Vision 20/20 paper encourages improvements within BT safety by devel-opments of IVD into an effective method of independent treatment verication. 2013 American Association of Physicists in Medicine . [http://dx.doi.org/10.1118/1.4810943 ]

Key words: in vivo dosimetry, brachytherapy, treatment errors, quality assurance

I. INTRODUCTION

In vivo dosimetry (IVD) has been used in brachytherapy(BT) for decades and has been referred to in InternationalCommission on Radiation Units and Measurements (ICRU)recommendations. 1 The initial motivation for performingIVD in BT was mainly to assess doses to organs at risk (OAR)by direct measurements, because precise evaluation of OARdoses was difcult without 3D dose treatment planning. Withthe introduction of 3D image-guided BT, it is now possible tocalculate 3D tumor and OAR doses as well as dose volumehistogram (DVH) parameters by the treatment planning sys-tem (TPS). 24 Recording and reporting of dose based on 3Dimages is an important step forward. Current 3D image-baseddose calculations are often more accurate for assessments of OAR doses than IVD measurements. However, there are sit-uations with signicant dose calculation uncertainties, in par-

ticular for low-energy photon-emitting sources and in hetero-geneous media, where IVD may contribute to more precisedose reporting. 5 Furthermore, potential organ movement inbetween imaging and treatment contributes to uncertainties indelivered dose, and IVD may have a potential role for identi-cation of organ or applicator movements.

The complexity of BT has increased with the introductionof remote afterloading and 3D image-based dose planning.However, independent and patient specic quality assurance(QA) of dose delivery is not performed systematically, despitethe risk of errors during the many manual steps involved in

treatment planning and delivery. Furthermore, BT is typicallyadministered with large doses per fraction ( > 5 Gy), whichmeans that the consequence of a fractional error may be sub-stantial when compared to typical external-beam radiother-apy (EBRT) with delivery of smaller doses per fraction (e.g.,2 Gy). From this perspective, IVD is very relevant in BT asan independent method for detection of deviations or errors. 6

Unfortunately, the interest has suffered much from difcul-ties and uncertainties of dose measurement, in particular thechallenges of precise detector positioning in the high dosegradient elds. Error detection sensitivity and specicity of current systems has been compromised by such uncertainties,and therefore it seems that current IVD is only able to detectgross errors (Sec. IV.C ), which happen less frequently. Fur-thermore, there has been a lack of good infrastructure in termsof commercially available dosimetry systems with straightfor-ward procedures, which do not require extensive manpower

and expertise. Substantial progress is needed in dose measure-ment methodology and infrastructure in order to bring IVD toits full potential.

Whereas IVD in BT needs further development to becomewell integrated into routine clinical practice, the situation isdifferent in EBRT where IVD is more widely used and ac-cepted as an independent check of dose delivery. 7, 8 Confor-mal EBRT is characterized by at dose proles and homoge-neous dose in the target region. Therefore, conformal EBRTIVD for target dose verication has not suffered from the par-ticular challenge typical for BT, which is detector positioning

070902-1 Med. Phys. 40 (7), July 2013 2013 Am. Assoc. Phys. Med. 070902-10094-2405/2013/40(7)/070902/15/$30.00
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070902-2 Tanderup et al. : In vivo dosimetry in brachytherapy 070902-2

in high gradient elds. However, due to the heterogeneous u-ence proles and dose gradients, 9 IVD in IMRT and VMATfor dose assessments in OARs, for instance, would involvesome of the same challenges as are seen with BT. The energydependence of detectors is often more crucial in BT as com-pared to EBRT because of the lower photon energy appliedin BT. However, most small detectors that are used for IVDin EBRT, 7 are in principle also suitable in BT. TransmissionIVD based on, e.g., EPID has much potential for EBRT, 10 buthas not yet been much exploited for BT. In the accompanyingVision 20/20 paper, 11 the current and future justications of performing external beam IVD are discussed, and a compre-hensive review of detectors used for IVD is provided.

The purpose of the current Vision 20/20 paper is to discusscurrent and future justications of IVD for BT, and to iden-tify current challenges that need to be addressed in order toadvance the eld over the next decade.

II. JUSTIFICATION FOR IN VIVO DOSIMETRY

II.A. Errors and treatment variations in brachytherapy

There is currently no systematic overview of the type andfrequency of errors which occur in BT. Existing reports of BTaccidents and errors are mainly based on retrospective eventcollection since prospectively structured investigations havenot yet been performed on a multicenter scale. Furthermore,since current IVD systems suffer from unknown or poor sen-sitivity and/or specicity (see below), there are an unknownnumber of BT errors that remain undetected.

The International Commission on Radiological Protection(ICRP) Report Nos. 86 (Ref. 12) and 97 (Ref. 13) as well asIAEA safety report series 17 (Ref. 14) describe errors thathave occurred in BT. BT errors and accidents are mainly

related to human errors, although some errors are causedby mechanical events related to malfunction of the equip-ment. Examples of human errors are incorrect medical indi-cation, source strength, patient identication, diagnosis or siteof treatment, prescription, data entry, catheter, or applicator.High dose-rate (HDR) and pulsed dose-rate (PDR) afterload-ing techniques may introduce source positioning errors whichare related to procedures specic for afterloading dose plan-ning and treatment delivery. Source positioning errors mayalso occur in low dose-rate (LDR) manual loading proceduresdue to manual misplacement or source migration after theplacement.

Afterloading BT embraces a variety of approaches to treat-

ment planning, each involving specic error scenarios. Treat-ment planning can be performed without the use of a TPSby directly dening the target from x-ray image or clinicalndings and applying a standardized or manually optimizedtreatment plan. An example would be an esophagus treat-ment where the treatment length, source offset, step size, anddwell times may be directly dened on site in some clinicsand followed by a more or less manual entry of treatment pa-rameters into the afterloader control software. For this sce-nario, the risk of errors is mainly related to the denition andmanual entry of parameters. A number of manual steps are

avoided with 3D image-based treatment planning. However,other sources of potential errors are introduced in this pro-cedure. With 3D image-based dose planning, both target andsource catheters are dened with imaging modalities such asultrasound (US), magnetic resonance imaging (MRI), or com-puted tomography (CT). Mistakes or uncertainties in identi-cation of source catheters or denition of applicator lengthcan lead to source positioning errors. Dose optimization mayinvolve a high degree of dwell time modulation, which meansthat the consequence of source positioning errors can lead tosignicant errors throughout the volumetric dose distribution.The treatment plan is usually directly exported from the treat-ment planning system to the treatment control station (TCS)and the afterloader. The automatic transfer reduces the risk of incorrectly entered parameters, although there is still a risk that a wrong plan is exported or imported. After treatmentplan transfer, the afterloader is connected to the applicators;this process involves a risk of misconnection of the sourcetransfer guide tubes.

Organ or applicator movement in between imaging andtreatment represents a limitation on the accuracy of dose de-livery unless imaging is performed immediately before deliv-ery in a BT suite. For prostate BT, there have been reportsof needle movements, 15, 16 and for gynecological BT, organmovement has been seen as well as occasional relocation of the applicator. 17 IVD may be a tool for detection of such dis-placements and movements. However, direct inspection of theapplicator (e.g., measurement of free needle length in prostateBT) or reimaging directly before treatment delivery may be analternative way to validate that the dose delivery and doserecording are appropriate. 18 Neither the use of repeated imag-ing nor IVD has demonstrated wide practical application fordetection of organ and applicator movement. The conditionsunder which each of these may be practical and/or precise

enough for use in clinical practice still remain to be claried.Certain errors can be identied by the afterloader safetysystems which include builtin dummy check sources, a radi-ation detector, and source cable length control. 19 However,afterloader safety systems are only able to detect a subset of all possible errors that may occur. Additional manual safetychecks of the treatment planning and delivery procedure maybe introduced such as verication of applicator reconstruc-tion or source guide tube connection by a second observer.In addition, as documented in ICRP and IAEA reports, 1214

there are a number of errors that are not detected by safetysystems or manual checks. IVD has the potential to comple-ment other QA and quality control (QC) procedures, as part

of the greater process of quality management, by providingan independent overall verication of the treatment delivery(Table I).

II.B. Recording of dose in individual patients

The increasing use of image-guided BT has been a hugestep forward for the calculation and recording of tumor andOAR doses. In most cases, dose calculation is more accuratethan IVD, mainly due to the challenge of precise detector po-sitioning to measure the specic OAR or tumor doses (see,

Medical Physics, Vol. 40, No. 7, July 2013


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TABLE I. QA and detection of errors and variations occurring with afterloading BT.

Quality item Typical quality test Role of in vivo dosimetry

Source calibration Independent source calibration in the department Minor importance, but may in certain situationsreveal calibration errors (if the in vivo dosimetercalibration is independent from the actualsource).

Afterloader source positioning and dwell time(nonpatient specic)

Autoradiography, commissioning of applicators,other source stepping and dwell time QA

Minor importance, but may in certain situationsreveal errors which have not been identied with

standard nonpatient specic QA.Afterloader malfunc tion Unpredictable afterloader malfunction is

difcult to target with general QA.Major relevance, since afterloader malfunctionmay have signicant impact on dose, and IVDhas good potential to reveal such errors.

Patient identication Manual check Not relevantCorrect treatment plan Manual check Relevant since it may detect if a wrong plan is

used for treatment, if DICOM transports to theafterloader and dosimeter software areindependent.

Intra- and interfraction organ/applicatormovement

Reimaging performed just before treatmentdelivery can in some cases be used to assessorgan or tumor dose in image-guided BT.

The relevance depends on detector positioning.If the detector is xed to the applicator, it willnot reveal applicator movement, contrary tomeasurements in, e.g., urethra. For the organdose change detection, there are signicant

challenges to position the detector precisely(reimaging may be preferred).

Applicator reconstruction and fusion errors Manual check Relevant. Can detect applicator reconstructionerrors when the dosimeter is placed in anoptimal geometry.

Applicator length/source-indexer length Manual check Major relevance, since source-indexer lengtherrors may have signicant impact on dose, andreal time IVD has good potential to reveal sucherrors.

Source step size (patient specic) Manual check Major relevance if source step size is enteredmanually. Otherwise the appropriate method tocheck source stepping is part of nonpatientspecic QA.

Interchanged guide tubes Manual check Major relevance, since interchanged guide tubes

may have signicant impact on dose, and IVDhas good potential to reveal such errors.

Recording of dose General QA related to dose calculation in theTPS

Relevant when dose recording is not calculatedwith sufcient accuracy by 3D image based TPScalculation (e.g., lack of inhomogeneity orradiation scatter corrections).

e.g., Sec. IV.C ). However, for certain clinical situations TPSbased dose calculations are currently associated with system-atic deviations due to lack of corrections for heterogeneitiesand scatter conditions. 20 This is particularly true for low en-

ergy sources such as 125

I or 103

Pd used in permanent implantsof prostate, lung, and recently breast. 2123

Some dosimetry systems dene specic points or volumesfor dose reporting for individual patients such as the ParisSystem for interstitial implants; 24 ICRU 38, 1 GEC EuropeanSociety for Radiotherapy and Oncology (ESTRO), 2 and ABSfor cervix BT; 25, 26 as well as ABS (Ref. 27) and GEC ESTRO(Refs. 28 and 29) for prostate implants. This kind of report-ing is important in treatment outcome assessments. However,the reporting is mostly based on treatment planning identi-cation of such points/volumes. In the situation where the

tumor and OARs move and/or get deformed, as is the caseduring permanent prostate implants, IVD can provide ad-ditional information about the dose delivered to the tumorand/or OAR for the given patient. In particular, for LDR and

PDR treatments that involve long irradiation times, there maybe anatomical changes such as prostate swelling, applicatormovement, and organ movement, and IVD may be used tomonitor the treatment progression. There have been studiesof the point or segment dose measurements in rectum or ure-thra for gynecological 30, 31 or prostate implants 3234 or in thetumor. 35, 36 Some results conrm the agreement between thecalculated and delivered doses, while others point to discrep-ancies between them. The reasons for these disagreementsare not always clear and underscore the technical difcultiesfaced by IVD in BT.



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III. CURRENT CLINICAL PRACTICE

Typical sites for IVD are rectum, 3740 and bladder orurethra. 32, 33, 41 Noninvasive detector positioning far from thesource, e.g., on the skin, make the measurements insensitiveto error detection because of low signal and difculties toknow precisely the relation between the source(s) and detec-tor(s). IVD on skin is of relevance during the treatment of breast cancer 4244 since the skin is an OAR close to the treated

volume and has signicant dose calculation uncertainties.45

The practice of using IVD varies considerably amongcountries. In most countries, systematic use of IVD is not of-ten incorporated as a standard QA or QC procedure. How-ever, there is specic legislation in a number of countriesmaking IVD obligatory. For example, France recently intro-duced a law that requires some form of IVD be performed onall EBRT patients. 46 Unfortunately, there are no reports avail-able about the value and benet of routine BT IVD in thesecountries. In patterns-of-care studies from Europe and LatinAmerica, it has been difcult to collect responses that homo-geneously represent all countries. 47, 48 However, it seems thatIVD is available in many institutions because it is reported

to be used by 20%33% of the centers. 4749 However, it isnot further described how often, in which disease sites, or inhow many patients. A recent survey by Sawakuchi et al. 103

on Canadian cancer clinics showed that most of the clinicsperform some form of IVD for special EBRT techniques.However, no IVD is performed routinely for BT treatmentsin Canada. A Japanese patterns-of-care study of cervix can-cer reports that rectal and bladder IVD was used in 27% and3% of the BT patients, respectively. 50 IVD was carried out in1.2% U.S. centers that performed vaginal BT in endometrialcancer patients. 51 From available literature and institutionalreports, it seems that IVD most often appears as diode rectaldosimetry performed during intracavitary BT in gynecolog-ical cancer. There are a number of groups reporting institu-tional use of IVD in prostate cancer, but there are no generalreviews or reports that indicate this technique is commonlyused, or what was the observed error rate.

IV. CHALLENGES SPECIFIC TO IN VIVO DOSIMETRY IN BRACHYTHERAPY

IV.A. High dose gradients and detector positioning

The BT dose distributions are characterized by steep dosegradients that depend strongly on the distance from the detec-

tor to the source. At a distance of 4 mm from a linear source,the dose gradient is approximately 50%/mm. The gradient de-creases to around 6%/mm and 5%/mm at distances of 20 and35 mm, respectively. Therefore, even small uncertainties indetector positioning may lead to signicant uncertainties indose measurements. The ability of IVD to detect errors de-pends critically on where the detectors can be placed and howwell these detector positions are known. The optimal regionfor detector placement balances the favorable signal-to-noiseratio (SNR) with the smallest possible impact of positionaluncertainties. 35, 36 This optimal region is different and specic

for each detector and patient category due to differences inpositional uncertainties of the detector as well as sensitivity,energy dependence, and angular dependence of the detectorresponse.

The steep dose gradient induces additional challengeswhen IVD is used for individual measurement of organ dose.The dosimeter needs to be positioned in a clinically relevantregion, and for the bladder and rectum, it is a major difcultyto establish a stable dosimeter position directly adjacent tothe most exposed part of the organ wall. 52 The anatomy of the urethra is more favorable for performing accurate IVD inprostate BT since this organ is smaller and less deformable.Several challenges regarding optimal dosimeter positioningcould be solved with dedicated clinical components, e.g., ure-thral catheters and rectal or bladder balloons, that would bothstabilize and offer accessibility at desired dosimetry sites (seeSec. VI.A ).

Ease of positioning as well as good detector stability canbe obtained by insertion of extra invasive catheters or needles.However, the potential use of such invasive procedures raisesethical issues because of accompanying risks for the patientsuch as infection. The extra procedure must be of clear ben-et to the patient and since IVD still has to demonstrate thatit adds signicant improvement in terms of safety and qual-ity there is currently reluctance among clinicians to introduceextra invasive procedures.

IV.B. Energy dependence of detectors

Another major challenge for IVD in BT is the energy de-pendence (relative absorber dose sensitivity) (Ref. 53) of ex-isting detectors in the intermediate-to-the-low energy range of the photon or gamma energy spectra that are commonly en-

countered (60

Co, 137

Cs down to 103

Pd) covering>

1 to 50%.In order to avoid false alarms, current error decision cri-

teria are usually high, which means that the error detectionsensitivity is low. Currently, at error criteria are mainly usedin clinical practice. However, a at criterion of, e.g., 10% mayresult in false alarms when the detector is close to the source,where positional uncertainties of the detector lead to dose un-certainties larger than 10%. 36 On the other hand, 10% maybe too large for treatment error detection at larger source-detector distances where the inuence of positional uncertain-ties is less. 36

V. DETECTORS: STATE OF THE ARTMany dose-measurement systems have been used in BT

in spite of the practical challenges encountered or the

F IG . 1. Rectal IVD in PDR 192 Ir cervix cancer BT with tandem ring applicator for BT fractions 1 (BT1) and 2 (BT2). Dashed lines indicate bounds of the 95%prediction interval.



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TABLE II I. Characteristics of detectors and dosimetry systems of importance for precise routine IVD in brachytherapy. The items are rated according to:advantageous ( ++ ), good ( + ), and inconvenient ( ).

TLD Diode MOSFET Alanine RL PSD

Size + + / + / ++ ++ ++Sensitivity + ++ + ++ + / ++Energy dependence + + ++Angular dependence ++ + + ++ ++Dynamic range ++ ++ + ++ ++

Calibrationprocedures, QA,stability, robustness,size of system, easeof operation

+ ++ ++ / + + / ++

Commercialavailability

++ ++ ++ ++ +

Online dosimetry ++ + ++ ++Main advantages No cables, well

studied systemCommercialsystems atreasonable price,well studied system

Small size,commercial systemat reasonable price

Limited energydependence, nocables

Small size, highsensitivity

Small size, noangular and energydependence,sensitivity

Main disadvantages Tedious proceduresfor calibration and

readout, not onlinedosimetry

Angular and energydependence

Limited life of detectors, energy

dependence

Not sensitive to lowdoses, tedious

procedures forcalibration andreadout, not onlinedosimetry,expensive readoutequipment notavailable in clinics

Needs frequentrecalibration, stem

effect, notcommerciallyavailable

Stem effect

shortcomings in their physical properties such as en-ergy response, signal noise ratio, signal stability, read-out precision, and positional accuracy. 54 In principle, de-tectors that are commonly used for the EBRT absorbed

dose measurements may be good candidates for appli-cation for IVD for BT. Few studies have been con-ducted in the past to compare the performance of thesedetectors for both high dose BT and EBRT. 5860 Ther-moluminescent dosimeters (TLD), 32, 42, 6163 semiconductordiodes, 30, 64 metal-oxide-semiconductor eld-effect transis-tors (MOSFET), 33, 34, 65 radioluminescence (RL) and opticallystimulated luminescence (OSL) detectors, 66 plastic scintil-lation detectors (PSD), 41, 6770 alanine detectors, 39, 71 radio-photoluminescent glass dosimeters (RPLGD) (Refs. 55, 56,and 72) have been used for IVD in BT to measure dosesover an assortment of disease sites. The characteristics andthe operation of these detectors are briey described below,

and have also been presented and discussed in the accompa-nying Vision 20/20 paper for EBRT, 11 in review papers, 73 aswell as in textbooks. 74, 75

There is no ideal detector for all BT measurements be-cause of the severe requirements needed and demands ex-pected of the dosimeters. All currently used detectors exhibitvarying degrees of artifacts such as volume-averaging, self-attenuation, response angular anisotropy, energy dependence,and a nonlinear dose response. Therefore, BT detector se-lection is crucial and is dictated by the radioactive source inquestion, the spatial locations of the measurement points with

respect to the source, practical insertion(s) of the detectors,and the disease site. Only detector designs that can be easilyinserted within either intraluminal catheters or special appli-cators inserted into patients should be considered. Table III

presents an overview of characteristics of the most relevantdetectors for IVD in BT and an evaluation of their advantagesand disadvantages.

V.A. TLDs and RPLGDs

TLDs have been used for HDR 192Ir BT to measure thedose to the urethra and/or rectum during prostate treatments(2428). TLDs come in a variety of materials and forms andcan be shaped to easily t into various areas of interest. Thelithium uoride (LiF) TLD rods are the most widely usedform, because they can be easily inserted into catheters. How-ever, they require special preparation (annealing, individual

calibration, careful handling, fading correction, etc.) and donot provide a direct reading right after the treatment. Thecombination of these properties places them into a secondarychoice compared to other dosimetry systems that are capableof providing reading in real time.

RPLGDs have a similar reading process to TLDs, exceptultraviolet light (and not heat) is used to stimulate the detec-tor. Irradiation of the silver-activated phosphate glass convertssilver ions to stable luminescent centers; when exposed to ul-traviolet light, the luminescent centers produce uorescencein proportion to the absorbed radiation dose. These detectors



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have been used for IVD (4244) by Nose et al. 55, 56 forHDR interstitial BT for head-and-neck cancer (61 patients)and pelvic malignancies (66 patients). In the case of the pelvicpatients, the RPLGDs were sutured to the anterior wall of therectum or positioned inside a Foley catheter inside the ure-thra. Deviations greater than 20% were found between themeasured and calculated doses and were attributed to the in-dependent movement of the organs and applicators betweenthe planning and treatment delivery times.

V.B. Semiconductor diodes

Diodes are another type of semiconductor solid-statedosimeters, typically based on silicon. They are mostly usedfor EBRT but have been also employed for in vivo verica-tion of BT plans. They have the advantage of providing userswith an immediate readout, high sensitivity, good mechan-ical stability, fairly small size. Unfortunately, they are alsoknown for the undesirable dosimetric characteristics whichinclude directional dependence, energy dependence, temper-ature dependence, and changes in sensitivity due to radiationdamage. As these characteristics affect the accuracy of thedosimetry system, they must be thoroughly characterized inphantom before clinical use for the specic radiation sourceor application. 57, 76

Waldhusl et al. 64 and Seymour et al. 57 both used exiblediode array manufactured by PTW for IVD for patients un-dergoing HDR 192Ir treatments. Waldhusl et al. 64 evaluatedsuitability of rectal probes consisting of ve diodes (separatedby 15 mm) and bladder probes consisting of a single diode forIVD of cervix cancer patients. Their measurements resulted indifferences between calculated and measured doses rangingfrom 31% to + 90% (mean 11%) for the rectum and from 27% to + 26% (mean 4%) for the bladder. They also re-

ported that shifts in probe position of 2.5 mm for the rectalprobe and 3.5 mm for the bladder probe caused dose differ-ences exceeding 10%. Seymour et al. 57 performed a dosimet-ric evaluation of the ve diode array in the routine verica-tion of planned dose inside the rectum for prostate (HDR) BTusing a real-time planning system. The deviations betweenthe diode measurements and the TPS predicted values rangedfrom 42% to + 35% (with 71% of the measurements within10% of the predicted values). Waldhusl et al. 64 and Sey-mour et al. 57 estimated that the overall uncertainty involved inphantom dose measurement, after correcting for all the factorsaffecting diode response were 7% (SD) and 10% (SD),respectively.

V.C. MOSFET detectors

MOSFETs are miniature n- or p-type silicon (Si) semicon-ductors. For dosimetry, mostly p-type detectors are used. Ingeneral, MOSFETs as all semiconductors, exhibit tempera-ture dependence. However, this effect has been overcome byspecially designed dual-MOSFET-dual bias detectors 77 pro-duced by Best Medical Canada. These detectors can be pro-duced either in standard size, or as micro-MOSFETs. The lat-ter ones are particularly suitable for BT due to their small

size (8 2.5 1.3 and 0.2 0.2 5 10 4 mm 3 for ex-ternal and sensitive volume dimensions, respectively). Theyare also available in the form of an array of ve detectors.Micro-MOSFETs have almost isotropic response to radiation.Unlike single dual-MOSFET-dual bias detectors, MOSFETarrays have some temperature dependence (the temperaturecoefcient = 0.6%/ C). 34 Most published studies on IVD inBT involve detectors and dosimetry system from Best Med-ical Canada. Another MOSFET dosimetry system used inBT comes from the Centre for Medical Radiation Physics(CMRP), University of Wollongong. 78 It was found that theirresponse degrades with exposure to radiation and varies withdistance from a source due to its dose rate and energy depen-dence. MOSFET system from CMRP is not yet available inthe market.

The two main disadvantages of MOSFETs for BT mea-surements are: (1) they are not tissue equivalent, which makestheir dose response vary with radiation quality and (2) theyhave a rather limited lifetime. One of their main practicalitieslies in their small size allowing their insertion inside intra-luminal catheters or even needles and the possibility of hav-ing multiple MOSFET sensors along one single line. Recentcoupling of a MOSFET detector with a sensor capable of de-tecting the position of the MOSFET in 3D (RADPOS), hasrenewed interest in their use.

MOSFETs have been used to characterize the HDR 192IrLeipzig surface applicators and found to agree with lms andMonte Carlo calculations within 3%. 79

Cygler et al. 33 performed in 2006 a feasibility study usingmicro-MOSFETS (external dimensions: 1 mm diameter by0.5 mm thickness) during permanent low-dose rate prostateimplants as a tool for in vivo measurement of the initial doserate within the urethra and as a mean to help evaluate the over-all quality of the implant. In this study, IVD in the urethra was

carried out by moving the MOSFET detector along the ure-thra in 1 cm steps. The estimated uncertainty of the MOSFETposition was within 1 mm. The detector was left at each po-sition to accumulate dose for 10 min, long enough to providea reasonable measurement signal.

Bloemen-van Gurp et al. 34, 80 performed two studies in2009 using a linear MOSFET array during permanent prostateimplant. The overall uncertainty in the measurement proce-dure, determined in a simulation experiment, was 8.0% andan action level of 16% (2 SD) for detection of errors in theimplantation procedure is achievable after validation of thedetector system and measurement conditions. In their secondstudy, they reported on a technique to monitor the dose rate in

the urethra and performed IVD in ve patients during and af-ter implantation of 125I seeds. They concluded that IVD withMOSFET array during the procedure is a feasible techniqueto evaluate the dose in the urethra for permanent prostateBT. This study showed the challenges of performing IVD inBT and the extensive analysis needed to reach a meaningfulconclusion.

Cherpak et al. 81 performed real-time measurements of ure-thral dose and position using a RADPOS Array (Best Medi-cal Canada) during permanent seed implantation for prostateBT. RADPOS Array is a modied RADPOS detector. 82



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Cherpak et al. 81 performed measurements on 17 patients andconcluded that the modied RADPOS detector with MOS-FET array instead of a single MOSFET is able to provide ac-curate real-time dose information which can be used to moni-tor dose rates while implantation is performed and to estimatetotal integrated dose. Reniers et al. 83 in 2012, in a feasibilitystudy on a phantom, have studied the utility of using a RAD-POS system for IVD for gynecological BT. They reported thatthe RADPOS sensor, if placed, for example, in the bladderFoley balloon, would detect a 2 mm motion of the bladder, ata 5% chance of a false positive, with an action level limit of 9% of the dose delivered. The authors also found that sourceposition errors caused by, e.g., a wrong rst dwell position,are more difcult to detect. With a single RADPOS detectorpositioned in the bladder, dwell position errors below 5 mmand resulting in a dose error within 10% could be detected inthe tandem but not in the colpostats.

V.D. Alanine

L- -alanine is a nonessential amino acid that has beenused for electron paramagnetic resonance (EPR) dosimetryin radiation therapy. Alanine can exist in a form of a whitepowder or can be formed in the shape of rods, pellets, lms,etc. 84 During irradiation of alanine, permanent free radicalsare formed. The concentration of these radicals is proportionalto absorbed dose and can be measured by EPR spectroscopy.So alanine is a chemical dosimeter, since dose measurementis based on detection of chemical species formed during irra-diation. Alanine has some important advantages as a dosime-ter. Its response is almost independent of radiation energy anddose rate. It can be formed into small shapes and requires nobias or wiring. The readout of the radical concentration is non-destructive and has very little fading with time.

Unfortunately, it also has disadvantages that limit its use-fulness in clinical dosimetry. The main disadvantage is a re-quirement of expensive EPR equipment not easily availablein clinics. Alanine does not provide an immediate readout of the dose and it is generally insensitive to doses < 2 Gy. It alsohas some temperature and humidity dependence. In spite of these limitations, some feasibility studies were conducted toevaluate its usefulness in BT. Apart from the phantom stud-ies aimed mostly at the characterization of the radioactivesources, 8587 few reports exist on using alanine for IVD of gynecological treatments. 39, 88 Alanine is commercially avail-able, but the tedious readout procedure needs to be establishedindividually in each department. At present, use of alanine in

the clinics is very limited due to the readout equipment beingvery expensive and it is hard to foresee that this will changein the near future.

V.E. RL and OSL detectors

Recent advances in optically stimulated luminescencedosimeters (OSLDs) have opened new possibilities for theirapplication in radiation therapy. 89, 90 OSLDs are gradually re-placing TLDs as personal radiation monitoring dosimeters forindustry and public health workers because of their instanta-

neous reading capabilities, faster processing, and the abilityto store their reading without much degradation of the opticalsignal (permanent record). To operate in the OSL mode, thecrystals need an external stimulation (laser or diode) to extractthe reading postirradiation. The same crystal can also operatein the RL mode providing the information about the dose rateduring the irradiation, thus, serving as a true real-time onlinedetector. Al 2O3 :C can be formed as crystals with diameter< 1 mm which can t inside BT catheters. Even though thesensitive detecting material of these detectors (Al 2O3 :C) isnot water-equivalent, they have good potential for IVD in BTdue to their ability to provide feedback in real time.

RL systems for online dose measurements are not avail-able. However, a prototype system developed by Andersenet al. 66 in 2009 was investigated to facilitate the preventionand identication of dose delivery errors in remote afterload-ing BT. The system consists of a small Al 2O3 :C crystal cou-pled with the optical ber which carries the light signal gen-erated in the crystal to the detection system. The system iscapable to operate either in the RL or OSL mode. The sys-tem allows for automatic online IVD directly in the tumor re-gion using small detector probes that t into applicators suchas standard needles or catheters. In the RL mode, the sys-tem is capable of measuring the absorbed dose rate (with a0.1 s time resolution) and in the OSL modethe total ab-sorbed dose. The calibrated system was found to be linearin the tested dose range. The reproducibility for the RL/OSLmeasurements was found to be 1.3% (SD). Under certain con-ditions, the RL signal could be greatly disturbed by the so-called stem signal (i.e., unwanted light generated in the bercable upon irradiation). 91 When taking into account the ef-fect of reproducibility, energy response, angular dependence,stem effect, instrument and crystal temperature, light guidetransmission on the reading, and the calibration uncertainty,

the combined estimated uncertainty budget was found to be8% (SD) and 5% (SD) for RL and OSL, respectively. Thisinitial study was followed up with a clinical protocol study onve cervix cancer patients undergoing PDR BT. 35 For threeof the patients, the authors found no signicant differences( p > 0.01) between IVD and TPS calculated reference values(TG 43) at the level of dose per dwell position, dose per appli-cator, or total dose per pulse. For the two other patients, theynoted signicant deviations for three individual pulses and forone dosimeter probe. These differences could have been dueto applicator movement during the treatment and/or an incor-rectly positioned probe, respectively.

Kertzscher et al. 36 in 2011 tested the ability of a RL sys-

tem to identify afterloading PDR and HDR gynecological andprostate BT errors in real time using a novel statistical er-ror decision criterion. Their phantom studies showed that outof 20 interchanged guide tube errors, time-resolved analysisidentied 17 while accumulated dose identied only two. Ac-cumulated dose comparisons could leave 10 mm dosimeterdisplacement errors unidentied and while dose rate compar-isons correctly identied displacements 5 mm. This phan-tom study demonstrated that Al 2O3:C real-time dosimetry hasthe potential to detect interchanged guide tube errors duringPDR and HDR BT and has the ability to identify applicator



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displacements 5 mm. Another important aspect of this studywas to highlight the shortcoming of using a constant error cri-terion and instead to recommend using a statistical error cri-terion.

V.F. Plastic scintillation detectors

Plastic scintillation detectors are a promising option forIVD. PSDs are composed of organic scintillation material(scintillator or scintillating optical ber) that emits light pro-portionally to the dose deposited in their detector volume. Thelight produced in the detector is usually optically coupled toa ber-optic light guide and transmitted toward a photodetec-tor. The properties of plastic scintillation detectors have beenstudied for high-energy external beams. 67, 92 High spatial res-olution, linearity with dose, energy independence in the mega-voltage energy range, and water equivalence are among theadvantages that have been demonstrated for such detectors.Cerenkov light production has also been identied in the op-tical guide. 67, 92, 93 This light component, often referred to asstem effect, is produced in the ber when struck by radiationover a certain energy threshold, which depends on ber mate-rial, and needs to be removed to perform accurate dosimetry.Different methods have been proposed to efciently accountfor this spurious effect. 94, 95 Using these detectors, possibil-ity of real-time IVD has been demonstrated under externalbeam radiation 96 and accuracy of better than 1% has beenachieved. New evidence pointing to possible temperature de-pendence has recently been reported as a characteristic beingexhibited by plastic scintillation detectors. 97 An average of a0.6% decrease in measured dose/ C relative to dose measuredat room temperature was observed in the range of 1550 C.At the present time, it is not clear if this thermal dependencecomes from the construction of the materials used in the de-

sign, the composition of the organic scintillator itself, or iscoming from the optical train. Since the exact mechanism isnot well understood, this early communication concluded thatfurther research is warranted.

PSDs have the capability to perform accurate online IVDduring HDR 192Ir BT, 58, 68, 69 because they could be cut andshaped in size that can be easily inserted into catheters orarranged around applicators that are commonly used in BT.Lambert et al. 58 performed a comparative phantom study of PSDs to other commercially available detectors (MOSFET,diamond detector, and TLD). Based on size, accuracy, andreal-time possibilities, the authors claimed that PSDs showedthe best combination of characteristics to perform dosimetry

during HDR 192 Ir BT. Because the energy emission spectrumofan 192 Ir radiation source is mainly higher than the Cerenkovproduction threshold energy, the need for a stem removal tech-nique has been stressed for clinically relevant situations. 68 Astudy using a prostate phantom was performed by Therriault-Proulx et al. 69 The authors used a redgreenblue (RGB) pho-todiode as the photodetection component, allowing for the re-moval of the Cerenkov component through the polychromaticapproach. Thirteen catheters were implanted in the phantom:12 for dose delivery and one for the PSD. The PSD dose rateswere measured in real-time during the treatment delivery us-

ing a HDR 192Ir source. The average accumulated dose mea-sured at the PSD location for ve consecutive treatment deliv-eries was 275 14 cGy, in good agreement with the expecteddose of 275 cGy as calculated by the treatment planning sys-tem. Another phantom study using an array of 16 PSDs inan insertable applicator that enables quality assurance of thetreatment delivery and provides an alert to potential radiationaccidents during HDR BT treatments has been performed byCartwright et al. 70 The systempresented is capable of measur-ing doses in a phantom for 1 s exposures with an uncertaintybetween 2% and 3% for most of the PSDs.

Suchowerska et al. 41 described a plastic scintillator systemconsisting of a 0.5 mm diameter by 4 mm length BC400 scin-tillator optically coupled to a 0.48 mm core PMMA opticalber to transmit the signal. They have used a PTW-FreiburgOPTIDOS Reader to read the signal produced by their scin-tillator detector. 41 The OPTIDOS reader, consisting of a pho-tomultiplier and an electrometer unit, was originally designedto measure the dose rate of 90Sr/ 90 Y beta emitting sources aswell as for 32 P intravascular BT using different plastic scintil-lator detectors designed and manufactured by PTW-Freiburg.Note that the PTW-Freiburg scintillation detectors and OPTI-DOS reader system are no longer commercially available. Theclinical feasibility of this study examined urethral dose mea-surements in 24 patients during HDR prostate BT. The authorsof this study did not report any temperature dependence fortheir measurement performed inside the urethra nor any stemeffect when using these PSDs. After the rst 14 patients, im-provements to the dosimeter systemdesign were implementedthat increased positional accuracy and system reliability, withthe maximum dose departure from the calculated dose beingwithin 9% for all of the ten remaining patients and concludedthat dose to the urethra could be accurately measured usingthe improved system.

At the present time there are no PSDs or PSD systemsthat are commercially available for use for in vivo dosime-try for BT. The only PSD system available commercially isthe EXRADIN W1 Scintillator manufactured by StandardImaging which was designed for external beam radiother-apy and more specically for the characterization of smalleld dosimetry ( http://www.standardimaging.com/product_home.php?id=124 ).

VI. DIRECTIONS FOR THE FUTURE

VI.A. Detectors and technology

Most of the development efforts for IVD systems havebeen focused to the front end of the detection system: the de-tector element(s) or the sensitive material and their dosimetriccharacteristics to correct for the effects inuencing their re-sponse. Future developments would have to be focused on theback end of the detection system utilized to process the data(i.e., the readings of the detector) to make the next generationIVD systems user friendly with automatic data display, re-quiring less manpower, with no postdata analysis or specialexpertise needed. Furthermore, in order to be successful forwidespread use, any new technological innovation for such

http://www.standardimaging.com/product_home.php?id=124http://www.standardimaging.com/product_home.php?id=124http://www.standardimaging.com/product_home.php?id=124http://www.standardimaging.com/product_home.php?id=124


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systems will have to be well integrated into the routine clini-cal application being targeted.

Given existing alternatives for accurate BT dosimeters, fu-ture requirements will likely be made on IVD systems that canmonitor the dose in real time, are sensitive to displacementsof all applicators involved in the treatment, can identify organmotion, and that can provide immediate alerts of any potentialgross error during ongoing treatments. Passive detectors, suchas TLDs, OSLDs (when used in the passive mode), RPLDs,alanine, radiographic and radiochromic lms, gels, are not ca-pable of monitoring the time-resolved treatment delivery. Afew studies have introduced the possibility of using the instan-taneous dose rate for patient QC checks. 31, 35, 36 These stud-ies indicate that time-resolved dosimetry has potential to bemore sensitive to error detection than dose verication basedon integral dose. Therefore, future research will probably fo-cus on further developing systems that would have the abil-ity to sample the dose rate in real time while the radiationtreatment is being delivered to the patient. Currently, goodcandidates for real-time IVD are RL, 35, 36 PSDs, 69 and MOS-FETs. These detectors are capable of sampling or measuringthe dose rate which could be useful for certain applicationsfor which thresholds in dose deviations could be set and/orupper and lower limits for dose values to prevent gross errorsand potentially alert the users whether the treatment shouldor should not be terminated. Although semiconductor diodesprovide an immediate readout, they are not good candidatesfor real-time IVD due to their many undesirable dosimetriccharacteristics (see Table I).

Recently, it has been shown that it is possible to developdetectors composed of multiple different color PSDs (mPSD)using a single optical transmission line and capable of mea-suring the dose accurately (Fig. 2).98 Detectors of this typecould be used for LDR or HDR interstitial BT applications.

Additional carrier catheters could be sutured within thevicinity of the implant or nearby a critical structure to monitorthe dose from the planned implant. The carrier catheters arenot part of the implant but additional intraluminal cathetersfor the sole purpose to accommodate the detectors. The read-ings consist of the light spectrum emitted by each color PSD.The extraction of each corresponding color from the totalspectrum measured will provide the dose deposited at corre-sponding color PSD. This type of detector has the advantageof simultaneous dose rate measurements in multiple pointswith the potential to improve error detection capabilities.

F IG . 2. mPSD line detector inserted into a exible catheter.

F IG . 3. An example of integrating a detector to a rectal balloon. In this case,a 0.5 mm diameter by 1.0 mm long plastic scintillating ber coupled to aclear transmitting ber-optic and an inatable rectal balloon (upper left) werefully integrated into an inatable rectal balloon with the detector permanentlymoulded to it (upper right). Another example illustrating integrating a com-bination of line detectors and point detectors integrated to an applicator isshown below. A semicylindrical cut of the rectal balloon surface onto which,in this case scintillating line and point probes are attached for detection of dose along the rectal wall. The individual line and point probes slide intocapillary tubes permanently attached to the balloon surface.

Stable and clinically relevant detector positioning remainsone of the most important and critical issues for IVD. Inser-tion of additional detector catheters may be performed with

the purpose of optimizing detector positioning, e.g., by in-serting an additional interstitial needle for housing a dosime-ter probe in the tumor region. A smaller invasive impact maybe achieved by inserting a sterilized dosimeter in the urethralcatheter for urethral dose measurements. However, such in-vasive procedures raise ethical issues as discussed in Sec.IV.A . Another option is to mould detectors within an appli-cator (see example in Fig. 3), which has advantages such asxing the sensitive volume within the geometry of the appli-cator and therefore reducing the positional uncertainty of thedetector. The applicator could potentially be designed to con-strain movements of OARs and/or the target region. Similarmeasures could be achieved with a urethral catheter with a

closed-end lumen dedicated for housing a dosimeter probe inthe urethra or along the bladder wall.

Improved integration between afterloader and dosimetrysystem is warranted. The Bebig Multisource afterloader (byEckert & Ziegler Bebig GmbH, Berlin, Germany) offers in-tegrated diode IVD where the dosimetry system can be op-erated from the control unit. It permits the specication of dose limits and the display of rectum and bladder doses.A further step forward for integration would be automatedDICOM import to the dosimeter software and signal commu-nication between the dosimeter software and the afterloader.



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The communication would help synchronize the dosimeterreadout with the onset of the treatment, hence, optimize thecomparison between the delivered treatment with the time andsource coordinates from the imported DICOM RT plan. An-other attractive solution for future IVD in BT is the integra-tion of one or several dosimeter probes into the afterloadingmachinery. Such an afterloader could offer motorized feedingof dosimeter probes into BT catheters already inserted intothe patient but unoccupied by the source. Positioning technol-ogy attached onto both the source wire and dosimeter probecould both minimize their positional uncertainties and opti-mize the relative source-to-dosimeter distances. In vivo de-tector positioning directly inside the source catheters, e.g.,needles and intracavitary tubes, would in principle alreadybe possible with sufciently small dosimeter probes as theRADPOS, MOSFETs and ber-coupled scintillator, and RLprobes.

Recently developed RADPOS system 82, 99, 100 allows for si-multaneous measurement of dose and position. This detectoris particularly suited for BT applications and is being exploredto study not only its sensitivity for error detection during HDRtreatments 81 but also for applicator movement during vaginalcylinder treatments and prostate movement during permanentprostate implants. 81 RADPOS is capable of detecting prostatemovement during each needle insertion, as well as the changein the urethral dose after the removal of the ultrasound probefrom the rectum. 81 Since the RADPOS probe is visible on x-ray images, it allows to link the coordinates of the point of measurement before and during the treatment.

VI.B. Error detection criteria

A signicant challenge of future IVD is to dene relevanterror/decision criteria which take into account that both sen-

sitivity and specicity of treatment error detection is soundand robust in a clinical setting. More advanced error deci-sion criteria could involve a statistical approach where thecomparison between calculated and measured doses takesinto account the uncertainty components for both calculatedand measured doses. The calculated dose is based on assess-ment of both source and detector positions as they are iden-tied, e.g., in 3D images (US, CT, or MRI) during treat-ment planning. The identication of both source and detectorposition is correlated with specic reconstruction uncertain-ties. The inuence of positional uncertainties on the calcu-lated dose may be quantied by simulation which incorpo-rates the source/detector geometry as known from the TPS

and an assumption of a certain distribution of positioningerrors. 35, 36 Furthermore, dose calculation is correlated withuncertainties due to the shortcomings of dose calculation al-gorithms imposed, e.g., by inhomogeneities and scatter con-ditions. The uncertainty on the measured dose has a numberof components which are related to the detector characteris-tics. Based on comparison between calculated and measureddoses, the measurement should be categorized into Alarmor No alarm. A certain action level should be dened bybalancing between sensitivity and false alarms (Table II). Theaction level can be based on a statistical evaluation of the

incidence of a type 1 error (false alarm), e.g., p = 0.05 or p = 0.01 which means that 5% or 1% of all correct treatmentswill induce a false alarm, respectively.

The accuracy of the Alarm classication depends on themagnitude of components in the entire uncertainty budget andas such can be optimized by reducing uncertainties. These fac-tors relate to the dosimeter technology, e.g., calibration accu-racy and energy dependence, and to clinical procedures, e.g.,image reconstruction and patient-DICOM matching. An op-timized dosimetry integration into the entire BT workowwould reduce the incidence of false alarms (type I errors)and/or decrease the failure to detect treatment errors (typeII errors). This would improve treatment error detection andminimize the risk of making erroneous decisions regardingunnecessary treatment interruptions or termination.

An interesting strategy for further improvement of errordecision criteria could be development of a gamma analysisfor IVD according to the principles which have been usedin EBRT for comparison of measured and expected doses,e.g., with EPID dosimetry. 101 With a gamma analysis an er-ror criterion would be based not only on a dose difference butcould also combine it with a distance-to-agreement criterion.In such an analysis, the upfront knowledge of the geometri-cal uncertainties of the detector and source positioning couldbe incorporated into the model in order to decide on relevantdistance-to-agreement criteria.

VI.C. Clinical operation, infrastructure, and workow

Patient involvement should be considered so that the pa-tient is as comfortable as possible and not stressed by ad-ditional procedures if possible. Current rectal diode systemsand/or additional catheter insertion into the urethra/bladderinvolve some patient discomfort. Reduction of detector size

may contribute to improved patient acceptance. Optimally,the use of BT source catheters for in vivo detectors, as dis-cussed in Sec. VI.A , would not require any extra insertion of catheters, and could potentially make the in vivo system com-pletely invisible for the patient.

A major barrier for routine implementation of IVD is theadded workload for the personnel. Developments of new sys-tems should involve considerations of time consumption, clin-ical robustness, and ease of use. The Quality ManagementProgram should be optimized in order to limit the time con-sumption for the personnel. The measurements should be pre-sented and visualized to the user in such a way that the evalu-ation and interpretation of the results is as straightforward as

possible and so that a clear action can be taken from the mea-surements. The IVD system should also not distract personnelfrom other important tasks related to treatment planning anddose delivery.

An example of a general dosimetry integration into an im-age guided BT workow is shown in the right pane of Fig. 4.Some potential sources of errors generated during such treat-ment procedures are specied in the left pane, where thosedetectable with IVD are highlighted.

An optimal dosimetry integration would involve sourceapplicators with integrated dosimeter housing, which would



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Infrastructure: Is online dosimetry exploited? Is auto-matic analysis of data incorporated?

Detector position: Is the positional accuracy of the de-tector addressed and optimized?

Error decision criteria: Fixed level or statistical ap-proach?

Sensitivity and specicity: Is the sensitivity and speci-city of the system evaluated?

Communication: Is the dosimetry system able to com-municate with TPS and/or afterloader?

Prospective IVD: Is IVD used prospectively and system-atically to evaluate the incidence of errors?

Recent progress of IVD shows that some of these pointshave already been addressed individually in different publi-cations. However, the aim and vision for IVD is to create asystem that embraces all the above aspects.

VII. CONCLUSIONS

The specic role of IVD in BT needs to be dened and es-tablished. So far, recommendations for BT practice rarely in-clude the recommendation to perform IVD. This fact is mostlikely mainly inuenced by the poor ability of current sys-tems to detect errors. Nevertheless, IVD is used in several de-partments and there is good potential to improve its utilityand use. Most importantly, incorporation of routine IVD intoclinical practice requires that the error detection capability isimproved. Second, streamlined procedures are needed whichare automatic as far as possible so that the work load is notexcessive and so that the medical physicist is not distractedby technical operation. The systems need to be commerciallyavailable and affordable. Further utilization and dissemina-tion of IVD will only be feasible if it is cost effective to as-

sign resources for its infrastructure. Altogether, it should bedemonstrated that IVD can be developed to become sensitiveto errors that may have clinical impact and avoidance of errorsshould be veried.

Proceeding from this, it is crucial to come to a compre-hensive description of errors in order to make progress withinBT safety. Systematic IVD in a multicenter setting would be astep forward for detecting and understanding errors and theirfrequencies. Support of international databases for error re-porting and for logging user experiences is important, sincepublications from academic centers do not reect the major-ity of patient treatments. The Radiation Oncology Safety In-formation System (ROSIS) database supported by ESTRO al-

ready supports reporting of BT incidents and the rst reportsfrom ROSIS include such incidents. 102 Such practice has po-tential to facilitate signicant improvements in quality for BTby (1) advancing the use of IVD systems in order to preventand avoid BT errors and (2) making it possible to focus on themost relevant sources of errors.

It is the opinion of the authors that IVD in BT is currentlynot well established in clinical routine to be used for sensitiveand specic error detection. However, this situation shouldchange over the coming years by investing in development of IVD with the goal of establishing an efcient means of inde-

pendent verication of dose delivery in BT. As soon as IVD inBT becomes better established, there will be a strong need forrecommendations from professional organizations (e.g., ES-TRO, ASTRO, AAPM, ABS).

ACKNOWLEDGMENT

The authors have no nancial ties to any of the discussed

detector types and/or to a commercial company.

a) Author to whom correspondence should be addressed. Electronic mail:[email protected]

1 International Commission on Radiation Units and Measurements, Doseand volume specication for reporting intracavitary therapy in gynecol-ogy, ICRU Report No. 38 (ICRU, Bethesta, MD, 1985).

2 R. Ptter et al. , Recommendations from gynaecological (GYN) GECESTRO working group (II): Concepts and terms in 3D image-based treat-ment planningin cervix cancer brachytherapy-3D dose volume parametersand aspects of 3D image-based anatomy, radiation physics, radiobiology,Radiother. Oncol. 78 , 6777 (2006).

3 T. Major, C. Polgar, K. Lovey, and G. Frohlich, Dosimetric character-istics of accelerated partial breast irradiation with CT image-based mul-

ticatheter interstitial brachytherapy: A single institutions experience,Brachytherapy 10 , 421426 (2011).

4 W. S. Bice, Jr. et al. , Centralized multiinstitutional postimplant analysisfor interstitial prostate brachytherapy, Int. J. Radiat. Oncol., Biol., Phys.41 , 921927 (1998).

5 M. J. Rivard, J. L. Venselaar, and L. Beaulieu, The evolution of brachytherapy treatment planning, Med. Phys. 36 , 21362153 (2009).

6 J. Van Dyk, R. B. Barnett, J. E. Cygler, and P. C. Shragge, Commission-ing and quality assurance of treatment planning computers, Int. J. Radiat.Oncol., Biol., Phys. 26 , 261273 (1993).

7 B. Mijnheer, State of the art of in vivo dosimetry, Radiat. Prot. Dosim.131 , 117122 (2008).

8 AAPM, Report of TG 62 of the Radiation Therapy Committee: Diodein vivo dosimetry for patients receiving external beam radiation therapy,AAPM Report No. 87 (Medical Physics Publishing, Madison, WI, 2005).

9 A. J. Vinall, A. J. Williams, V. E. Currie, E. A. Van, and D. Huyskens,

Practical guidelines for routine intensity-modulated radiotherapy veri-cation: Pre-treatment verication with portal dosimetry and treatment ver-ication with in vivo dosimetry, Br. J. Radiol. 83 , 949957 (2010).

10 A. Mans et al. , Catching errors with in vivo EPID dosimetry, Med. Phys.37 , 26382644 (2010).

11 B. Mijnheer, A. S. Beddar, J. Izewska, and C. S. Reft, In vivo dosimetryin external beam radiotherapy, Med. Phys. 40 (7), 070903 (19pp.) (2013).

12 P. O. Lopez, P. Andreo, J.-M. Cosset, A. Dutreix, and T. Landberg, Pre-vention of accidental exposures to patients undergoing radiation therapy,ICRP Publication 86, Annals of the ICRP (Pergamon, New York, 2000).

13 L. P. Ashton, J.-M. Cosset, V. Levin, A. Martinez, and S. Nag, Preventionof high-dose-rate brachytherapy accidents, ICRP Publication 97, Annalsof the ICRP (Pergamon, New York, 2004).

14 IAEA, Lessons learned from accidental exposures in radiotherapy,IAEA Safety Report Series 17 (IAEA, Vienna, 2000).

15 K. Yoshida et al. , Needle applicator displacement during high-dose-rate

interstitial brachytherapy for prostate cancer, Brachytherapy 9

, 3641(2010).16 T. Simnor et al. , Justication for inter-fraction correction of catheter

movement in fractionated high dose-rate brachytherapy treatment of prostate cancer, Radiother. Oncol. 93 , 253258 (2009).

17 A. A. de Leeuw, M. A. Moerland, C. Nomden, R. H. Tersteeg,J. M. Roesink, and I. M. Jrgenliemk-Schulz, Applicator reconstructionand applicator shifts in 3D MR-based PDR brachytherapy of cervical can-cer, Radiother. Oncol. 93 , 341346 (2009).

18 N. Milickovic et al. , 4D analysis of inuence of patient movementand anatomy alteration on the quality of 3D U/S-based prostate HDRbrachytherapy treatment delivery, Med. Phys. 38 , 49824993 (2011).

19 K. Koedooder, W. N. van, H. N. van der Grient, Y. R. van Herten,B. R. Pieters, and L. E. Blank, Safety aspects of pulsed dose rate

http://dx.doi.org/10.1016/j.radonc.2005.11.014http://dx.doi.org/10.1016/j.brachy.2010.12.006http://dx.doi.org/10.1016/S0360-3016(98)90123-7http://dx.doi.org/10.1118/1.3125136http://dx.doi.org/10.1016/0360-3016(93)90206-Bhttp://dx.doi.org/10.1016/0360-3016(93)90206-Bhttp://dx.doi.org/10.1093/rpd/ncn231http://dx.doi.org/10.1259/bjr/31573847http://dx.doi.org/10.1118/1.3397807http://dx.doi.org/10.1118/1.4811216http://dx.doi.org/10.1016/j.brachy.2009.04.006http://dx.doi.org/10.1016/j.radonc.2009.09.015http://dx.doi.org/10.1016/j.radonc.2009.05.003http://dx.doi.org/10.1118/1.3618735http://dx.doi.org/10.1118/1.3618735http://dx.doi.org/10.1016/j.radonc.2009.05.003http://dx.doi.org/10.1016/j.radonc.2009.09.015http://dx.doi.org/10.1016/j.brachy.2009.04.006http://dx.doi.org/10.1118/1.4811216http://dx.doi.org/10.1118/1.3397807http://dx.doi.org/10.1259/bjr/31573847http://dx.doi.org/10.1093/rpd/ncn231http://dx.doi.org/10.1016/0360-3016(93)90206-Bhttp://dx.doi.org/10.1016/0360-3016(93)90206-Bhttp://dx.doi.org/10.1118/1.3125136http://dx.doi.org/10.1016/S0360-3016(98)90123-7http://dx.doi.org/10.1016/j.brachy.2010.12.006http://dx.doi.org/10.1016/j.radonc.2005.11.014


15/16


brachytherapy: Analysis of errors in 1300 treatment sessions, Int. J. Ra-diat. Oncol., Biol., Phys. 70 , 953960 (2008).

20 L. Beaulieu et al. , Report of the Task Group 186 on model-based dosecalculation methods in brachytherapy beyond the TG-43 formalism: Cur-rent status and recommendations for clinical implementation, Med. Phys.39 , 62086236 (2012).

21 J. G. Sutherland, K. M. Furutani, Y. I. Garces, and R. M. Thomson,Model-based dose calculations for 125 I lung brachytherapy, Med. Phys.39 , 43654377 (2012).

22 H. Afsharpour et al. , Consequences of dose heterogeneity on the biologi-cal efciency of 103 Pd permanent breast seed implants, Phys. Med. Biol.57 , 809823 (2012).23 S. A. White,G. Landry, G. F. van, F. Verhaegen,and B. Reniers, Inuenceof trace elements in human tissue in low-energy photon brachytherapydosimetry, Phys. Med. Biol. 57 , 35853596 (2012).

24 ICRU, International Commission on Radiation Units and Measurements,Dose and volume specication for reporting interstitial therapy, ICRUReport No. 58 (ICRU, Bethesta, 1997).

25 S. Nag et al. , The American Brachytherapy Society recommendations forlow-dose-rate brachytherapy for carcinoma of the cervix, Int. J. Radiat.Oncol., Biol., Phys. 52 , 3348 (2002).

26 A. N. Viswanathan and B. Thomadsen, American Brachytherapy Societyconsensus guidelines for locally advanced carcinoma of the cervix. Part I:General principles, Brachytherapy 11 , 3346 (2012).

27 B. J. Davis et al. , American Brachytherapy Society consensus guide-lines for transrectal ultrasound-guided permanent prostate brachytherapy,Brachytherapy 11 , 619 (2012).

28G. Kovacs et al. , GEC/ESTRO-EAU recommendations on temporarybrachytherapy using stepping sources for localised prostate cancer, Ra-diother. Oncol. 74 , 137148 (2005).

29 C. Salembier et al. , Tumour and target volumes in permanent prostatebrachytherapy: A supplement to the ESTRO/EAU/EORTC recom-mendations on prostate brachytherapy, Radiother. Oncol. 83 , 310(2007).

30 R. Alecu and M. Alecu, In vivo rectal dose measurements with diodes toavoid misadministrations during intracavitary high dose rate brachyther-apy for carcinoma of the cervix, Med. Phys. 26 , 768770 (1999).

31 K. Tanderup, J. J. Christensen, J. Granfeldt, and J. C. Lindegaard, Geo-metric stability of intracavitary pulsed dose rate brachytherapy monitoredby in vivo rectal dosimetry, Radiother. Oncol. 79 , 8793 (2006).

32 I. A. Brezovich, J. Duan, P. N. Pareek, J. Fiveash, and M. Ezekiel, In vivourethral dose measurements: A method to verify high dose rate prostatetreatments, Med. Phys. 27 , 22972301 (2000).

33J. E. Cygler, A. Saoudi, G. Perry, C. Morash, and C. E., Feasibility studyof using MOSFET detectors for in vivo dosimetry during permanent low-dose-rate prostate implants, Radiother. Oncol. 80 , 296301 (2006).

34 E. J. Bloemen-van Gurp et al. , In vivo dosimetry using a linear MOSFET-array dosimeter to determine the urethra dose in 125 I permanent prostateimplants, Int. J. Radiat. Oncol., Biol., Phys. 73 , 314321 (2009).

35 C. E. Andersen, S. K. Nielsen, J. C. Lindegaard, and K. Tanderup, Time-resolved in vivo luminescence dosimetry for online error detection inpulsed dose-rate brachytherapy, Med. Phys. 36 , 50335043 (2009).

36 G. Kertzscher, C. E. Andersen, F. A. Siebert, S. K. Nielsen, J. C. Lin-degaard, and K. Tanderup, Identifying afterloading PDR and HDRbrachytherapy errors using real-time ber-coupled Al 2 O3 :C dosimetryand a novel statistical error decision criterion, Radiother. Oncol. 100 ,456462 (2011).

37 D. OConnell, C. A. Joslin, N. Howard, N. W. Ramsey, and W. E. Liv-ersage, The treatment of uterine carcinoma using the Cathetron. Part I.

Technique, Br. J. Radiol. 40

, 882887 (1967).38 C. A. Joslin, C. W. Smith, and A. Mallik, The treatment of cervix cancerusing high activity 60 Co sources, Br. J. Radiol. 45 , 257270 (1972).

39 K. Schultka, B. Ciesielski, K. Serkies, T. Sawicki, Z. Tarnawska, andJ. Jassem, EPR/alanine dosimetry in LDR brachytherapy: A feasibilitystudy, Radiat. Prot. Dosim. 120 , 171175 (2006).

40 M. Allahverdi, M. Sarkhosh, M. Aghili, R. Jaberi, A. Adelnia, andG. Geraily, Evaluation of treatment planning system of brachytherapyaccording to dose to the rectum delivered, Radiat. Prot. Dosim. 150 , 312315 (2012).

41 N. Suchowerska, M. Jackson, J. Lambert, Y. B. Yin, G. Hruby, andD. R. McKenzie, Clinical trials of a urethral dose measurement system inbrachytherapy using scintillation detectors, Int. J. Radiat. Oncol., Biol.,Phys. 79 , 609615 (2011).

42 J. A. Raf et al. , Determination of exit skin dose for 192 Ir intracavitaryaccelerated partial breast irradiation with thermoluminescent dosimeters,Med. Phys. 37 , 26932702 (2010).

43 R. A. Kinhikar et al. , Clinical application of a OneDose MOSFET forskin dose measurements during internal mammary chain irradiation withhigh dose rate brachytherapy in carcinoma of the breast, Phys. Med. Biol.51 , N263N268 (2006).

44 C. A. Mangold, A. Rijnders, D. Georg, L. E. Van, R. Ptter, andD. Huyskens, Quality control in interstitial brachytherapy of the breastusing pulsed dose rate: Treatment planning and dose delivery with an Ir-192 afterloading system, Radiother. Oncol. 58 , 4351 (2001).

45 M. J. Rivard et al. , Update of AAPM Task Group No. 43 Report: A re-vised AAPM protocol for brachytherapy dose calculations, Med. Phys.31 , 633674 (2004).

46 R. Bachelot-Narquin, Measures taken by the French Health Minister toensure safety in radiotherapy treatments, Safety in External Radiother-apy Treatments (ASN, Paris, 2009), Vol. 185, pp. 57 (available URL:http://www.conference-radiotherapy-asn.com ).

47 F. Guedea et al. , Overview of brachytherapy resources in Europe: A sur-vey of patterns of care study for brachytherapy in Europe, Radiother.Oncol. 82 , 5054 (2007).

48 F. Guedea et al. , Overview of brachytherapy resources in Latin America:A patterns-of-care survey, Brachytherapy 10 , 363368 (2011).

49 R. Ptter, L. E. Van, N. Gerstner, and A. Wambersie, Survey of the use of the ICRU 38 in recording and reporting cervical cancer brachytherapy,Radiother. Oncol. 58 , 1118 (2001).

50 T. Toita et al. , Patterns of radiotherapy practice for patients with cervical

cancer(1999-2001): Patterns of care study in Japan, Int. J. Radiat. Oncol.,Biol., Phys. 70 , 788794 (2008).

51 W. Small, Jr., B. Erickson, and F. Kwakwa, American Brachytherapy So-ciety survey regarding practice patterns of postoperative irradiation for en-dometrial cancer: Current status of vaginal brachytherapy, Int. J. Radiat.Oncol., Biol., Phys. 63 , 15021507 (2005).

52 K. S. Kapp, G. F. Stuecklschweiger, D. S. Kapp, and A. G. Hackl,Dosimetry of intracavitary placements for uterine and cervical carci-noma: Results of orthogonal lm, TLD, and CT-assisted techniques, Ra-diother. Oncol. 24 , 137146 (1992).

53 D. W. O. Rogers, General characteristics of radiation dosimeters and aterminology to describe them, in Clinical Dosimetry Measurements in Radiotherapy , edited by D. W. O. Rogers and J. Cygler (Medical PhysicsPublishing, Madison, 2009), pp. 137146.

54 J. F. Williamson and M. J. Rivard, Quantitative dosimetry methodsfor brachytherapy, in Brachytherapy Physics , edited by B. Thomadsen,

M. J. Rivard, and W. Butler (Medical Physics Publishing, Madison, WI,2005).55 T. Nose et al. , In vivo dosimetry of high-dose-rate brachytherapy: Study

on 61 head-and-neck cancer patients using radiophotoluminescence glassdosimeter, Int. J. Radiat. Oncol., Biol., Phys. 61 , 945953 (2005).

56 T. Nose et al. , In vivo dosimetry of high-dose-rate interstitial brachyther-apy in the pelvic region: Use of a radiophotoluminescence glass dosimeterfor measurement of 1004 points in 66 patients with pelvic malignancy,Int. J. Radiat. Oncol., Biol., Phys. 70 , 626633 (2008).

57 E. L. Seymour, S. J. Downes, G. B. Fogarty, M. A. Izard, and P. Met-calfe, In vivo real-time dosimetric verication in high dose rate prostatebrachytherapy, Med. Phys. 38 , 47854794 (2011).

58 J. Lambert, T. Nakano, S. Law, J. Elsey, D. R. McKenzie, and N. Suchow-erska, In vivo dosimeters for HDR brachytherapy: A comparison of adiamond detector, MOSFET, TLD, and scintillation detector, Med. Phys.34 , 17591765 (2007).

59

A. S. Kirov, J. F. Williamson, A. S. Meigooni, and Y. Zhu, TLD,diode and Monte Carlo dosimetry of an 192 Ir source for high dose-ratebrachytherapy, Phys. Med. Biol. 40 , 20152036 (1995).

60 M. Westermark, J. Arndt, B. Nilsson, and A. Brahme, Comparativedosimetry in narrow high-energy photon beams, Phys. Med. Biol. 45 ,685702 (2000).

61 G. Anagnostopoulos et al. , In vivo thermoluminescence dosimetry doseverication of transperineal 192 Ir high-dose-rate brachytherapy using CT-based planning for the treatment of prostate cancer, Int. J. Radiat. Oncol.,Biol., Phys. 57 , 11831191 (2003).

62 R. Das, W. Toye, T. Kron, S. Williams, and G. Duchesne, Thermolumi-nescence dosimetry for in vivo verication of high dose rate brachyther-apy for prostate cancer, Australas. Phys. Eng. Sci. Med. 30 , 178184(2007).

http://dx.doi.org/10.1016/j.ijrobp.2007.11.003http://dx.doi.org/10.1016/j.ijrobp.2007.11.003http://dx.doi.org/10.1118/1.4747264http://dx.doi.org/10.1118/1.4729737http://dx.doi.org/10.1088/0031-9155/57/3/809http://dx.doi.org/10.1088/0031-9155/57/11/3585http://dx.doi.org/10.1016/S0360-3016(01)01755-2http://dx.doi.org/10.1016/S0360-3016(01)01755-2http://dx.doi.org/10.1016/j.brachy.2011.07.003http://dx.doi.org/10.1016/j.brachy.2011.07.005http://dx.doi.org/10.1016/j.radonc.2004.09.004http://dx.doi.org/10.1016/j.radonc.2004.09.004http://dx.doi.org/10.1016/j.radonc.2007.01.014http://dx.doi.org/10.1118/1.598598http://dx.doi.org/10.1016/j.radonc.2006.02.016http://dx.doi.org/10.1118/1.1312811http://dx.doi.org/10.1016/j.radonc.2006.07.008http://dx.doi.org/10.1016/j.ijrobp.2008.08.040http://dx.doi.org/10.1118/1.3238102http://dx.doi.org/10.1016/j.radonc.2011.09.009http://dx.doi.org/10.1259/0007-1285-40-480-882http://dx.doi.org/10.1259/0007-1285-45-532-257http://dx.doi.org/10.1093/rpd/nci528http://dx.doi.org/10.1093/rpd/ncr415http://dx.doi.org/10.1016/j.ijrobp.2010.03.030http://dx.doi.org/10.1016/j.ijrobp.2010.03.030http://dx.doi.org/10.1118/1.3429089http://dx.doi.org/10.1088/0031-9155/51/14/N01http://dx.doi.org/10.1016/S0167-8140(00)00270-Xhttp://dx.doi.org/10.1118/1.1646040http://www.conference-radiotherapy-asn.com/http://dx.doi.org/10.1016/j.radonc.2006.11.011http://dx.doi.org/10.1016/j.radonc.2006.11.011http://dx.doi.org/10.1016/j.brachy.2010.12.003http://dx.doi.org/10.1016/S0167-8140(00)00266-8http://dx.doi.org/10.1016/j.ijrobp.2007.10.045http://dx.doi.org/10.1016/j.ijrobp.2007.10.045http://dx.doi.org/10.1016/j.ijrobp.2005.04.038http://dx.doi.org/10.1016/j.ijrobp.2005.04.038http://dx.doi.org/10.1016/0167-8140(92)90372-2http://dx.doi.org/10.1016/0167-8140(92)90372-2http://dx.doi.org/10.1016/j.ijrobp.2004.10.031http://dx.doi.org/10.1016/j.ijrobp.2007.09.053http://dx.doi.org/10.1118/1.3615161http://dx.doi.org/10.1118/1.2727248http://dx.doi.org/10.1088/0031-9155/40/12/002http://dx.doi.org/10.1088/0031-9155/45/3/308http://dx.doi.org/10.1016/S0360-3016(03)00762-4http://dx.doi.org/10.1016/S0360-3016(03)00762-4http://dx.doi.org/10.1007/BF03178424http://dx.doi.org/10.1007/BF03178424http://dx.doi.org/10.1016/S0360-3016(03)00762-4http://dx.doi.org/10.1016/S0360-3016(03)00762-4http://dx.doi.org/10.1088/0031-9155/45/3/308http://dx.doi.org/10.1088/0031-9155/40/12/002http://dx.doi.org/10.1118/1.2727248http://dx.doi.org/10.1118/1.3615161http://dx.doi.org/10.1016/j.ijrobp.2007.09.053http://dx.doi.org/10.1016/j.ijrobp.2004.10.031http://dx.doi.org/10.1016/0167-8140(92)90372-2http://dx.doi.org/10.1016/0167-8140(92)90372-2http://dx.doi.org/10.1016/j.ijrobp.2005.04.038http://dx.doi.org/10.1016/j.ijrobp.2005.04.038http://dx.doi.org/10.1016/j.ijrobp.2007.10.045http://dx.doi.org/10.1016/j.ijrobp.2007.10.045http://dx.doi.org/10.1016/S0167-8140(00)00266-8http://dx.doi.org/10.1016/j.brachy.2010.12.003http://dx.doi.org/10.1016/j.radonc.2006.11.011http://dx.doi.org/10.1016/j.radonc.2006.11.011http://www.conference-radiotherapy-asn.com/http://dx.doi.org/10.1118/1.1646040http://dx.doi.org/10.1016/S0167-8140(00)00270-Xhttp://dx.doi.org/10.1088/0031-9155/51/14/N01http://dx.doi.org/10.1118/1.3429089http://dx.doi.org/10.1016/j.ijrobp.2010.03.030http://dx.doi.org/10.1016/j.ijrobp.2010.03.030http://dx.doi.org/10.1093/rpd/ncr415http://dx.doi.org/10.1093/rpd/nci528http://dx.doi.org/10.1259/0007-1285-45-532-257http://dx.doi.org/10.1259/0007-1285-40-480-882http://dx.doi.org/10.1016/j.radonc.2011.09.009http://dx.doi.org/10.1118/1.3238102http://dx.doi.org/10.1016/j.ijrobp.2008.08.040http://dx.doi.org/10.1016/j.radonc.2006.07.008http://dx.doi.org/10.1118/1.1312811http://dx.doi.org/10.1016/j.radonc.2006.02.016http://dx.doi.org/10.1118/1.598598http://dx.doi.org/10.1016/j.radonc.2007.01.014http://dx.doi.org/10.1016/j.radonc.2004.09.004http://dx.doi.org/10.1016/j.radonc.2004.09.004http://dx.doi.org/10.1016/j.brachy.2011.07.005http://dx.doi.org/10.1016/j.brachy.2011.07.003http://dx.doi.org/10.1016/S0360-3016(01)01755-2http://dx.doi.org/10.1016/S0360-3016(01)01755-2http://dx.doi.org/10.1088/0031-9155/57/11/3585http://dx.doi.org/10.1088/0031-9155/57/3/809http://dx.doi.org/10.1118/1.4729737http://dx.doi.org/10.1118/1.4747264http://dx.doi.org/10.1016/j.ijrobp.2007.11.003http://dx.doi.org/10.1016/j.ijrobp.2007.11.003


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63 W. Toye, R. Das, T. Kron, R. Franich, P. Johnston, and G. Duchesne,An in vivo investigative protocol for HDR prostate brachytherapy usingurethral and rectal thermoluminescence dosimetry, Radiother. Oncol. 91 ,243248 (2009).

64 C. Waldhusl, A. Wambersie, R. Potter, and D. Georg, In-vivo dosimetryfor gynaecological brachytherapy: Physical and clinical considerations,Radiother. Oncol. 77 , 310317 (2005).

65 J. M. Fagerstrom, J. A. Micka, and L. A. DeWerd, Response of an im-plantable MOSFET dosimeter to 192 Ir HDR radiation, Med. Phys. 35 ,57295737 (2008).

66 C. E. Andersen, S. K. Nielsen, S. Greilich, J. Helt-Hansen, J. C. Linde-

gaard, and K. Tanderup, Characterization of a ber-coupled Al 2 O3 :C lu-minescence dosimetry system for online in vivo dose verication during192 Ir brachytherapy, Med. Phys. 36 , 708718 (2009).

67 A. S. Beddar, T. R. Mackie, and F. H. Attix, Water-equivalent plasticscintillation detectors for high-energy beam dosimetry: I. Physical charac-teristics and theoretical consideration, Phys. Med. Biol. 37 , 18831900(1992).

68 J. Lambert, D. R. McKenzie, S. Law, J. Elsey, and N. Suchowerska, Aplastic scintillation dosimeter for high dose rate brachytherapy, Phys.Med. Biol. 51 , 55055516 (2006).

69 F. Therriault-Proulx, T. M. Briere, F. Mourtada, S. Aubin, S. Beddar,and L. Beaulieu, A phantom study of an in vivo dosimetry system us-ing plastic scintillation detectors for real-time verication of 192 Ir HDRbrachytherapy, Med. Phys. 38 , 25422551 (2011).

70 L. E. Cartwright, N. Suchowerska, Y. Yin, J. Lambert, M. Haque, andD. R. McKenzie, Dose mapping of the rectal wall during brachyther-

apy with an array of scintillation dosimeters, Med. Phys. 37 , 22472255(2010).

71 M. Anton et al. , In vivo dosimetry in the urethra using alanine/ESR dur-ing 192 Ir HDR brachytherapy of prostate cancer: A phantom study, Phys.Med. Biol. 54 , 29152931 (2009).

72 S. M. Hsu et al. , Clinical application of radiophotoluminescent glassdosimeter for dose verication of prostate HDR procedure, Med. Phys.35 , 55585564 (2008).

73 A. Ismail et al. , Radiotherapy quality assurance by individualized in vivodosimetry: State of the art, Cancer Radiother. 13 , 182189 (2009).

74 J. E. Cygler, K. Tanderup, A. S. Beddar, and J. Perez-Calatayud, In vivodosimetry in brachytherapy, in Comprehensive Brachytherapy: Physicaland Clinical Aspects , edited by J. Venselaar, D. Baltas, A. S. Meigooni,and P. Hoskin (Taylor & Francis, London, 2012), pp. 379397.

75 D. W. O. Rogers and J. Cygler, Clinical Dosimetry Measurements in Ra-diotherapy (Medical Physics Publishing, Madison, 2009).

76A. Piermattei, L. Azario, G. Monaco, A. Soriani, and G. Arcovito, p-typesilicon detector for brachytherapy dosimetry, Med. Phys. 22 , 835839(1995).

77 M. Soubra, J. Cygler, and G. Mackay, Evaluation of a dual bias dualmetal oxide-silicon semiconductor eld effect transistor detector as radia-tion dosimeter, Med. Phys. 21 , 567572 (1994).

78 V. O. Zilio, O. P. Joneja, Y. Popowski, A. Rosenfeld, and R. Chawla,Absolute depth-dose-rate measurements for an 192 Ir HDR brachytherapysource in water using MOSFET detectors, Med. Phys. 33 , 15321529(2006).

79 H. Niu, W. C. Hsi, J. C. Chu, M. C. Kirk, and E. Kouwenhoven, Dosi-metric characteristics of the Leipzig surface applicators used in the highdose rate brachy radiotherapy, Med. Phys. 31 , 33723377 (2004).

80 E. J. Bloemen-van Gurp et al. , In vivo dosimetry with a linear MOSFETarray to evaluate the urethra dose during permanent implant brachyther-apy using iodine-125, Int. J. Radiat. Oncol., Biol., Phys. 75 , 12661272

(2009).81 A. Cherpak, J. Cygler, and G. Perry, Real-time measurement of urethraldose and position using a RADPOS array during permanent seed implan-tation for prostate brachytherapy, Med. Phys. 38 , 3577 (2011).

82 A. Cherpak, W. Ding, A. Hallil, and J. E. Cygler, Evaluation of a novel4D in vivo dosimetry system, Med. Phys. 36 , 16721679 (2009).

83 B. Reniers, G. Landry, R. Eichner, A. Hallil, and F. Verhaegen, In vivodosimetry for gynaecological brachytherapy using a novel position sen-sitive radiation detector: Feasibility study, Med. Phys. 39 , 19251935(2012).

84 M. Farahani, F. C. Eichmiller, and W. L. McLaughlin, New method forshielding electron beams used for head and neck cancer treatment, Med.Phys. 20 , 12371241 (1993).

85 S. Olsson, E. S. Bergstrand, A. K. Carlsson, E. O. Hole, and E. Lund,Radiation dose measurements with alanine/agarose gel and thin alaninelms arounda 192 Ir brachytherapysource, using ESR spectroscopy, Phys.Med. Biol. 47 , 13331356 (2002).

86 C. S. Calcina, A. A. de, J. R. Rocha, F. C. Abrego, and O. Baffa, Ir-192 HDR transit dose and radial dose function determination using ala-nine/EPR dosimetry, Phys. Med. Biol. 50 , 11091117 (2005).

87 A. C. De, S. Onori, E. Petetti, A. Piermattei, and L. Azario, Alanine/EPRdosimetry in brachytherapy, Phys. Med. Biol. 44 , 11811191 (1999).

88 B. Ciesielski, K. Schultka, A. Kobierska, R. Nowak, and Z. Peimel-Stuglik, In vivo alanine/EPR dosimetry in daily clinical practice: A fea-sibility study, Int. J. Radiat. Oncol., Biol., Phys. 56 , 8

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In Vivo Dosimetry in Brachytherapy (1)