ABSTRACT PRESENTER: LIST OF CONTRIBUTORS: CURRENT ... · ABSTRACT PRESENTER: Dr. Merav Akiva Ben David LIST OF CONTRIBUTORS: Yael Sellam, Dr.Shira Galper, Ilanit Dromi Shahadi, Ilana

ABSTRACT PRESENTER:

Jon Feldman

LIST OF CONTRIBUTORS:

CURRENT SUBMISSION:

New Submission

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RADIOTHERAPY

HEADLINE:

Lip Cancer Brachytherapy Improvements Using Backscattering Materials

BACKGROUND :

Due to its location, lip cancer is usually detected at an early stage and single-modality therapy will usually suffice. Surgery or radiotherapy can be utilized, with similar local control and overall survival results. The extent of surgical resection depends on tumor size, larger lesions may however require wide resections with consequently cosmetic issues, and may result with disruption of the oral sphincter (orbicularis oris muscle). In this study we are looking into a new way to improve brachytherapy homogeneity. We hypothesize that novel apparatus using backscattering materials will shape a more homogeneous dose distribution to lip cancer brachytherapy, while protecting the organs at risk.

MATERIALS AND METHODS:

backscattering materials with different dimensions, using combination of different metals were utilized on a lip brachytherapy phantom and compared in Monte Carlo simulations. We used the EGS5 code system for calculations. The dose results were normalized for comparisons.

RESULTS:

We found that the led backscatter and copper backscatter improve the dose homogeneity in the tissue compared to the central source in the sleeve alone. Moreover the dose beyond the shield markedly reduced, suggesting better protection to the organs at risk, when will use in vivo. The Graphs of the simulations results are to be presented in the talk.

CONCLUSIONS:

metal shielding in lip brachytherapy may improve dose homogeneity and reduce dose to organs at risk as suggested from our phantom model.

ABSTRACT PRESENTER:

Dr. Merav Akiva Ben David


Yael Sellam, Dr.Shira Galper, Ilanit Dromi Shahadi, Ilana Gelernter, Anatoly Shenkar, Dr. Zvi Symon.

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY,Breast

HEADLINE:

Local recurrence of breast cancer : Salvage lumpectomy –as a safe option for local treatment

BACKGROUND :

The best local management for breast cancer recurrence following conservative treatment for breast cancer continues to be an open question. In this study, we compared patients' outcome after re-lumpectomy (salvage lumpectomy) vs. patients who underwent mastectomy for ipsilateral breast tumor recurrence (IBTR).


Between 1987 and 2014 we identified 118 patients with pT0-2, N0-3, M0 breast cancer who had breast conserving surgery and radiation therapy as their primary treatment, and subsequently had IBTR. Their demographic, tumor and treatment data were collected. 47 patients underwent salvage lumpectomy (group A) and 71 salvage mastectomy (group B) as the local treatment for their 1st recurrence.

RESULTS:

Median follow-up was 13 years for all patients (2-29 years). The median disease free interval at 1st recurrence for group A and B, 12 and 7 years respectively (p=0.004). The median age of 1st diagnosis for group A and B, 52 and 47, respectively (p=0.011). The mean tumor size at 1st diagnosis for group A and B, 1.2cm and 1.6cm, respectively (p=0.008). 40% of group A patients underwent re-irradiation, none developed 3rd recurrence event. Out of groups A and B, 5 and 6 patients (10%,8%) respectively, developed local recurrence as a 3rd event. The median DFI between 2nd and 3rd recurrence for groups A and B, 7 and 16 years, respectively (p=0.113). Multivariate analysis reveals that age at 1st diagnosis, tumor size at 1st and 2nd recurrence, number of positive LN, grade, type of axillary surgery, neo/adjuvant therapy, had no effect on 2nd recurrence; however, having salvage lumpectomy vs. mastectomy has higher chances of 2nd recurrence (p=0.043). For patient who had 2nd recurrence (3rd event), re-irradiation (salvage lumpectomy group) was associated with lower chances (p=0.077) and positive HER2 (mastectomy group) were associated with higher chances for subsequent recurrence (p=0.054). At a median follow-up of 13 years, all salvage lumpectomy patients are alive, NED. 7% of group B died due to BC.

CONCLUSIONS:

Salvage lumpectomy following IBTR is a safe choice with low risk for recurrence and should be considered in appropriate cases as an acceptable option for local treatment of breast cancer recurrence, with or without re-irradiation.

ABSTRACT PRESENTER:

Inbar Finkel


Molad JA, Blumenthal DT, Bokstein F, Findler M, Finkel I, Bornstein NM, Yust-Katz S, Auriel E

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Mechanisms of post-radiation injury: cerebral microinfarction not a significant factor.

BACKGROUND :

Post-radiation leukoencephalopathy is characterized by cognitive impairment and white matter alternations on imaging. Cerebral small vessel disease (SVD) is one of several suggested etiologies. Cerebral microinfarction (CMI) is a recently described marker of SVD. We sought to examine the rate of CMI as a biomarker of ongoing ischemia among patients who underwent brain radiotherapy (RT).


110 patients treated with RT for primary or metastatic brain tumors were enrolled. A total of 685 brain MRI tests performed 1-108 months post-radiation were examined. The annual incidence of CMI was calculated

RESULTS:

Only 2 definite CMI were found (2/685, 0.3 %). The calculated annual incidence of CMI was 0.11. This incidence is similar to the normal population, and lower than the reported incidence in patients with intracerebral hemorrhage or cognitive impairment.

CONCLUSIONS:

CMI incidence in patients treated with brain RT is similar to the general population. This finding suggests that post-radiation leukoencephalopathy and cognitive impairment are not due to active SVD solely but rather secondary to other causes such as inflammation, metabolic or direct cell damage.

ABSTRACT PRESENTER:

Egor Borzov


Alex Nevelsky, Raquel Bar-Deroma

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Comparison of Quality Assurance results for stereotactic plans performed with two different phantoms

BACKGROUND :

Stereotactic treatments often require complex planning. Quality Assurance for such plans can be challenging due to small fields dosimetry problems and presence of high dose gradients. The objective of this work was to compare QA results measured with Scandidos Delta4+ phantom with the High Resolution option and PTW Octavius 4D phantom with 1000SRS detector array dedicated for QA of stereotactic plans.


Plans for ten patients were created with Monaco TPS and were delivered with Elekta Versa HD linac in 6 MeV FFF mode. TPS doses were calculated with 1 mm spatial grid and MC calculation uncertainty of 1%. The same procedure was applied to both phantoms to perform position and output corrections before measurements. For all plans isocenter was into area with high density of detectors. For Delta4+ measurements were carried out twice: with phantom position in linac isocentre and with 2.5 mm transverse shift. Measured doses were merged to obtain High Resolution results. Gamma indexes were calculated using global maximum and 20% dose threshold. Passing criteria was 3%/2mm, 2%/2mm and 1%/1mm. All measurements and processing were done with corresponding software: Scandidos and Verisoft. For correct results comparison gamma indexes for the Octavius phantom were calculated as mean values for sagittal and coronal planes.

RESULTS:

All necessary measurements were performed and gamma indexes were calculated. For the Delta4+ phantom, no statistical difference was found between gamma indexes measured with the regular and with the High Resolution mode for all passing criteria. Comparing the results measured with the Delta4+ and the Octavius phantoms, there was no statistical difference for gamma indexes calculated with 3%/2mm and 2%/2mm criteria. For the 1%/1mm criterion, gamma indexes measured with the Octavius phantom were lower (with p

CONCLUSIONS:

QA results of stereotactic plans measured with Delta4+ phantom and Octavius 4D phantom with the dedicated 1000SRS detector array were not statistically different. Further work on sensitivity of both phantoms to introduced errors is needed.

ABSTRACT PRESENTER:

Alex Nevelsky


CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Lessons learned from participation in the planning competition.

BACKGROUND :

Plan Challenge (PC) is a treatment planning competition organized in cooperation with the American Association of Medical Dosimetrists (AAMD). The purpose of the presentation is to share lessons learned from participation in the last two competitions


PC held in 2015 dealt with the case of whole brain irradiation with simultaneous integrated boost to the brain mets and hippocampal sparing. PC held this year dealt with the case of prostate SBRT. Patient model (CT images) and patient anatomy (RT structure sets) could be downloaded through the web interface and imported into treatment planning system (TPS). Planning was performed according to the well-defined goals and scoring algorithm. Plans with the highest overall score reflected best plan quality. Analysis of results as function of TPS, treatment technique, treatment equipment etc was supplied by the organizers

RESULTS:

VMAT approach allowed achieving the highest plan score. It also had significantly shorter delivery time. There were only minor differences between TPS of various vendors. Score distribution for each TPS was Gaussian in shape with large variation, emphasizing the role of the planner in achieving best plan quality. Treatment plans created for linacs had comparable and even slightly better quality than plans created for Tomotherapy and CyberKnife machines

CONCLUSIONS:

Participation in PC allows learning from the critical structures list and their delineation performed by well-recognized specialists and getting acquainted with the dosimetric constraints used in clinical cases which are dealt with in PC. In addition, a participant gets the opportunity to compare his performance (anonymously) with the others and learn from the best performers which share their knowledge for each TPS

ABSTRACT PRESENTER:

Annette Wygoda


Ruth Dadush-Azuz; Marc Wygoda

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Intensity-Modulated Therapy Dose Prescription for Pelvis and Prostate Treatments: ICRU 83 as guideline

BACKGROUND :

When delivering a radiotherapy treatment, parameters such as volume and dose have to be specified for different purposes: Prescription, Recording, Reporting. In 1978, the ICRU (International Commission on Radiation Units and Measurement) recognized the need for a general dose-specification system, and published a first report since then followed by updates taking into account the technological evolutions. Today, ICRU 83 report represents the gold standard for volume and dose definitions in intensity-modulated treatments. Using ICRU formalism, a research was conducted on pelvis treatments dose specification for Intensity Modulated Treatments.


In Eclipse Treatment Planning System, the planned and delivered dose, based on the physician’s dose prescription, is the result of one of the different volumetric normalization options applied, the most commonly used being: Target Mean, Target Median, Minimum dose to PTV. Dose Volume Histograms (DVHs) of the PTVs were created using each of these options as well as Isocenter normalization previously used in 3D, and compared.

RESULTS:

The different normalization methods lead to quite different dose distributions in terms of Minimum, Maximum, Median and Mean Dose. The Median Dose normalization method corresponded in many cases to the previously used 3D Isocenter normalization method.

CONCLUSIONS:

Volumetric Dose characterization is complex, and requires departmental guidelines defining the relation between Prescription and Planning in order to ensure delivery of comparable doses to all patients treated.

ABSTRACT PRESENTER:

Roxolyana Abdah-Bortnyak


Tanya Mashiach1, Ron Epelbaum1,2, Salem Billan1, Osnat Bairey3,4, Rachel Bar-Shalom1, Mark Vygoda10, Elinor Barzilai1, Luiza Akria6, Tamar Tadmor2,7, Uri Abadi9, Olga Kagna1, Rosa Ruchlemer11, Neta Goldschmidt10, Netanel A. Horowitz1,2, David Lavie10, Dina Ben-Yehuda, Ofer Shpilberg3, Ora Paltiel10 Eldad J. Dann1,2 1Rambam Health Care Campus, Haifa; 2Rappaport Faculty of Medicine, Technion, Haifa; 3Rabin Medical Center, Petach Tikva; 4Sackler School of Medicine, Tel Aviv University, Tel Aviv; 5Assaf Harofeh Medical Center, Zerifin; 6Galil Medical Center, Nahariya; 7Bnai Zion Medical Center, Haifa; 8Kaplan Medical Center, Rehovot; 9Meir Medical Center, Kfar Saba; 10Hadassah-Hebrew University Medical Center, Jerusalem; 11Shaare Zedek Medical Center, Jerusalem, Israel

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Treatment of early Hodgkin lymphoma patients based on interim PET/CT results. Who is in need for involved site Radiation therapy and for whom substitution with more chemotherapy is safe and efficacious?

BACKGROUND :

The need for radiation therapy in patients with early HD is a matter of a long ongoing debate. While radiation therapy was the most effective therapy historically, the long term toxicity in young patients is a cause of a major concern. Current study assessed the outcome obtained in patients with early disease treated according to predefined risk factors and interim PET.


Patients with early HL (stages I-IIA) were categorized into early favorable (EFD) and unfavorable (EUD) disease groups according to the absence or presence of ≥1 of the following factors: extra-nodal disease, bulky mediastinal mass >10 cm, erythrocyte sedimentation rate >50, three or more sites of disease, age >50 years, lymphocytic depleted histology. All patients initially received ABVDx2. Subsequently, if the interim PET (PET-2) was negative, therapy was completed with 0 / 2 ABVD cycles with involved site radiation therapy (ISRT) or substituted with 2/4 ABVD for EFD/EUD respectively. If the PET-2 was positive, patients received additional 2 ABVD cycles, respectively with ISRT. Patients who had disease progression or relapse were evaluated for relapse pattern: within radiation site, within sites and new sites, in new sites out of radiation field. Same analysis was carried out for patients who did not have RT according to putative field of irradiation. Local failure defined as recurrence in the area of the initial disease.

RESULTS:

171 patients with EFD/EUD were included for the analysis. 10 of the 93 patients (11%) relapsed in the radiotherapy and 10 out of 78 patients (13%) in non-RT group. For non-bulky interim PET negative group local relapse was: 5/58 patients (8.6%) in RT and 4/80 patients (5%) in non-RT group (p-value 0.35).Out of field recurrence was: 7/58 (12%) in RT group and 3/80 (4%) in non-RT group. Between interim PET positive group (20 pts), 15 patients received RT, and 5 pts chemotherapy only. Significant difference in relapse rate was observed in PET positive patients according to treatment: 2/15 relapses in RT and 4/5 in non-irradiated (p-value 0.006). In interim PET positive non-bulky group that received RT (11 pts), 2 local failures were diagnosed. In non-RT PET positive non-bulky group (2 pts), 2 relapses detected, all local. Three out of 3 pts with bulky disease and PET positive in chemotherapy only group developed local failure and none in radiotherapy group.

CONCLUSIONS:

Radiotherapy did not reduce local failure in the group of non-bulky early HD patients that achieved early rapid complete metabolic response to chemotherapy. Additional two cycles of chemotherapy decreased a generalized failure. Omission of radiotherapy in this group of patients can be reasonable. For patients with delayed response to chemotherapy, radiotherapy significantly reduced relapse. Radiotherapy is mandatory in all patients with early HD with interim PET positive disease.

ABSTRACT PRESENTER:

Igor Albitskiy


Haitam Nasrallah

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY,LUNGS

HEADLINE:

A Single center analysis of Stereotactic Body Radiation Therapy in Pulmonary Tumors

BACKGROUND :

Recently , the development of new radiotherapy techniques have improved the results of local treatment for primary and secondary tumors to the level "not inferior" than that of a surgical approach. Nowadays, stereotactic body radiation therapy (SBRT) is widely used for definitive treatment of primary and metastatic lesions. Aim: The aim of the study is to summarize our experience with SBRT in pulmonary lesions and to analyze local control and complications.


Between August 2013 and May 2015, 80 patients have been treated with SBRT at our center. The diagnosis in 62 of these patients (78%) was non small lung carcinoma (NSCLC); 80% of them had adenocarcinoma and 20% had squamous cell carcinoma. The remaining 18 patients were treated due to lung metastasis from other primaries ( kidney, thyroid, and colon cancer). The median age of these patients was 72.3 year, and the median follow up was 19.5 months.

RESULTS:

Local control was achieved in 76 patients (95.2%). During the follow-up, regional progression was observed in 13 patients (16.3%) and metastatic spread after SBRT was noted in 6 patients( 7.2%). Overall survival at the follow up period was 88%. Two patients developed grade 2 pneumonitis. No grade 3-4 toxicity was observed.

CONCLUSIONS:

SBRT for primary and metastatic lung tumors is a well-tolerated and provides a high rate of local control.

ABSTRACT PRESENTER:

galia jacobson


dr shira galper, mrs ilanot dromi shahadi, prof zvi simon, dr merav akiva ben david

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY,Supportive & Palliative care,Breast

HEADLINE:

palliative radiation to the breast, effectivness, fractionation and toxicity

BACKGROUND :

Patients with advanced breast cancer may experience pain, discomfort, bleeding, discharge and ulceration of the tumor, which severely affect a patient's quality of life. Effectiveness of palliative radiation therapy (RT) to the breast was evaluated in this study.


We retrospectively reviewed the RT records of patients who underwent palliative RT for breast cancer at our institution between 2006-2016. Thirty-six patients were identified, and we herein report their clinical outcomes, demographics, and treatment characteristics.

RESULTS:

The mean age was 62 years (range33-85). All patients had stage IV disease and twenty (55%) were metastatic at diagnosis. Eight (22%) patients received prior RT. The most common indication for palliative RT was pain (43%). The mean tumor size was 6cm, seventeen (43%) had ulcerating lesion, eighteen (46%) had discharge, often with offensive odor, eight (20%) had bleeding requiring blood transfusion. Mean follow up was 15 months (range1-50). The mean radiation dose received for palliative RT was 40.2Gy, converted to EQD2 (75% had 3Gy/Fx to a total dose of 30-45Gy, 20% had 1.8-2.65Gy/Fx to a total dose of 36-50Gy and 4 had 8Gy/fx). Thirty-one (86%) patients reported clinical improvement, twenty (55%) reported decrease in pain level, twenty seven (75%) reported decrease in tumor size. Eight (22%) needed re-irradiation, three of them received single fraction of 8Gy initially. Among the 4 patients treated with 8Gy initially, three needed re-irradiation due to recurrent symptoms. Radiation-associated toxicities reported by fifteen (39%) patients included grade 1-2 dermatitis, previous RT was not a risk factor for toxicity.

CONCLUSIONS:

Our data suggest that fractionated palliative RT for breast tumor is an effective treatment for pain, bleeding, ulceration, discharge and discomfort with tolerable toxicity. 8Gy fraction was less effective and often required re-irradiation. Literature regarding palliative RT to the breast is scarce, and prospective protocols are needed.

ABSTRACT PRESENTER:

Gilad Amiel


Tareq Aro, David Kakiashvili, Kamil Malshy, Valentin Shabataev, Gilad E. Amiel

CURRENT SUBMISSION:

New Submission


GU,RADIOTHERAPY

HEADLINE:

Safety & Feasibility of Bladder and Prostate Robotic Surgery After Radiation Therapy

BACKGROUND :

Open surgery for removing the bladder and/or prostate after radiation therapy is a challenging procedure with a high complication rate. We wanted to assess the feasibility and complication rates in similar cases utilizing robot surgery.


We identified 13 patients undergoing robotic surgery after radiation therapy in our robotic surgery database. Ten underwent a cystectomy and 3 radical salvage prostatectomy. We collected demographic, surgery and post-surgery data during their hospital stay.

RESULTS:

In the cystectomy group there were 6 females and 4 males, mean age 68 years. Three of the patients were 81, 84 and 85 years old. Two female patients had prior brachytherapy due to cervical cancer and developed a small contracted bladder with vesico-vaginal fistula. Two males with external beam radiation and one male with brachytherapy for prostate cancer developed TCC. One male with squamous cell carcinoma and 4 others with TCC that received chemo-radiation in the past, were sent to salvage cystectomy due to local recurrence. Five patients received neoadjuvant chemotherapy prior to surgery. Mean operating time was 6:53 hours. Mean operative blood loss 461 ml. Three patients received 2 units of packed cells apiece during surgery due to blood loss of 800 ml each. The mean blood loss for the others was 291 ml. One female patient with prior multiple open abdominal surgeries had adhesions that required conversion to open surgery which ended with bowel injury and cystectomy was aborted. Post-operative complications consisted of transient ileus in 3 patients. Mean hospital stay was 6 days (range 4-8 days). Six patients were discharged with a drain due to increased serous drainage, which was later removed in our clinic. In the radical prostatectomy group mean operative time was 2:46 hours, mean blood loss was 133 ml, there were no intra-operative or post-operative complications. Mean hospital stay was 5 days (range 3-8 days).

CONCLUSIONS:

Robotic cystectomy and/or prostatectomy after radiation therapy to the pelvis is an effective and safe procedure. Nonetheless, it has the risk of increased blood loss during surgery, increased hospital stay and more serous secretions through the drains compared to robotic surgery in patients without prior radiation therapy.

ABSTRACT PRESENTER:

Salem Billan


Veronique Bakouche, Roxolyana Abdah-Bortnyak

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Outcome of patients with nasopharyngeal carcinoma treated with reduced volume conformal radiotherapy

BACKGROUND :

Optimal target volumes for primary nasopharyngeal tumor are the subject of debates. Reduced volume of high dose irradiation in modern radiotherapy may reduce the treatment-related side effects without compromising of outcome. The purpose of study was to compare dosimetric parameters of primary tumor volumes for patients with nasopharyngeal carcinoma treated according to institutional protocol and RTOG guidelines and to evaluate the outcome


36 treatment plans of patients with nasopharyngeal carcinoma treated between February 2007 and March 2014 were viewed retrospectively. Planning target volume for 50 Gy to primary tumor included the gross tumor, and entire nasopharyngeal mucosa with 0.5 cm margins. Delineation of primary tumor according to RTOG 0615 guidelines was done for each case for hypothetical comparison. PTV 50 volumes were compared with RTOG 0615 PTV 59.4-P (59.4 Gy to primary tumor). Outcome analysis was performed.

RESULTS:

Median follow-up was 48 months (range 21-108 months). Median volume of PTV 50 was: 209.0 cc, range 92.6 -568.0 cc. Median volume of RTOG 0615 PTV 59.4-P was: 279.7 cc, range 123.6-425.1 cc. Isolated local relapse as first site of recurrence occurred in 5 patients (14%): 2 patients with stage III, 2 with IVA and 1 with IV b disease; all had advanced local disease at initial diagnosis. All local recurrences occurred in the PTV 69-70 region.

CONCLUSIONS:

Use reduced volume technique for primary nasopharyngeal tumor provided acceptable long term local control.

ABSTRACT PRESENTER:

Erez Beiser


Erez Beised, Viacheslav Soyfer*, Ilia Novikov, Ido Wolf and Benjamin W. Corn

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Impact of Clinical Emergency Status on Prioritization of Radiotherapeutic Management

BACKGROUND :

Radiation therapy, an effective treatment for spinal cord compression, is ideally initiated within 48-hours from diagnosis. Conventional fractionation implies 5 daily treatments per week. Indeed, most departments of radiation oncology are closed for the weekend. The incidence of spinal cord compression is expected to be distributed equally throughout the days of the week. Several investigators reported the pattern of daily distribution of treatment initiation. Concern has been raised about the spike in emergent referrals for radiotherapy on the last day preceding the weekend (US: Friday; Israel: Thursday). We sought to determine the pattern of emergent referral for radiotherapy and initiation of treatment in our Israeli facility.


We evaluated 155 hospitalized patients admitted to our institution with a diagnosis of spinal cord compression between 2013-2015. Our coding entailed matching between the hospital records and the electronic charts of the department of radiotherapy (Mosaiq, Aria systems). Statistical analyses were performed using the Exact binomial test.

RESULTS:

There were 71 women and 84 men studied. The median age of the patients was 65. The distribution of the referrals for the treatment of spinal cord compression throughout the week was as follows: Sunday 18.52%, Monday 18.52%, Tuesday 22.22%, Wednesday 13.89%, Thursday 20.37%, Friday 6.48%. Initiation of treatment was as follows: Sunday 16.13% , Monday 12.26%, Tuesday 20.00%, Wednesday 16.13%, Thursday 32.26% , Friday 2.58% %,Saturday 0.65% .

CONCLUSIONS:

We confirmed that there is a significant spike in treatment of spinal cord compression on Thursdays relative to other weekdays at our hospital and a marked decrease in emergent treatments on the weekends. The problem was compounded by the fact that a moderate number of patients referred on Wednesdays were not treated until Thursdays. We believe that efficiency of initiating treatment for spinal cord compression is a meaningful index of quality. We have devised measures to improve the outcome cited herein and encourage other Israeli institutions to conduct a similar analysis. Prioritization of the treatment of medical emergencies is a viable indicator of quality and must be continually improved.

ABSTRACT PRESENTER:


CURRENT SUBMISSION:

Updating Submitted Abstract


RADIOTHERAPY

HEADLINE:

A dosimetric comparison between conformal radiotherapy using classic anatomical landmark vs VMAT in rectal cancer.

BACKGROUND :

Common lymphatic drainage site for locally advanced rectal cancer (LARC) includes the internal iliac, presacral and perirectal lymph nodes. Traditionally rectal cancer radiation therapy (RT) uses a bony land marks fields in order to cover the prescribed lymph nodes. The anterior border of the lateral fields are 2-3 cm anterior to sacral promontorium, may miss a good coverage of the internal iliac lymph nodes. The aim of the study is to investigate if bony land marks border, sufficiently covers the internal iliac nodes and to compare tumor volume coverage, conformality and normal tissue avoidance using classic bony landmarks (c3DCRT), contoured elective clinical target volume (f3DCRT) and volumetric modulated arc therapy (VMAT) in LARC.


CT datasets of 11 patients with LARC who had completed treatment in c3DCRT were evaluated. The elective clinical target volumes and organs of risk were contoured and f3DCRT, VMAT plans were generated for all pts. Planning target volume (PTV) and gross tumor volume (GTV) coverages used in our clinic, are V42.67Gy

RESULTS:

The mean PTV 95 coverages were significantly low for c3DCRT plans while the lymph node coverage was better for f3DCRT. No difference was found in PTV coverages between of f3DCRT and VMAT plans . No significant difference was found for organs at risk constraints i.e. bladder and small bowels. It is verified that by using c3DCRT, the anterior border of the lateral fields are 2-3 cm anterior to sacral promontorium miss's coverage of the internal iliac lymph nodes or exposes smaller bowel compared to f3DCRT

CONCLUSIONS:

f3DCRT planning improves tumor volume coverage without significant difference in doses to critical structure. This planning with contoured elective clinical target volume may improve the clinical outcome in LARC hence, needs further treatment evaluation.

ABSTRACT PRESENTER:

Dimitri Bragilovski


D.Bragilovski MSc, A.Jarufi, G.Heldenberg Wilf, S. Gardin BSN, D. Limon, B. Brener MD Prof., MD, A.Popovtzer MD, T.Weiss MD , E. Fenig MD Prof

CURRENT SUBMISSION:



RADIOTHERAPY

HEADLINE:

Implementing Electronic Medical Record for Radiation Oncology at Davidoff Cancer Center

BACKGROUND :

In Oct. 2015 our department performed a conceptual transformation and moved to work in a paperless form ,we expected this change to have a large impact on the routine work of a radiation oncology department in many ways: The ability to readily access information wherever and whenever needed, without compromising safety, treatment quality, confidentiality, productivity at radiotherapy department and interaction with other departments .The goal of this study is to review the impact of this change on the departments flow did the update of Oncology Information System (Aria), we decided to move our department to be paperless in the beginning of 2017. In December 2016 we initiated the process of conversion to an electronic medical record (EMR) eliminating the need for paper charts. Key goals included the ability to readily access information wherever and whenever needed, without compromising productivity at radiotherapy department and any else unit at the Hospital.


In early, 2015, we formed a multi-disciplinary team of Radiation Oncology physicians, nurses, therapists, administrators, physicists, and information technology (IT) specialists. The team identified all existing processes and associated information/reports, established the framework for the EMR system and generated, tested and implemented specific EMR processes. In December 2015 we initiated the process of conversion of Radiotherapy unit to paperless.

RESULTS:

Two broad classes of information were identified: 1) Information which must be readily accessed by anyone in the health system. 2) Information that used solely within the Radiation Oncology department. To manage the Global patient information, we utilized the "Chameleon", which required a development of procedures that need to be applied at Radiotherapy department. Radiation Oncology data, managed by our updated system (ARIA, Varian Medical Systems.) The work flow was coordinated by Aria's Care path. The ability to access both systems simultaneously from a single workstation (WS) was essential. As of 1st January, 2017, all new treatments were managed solely with an EMR. The EMR made information more widely accessible without compromising the patients safety, treatment quality, or confidentiality. However, compared to paper charts, time required by clinicians to access/enter patient information has substantially increased. This had no effect on the amount of patients treated between January to July 2016 which was not significantly different than 2015, 1631 vs 1478 .Nor did the amount of patient per machine. In general we have noticed a learning curve in the productivity, substantial growth will require better integration of the system components, decreased access times, and improved user interfaces. One year after conversion to an EMR, most of the department staff favored the EMR over the previous paper charts.

CONCLUSIONS:

Successful implementation of a Radiation Oncology EMR is feasible; however it requires not only the effort and commitment of all functions of the department, but support from senior health system management, corporate IT, and vendors. Realization of the full benefits of an EMR will require experience, faster/better integrated software, and continual improvement in underlying clinical processes.

ABSTRACT PRESENTER:

Amineh Khatib Hamad


A, Khatib Hamad, MSc, D. Bragilovski MSc, Y. Krutman, PhD, S. Koren, PhD, E. Fenig MD Prof

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Commissioning of OSLDs and their implementation into the clinic for in vivo dosimetery for TSEI patients

BACKGROUND :

Total Skin Electron Irradiation (TSEI) was introduced into our clinic about a year ago. Due to the fact that the expected vertical uniformity is ±8% which translates to ±15% at the patient due to variable skin distances (1), there is a need for accurate in vivo dosimetry. Also since the patient is rotated on a stand, it is preferable that the system is wireless. Optically Simulated luminescent Dosimeters (OSL) with Aluminium oxide carbon doped were commissioned and implemented for this purpose.


The energy used in the TSEI treatment is the 9HDTSE with a dose rate of 2500 mu/min. At the patient level the energy drops to 4MeV with a dmax of 4mm, thus dose is deposited at the skin. Upon receipt of the OSLD's (Landauer) the system was set up and two sets were radiated with 6MV beam as per the recommendation of the company. A linear and a nonlinear curve were established. A set of calibration and constancy OSLDs with known doses are used to QA the system. The performance of the OSLDs such as fading, linearity and reproducibility were checked prior to introducing them into the clinic. Also a QA procedure for their monthly and annual QA developed in application to TSI. On average 18 OSLDs were used per patient. They were placed on the patient skin on different anatomical sites in order to be able to estimate areas of under or over doses. Upon reading the OSLDS a table of results was presented to the physician. Appropriate boosts were planned accordingly.

RESULTS:

The OSLDs cannot be read directly after radiation. It was found that an hour at least should pass prior to reading for more accurate results. The electrons trapped in shallow levels can still escape and contribute to dose. Two calibration curves were established for the linear range from 0 to 300cGy and non linear range for doses up to 1300cGy. Fig 1: Non linear curve Reuse of the OSLDs is practiced at our clinic and this is done with the annealer provided by Landauer. Prior to deleting the OSLD is read, placed into the annealer which has a light source. The OSLD is exposed for 25 to 30 seconds depending on the dose it was exposed to. The OSLD read after annealing reaches down to 5 cGy A table representing the data measured for each patient for each session was created and inserted into the ARIA documents for documentation of dose receieved.

CONCLUSIONS:

The OSLDs are easy to handle and convenient for this sort of treatment. It allowed a good source of reevaluation of the patient treatment as this modality is very clinical and results are seen as the treatment progresses. A daily, monthly and annual QA procedures are a good integration of the while QA system at out clinic. Patients were radiated with single electron fields to boost the under dosed areas.

ABSTRACT PRESENTER:

Yariv Orly


Yariv Orly, MD, Nachalon Yuval, MD, Limon Dror, MD, Moore Assaf, MD, Popovtzer Aron, MD

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

THE OUTCOME OF RADIOTHERAPY FOR THE TREATMENT OF LARYNGEAL SQUAMOUS CELL CARCINOMA IN THE VERY ELDERLY POPULATION.

BACKGROUND :

Radiotherapy is a well-established treatment for laryngeal squamous cell carcinoma. Despite its rising incidence, data regarding the outcome of this treatment modality in the very elderly population are scarce.


A retrospective chart review study was conducted in the Davidoff Cancer Center. Elderly patients (age >85 years) with squamous cell carcinoma of the larynx treated with radiotherapy with or without surgery were included in the study. Demographic and clinical data were collected from patients’ files.

RESULTS:

Twenty seven patients diagnosed between 2000 and 2012 were included in the analysis. Two females and twenty five males, with median age at diagnosis of 87 years (range, 85-97). Median radiotherapy dose was 60 Gray given in 25 fractions. Stage at diagnosis was I, II, III, IVA in 26.5%, 17.6%, 14.7% and 17.6%, respectively. There were two perioperative deaths. None of the patients had a recurrence, no patient discontinued treatment due to toxicity and there was no radiotherapy related mortality. The median overall survival was 2.24 years (range, 0-9).

CONCLUSIONS:

Laryngeal cancer in very elderly patients has similar demographic and clinical characteristics to general population. Our results imply that modern radiotherapy in standard fractionation is both an effective and safe treatment modality for laryngeal squamous cell carcinoma in the elderly population. Considering the high rate of comorbidities in this population, it may sometimes be the only viable treatment modality. Further, large scale – comparative studies are highly required.

ABSTRACT PRESENTER:

Eli Sapir


Yebin Tao, Julles Lin, Laura Kolla, Mathiew Schipper, Rashmi Chugh, Scott M. Schuetze, J.Sybil Biermann, Theodore S. Lawrence, Mary Feng

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY,Sarcoma

HEADLINE:

SBRT or Surgery for pulmonary metastases in sarcoma

BACKGROUND :

Aggressive management of oligometastases from sarcoma can result in long-term survival and a chemotherapy-free holiday. Surgical resection is considered to be the treatment of choice, with stereotactic body radiotherapy (SBRT) generally offered to patients who are not candidates for surgical resection due to co-morbidities or concern about residual lung function. We examined outcomes of resection and SBRT for patients with sarcoma oligometastases at our institution and identified predictive factors for local control, with the hypothesis that overall local control would be similar.


After IRB-approval, we queried our institutional thoracic surgery and radiation oncology databases, supplemented with an institutional query using diagnosis and billing codes for sarcoma, lung metastases, lung resections, and SBRT. We applied inverse probability of treatment weighting to adjust for imbalances in treatment assignment. Freedom from local progression (FFLP) for surgical resection was defined as absence of recurrence at the resection line, while FFLP for SBRT was defined as the absence of progression within or at the PTV margin

RESULTS:

Between 1997 and 2014, 78 patients (pts) with 127 lung lesions were treated with surgical resection and 26 pts with 47 pulmonary metastases were ablated with SBRT. Median tumor size was 1.5 cm (0.1-12.8) and 1.4 cm (0.4-4.8), respectively, for surgically and SBRT-managed pulmonary metastases. Median follow-up was 20.9 months (1 to 224) and 15.3 months (2 to 57) for patients treated with surgical resection and SBRT, respectively (P =0.01). On average, pts in the SBRT group were older (age 60 v 52, P =0.03), had received more prior systemic therapies (1.98 vs. 1.29, P=0.01) and had a higher presence of active extrathoracic disease at treatment start (59.6% vs. 29.9%, P

CONCLUSIONS:

In this series SBRT provides similar LC, PFS, and OS compared with surgical resection of lung metastases from sarcoma, and thus may serve as a safe alternative to surgical resection. A randomized, prospective study is required to determine if there is comparable long-term survival with SBRT vs. surgery for treatment of sarcoma lung metastases.

ABSTRACT PRESENTER:

Eli Sapir


Tao Yebin, Schipper Mathew, Bazzi Latifa, Novelli Paula, Devlin Paulina, Owen Dawn, Cuneo Kyle, Lawrence Theodore, Parikh Neehar, Feng Mary

CURRENT SUBMISSION:

New Submission


GI,RADIOTHERAPY

HEADLINE:

SBRT as an Alternative to TACE in HCC

BACKGROUND :

There is little data to guide non-surgical treatment selection for patients with HCC. Therefore, we carried out a single institutional comparison of transarterial chemoembolization (TACE) and SBRT outcomes in a similar group of patients


From 2006 to 2014, 209 patients with 1-2 tumors underwent TACE (n=84) to 114 tumors or image-guided SBRT (n=125) to 173 tumors. Propensity score analysis with inverse probability of treatment weighting was used to compare outcomes between treatments while adjusting for imbalances in treatment assignment. Local control (LC), toxicity, and overall survival (OS) were retrospectively analyzed.

RESULTS:

TACE and SBRT groups were similar with respect to the number of tumors treated per patient, underlying liver disease and baseline liver function. Patients treated with SBRT were older (65 vs 61 yrs, p=0.01) and had smaller tumors (2.3 vs 2.9 cm, p

CONCLUSIONS:

SBRT is a safe alternative to TACE for 1-2 tumors, and provides better LC, with no observed difference in OS. Prospective comparative trials of TACE and SBRT are warranted.

ABSTRACT PRESENTER:

DIRK BARTKOSKI


,MOHAMMAD SALEHPOUR, DROR ALEZRA

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

APPARATUS AND METHODS FORMAGNETIC CONTROL OF RADIATION ELECTRON BEAM

BACKGROUND :

New developments in particle accelerator technology have opened innovative approaches to external beam radiation therapies, particularly in area of electron therapy. The shallow penetration depths of current electron modalities may be expanded to include the full range of clinical depths >50 cm with the use of very high energy electrons in the range of 100-250 MeV. The work presented will outline the further development of a delivery system to produce magnetically optimize very high energy electron therapy (MOVHEET) beams as a result of a collaboration between MD Anderson Cancer Center and The Chaim Sheba Medical Center.


This method uses and array of magnets to dynamically modify the electron beam in order to produce dose peaks with >50% reduction in entrance dose. Furthermore, new magnetic techniques will be presented that expand the application of MOVHEET with emphasis on converging beams from strong-focusing magnets.

RESULTS:

These techniques allow for dose painting with variable depth dose peaks with reduced posterior radiation tails compared with photons and the ability to produce spread-out regions of dose similar to Bragg peaks in proton therapy.

CONCLUSIONS:

It is the goal of the work to introduce a new modality of treatment with benefits similar to that of protons with significantly reduced cost and space.

ABSTRACT PRESENTER:

Mrs Orit Arsenault


Aron Popovtzer MD [email protected] Dimitri Bragilovski [email protected]

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY,Head and neck

HEADLINE:

Comparison between 3 different techniques for Larynx treatment planning

BACKGROUND :

Conventional parallel-opposed radiotherapy (PORT) is the considered the standard technique for early-stage glottic carcinoma. However it has been suggested that the implementation of more modern methods such as intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). May allow the sparing of organs at risk (OAR) including the carotid artery, thyroid gland, submandibular gland , and the remaining functional larynx. Others suggest that the field is small and in contrast may have a negative effect on the spinal cord dosage .In this study we sought to evaluate this dilemma


Ten patients with early stage glottic cancer(T1,T2) were evaluated .All were planned in 3 methods ,PORT ,, IMRT & VMAT. In all cases the coverages was planned to 95% coverage of the 95 % of the PTV .All plans were planned by Varian's Eclipse treatment planning system,6MV for Truebeam with HD-MLC.

RESULTS:

The Dose volume histogram (DVH) of all OAR was calculated and a comparison of the mean dosage was performed .We compared the conformality of treatment and average expected treatment time .Results :The mean dose of the carotid artery was20 x for the vmat & for IMRT and 40 for the PORT. The conformality was superior in the VMAT.The treatment time was shortest for PORT and longest for IMRT

CONCLUSIONS:

In this study we demonstrated the potential advantage in the implementation of modern treatment planning for early stage glottic carcinoma ,including improvement in the DVH of OARS as well as improvement of the conformality .However long-term clinical data are lacking, and there still exists s a significant chance of geographical miss due to setup error or swallowing motion. Therefore further clinical studies are necessary before reaching final conclusions

ABSTRACT PRESENTER:

LIAT HAMMER


Liat Hammer, David Hausner, Ofir Morag, Dror Alezra, Maoz Ben Ayun, Lev Tsvang, Akram Saad, Tamar Katzman, Kinneret Shefer, Talia Golan, Zvi Symon, Yaacov R. Lawrence

CURRENT SUBMISSION:



GI,RADIOTHERAPY,Supportive & Palliative care

HEADLINE:

Celiac Plexus Radiosurgery a new modality for cancer pain management – interim analysis of a pilot clinical trial

BACKGROUND :

Many patients with pancreatic cancer suffer from a characteristic syndrome of severe lower back pain radiating to the epigastrium, thought due to celiac plexus invasion. Contemporary approaches (opioids, celiac blocks, systemic chemotherapy) are often inadequate. This single-institution prospective clinical trial evaluated a unique and novel therapeutic approach: stereotactic radiotherapy focused on the celiac plexus, NCT02356406.


Eligibility criteria included typical celiac-pain syndrome, significant pain despite opioid usage (Numerical rating scale > 4/10), prognosis > 8 weeks, ECOG 0-3. Exclusion criteria included previous abdominal radiation. Target volume encompassed the celiac plexus from D12 to L2, along the anterolateral aspect of the aorta. Radiation dose was originally 9 Gy*5, but later amended to a single fraction 25 Gy. The primary endpoint was pain relief 3 weeks post-treatment. Secondary endpoints included pain at 6 weeks, analgesic use, toxicity (CTCAE v4.03), and quality of life. Evaluable patients were defined as those completing treatment per protocol and completing at least one post treatment assessment.

RESULTS:

Seventeen subjects were eligible and underwent SBRT to the celiac plexus, median age 61 years, (range 37-83). Median ECOG was one. Fourteen patients had pancreatic cancer, two gastric-duodenal cancer, and one colon cancer. Six patients were non-evaluable (did not complete treatment, eligibility violation, or not complete post-treatment evaluations). Eleven patients were evaluable, three received 9Gy*5, eight received 25Gy*1. Toxicity was minimal, and limited to grade 1-2 (two patients reported mild worsening of pain immediately following treatment, some limited nausea/vomiting). All patients reported decreased celiac pain: median pain level prior to RT was 6/10 and was reduced to 1.5/10 NRS score (p

CONCLUSIONS:

Celiac plexus radiosurgery appears feasible, well tolerated and effective. Accrual to the trial is ongoing and a multi-center clinical trial planned.

ABSTRACT PRESENTER:


Sion Koren, Ziv Medical Center, Safed, Israel Alain Guemnie Tafo, Gustave Roussy Cancer Center, Paris, France Gilad Cohen, Memorial Sloan Kettering Center Center, NY, New York, USA

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

A Brachytherapy patient specific QA using the ArcCheck- a cylindrical diode array.

BACKGROUND :

Recently procedures of hypo-fractionated treatments using HDR brachytherapy is more common in radiation oncology centers. The use of HDR for prostate treatment with a single fraction as a boost or as an 18 Gy monotherapy are performed using ultrasound image guidance with updated TPS. PDRs are performed using a custom applicator with several catheters. As required, the source air KERMA is constantly measured using well chamber, but the spatial dose distribution for different applicators and treatment modalities is not to be examined. We are suggesting the use of the ArcCheck central void as a nest for HDR and PDR applicators for the usage of patient specific QA and as a tool in applicator commissioning procedures.


3 Applicators were placed in the ArcCheck empty plug hole. We have conducted a CT scan and reconstructed the catheters using TPS. We have applied a split ring and tandem applicator plan on the catheters using the dwell times and positions. The HDR plan was then delivered and a dose was scored. For absolute calibration, a common dose calibration procedure was done using a single catheter in a single dwell position that exposed the diodes participating in the calibration procedure to a recalculated dose.

RESULTS:

A two dimensional gamma analysis was applied. All correction factors were disabled, as they set for external beam purpose. A relative Gamma analysis with 3% dose difference (local) 3mm distance to agreement showed a 81.4% passing rate. By applying the dose calibration file we have received a 90.2% passing rate for 2% 2mm Gamma.

CONCLUSIONS:

We have demonstrated the feasibility of the ArcCheck to perform patient specific QA for HDR and PDR Brachytherapy procedures. The ArckCheck is found suitable for daily QA procedures and applicator commissioning. A strict sub millimeter distance to agreement is needed for Brachytherapy patient specific QA. An Ir-192 dose calibration routine is needed for the ArcCheck, taking into account the low energy photons over response when measuring with diodes.

ABSTRACT PRESENTER:

Aron Popovtzer


Inbal Hazkani,Itzhak Haviv,Irit Ben-Aharon ,Leon Lubimov,Dimitri Bragilovski ,Menachem Motiei,Rachela Popovtzer,Aron Popovtzer

CURRENT SUBMISSION:

New Submission


TRANSLATIONAL RESEARCH,RADIOTHERAPY,Head and neck

HEADLINE:

The impact of molecular profiling guided targeted gold nanoparticles on radiosensitivity of metastatic salivary gland Adenoid Cystic Carcinoma

BACKGROUND :

Molecular Profiling has an established role in selection of treatment for metastatic disease, however its role in improving radiosensitivity and improving functional imaging has not been evaluated .The main goal of this study was to evaluate the role of molecular profiling as a method to target gold nanoparticles (GNP) in order to enhance radiosensitivity. A second goal was to evaluate the role of molecular profiling as a tool to improve our functional imaging abilities .We have chosen a metastatic Adenoid Cystic Carcinoma (ACC) tumor as a model


16 nude mice were implanted with human parotid ACC found to have an Anaplastic Lymphoma Kinase (ALK) receptor mutation .The mice were treated with radiation, Crizotinib, GNP and radiation , and GNP conjugated to Crizotinib with radiation, and followed for four weeks.

RESULTS:

We demonstrated that ALK targeted GNP enhanced the radiation effect and had a significant impact on tumor growth (P

CONCLUSIONS:

Molecular profiling for targeting GNP can serve as a method to enhance radiosensitivity and improve imaging in salivary gland ACC

ABSTRACT PRESENTER:

sarit appel


DR ZVI SYMON DR JEFFRY GOLDSTEIN MAOZ BEN AIYUN DR RABIN TANIA

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Non-small cell lung cancer invading the vertebra: what is the optimal strategy for radiation?

BACKGROUND :

Non-small cell lung cancer that invades the vertebra (T4) may cause significant morbidities if uncontrolled locally with limited options for salvage re-irradiation. The spinal foramina and vertebral body are sites of potential tumor invasion and sparing them may compromise local tumor control probabilities. In our institution, we incorporated the strategy of including the entire vertebra and the spinal canal to the allowed dose in two strategies: shrinking fields and integrated boost. We hypothesized that treating with integrated boost including the spine canal and the vertebral body will result in higher tumor BED than treatment with shrinking fields with off spine boost.


we retrospectively reviewed 14 cases that were T4 and treated with radiation therapy in our institute and included the spine and vertebra, during the years 2013-2016. We searched the radiation plans for mean dose to GTV, spine and fraction size. We calculated the biologically effective doses (BED) per the linear quadratic model, for the GTV using α/β=10 and for the spine using α/β=3. In the shrinking fields two calculations were done for each step

RESULTS:

1. Shrinking field: median prescription dose was 59 Gy (55-66Gy) in 2 Gy per fraction in 29(26-33) fractions Median GTV dose was 61.3 Gy (57-68.7Gy). The maximal dose to spine with the composite planes, including the exit dose from the boost plan was median of 50.6 Gy (48.4-53.5Gy). Median BED to PTV was 71Gy (68.1-79.2Gy) GTV was 74.3 Gy (66.6-83 Gy) and to the spine was 82.2 Gy (75.3-86.4Gy) 2. Integrated boost: median prescription dose was 61.6 Gy (54-66) in 2.21 Gy per fraction (1.96-2.28Gy) in 28 (28-33) fractions. The median GTV dose was 62.6 Gy (55-64.7 Gy). The median maximal dose to the spine was 50 Gy (47.8-52.7Gy), in 1.8 Gy per fraction (1.6-1.9Gy). Median BED to PTV was75.2 Gy (64.8-79.2Gy) GTV was 76.4 Gy (66.6-78.5Gy), and the median BED to the spine 79.2 Gy (75-85.9Gy).

CONCLUSIONS:

Integrated boost strategy resulted in modestly higher BED to the PTV and GTV than shrinking fields, and lower BED to the spine, thus safer. Thus, the integrated boost strategy should be preferred.

ABSTRACT PRESENTER:

Lev Tsvang


L. Tsvang1; A. Dubouloz2; A. Dror1; T. Zilli2; R. Miralbell2; Z. Symon1 1Chaim Sheba Medical Center, Department of Radiation Oncology, Ramat Gan, Israel; 2Geneva University Hospitals, Department of Radiation Oncology, Geneva, Switzerland

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Meeting dose objectives in Stereotactic Body Radiation Therapy for prostate cancer : water vs. air filled endorectal balloon?

BACKGROUND :

To compare the achievement and cost of dose objectives defined for a European multicenter phase II trial of urethra-sparing SBRT using a water vs. air filled endorectal balloon (ERB) .


Ten patients simulated with a 100cc filled ERB for prostate SBRT were analyzed. Hounsfield units in the balloon were adjusted for comparison of air and water. Prescription to the PTV was 36.25 Gy in 5 fractions of 7.25 Gy. The urethral dose prescription (urethral planning risk volume, uPRV) was 32.5 Gy. Treatment plans were optimized using volumetric intensity-modulated arc treatment (VMAT) technique (RapidArc, Eclipse, Varian) and dose was delivered with two arcs. We hypothesized that the optimization algorithm would perform better with water-filled EBR vs. air due to homogeneity of tissue density. Thus, two optimizations were run for each air-filled balloon: one with the same objective template as water and a second improved optimization (IO) which drives improved PTV coverage. The plans were compared for following parameters according to the research protocol: PTV98%, PTV95%, PTV2%, PTV-Rectal wall intersection PTV-R 98%, PTV-R2%, PTV-Rmean, RwallDmax, Rwall100%, Rwall90%, Rwall80%, Homogeneity Index HI PTV-R.

RESULTS:

The goal of PTV 98% covered by the 95% prescription dose was achieved for all water filled ERB and only 60% of air filled ERB (p=0.02, chi2). Improved optimization (IO) for air achieved the goal in 80% of air filled ERB. The PTV-R98% (representing overlap of anterior rectal wall and PTV) dose coverage was significantly less for air vs. water: 89.9%±1.6 vs. 94.4%±1.6 (p

CONCLUSIONS:

Water filled ERB provide superior PTV coverage than air at the cost of exposing a greater volume of rectal tissue to doses above 100% of the prescription dose. Strategies to improve PTV coverage for air filled ERB succeed in most patients, yet will increase dose to the anterior rectal wall. The clinical impact of exposing minute volumes of rectal wall to ultra-high doses is unknown and will be clinically correlated with longer follow-up of patients treated in this protocol.

ABSTRACT PRESENTER:

Maoz Ben Ayun


CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Mobius 3D/FX Software for 3D/Dynamic Plans Verification; Sheba Experience

BACKGROUND :

Mobius 3D (v2.0.1) is QA software performing 3D/dynamic treatment plan verification. M3D uses independently developed collapsed cone (CC) convolution /superposition (CS) algorithm which makes it suitable for wide range of treatment techniques. Further to the approval of the plan in the treatment planning system (TPS), DICOM files are pushed from the TPS to the M3D software. The M3D starts calculating automatically, including evaluation of 3D gamma test, dose volume histograms (DVH), monitor units (MU), and region of interest (ROI) overview. By using the Mobius FX add-on module, one can import the treatment log data created by the Linac during delivery of a pre-treatment fraction of the plan, and perform 3D/IMRT/Vmat QA of the delivered plan. In addition, the Mobius FX treatment summary screen displays an interactive analysis of the delivered dose over the all course of the patient treatment.


We used the Mobius system on TrueBeam accelerator equipped with millennium mlc, and Novalis accelerator equipped with HD mlc. We have validated the Mobius system by increasing degree of complexity from 3D plans to modulated plans using a homogeneous phantom and heterogeneous CT slices (patients CT). Over 150 different treatment plans (3D+IMRT/Vmat) were analyze with M3D/FX software

RESULTS:

MU differences between the Eclipse TPS and Mobius were up to 0.5% for 3D conformal plans, Gamma passing rate (3%-3mm) was above 99% for most of the plans. For dynamic plans(Vmat,IMRT),MU differences were up to 2.0% and Gamma passing rate (3%-3mm) was above 97.5% for most of the plans. When using the MobiusFX software, the delivered 3D dose was re-calculated using log files of the patient's CT and compared directly with the prescribed treatment plan for every fraction. Gamma passing rate (3%-3mm) was above 97% for most of the treatment fractions

CONCLUSIONS:

M3D/FX is an accurate and reliable software for examination and evaluation of calculated 3D/dynamic plans and can easily be adopted as a second independent calculation as part of the physicist QA check to this kind of treatment plans; However to verify dynamic plans before treatment, we still believe there is an uncompromised need to use conventional IMRT QA methods by measuring the dose distribution in a dedicated phantom

ABSTRACT PRESENTER:

Uri Amit


U. Amit, J. D. Goldstein, T. Davidson, M. Hahiashvili, E. Goshen, Y. Oksman, R. Berger, A. Saad, I. Sadetsky,N. Weizman, B. Chikman, Y. R. Lawrence, S. Ben-Haim, and Z. Symon

CURRENT SUBMISSION:

New Submission


GU,RADIOTHERAPY

HEADLINE:

The Role of Prostate Specific Membrane Antigen (PSMA) PET/CT in the Management of Patients with Prostate Cancer: Implications for Selection of Patients for Radiation Therapy

BACKGROUND :

Gallium-68 - Prostatic Specific Membrane Antigen (PSMA) PET/CT has been recently introduced for the assessment of patients with prostate cancer. Advantages with the use of PSMA compared to other functional imaging agents include selective uptake in patients with high Gleason score and low dependency on serum PSA level. Few studies have reported its value in disease management. We report our initial experience with PSMA PET/CT imaging on disease management in patients with biochemical failure or metastatic disease.


Seventy patients, mean age 71 years (range 54-90), who were referred for PSMA PET/CT for staging (n=6), biochemical failure (n=44) or evaluation of known metastatic disease (n=20) were included. Mean Gleason score: 7.6 (range 6-10) and mean PSA: 11.2ng/ml (range 0.04-129). The initial pre-scan therapy plan and revised post-scan recommendations were documented according to National Comprehensive Cancer Network (NCCN) guidelines. Effects on radiation therapy planning and treatment were recorded.

RESULTS:

PSMA-PET/CT was positive in 54/70 pts. (77.1%; SUV max 10.7+8.8). Abnormal findings were in the: prostate (n=16; 29.6%), prostate fossa (n=5, 9.3%), lymph nodes (n=29; 54%), bone (n= 25; 46%), and liver or lung (n=3; 6%). Positivity was dependent on PSA level: PSA 5ng/ml: 31/31(100%). PSMA PET/CT changed clinical management in 4/6 (67%) patients at initial staging, in 29/44 (66%) patients with biochemical failure and in 1/20 (5 %) patients with known metastatic disease. Changes included: Androgen Deprivation Therapy (ADT) to local therapy with salvage radiation for oligo-metastatic disease, and in 1 case definitive treatment (n=13), ADT to observation (n=8), local therapy to ADT (n=6), change in radiation therapy plan (n=5), local therapy to observation (n=1), and observation to ADT (n=1).

CONCLUSIONS:

PSMA PET/CT had a significant impact on clinical management in 66% of prostate cancer patients referred for staging or initial biochemical failure but had little benefit when used for management of known metastatic disease (5%). The use of PSMA imaging for staging in patients referred for radiation therapy improved selection of treatment volumes and dose. Patients with biochemical failure were offered expanded treatment options that included salvage SBRT for oligo-metastatic disease.

ABSTRACT PRESENTER:

Noam Weizman


N. Weizman, K. Baidun, A. Goldstein, U. Amit, Y. Lawrence, S. Appel, M. Benayun, S. Dubinski, I. Orion, D. Alezra, H. Gnessin, Z. Symon, and J. D. Goldstein

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY,Breast,LUNGS

HEADLINE:

Effects of Continuous Positive Airway Pressure (CPAP) used for Respiratory Motion Management in Patients Receiving Chest Radiation to the Heart: An Analysis of Size, Position, and Motion

BACKGROUND :

CPAP used during radiation treatment reduces tumor motion and expands lung volume. CPAP’s effect on size, position and motion of the heart has not been reported previously. We hypothesized that the physiologic effects seen with use of CPAP: expansion of the thoracic cavity caused by reduction of motion and flattening of the diaphragm as well as decreased venous return to the heart, affects cardiac parameters important for radiation treatment. We measured the effects of CPAP on the heart in a cohort of patients receiving radiation therapy for lung tumors.


IRB approval was given in December 2013. Patients with primary or secondary lung tumors underwent 4D CT simulation twice using identical positioning with free breathing and with CPAP. The heart was contoured according to RTOG guidelines on all 3D and 4D CT imaging studies. The TPS was used to co-register all scans using the vertebral bodies for fusion and to measure and compare changes in the size, center of mass and excursion of the heart and lung. Wilcoxon signed rank test was used to assess differences between variables.

RESULTS:

Studies were reviewed from 9 patients. CPAP use decreased mean heart size on 3D and 4D scans by 6% (95% CI: 2%-8.5 %, p

CONCLUSIONS:

The use of CPAP decreased heart size, shifted heart position caudally, reduced heart motion and increased total lung volume. The increase in total lung volume was correlated with the changes observed in position and motion of the heart. CPAP should be evaluated further as a novel cardiac motion management strategy to reduce heart exposure when offering radiation therapy.

ABSTRACT PRESENTER:

J. D. Goldstein


T. Davidson, M. Ben-David, S. Galper, T. Haskin, M. Howes, R. Scaifed, N. Kanana, U. Amit, N. Weizman, B. Chikman, E. Goshen, S. Ben-Haim, Z. Symon, and J. D. Goldstein

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY,Breast

HEADLINE:

The Use of PET-CT Imaging to Determine Internal Mammary Lymph Node Involvement and Location for Radiation Therapy Treatment Planning in Breast Cancer Patients

BACKGROUND :

Adjuvant internal mammary lymph node (IMN) radiation has been delivered using 2D techniques which specify predetermined depths for dose prescription and anatomical landmarks for field placement. Conformal 3D techniques use the internal mammary vessels (IMV) to localize the IMN. We evaluated if use of FDG PET-CT to localize involved IMN (i-IMN) may improve treatment planning.


PET-CT images from breast cancer patients (n=80) at staging (n=40) or recurrence (n=40) were studied. I-IMN size and location were recorded. I-IMN coverage using 2D planning was evaluated using depths of 2-6 cm for dose specification and sternal midline or edge for field placement. 3D planning was evaluated using 4 different IMN-CTV’s created by contouring the IMV from the 1st IC to the 3rd or 4thIC space ± 0.5cm medial/lateral IMV expansion.

RESULTS:

I-IMN at time of recurrence were more common on the left (39) than right (21) (p=.045).All i-IMN were ipsilateral. Most (98.2%) were within 5cm of sternal midline: 88.4% were adjacent or lateral and 11.6% were posterior to the sternal edge. Geographic miss or excess normal tissue exposure were dependent on selection of the sternal border used for field placement. Mean depth from the skin surface was 3.4cm (range: 1.1cm-7.3cm). Prescriptive depths of 4cm, 5cm and 6cm resulted in geographic miss of 25%, 10.7%, and 5.3% respectively. Most i-IMN were in the1st-3rd (94.6%) IC space. Few were in the 4th (4.5%) or 5th (0.9%) IC. Most i-IMN (83%) were adjacent to the IMV. 14% were ≤0.5 cm and 3% were >0.5cm beyond the IMV edge. The IMV-CTV defined by the 1st – 3rd IC encompassed 78% of i-IMN. I-IMN coverage increased with: margin expansion (93%), inclusion of the 4th IC space (82%), or both 97%.

CONCLUSIONS:

Geographic miss of tumor and exposure of normal tissue to excess radiation were associated with 2D techniques. Coverage improved using 3D techniques. The IMN-CTV that included the 1st-3rd IC space with a 0.5cm medial/lateral margin expansion encompassed almost all i-IMN identified on PET-CT imaging. Inclusion of the 4th IC space offered modest improvement and may be considered if additional heart exposure can be avoided.

ABSTRACT PRESENTER:

Viacheslav Soyfer


Viacheslav Soyfer, Elihau Gez, Oder Brautbar and Benjamin W. Corn

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY,Supportive & Palliative care

OTHER:

Biology, anatomy and cancer

HEADLINE:

Palliative Irradiation of Sacral Metastases: Must the Entire Bone be Treated?

BACKGROUND :

Bone metastases are common among patients with cancer. The sacrum, as a target for radiotherapy, raises a conceptual question: should the structure be regarded as a single bone or five distinct bones. If the entire sacrum must be irradiated whenever a component of the sacrum is involved by metastatic disease then there is likely to be a higher risk for rectal morbidity. We set out to determine whether the sacrum must be construed as a single osseous unit or if the component vertebrae can be viewed as individual targets.


Methods and Materials: The images of 54 patients with sacral metastases referred to radiation treatment were centrally collected and reviewed. The extent of the sacral involvement was meticulously documented in each case. For each patient, the location of the rectum was recorded relative to the individual sacral bones.

RESULTS:

In 23 cases (43%) only S1 & S2 were involved by metastatic disease. In 18 cases (33%) there was metastatic involvement of S1-S3. In only 2 individuals (4%) there was involvement of S4 and S5. In 11 cases (20%), the entire sacrum was infested by metastatic disease. In only 5 cases (9%) the rectum extended as high as S1. In 22 cases (41%) the upper pole of the rectum reached the S3 level. In toto, there were 34 cases (63%) where the inferior extension of sacral metastatic involvement did not overlap with the upper pole of the rectum.

CONCLUSIONS:

The distal part of the sacrum is rarely involved in the metastatic process. Avoidance of radiation therapy to the lower sacrum enables effective sparing of the adjacent rectum. Radiation oncologists, called upon for palliative treatment of the sacrum, are advised to regard the sacrum as an composite of individual bones rather than as large osseous unit.

ABSTRACT PRESENTER:

Ran Ben Hur


CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

In-house software for Daily/Weekly photon beams QA based on EPID dosimetry was developed in OCTAVE.

BACKGROUND :

EPID dosimetry is relative dose verification. It allows the recording of dose distributions and the export of DICOM files from which we analyze a daily or weekly QA images. Constancy, Flatness and Symmetry are analyzed using a dose distribution of a 10x10 cm2 field size for each of the linacs and for all photon energies.


A 10x10 cm2 open field is irradiated in each of the linac with each of clinical photon energies available in our clinic. The recorded image is exported from varian's eclips by means of DICOM file for analysis. An open source numerical software Octave version 4.01 was utilized for writing the code for a daily/weekly QA (DQA). Using TG-142 for tolerances and region of interest, we used with a 3% disagreement levels for constancy, flatness and symmetry and 80% of the active region determined by the FWHM of the data was used. For constancy check a new baseline was set as the first image succeeding each dose calibration in the linac. An average of 4 central axis pixels of the EPID cumulative units were recoded as the central axis relative dose for comparison. Flatness and Symmetry is calculated by TG-45 protocol in both the left to right direction and gantry to target direction.

RESULTS:

The analysis database was created successfully and a graphic report is produced.

CONCLUSIONS:

The DQA software is demonstrated for the technique described above. Further applications of DQA will be developed in the future.

ABSTRACT PRESENTER:

Dror Limon


Grace Kim, Frances McSherry, James Herndon, Peter Fecci, Justus Adamson, John Sampson, Scott Floyd, Zhiheng Wang, Gordana Vlahovic, Fang-Fang Yin and John Kirkpatrick

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY,CNS

HEADLINE:

Single Fraction Stereotactic Radiosurgery for Multiple Brain Metastases

BACKGROUND :

Treating multiple brain metastases (BM) poses a clinical challenge. Due to the neurocognitive damage from whole brain radiotherapy (WBRT), there is an increased interest in the use of stereotactic radiosurgery (SRS) for this indication. In this study, we summarize our institutional experience with the use of single fraction linear accelerator based SRS for multiple BM.


All the patients that were treated with SRS for four or more BM were included in this IRB approved retrospective, single institution study. All SRS procedures were LINAC based frameless treatments.

RESULTS:

Between 2013-2015, Fifty-nine patients were treated for 4 or more BM with single fraction SRS. Median follow-up time was 15.2 months (mo). Average age was 61.8 years; the most common primary histology was non-small cell lung cancer (35.6%); more than half had previous WBRT or SRS. Number of treated lesions ranged from 4-23, with a median of 5 lesions per patient. The mean planning treatment volume (PTV) of total treated lesions, per patient, was 7.4cc. Doses per lesion ranged from 7-20Gy, with an average dose for the entire treated lesions of 19.4Gy. The median survival for the entre cohort was 5.8mo. While number of treated lesions didn't influence survival, better survival was noted for a total PTV 10 cc, 7.1mo vs 4.2 mo (p=0.0001). A dose of more than 19Gy for the entire PTV also correlated with better survival (6.6mo vs. 5mo, p=0.0172). Dose to normal brain > 12Gy greater than 10cc, was a poor prognostic factor for overall survival (8.6mo vs. 5.1mo, p=0.0028).

CONCLUSIONS:

In single fraction SRS in patients with multiple brain metastases, total lesion volume 19 Gy and volume of normal brain receiving > 12 Gy

ABSTRACT PRESENTER:

shlomi alani


1. Shlomi Alani Ziv medical center, 2. Albert Schlocker Tel Aviv Medical Center , 3. Nir Honig Sheba Medical Center, 4 Galit Elikhis Tel Aviv Medical Center , 5. Moshe Levita Tel Aviv Medical Center

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Application of Taguchi Methodology for Optimizing Parameters of Cone Beam CT for Optimal Image Quality

BACKGROUND :

Taguchi Method is a statistical approach to optimizing multiple process parameters to determine a combination resulting in the best output. This study utilizes the Taguchi Method to evaluate the image quality parameters of Varian OBI v2 CBCT for adaptive radiotherapy image sets.The CATPHAN 600 CT phantom, which includes several modules for measuring image quality indices for imaging protocols’ various parameters, was utilized.


Taguchi developed a unique mathematical design of orthogonal arrays to study an entire parameter space with few experiments. The experimental results are transformed into what Taguchi referred to as signal-to-noise ratio (t-S/N) that is a measure of quality characteristics deviating from or nearing to a desired value. Analyses of variance (ANOVA) were employed to study the performance characteristics of the CBCT image quality. In this analysis, three factors of the acquisition protocol were considered: (a) CT slice thickness; (b) image reconstruction filter types; (c) matrix size. Respectively, a suitable orthogonal array was selected (3x3x3) to perform the experiments. After conducting the experiments the image quality parameters: pixel value stability, noise, contrast-to-noise ratio, and uniformity were measured, and t-S/N for each parameter was calculated.

RESULTS:

The quantified t-S/N values analyzed in JMP software. The optimal combination of three factors was determined to be comprised of (a) 1 mm CT slice thickness; (b) “sharp” filter; (c) 512x512 matrix. The dominant factors influencing image quality are (b) filter type, and the cross interaction between the filter type and the CT slice thickness (aXb). Matrix size (c) plays a relatively minor role since it was incapable of yielding a 95% confidence level in the ANOVA test.

CONCLUSIONS:

The Taguchi Method provides simple, systematic, and efficient methodology for optimizing the process parameters for evaluating image quality for CBCT studysets and may allow us to improve adaptive radiotherapy as it matures.

ABSTRACT PRESENTER:

shlomi alani


1. Shlomi Alani Ziv Medical Center 2. Nir Honig Sheba Medical Center 3. Albert Schlocker Tel Aviv Medical center 4. Ben Corn Tel Aviv Medical Center

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Detection of Low Contrast Objects Optimization of CT Simulation Reconstruction Protocol Phantom Study

BACKGROUND :

To evaluate the detection of small and low-contrast regions using CT simulation. Phantom containing a contrast detail modulus for detection of low-contrast structures used to optimize CT reconstruction protocol for abdomen. The parameters (A) pitch,(B) rotation time, and(C) reconstruction filter type were varied for assessment of image quality.


Three levels, three factors and nine experiments were identified. According to the Taguchi approach L9 orthogonal array has been selected. Imaging scans were obtained. The reconstruction parameters of the CT scanner (Brilliance Big Bore) pitch, rotation time, and reconstruction filter type were iteratively scanned according to the orthogonal array the study was performed using C a t p h a n 604, that was used to characterize image quality in terms of low-contrast resolution(CPT730 module). All CT scans images where analyzed by IMAGE-OWL software. The objective is to maximize the low-contrast resolution of the images. The ANOVA and F-tests are used to analyze the results using the JMP statistic software.

RESULTS:

The optimal settings and the predicted optimal values for low-contrast resolution was determined by Taguchi’s approach. The ANOVA is used to determine the optimum combination of process parameters more accurately by investigating the relative importance of process parameters. Results of ANOVA were generated for low-contrast resolution. It was observed that the pitch (61.4%) most significantly influenced followed by reconstruction filter type (29.7%). The Optimal setting level is A1-B1-C3 smooth filter 0.68 pitch and gantry rotation time 1.5 sec more measures were taken to evaluate the prediction error model is justified and results are validated.

CONCLUSIONS:

These experiments have several implications for clinical CT imaging. For detection of small low-contrast lesions (liver, pancreas, etc.). In the phantom model used in this study, Contrast detail values in the optimal level for 1% contrast 2mm for 0.5% contrast 4mm and for 0.3% contrast 7mm.

ABSTRACT PRESENTER:

shlomi alani


1. Shlomi Alani ziv medical center 2.Nir Honig sheba medical center

CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Multi-Criteria Optimization for SRS of Multiple Lesions by Single Isocenter using taguchi approach coupled with principal component analysis

BACKGROUND :

This study utilizes the Taguchi Method to evaluate the VMAT planning parameters of single isocenter treatment plans for multiple brain metastases. An optimization model based on Taguchi and Principal component analysis is employed to optimize the planning parameters including: arc arrangement, calculation grid size, calculation model, and beam energy on multiple performance characteristics, namely conformity index and dose to normal brain.


Treatment plans, each with 4 metastatic brain lesions were planned using single isocenter technique. The collimator angles were optimized to avoid open areas. In this analysis, four planning parameters (a-d) were considered: (a)-Arc arrangements: set1: Gantry 181cw179, couch0; gantry179ccw0, couch315; and gantry0ccw181, couch45. set2: set1 plus additional arc: Gantry 0cw179, couch270. (b)-Energy: 6-MV; 6MV-FFF (c)-Calculation grid size: 1mm; 1.5mm (d)-Calculation models: AAA; Acuros Treatment planning was performed in Varian Eclipse (ver.11.0.30). A suitable orthogonal array was selected (L8) to perform the experiments. After conducting the experiments with the combinations of planning parameters, the conformity index (CI) and the normal brain dose S/N ratio for each parameter was calculated. Optimum levels for the multiple response optimizations were determined.

RESULTS:

We determined that the factors most affecting the conformity index are arc arrangement and beam energy. These tests were also used to evaluate dose to normal brain. In these evaluations, the significant parameters were grid size and calculation model. Using the utility concept we determined the combination of each of the four factors tested in this study that most significantly influence quality of the resulting treatment plans: (a)-arc arrangement-set2, (b)-6MV, (c)-calc.grid 1mm, (d)-Acuros algorithm. Overall, the dominant significant influences on plan quality are (a)-arcarrangement, and (b)-beamenergy.

CONCLUSIONS:

Results were analyzed using ANOVA and were found to be within the confidence interval. Further investigation using this methodology. Such parameters might include: virtual OAR and optimization criterion such as normal tissue objective.

ABSTRACT PRESENTER:


CURRENT SUBMISSION:

New Submission


RADIOTHERAPY

HEADLINE:

Multi-lesion, multi-Rx, brain radiosurgery with novel single isocenter technique

BACKGROUND :

The literature is abundant with comparative studies of treatment planning techniques. As innovations in radiotherapy planning and treatment delivery, such as VMAT and Interdigitating MLCs, are rapidly adopted for clinical use, it is only natural that experienced clinicians develop crossover approaches to existing treatment techniques. This feasibility study was conducted to investigate a novel planning technique for radiosurgical treatment of multiple brain lesions with differing dose prescriptions, a single isocenter, interdigitating MLCs, and dynamic conformal arcs (IMDCA). Treatment plans using this technique were compared against multi-lesion, multi-Rx, single-isocenter, VMAT plans.


Six treatment plans for patients previously treated were selected for a prospective treatment planning study to evaluate Interdigitating MLC Dynamic Conformal Arc (IMDCA) technique. Arcs are planned for simultaneous irradiation to maximize beam on-time efficiency. To accommodate varying dose prescriptions, selected arcs are re-irradiated to increase dose. Beam weights are adjusted until all prescriptions are met. The number of lesions planned ranged between 2 to 4 (mode = 3). For comparative purposes, SRS VMAT plans were generated utilizing an established single-isocenter, 3 arc planning template. All plans were compared by means of Paddick conformity index (PCI), Radiation Therapy Oncology Group Conformity Index (RCI), gradient index (GI), and the normal brain volume receiving 10% (V10) of the highest prescription dose. The monitor units and delivery time were tabulated for each plan.

RESULTS:

IMDCA achieved conformal plans (PCI = 0.72 ± 0.03, RCI = 1.33 ± 0.03) with steep dose fall-off (GI = 3.79 ± 0.03) on average for all of the plans evaluated. The VMAT plans had slightly better conformity (PCI = 0.85 ± 0.03, RCI = 1.13 ± 0.03) than IMDCA, but overall worse GI (4.29 ± 0.06). VMAT plans had higher V10% values, required 50% more Monitor Units, and had 34% longer delivery time (average 4.5 minutes longer per treatment).

CONCLUSIONS:

IMDCA plans with varying dose prescriptions for multiple lesions, had comparable dosimetric coverage as VMAT plans, but were obtained with significantly lower integral dose, fewer monitor units, and quicker delivery time.

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ABSTRACT PRESENTER: LIST OF CONTRIBUTORS: CURRENT ... · ABSTRACT PRESENTER: Dr. Merav Akiva Ben David LIST OF CONTRIBUTORS: Yael Sellam, Dr.Shira Galper, Ilanit Dromi Shahadi, Ilana