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Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Basic Film DosimetryIndra J. DasIndra J. Das
University of Pennsylvania, Philadelphia, PA
CheeChee--WaiWai ChengChengArizona Oncology Center, Tucson, AZArizona Oncology Center, Tucson, AZ
SujathaSujatha PaiPaiState University of New York, State University of New York, Stony Brook, NY
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Basic Film Basic Film DosimetryDosimetry
WhatWhat is a film?is a film?
WhyWhy to use film ?to use film ?
HowHow to use film?to use film?
WhereWhere to use film?to use film?
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Historical PerspectiveHistorical Perspective18261826 Joseph Joseph NiepceNiepce First PhotographFirst Photograph
18361836 J. M.J. M. DaguerreDaguerre Concept of developerConcept of developer
18891889 Eastman KodakEastman Kodak Cellulose nitrate base for emulsionCellulose nitrate base for emulsion
18901890 Hurter &Hurter &DriffieldDriffield Defined the term optical densityDefined the term optical density
18951895 RoentgenRoentgen First RadiographFirst Radiograph
18961896 Carl Carl SchlussnerSchlussner First glass plate for radiographyFirst glass plate for radiography
19131913 KodakKodak Film on Cellulose nitrate baseFilm on Cellulose nitrate base
19181918 KodakKodak Double emulsion filmDouble emulsion film
19331933 DupontDupont XX--ray film with blue baseray film with blue base
19421942 PakoPako Automatic film processorAutomatic film processor
19601960 DupontDupont Polyester base introducedPolyester base introduced
19651965 KodakKodak Rapid film processingRapid film processing
19721972 KodakKodak XTL and XV film for therapyXTL and XV film for therapy
19831983 FujiFuji Computed radiography systemComputed radiography system
19941994 3M3M Dry process laser imagingDry process laser imaging
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Film Film DosimetryDosimetry��Silver halides Silver halides
��Radiographic filmRadiographic film��Available in various sizesAvailable in various sizes��Radiation range (Radiation range (mGymGy--GyGy))��Wet chemical processingWet chemical processing��Strong energy dependenceStrong energy dependence��DensitometerDensitometer-- anyany
��Self DevelopingSelf Developing��RadiochromicRadiochromic, , Gafchromic Gafchromic filmfilm
��Relatively smaller film (10x10 cmRelatively smaller film (10x10 cm22))��Radiation range (Radiation range (GyGy--100Gy)100Gy)��No processingNo processing��Little energy dependenceLittle energy dependence��DensitometerDensitometer-- Specialized (light sensitive)Specialized (light sensitive)
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Radiochromic Film
NiroomandNiroomand--Rad Rad et al, et al, Radiochromic Radiochromic film film dosimetry: Recommendations of AAPM dosimetry: Recommendations of AAPM Radiation Therapy Committee Task group Radiation Therapy Committee Task group 55, Med. Phys. 25(11), 209355, Med. Phys. 25(11), 2093--2115, 19982115, 1998
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Radiographic FilmRadiographic Film�� Base (Cellulose nitrate or Polyester) (typically 200 Base (Cellulose nitrate or Polyester) (typically 200 µµm)m)
�� Emulsion (10Emulsion (10--20 20 µµm; 2m; 2--5 mg/cm5 mg/cm33))
�� Gelatin (derivative from bone)Gelatin (derivative from bone)
�� grain (size: 0.1grain (size: 0.1 �� --3 3 µµm diameter)m diameter)�� AgBrAgBr (cubic crystal with lattice distance of 28 nm(cubic crystal with lattice distance of 28 nm
�� AgIAgI
�� KIKI
�� There are 10There are 1099--10101212 grains/cmgrains/cm22 in xin x--ray filmsray films
�� CoatingCoating
�� Very sensitive which may determine X & Y Very sensitive which may determine X & Y direction uniformitydirection uniformity
BaseBaseEmulsionEmulsion
2
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Photographic ProcessPhotographic Process
��Silver halides (Silver halides (AgBrAgBr,, AgClAgCl,, AgIAgI) ) are sensitive to radiation.are sensitive to radiation.
��Radiation event (latent image) Radiation event (latent image) can be magnified by a billion fold can be magnified by a billion fold (10(1099 ) with developer.) with developer.
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Emulsion of Film/RadiographEmulsion of Film/RadiographThe heart of film is emulsion which contains grains The heart of film is emulsion which contains grains
(crystals of silver halides) in gelatin(crystals of silver halides) in gelatin
Gelatin is suitable due toGelatin is suitable due to
�� it keeps grains well dispersedit keeps grains well dispersed
�� it prevents clumping and it prevents clumping and sedimentation of grains sedimentation of grains
�� it protects the unexposed grains it protects the unexposed grains from reduction by a developerfrom reduction by a developer
�� it allows easy processing of it allows easy processing of exposed grainsexposed grains
�� it is neutral to the grains in it is neutral to the grains in terms of fogging, loss of terms of fogging, loss of sensitivitysensitivity
Electron micrograph of grain in gelatinElectron micrograph of grain in gelatin
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Film ProcessingFilm Processing��Developing Developing [([(MetolMetol; methyl; methyl--pp--aminophenol sulphateaminophenol sulphate oror
PhenidonePhenidone; 1phenol 3pyrazolidone)]; 1phenol 3pyrazolidone)]
�� Converts all AgConverts all Ag++ atoms to Ag. The latent atoms to Ag. The latent image Ag image Ag ++ are developed much more are developed much more rapidly.rapidly.
��Stop BathStop Bath
�� dilute acetic acid stops all reaction and dilute acetic acid stops all reaction and further developmentfurther development
��Fixer, Hypo Fixer, Hypo (Sodium(Sodium ThiosulphateThiosulphate))
�� it dissolves all undeveloped grains.it dissolves all undeveloped grains.
��WashingWashing
��DryingDryingDas/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Latent imageLatent image��The change which causes the grains to be The change which causes the grains to be
rendered developable on exposure is rendered developable on exposure is considered to be the formation of latent image. considered to be the formation of latent image.
��It is composed of an aggregate of a few silver It is composed of an aggregate of a few silver atoms (4atoms (4--10).10).
��On average 1000 Ag atoms are formed per xOn average 1000 Ag atoms are formed per x--ray quantum absorbed in a grain. ray quantum absorbed in a grain.
��Gurney & Mott provided a clear picture of Gurney & Mott provided a clear picture of latent imagelatent image
Ref.Ref. HerzHerz, 1969, 1969
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
GrainGrain
SilverSilver
SpeckSpeck
XX--rayray
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Hurter &Hurter & DriffieldDriffield (1890)(1890)Optical Density (OD)Optical Density (OD)
OD= logOD= log1010(Io/I)(Io/I)
OD=logOD=log1010 (T) where T is transmittance(T) where T is transmittance
T=T=eeanan
a= average area/grain; n is number of exposed grains/cma= average area/grain; n is number of exposed grains/cm22; ; N is number of grains/cmN is number of grains/cm22
OD = log (T) = an logOD = log (T) = an log1010e = 0.4343 ane = 0.4343 an
n/N = an/N = aΦ ; Φ ; where where Φ
Φ electron fluenceelectron fluence
OD = 0.4343 aOD = 0.4343 a22NNΦΦ
OD is proportional to OD is proportional to Φ
Φ and hence dose and and hence dose and square of grain areasquare of grain area..
3
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Characteristic curveCharacteristic curveH&D CurveH&D Curve
Gradient, gamma, slope = Gradient, gamma, slope = (D(D22--DD11)/Log(E)/Log(E22/E/E11))
Speed (sensitivity)= Speed (sensitivity)= 1/Roentgens for OD equal to unity1/Roentgens for OD equal to unity
Latitude (Contrast): Latitude (Contrast): range of log exposure to give range of log exposure to give an acceptable density rangean acceptable density range
Log (exposure)Log (exposure)
Opt
ical
Den
sity
Op t
ical
Den
sity
basebase
slopeslope
shouldershoulder
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
5.55.500 0.50.5 1.01.0 1.51.5 2.02.0 2.52.5 3.03.0 3.53.5 4.04.0 4.54.5 5.05.000
0.50.5
1.01.0
1.51.5
2.02.0
2.52.5
3.03.0
3.53.5
4.04.0
Opt
ical
Den
sity
Opt
ical
Den
sity
Log Relative ExposureLog Relative Exposure
Haus Haus et al 1997et al 1997
Characteristic curves of various filmCharacteristic curves of various film
DxDx
RxRx
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Characteristics of Commercially Available Radiographic FilmsCharacteristics of Commercially Available Radiographic Films
FilmFilm Optimum DoseOptimum Dose GammaGamma LatitudeLatitudeCEA TVSCEA TVS 6060 4.44.4 0.350.35
CEA TLFCEA TLF 1919 3.63.6 0.40.4
AgfaAgfa Ortho STG2Ortho STG2 4.74.7 3.63.6 0.40.4
Agfa Agfa HTAHTA 3.53.5 2.72.7 0.30.3
Agfa Agfa RP1RP1 1.51.5 2.62.6 0.50.5
AgfaAgfa MR3MR3 4.24.2 2.12.1 0.60.6
Du PontDu Pont CronexCronex 4.04.0 2.62.6 0.50.5
Du Pont UVDu Pont UV 1.51.5 1.91.9 0.50.5
Fuji MIMAFuji MIMA 6.36.3 2.82.8 0.50.5
Fuji HRGFuji HRG 6.26.2 2.82.8 0.50.5
Kodak XVKodak XV 5050 2.92.9 0.60.6
Kodak TL 44 2.02.0 0.50.5
Kodak XLKodak XL 1.71.7 2.02.0 0.60.6
Kodak Kodak MinRMinR 12.312.3 1.81.8 0.40.4
Kodak TMATGKodak TMATG 2.52.5 2.52.5 0.40.4
Kodak OrthoKodak Ortho 4.54.5 2.32.3 0.40.4
Konica MGHKonica MGH 5.05.0 2.72.7 0.40.4
Roberts, BJR, 69, 70Roberts, BJR, 69, 70--71, 199671, 1996 Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
TabularTabular
CubicCubic
3D3D
Eastman Kodak Company, 2001Eastman Kodak Company, 2001
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Kodak, XV CEA, TVS
Cheng & Das, Med. Phys. 23, 1225, 1996Cheng & Das, Med. Phys. 23, 1225, 1996
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Kodak MinKodak Min--RR Kodak ECLKodak ECL
Unusual silver halide grain morphologiesUnusual silver halide grain morphologiesHausHaus, 2001, 2001
4
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Developed grain showing filamentary silver
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
00 1.01.0 2.02.0 3.03.0 4.04.0 5.05.0
Optical DensityOptical Density
00
1.01.0
2.02.0
3.03.0
4.04.0
5.05.0
6.06.0
7.07.0
Con
trast
Con
trast
RangeRange
Optimum Optical DensityOptimum Optical Density
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
8484 8686 9090 9292 9494 9696 9898 100100 1021028888
0.40.4
0.60.6
0.80.8
1.01.0
1.21.2
1.41.4
1.61.6
Developer Temperature (degree F)Developer Temperature (degree F)
Opt
ical
Den
sity
Opt
ical
Den
sity
DupontDupontKodak MRMKodak MRMFujiFujiKodak MR5Kodak MR5
Temperature Dependence of Various FilmsTemperature Dependence of Various Films
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Bogucki Bogucki et al, Med.Phys., 24, 581, 1997et al, Med.Phys., 24, 581, 1997
Cha
nge
in O
D p
er D
egre
e Pr
oces
sor T
empe
ratu
reC
hang
e in
OD
per
Deg
ree
Proc
esso
r Tem
pera
ture
(( δδO
DO
D// δδ
TT ))
9191 9292 9393 9494 9595 9696 9797 9898 9999
0.00.0
.02.02
.04.04
.06.06
.08.08
.10.10
Processor Temperature (degree F)Processor Temperature (degree F)
Kodak FilmsKodak Films
Min R MMin R M
Ektascan Ektascan HNHN
TT--Mat G/RAMat G/RA
Ektascan Ektascan IRIR
OD=KOD=K00T +KT +K11TT22
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
00 0.50.5 1.01.0 1.51.5 2.02.0 2.52.5 3.03.0 3.53.5 4.04.0
0.00.0
.02.02
.04.04
.06.06
.08.08
.10.10
Optical DensityOptical Density
Cha
nge
in O
D p
er D
egre
e Pr
oces
sor T
empe
ratu
reC
hang
e in
OD
per
Deg
ree
Proc
esso
r Tem
pera
ture
(( δδO
DO
D// δδ
TT ))
Kodak FilmsKodak Films
Min R MMin R M
Ektascan Ektascan HNHN
TT--Mat G/RAMat G/RA
Ektascan Ektascan IRIR
Bogucki Bogucki et al, Med.Phys., 24, 581, 1997et al, Med.Phys., 24, 581, 1997
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
91 F91 F33 C33 C
95 F95 F35 C35 C
99 F99 F37 C37 C
103 F103 F39 C39 C
0.160.16
0.180.18
0.200.20
0.220.22
2.82.8
3.03.0
3.23.2
3.43.4
3.63.6
--2020
00
2020
4040
BaseBase
++
FogFog
ContrastContrastAverageAverageGradientGradient
SpeedSpeed% change% change
TemperatureTemperature
Standard Processing CycleStandard Processing Cycle
5
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Various types of plots for film responseVarious types of plots for film responseO
ptic
alO
ptic
alD
ensi
tyD
ensi
ty
Log (exposure)Log (exposure)
(a)(a)
Opt
ical
Opt
ical
Den
sity
Den
sity
Exposure, DoseExposure, Dose
(c)(c)
Log
(Op t
ical
Log
(Op t
ical
Den
sity
)D
ensi
ty)
Log (exposure, dose)Log (exposure, dose)
(b)(b)
OpticalOptical DensityDensity
Expo
sure
, Do s
eEx
posu
re, D
o se
(d)(d)
DXDXTxTx
H&
DH
&D
Con
trast
Con
trast
Sens
itom
etric
Sens
itom
etric
Cal
ibra
tion
Cal
ibra
tion
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
D = DoseD = DoseDr = Dose rateDr = Dose rateE = EnergyE = EnergyT = type of radiation (xT = type of radiation (x--rays, electrons etc)rays, electrons etc)d = depth of measurementd = depth of measurementFS= Field SizeFS= Field SizeΘΘ = Orientation: parallel or perpendicular= Orientation: parallel or perpendicular
Optical Density = OD(D, Dr, E, T, d, FS, Optical Density = OD(D, Dr, E, T, d, FS, ΘΘ))
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Film Film Dosimetry Dosimetry in therapyin therapy
��1954,1954, GrankeGranke et al; tissue dose studies with 2 MV xet al; tissue dose studies with 2 MV x--raysrays
��1969,1969, DutreixDutreix et al; highlights of the problems in et al; highlights of the problems in film dosimetryfilm dosimetry
��1981, Williamson et al; Provided solution to the film 1981, Williamson et al; Provided solution to the film dosimetry problemsdosimetry problems
��1996, Cheng & Das; CEA film, better film for 1996, Cheng & Das; CEA film, better film for dosimetrydosimetry
��1997, Burch et al & 1997, Burch et al & YeoYeo et al; lateral scatter filteringet al; lateral scatter filtering
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Optimum propertiesOptimum properties
�� Linear with dose (dose dependence)Linear with dose (dose dependence)
�� Linear with dose rate (dose rate Linear with dose rate (dose rate independence)independence)
�� Radiation type (independent of photon and Radiation type (independent of photon and electron)electron)
�� Energy independentEnergy independent�� Uniformity in x & y (coating artifact)Uniformity in x & y (coating artifact)�� Processing conditionProcessing condition
�� FadingFading�� Delayed processingDelayed processing�� Atmospheric condition, temperature, humidityAtmospheric condition, temperature, humidity
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Exposure, RExposure, R
Opt
ical
Opt
ical
Den
sity
Den
sity
1010--22 1010--11 101000 101011 101022 101033 101044 10105500
11
22
33
44
55
66
0.033R/sec0.033R/sec
1.31R/sec1.31R/sec
62R/sec62R/sec
1100R/sec1100R/sec
Dose Rate DependenceDose Rate Dependence
Ehrlich, J.Opt.Soc.Am. 46,801, 1956Ehrlich, J.Opt.Soc.Am. 46,801, 1956Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
00 1010 2020 3030 4040 5050 6060 7070 8080Dose (cGy)Dose (cGy)
00
0.50.5
1.01.0
1.51.5
2.02.0
2.52.5
Net
Opt
ical
Den
sity
Net
Opt
ical
Den
sity
28 28 keVkeV 44 44 keVkeV
79 79 keVkeV
97 97 keVkeV
142 142 keVkeV
1.711.71 MeVMeV
Muench Muench et al, Med. Phys. 18, 769, 1991et al, Med. Phys. 18, 769, 1991
Kodak XV FilmKodak XV Film
Energy Dependence of Radiographic FilmEnergy Dependence of Radiographic Film
6
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
1010 100100 10001000
0.10.1
1.01.0
1010
100100
unfilteredunfiltered
filteredfiltered
Photon Energy, (Photon Energy, (keVkeV))
Rel
ativ
e re
spon
seR
elat
ive
resp
onse
RR.H. .H. HerzHerz, The photographic action, 1969, The photographic action, 1969
Energy response balancing with filter Energy response balancing with filter used in personnel monitoringused in personnel monitoring
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
00 2020 4040 6060 8080 100100
Dose (cGy)Dose (cGy)
0.00.0
1.01.0
2.02.0
3.03.0
4.04.0
5.05.0
Opt
ical
Den
sity
Opt
ical
Den
sity
Energy Dependence of CEA TVS filmEnergy Dependence of CEA TVS film
CsCs--137137CoCo--60604 MV4 MV6 MV6 MV10 MV10 MV18 MV18 MV
Cheng & Das, Med. Phys. 23, 1225, 1996Cheng & Das, Med. Phys. 23, 1225, 1996
Gamma raysGamma rays XX--raysrays
ODODγγ = 0.054 Dose= 0.054 Dose
ODODxx = 0.047 Dose= 0.047 Dose
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
0055 1010
5050
100100
Depth (cm)Depth (cm)
Dos
e (%
)D
ose
(%)
Air gapAir gap FilmFilm
00
0.250.25
0.500.500.75 mm0.75 mm
Effect of film air gap on depth doseEffect of film air gap on depth dose
Dutreix Dutreix et al, Ann NY et al, Ann NY Acad SciAcad Sci, 161, 33, 1969, 161, 33, 1969Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Air gapAir gap FilmFilm
0055 1010
5050
100100
Depth (cm)Depth (cm)
Dos
e (%
)D
ose
(%)
00
22
5 mm5 mm
Effect of film misalignment on depth doseEffect of film misalignment on depth dose
Dutreix Dutreix et al, Ann NY et al, Ann NY Acad SciAcad Sci, 161, 33, 1969, 161, 33, 1969
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Dutreix Dutreix et al, Ann NY et al, Ann NY Acad SciAcad Sci, 161, 33, 1969, 161, 33, 1969
Effect of film under alignment on depth doseEffect of film under alignment on depth dose
55 1010
Depth (cm)Depth (cm)
Air gapAir gap FilmFilm
00
5050
100100
Dos
e (%
)D
ose
(%)
0 mm0 mm
447 mm7 mm
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Methods to eliminate problems with FilmMethods to eliminate problems with Film
��To eliminate air trapped inside jacket, vacuum To eliminate air trapped inside jacket, vacuum packing could be used (CEA film).packing could be used (CEA film).
��To keep identical position and pressure, RMI To keep identical position and pressure, RMI sells film cassettes for dosimetry.sells film cassettes for dosimetry.
��Use film in water as suggested by van Use film in water as suggested by van BattumBattumet al, et al, RadiotherRadiother..OncolOncol. 34, 152, 1995. 34, 152, 1995
��Special phantom; Special phantom; BovaBova, Med. Dos. 15, 83, 1990, Med. Dos. 15, 83, 1990
7
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
CEA Films (TLF, TVS)CEA Films (TLF, TVS)
00 2020 4040 6060 8080 100100
Dose (cGy)Dose (cGy)
Opt
ical
Den
sity
Opt
ical
Den
sity
00
11
22
33
44Kodak TLKodak TL
120120
CEA TLFCEA TLFCEA TVSCEA TVS
Kodak XVKodak XV
Cheng & Das, Med. Phys. 23, 1225, 1996Cheng & Das, Med. Phys. 23, 1225, 1996Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
OD Vs DoseOD Vs Dose
PDDPDD = [= [a+b(OD) +c(OD)a+b(OD) +c(OD)22]]dd // [a+b(OD) +c(OD)[a+b(OD) +c(OD)22]]maxmax
OAR=OAR=[[a+b(OD) +c(OD)a+b(OD) +c(OD)22]]x x // [a+b(OD) +c(OD)[a+b(OD) +c(OD)22]]caxcax
D = m(OD) thenD = m(OD) then
DD22/D/D11 = OD= OD22/OD/OD11
For limited range and linear filmFor limited range and linear film
Dose = a+b(OD) +c(OD)2
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
OD depth and field size dependentOD depth and field size dependent
OD(D, d) = ODOD(D, d) = ODss[1[1--1010--αα(d)D(d)D]]
αα(d) = (d) = αα(d(dmm)[1+)[1+ββ(d(d--ddmm)])]
ββ = 0.0182= 0.0182 CoCo--6060
ββ = 0.0150= 0.0150 4 MV4 MV
ββ = 0.0062= 0.0062 10 MV10 MV
Williamson et al , Med. Phys. 8, 94, 1981Williamson et al , Med. Phys. 8, 94, 1981
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Depth (cm)Depth (cm)
0.80.8
0.90.9
1.01.0
1.11.1
1.21.2
1.31.3
1.41.4
00 55 1010 1515 2020 2525 3030
Film
Den
sity
Film
Den
sity
Williamson et al , Med. Phys. 8, 94, 1981Williamson et al , Med. Phys. 8, 94, 1981
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002Williamson et al , Med. Phys. 8, 94, 1981Williamson et al , Med. Phys. 8, 94, 1981
3030
4040
5050
6060
7070
8080
9090100100
110110120120
FilmFilmIon ChamberIon Chamber
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
3030
4040
5050
6060
7070
9595100100
9090
8080 FilmFilmIon ChamberIon Chamber
Williamson et al , Med. Phys. 8, 94, 1981Williamson et al , Med. Phys. 8, 94, 1981
8
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Sensitivity of film to scatterSensitivity of film to scatter��Depth and field size dependence of ODDepth and field size dependence of OD
��Van Van Battum Battum et al, film in wateret al, film in water
��Burch et al, lead filterBurch et al, lead filter
��Yeo Yeo et al , Lead filteret al , Lead filter
��Skyes Skyes et al, against filter methodet al, against filter method
��“although scatter filtering method appears to have “although scatter filtering method appears to have the desired effect it seems intuitively wrong to the desired effect it seems intuitively wrong to introduce a high Z filter in order to make an introduce a high Z filter in order to make an inadequate dosimeter, film, behave as if it is water inadequate dosimeter, film, behave as if it is water equivalent”equivalent”
��Suchowerska Suchowerska et al MC simulation to prove scatter as et al MC simulation to prove scatter as a problema problem
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
00 55 1010 1515 2020 2525
9494
9696
9898
100100
102102
104104
106106
108108
4x44x410x1010x10
20x2020x20
30x3030x30
Depth (cm)Depth (cm)
Opt
ical
Den
sity
(Nor
mal
ized
)O
ptic
al D
ensi
ty (N
orm
aliz
ed)
Van Van Battum Battum et al , et al , Radiother OncolRadiother Oncol, 34, 152, 1995, 34, 152, 1995
Effect of depth and field size on ODEffect of depth and field size on OD
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
00 22 44 66 20201818161614141212101088
Depth (cm)Depth (cm)
Rel
ativ
e D
ose
(%)
Rel
ativ
e D
ose
(%)
00
2020
4040
6060
8080
100100
4x44x410x1010x10
20x2020x20
Van Van Battum Battum et al , et al , Radiother OncolRadiother Oncol, 34, 152, 1995, 34, 152, 1995
FilmFilmIon ChamberIon Chamber
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
2
34
5
6
23 4
56
Scattered photon, hν’
Primary Photon, hν
Scattered electrons
Compton Scattering
11
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Yeo Yeo et al Med. Phys. 24, 1943, 1997et al Med. Phys. 24, 1943, 1997Burch et al, Med. Phys. 24, 775, 1997Burch et al, Med. Phys. 24, 775, 1997
FilmFilm Lead filterLead filter
PhotonPhoton
Parallel film OrientationParallel film Orientation
Movable positionMovable position
X, X, 6, 12, 19 mm6, 12, 19 mmt= 0.15, 0.30,t= 0.15, 0.30,.0.46, 0.76 mm.0.46, 0.76 mm
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002JuJu et al, Med. Phys., 29, 351et al, Med. Phys., 29, 351--355, 2002355, 2002
9
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
JuJu et al, Med. Phys., 29, 351et al, Med. Phys., 29, 351--355, 2002355, 2002
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
1.21.2
1.01.0
0.80.8
0.60.6
0.40.4
0.20.2
--1010 --55 00 55 1010Distance from central axis (cm)Distance from central axis (cm)
Rel
ativ
e do
se (r
atio
)R
elat
ive
dose
(rat
io)
Film no filterFilm no filterFilm with filterFilm with filterIon ChamberIon Chamber
Ju Ju et al, Med. Phys., 29, 351et al, Med. Phys., 29, 351--355, 2002355, 2002
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
00 22 44 66 88
Energy (Energy (MeVMeV))
0.00.0
2.02.0
4.04.0
6.06.0
8.08.0
10.010.0
Rel
ativ
e Fl
uenc
e (%
)R
elat
ive
Flue
nce
(%)
MC simulation of photon spectrum at various depthsMC simulation of photon spectrum at various depths
30 cm30 cm
10 cm10 cm
1.5 cm1.5 cm
Suchowerska Suchowerska et al, Phys. Med. Biol. 44, 1755, 1999et al, Phys. Med. Biol. 44, 1755, 1999Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
00 55 1010 1515 2020 2525 3030 3535 404000
2020
4040
6060
8080
100100
120120
140140
160160
180180
200200
Dos
e (
Do s
e ( c
Gy
cGy ))
Depth (cm)Depth (cm)
X=0 mmX=0 mm
Ion chamberIon chamber
X=6 mmX=6 mm
X=12 mmX=12 mm
4 MV, 25x25 cm4 MV, 25x25 cm22
0.76 mm 0.76 mm PbPb
Burch et al, Med. Phys., 24, 775, 1997Burch et al, Med. Phys., 24, 775, 1997
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
No No PbPb
Ion ChamberIon Chamber
Film+.46 mm Film+.46 mm PbPb
Depth (cm)Depth (cm)00 55 1010 1515 2020 2525 3030 3535 4040
00
2020
4040
6060
8080
100100
120120
4 MV, 25x25 cm4 MV, 25x25 cm22
No No PbPb
Film+.46 mm Film+.46 mm PbPb
Ion ChamberIon Chamber
Burch et al, Med. Phys., 24, 775, 1997Burch et al, Med. Phys., 24, 775, 1997
00 55 1010 1515 2020 2525 3030 3535 404000
2020
4040
6060
8080
100100
120120
Dos
e (
Dos
e ( c
Gy
cGy ))
Depth (cm)Depth (cm)
4 MV, 6x6 cm4 MV, 6x6 cm22
Effect of Effect of Pb Pb filter on depth dosefilter on depth dose
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002Danciu Danciu et al, Med. Phys. 28, 972, 2001et al, Med. Phys. 28, 972, 2001
2.02.000 0.50.5 1.01.0 1.51.5
Net
Opt
ical
Den
sity
Net
Opt
ical
Den
sity
0.00.0
1.01.0
1.51.5
2.02.0
2.52.5
3.03.0C0C0--6060KodakKodak
Dose (Dose (GyGy))
0.5g/cm0.5g/cm33
4 g/cm4 g/cm33
9 g/cm9 g/cm33
DepthDepth
Net
Opt
ical
Den
sity
Net
Opt
ical
Den
sity
Dose (Dose (GyGy))00 0.50.5 1.01.0 1.51.5
0.00.0
1.01.0
1.51.5
2.02.0
2.52.5
3.03.06 MV6 MVKodakKodak
0.5g/cm0.5g/cm33
4 g/cm4 g/cm33
9 g/cm9 g/cm33
DepthDepth
2.02.0
00 0.50.5 1.01.0 1.51.50.00.0
1.01.0
1.51.5
2.02.0
2.52.5
3.03.045 MV45 MVKodakKodak
0.5g/cm0.5g/cm33
4 g/cm4 g/cm33
9 g/cm9 g/cm33
DepthDepth
2.02.000 0.50.5 1.01.0 1.51.50.00.0
1.01.0
1.51.5
2.02.0
2.52.5
3.03.018 MV18 MVKodakKodak
0.5g/cm0.5g/cm33
4 g/cm4 g/cm33
9 g/cm9 g/cm33
DepthDepth
2.02.0
Dose (Dose (GyGy)) Dose (Dose (GyGy))
Sensitometric Sensitometric curves for 15x15 cmcurves for 15x15 cm22 fieldfieldwith perpendicular film exposurewith perpendicular film exposure
10
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Net
Opt
ical
Den
sity
Net
Opt
ical
Den
sity
Depth (cm)Depth (cm)1414 161600 22 44 66 88 1010 1212
Net
Opt
ical
Den
sity
Net
Opt
ical
Den
sity
1.01.0
1.51.5
2.02.0
2.52.5
3.03.0
3.53.5CoCo--6060
AgfaAgfa
KodakKodak
ParallelParallelPerpendicularPerpendicular
1414 161600 22 44 66 88 1010 1212
Net
Opt
ical
Den
sity
Net
Opt
ical
Den
sity
1.01.0
1.51.5
2.02.0
2.52.5
3.03.0
3.53.515 MV15 MVAgfaAgfa
KodakKodak
ParallelParallelPerpendicularPerpendicular
Depth (cm)Depth (cm)
1414 161600 22 44 66 88 1010 12121.01.0
1.51.5
2.02.0
2.52.5
3.03.0
3.53.56 MV6 MVAgfaAgfa
KodakKodak
ParallelParallelPerpendicularPerpendicular
Depth (cm)Depth (cm)
Net
Opt
ical
Den
sity
Net
Opt
ical
Den
sity
1414 161600 22 44 66 88 1010 12121.01.0
1.51.5
2.02.0
2.52.5
3.03.0
3.53.545 MV45 MV
KodakKodak
ParallelParallelPerpendicularPerpendicular
Depth (cm)Depth (cm)
Danciu Danciu et al, Med. Phys. 28, 972, 2001et al, Med. Phys. 28, 972, 2001Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Net Optical Density0 0.2 0.4 0.6 0.8 1.0 1.2
0
5
10
15
20
25
30
Dos
e (c
Gy)
6x6, 5 cm depth6x6, 5 cm depth25x25, 5 cm depth25x25, 5 cm depth6x6, 15 cm depth6x6, 15 cm depth25x25, 15 cm depth25x25, 15 cm depth
Sykes et al, Med.Phys., 26, 329, 1999Sykes et al, Med.Phys., 26, 329, 1999
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
eewweewweeww
PP PP
eewweeww
eeff
filmfilm# # eeww<< #<< # eef f
ODODperpendicular perpendicular << ODODparallelparallel
PerpendicularPerpendicular ParallelParallel
PhotonsPhotons
electronselectrons
((eeww))nn ((eeww))nn+(+(eeff))mm
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Gantry AngleGantry Angle
8080 8282 8484 8686 8888 9090
No r
mal
ized
Res
pons
eN
o rm
aliz
ed R
espo
nse
.96.96
.98.98
1.001.00
1.021.02
1.041.04
1.061.06
1.081.08
1.101.10
1.121.12
Kodak XV FilmKodak XV Film
SpectralSpectral
Spectral + air gapSpectral + air gap
Suchowerska Suchowerska et al. et al. PhyPhy. Med. Biol. 46, 1391, 2001. Med. Biol. 46, 1391, 2001
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002 Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
How Should we trust?
11
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
403530252015100.82
0.84
0.86
0.88
0.90
0.92
0.94
0.96
0.98
1.00
1.02
1.04
1.06
V-1
V-3V-2
CEA-1
V-4
CEA-2
V-5
Variation of cone factor, St, using film
Cone Diameter (mm)
Con
e Fa
ctor
(St)
Das et al, J. Das et al, J. RadiosurgRadiosurg. 3, 177, 2000. 3, 177, 2000Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
0 50 100 1500.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0 50 100 1500.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Opt
ical
den
sity
Kodak
B C D E Wellhöfer
Dose (cGy)Dose (cGy)
CEA
Bos et al, Med. Phy. 29 (in press) 2002
Film Scanner Light source Wavelength/color
Konica KFDR-S diode-laser 780 nmMultidata 9721 diode-laser redVidar VXR-12 standard fluorescent light whiteWellhöfer WD 102 infrared diode 950 nmX-rite Model 301 tungsten halogen bulb bluish white
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002Bos Bos et al, Med. et al, Med. PhyPhy. 29 (in press) 2002. 29 (in press) 2002
0 20 40 60 80 1000
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Dose (cGy)
TTA TAA PPA PAA
Opt
ical
den
sity
0 20 40 60 80 1000
0.5
1.0
1.5
2.0
2.5
3.0
3.5
TAA PAA AAA
Opt
ical
den
sity
0 20 40 60 80 1000
0.5
1.0
1.5
2.0
2.5
3.0
3.5Dose (cGy)
C
B
A
Kodak
TTT TTA PPP PPA AAA
Opt
ical
den
sity
Dose (cGy)
Effect Comparison OD difference at 50cGy
Kodak CEA
Batchcomposition
TAA vs.AAA
14% 9%
PAA vs.AAA
20% 2%
Irradiationconditions
TTA vs.TAA
2% 5%
PPA vs.PAA
2% 5%
Filmprocessing
TTT vs.TTA
11% 31%
PPP vs. PPA 38% 16%Combinedeffect
TTT vs.AAA
20% 32%
PPP vs. AAA 13% 13%
Interinstitutional Interinstitutional Variation in ODVariation in OD
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Advantage of film dosimetryAdvantage of film dosimetry
��Unrivaled spatial distribution of dose or energy Unrivaled spatial distribution of dose or energy imparted.imparted.
��Repeated reading of same film: permanent recordRepeated reading of same film: permanent record
��22--D distribution with single exposureD distribution with single exposure
��Small detector sizeSmall detector size
��Wide availability: Kodak,Wide availability: Kodak, AgfaAgfa, Fuji, Dupont, CEA , Fuji, Dupont, CEA
��Large area dosimetry: Especially for electron beamLarge area dosimetry: Especially for electron beam
��Linearity of dose (over a short dose range, OD can Linearity of dose (over a short dose range, OD can be treated linear with dose for most films)be treated linear with dose for most films)
��Dose rate independenceDose rate independence
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Film dosimetry Film dosimetry -- ConcernsConcerns��The main problem in using radiographic The main problem in using radiographic
film is the dependence of optical density film is the dependence of optical density (OD) on: (OD) on: �� Strong energy dependence (high sensitivity to Strong energy dependence (high sensitivity to
low energy photons due to photoelectric low energy photons due to photoelectric interactions in grainsinteractions in grains)); ;
�� Film plane orientation with respect to the Film plane orientation with respect to the beam direction; beam direction;
�� Emulsion differences amongst films of Emulsion differences amongst films of different batches, films of the same batch or different batches, films of the same batch or even in the same film; even in the same film;
�� Densitometer/Digitizer artifacts.Densitometer/Digitizer artifacts.
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
��OD depends on:OD depends on:�� Chemical processing Chemical processing
�� developer chemistry and temperaturedeveloper chemistry and temperature�� Processing timeProcessing time�� drying conditionsdrying conditions
��Sensitivity to environmentSensitivity to environment�� High temperature & humidity creating fadingHigh temperature & humidity creating fading�� Storage stabilityStorage stability
�� 0.050.05--0.1 OD in (60.1 OD in (6--60mR) among various films60mR) among various films (ref(refSoleimanSoleiman et al Med.et al Med. PhyPhy. 22, 1691, 1995). 22, 1691, 1995)
��Microbiological growth in gelatinMicrobiological growth in gelatin��SolarizationSolarization: At extremely higher doses, OD : At extremely higher doses, OD
decreasesdecreases
Film dosimetry Film dosimetry -- ConcernsConcerns
12
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
TG69 TG69 -- RADIOGRAPHIC FILM FOR RADIOGRAPHIC FILM FOR MEGAVOLTAGE BEAM DOSIMETRYMEGAVOLTAGE BEAM DOSIMETRY
��Film Dosimetry for commissioning and Film Dosimetry for commissioning and verifying special procedures in radiotherapy.verifying special procedures in radiotherapy.�� Enhanced Dynamic Wedge (EDW) Enhanced Dynamic Wedge (EDW)
�� Stereotactic Radiosurgery (SRS) Stereotactic Radiosurgery (SRS)
�� Intensity Modulated Radiotherapy (IMRT) Intensity Modulated Radiotherapy (IMRT)
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Disadvantage of film dosimetryDisadvantage of film dosimetry�� Chemical processing (except Gafchromic films)Chemical processing (except Gafchromic films)
�� OD depends on:OD depends on:�� developer temperaturedeveloper temperature�� drying conditionsdrying conditions
�� Strong energy dependence (high sensitivity to low Strong energy dependence (high sensitivity to low energy photons due to photoelectric interactions in energy photons due to photoelectric interactions in grainsgrains))
�� Sensitivity to environmentsSensitivity to environments�� high temperature and humidity crating fadinghigh temperature and humidity crating fading
�� Storage stabilityStorage stability
�� 0.050.05--0.1 OD in (60.1 OD in (6--60mR) among various 60mR) among various films films (ref (ref Soleiman Soleiman et al Med. et al Med. PhyPhy. 22, 1691, 1995). 22, 1691, 1995)
�� Microbiological growth in gelatinMicrobiological growth in gelatin
�� SolarizationSolarization: at extremely higher doses, OD decreases: at extremely higher doses, OD decreases
�� Absolute dosimetry is difficultAbsolute dosimetry is difficult
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Advantage of film dosimetryAdvantage of film dosimetry��Unrivaled spatial distribution of dose or energy Unrivaled spatial distribution of dose or energy
imparted.imparted.
��Repeated reading of same film: permanent Repeated reading of same film: permanent recordrecord
��Wide availability: Kodak,Wide availability: Kodak, AgfaAgfa, Fuji, Dupont, , Fuji, Dupont, CEA etc.CEA etc.
��Large area dosimetry: Especially for electron Large area dosimetry: Especially for electron beambeam
��Linearity of dose (over a short dose range, OD Linearity of dose (over a short dose range, OD can be treated linear with dose for most films)can be treated linear with dose for most films)
��Dose rate independenceDose rate independence
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
TG69 TG69 RADIOGRAPHIC FILM DOSIMETRYRADIOGRAPHIC FILM DOSIMETRY
Task group members:Task group members:S. Pai S. Pai --ChairChair
L. Reinstein L. Reinstein –– CoCo--ChairChairJ. WilliamsonJ. Williamson
J. PaltaJ. PaltaK. Lam K. Lam
T. LosassoT. LosassoE. GreinE. Grein
I. DasI. DasJ. DempseyJ. Dempsey
A. OlchA. Olch
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
TG69TG69�� Film Dosimetry Film Dosimetry -- IssuesIssues
�� Film selectionFilm selection�� Film orientationFilm orientation�� Phantom choicePhantom choice�� Film handlingFilm handling�� Beam quality issuesBeam quality issues�� Film Processor Film Processor �� Film Digitizer characteristicsFilm Digitizer characteristics
The primary mission of the task group is to The primary mission of the task group is to develop guidelines to allow optimal external develop guidelines to allow optimal external beam dose measurements.beam dose measurements.
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Self developing, turns dark blue soon after irradiationSelf developing, turns dark blue soon after irradiationNear tissue equivalent, > 0.1MeV energy independentNear tissue equivalent, > 0.1MeV energy independent� OD increases gradually with time (logt)
� Dependency on temperature during and post irradiation
� Dependency on densitometer wavelength and temperature
� Sensitivity may vary somewhat across film
� Affected by compression, water/humidity, high temperature
� Slightly reduced sensitivity at < 0.1MeV
� OD increases in UV and fluorescent light
RadiochromicRadiochromic filmfilmNiroomandNiroomand--Rad et al, Rad et al, Radiochromic Radiochromic film dosimetry: Task group 55, film dosimetry: Task group 55, Med. Phys. 25(11), 2093Med. Phys. 25(11), 2093--2115, 19982115, 1998
13
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
ProcessorsProcessors�� Using the newer automatic processorsUsing the newer automatic processors
�� Developer temperature Developer temperature
�� Processing time Processing time
�� Chemistry activity of the processorChemistry activity of the processor
held extremely stable to improve the reproducibility and the held extremely stable to improve the reproducibility and the stability of the film density. stability of the film density.
�� Development of recommendation for the processor Development of recommendation for the processor acceptance tests and QA.acceptance tests and QA.
�� Determination of correction factors for temperature and Determination of correction factors for temperature and chemical variations of the processors in general:chemical variations of the processors in general:
�� By processing the nonBy processing the non--exposed films (known density exposed films (known density films) intermixed with the experiment films and films) intermixed with the experiment films and calibration films.calibration films.
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
DensitometersDensitometers/ Digitizers/ Digitizers��Visual type densitometer (Dobson, Griffith & Visual type densitometer (Dobson, Griffith &
Harrison, 1926)Harrison, 1926)��Photoelectric typePhotoelectric type
�� light densitometer (wide spectrum)light densitometer (wide spectrum)�� Standard:Standard: McBethMcBeth,, XriteXrite, Nuclear Associate etc, Nuclear Associate etc
�� Light source coupled with CCD digitizerLight source coupled with CCD digitizer�� Fluorescent light source Fluorescent light source –– Vidar Vidar VXRVXR--16 Digitizer16 Digitizer�� LED light source LED light source -- Howtek MultiRADHowtek MultiRAD 460 Digitizer460 Digitizer
�� Laser densitometer (single wavelength)Laser densitometer (single wavelength)�� LumysisLumysis scanning systemscanning system
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Film
Incident light
Transmitted light
Diffuse
Specular
Double diffuse
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
��Scanning film Digitizer Artifacts:Scanning film Digitizer Artifacts:
�� Drift in OD; warmDrift in OD; warm--up effect of fluorescent lamp up effect of fluorescent lamp �� Use first 20Use first 20--30 minutes as warm30 minutes as warm--up timeup time
�� Scanner spatial distortionScanner spatial distortion�� Validated in both dimensions using known test patternsValidated in both dimensions using known test patterns
�� Interference artifacts Interference artifacts -- at the interface of film at the interface of film and the glass plate/film support.and the glass plate/film support. ((Multiple Multiple reflection due to changes in the index of reflection due to changes in the index of refraction)refraction)�� Use of diffused glass or antireflective coated glassUse of diffused glass or antireflective coated glass
ReinsteinReinstein et. al., Dempsey et.al.et. al., Dempsey et.al.
DigitizersDigitizers
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
-
Digitizer ArtifactsDigitizer Artifacts
GluckmanGluckman, et.al., et.al. Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
��Scanning film Digitizer Artifacts:Scanning film Digitizer Artifacts:�� Internal light scatter at OD discontinuities Internal light scatter at OD discontinuities
introducing OD nonintroducing OD non--linearity linearity �� Reduced by applying DFFT (Dempsey et.al)Reduced by applying DFFT (Dempsey et.al)
�� Light source/Detector response & linearity Light source/Detector response & linearity �� Signal to Noise ratioSignal to Noise ratio
�� Temporal Noise (electronic noise) Temporal Noise (electronic noise) �� Optimal OD of Optimal OD of << (??)(??)�� Lowering digitizing speed & using optimal resolutionLowering digitizing speed & using optimal resolution�� Reduced through the averaging of multiple scansReduced through the averaging of multiple scans
�� Spatial Noise (interference artifacts)Spatial Noise (interference artifacts)�� Application of Linear signal processing techniquesApplication of Linear signal processing techniques
Dempsey et.al.,Dempsey et.al., MerssemanMersseman et.al., andet.al., and MeederMeeder et.al.et.al.
DigitizersDigitizers
14
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
DigitizersDigitizers��Scanning film Digitizer Characteristics:Scanning film Digitizer Characteristics:
�� Fast high resolution 2D scannersFast high resolution 2D scanners�� Transmission optical densitometry Transmission optical densitometry �� Reflection densitometry Reflection densitometry –– limited OD range limited OD range
�� Spatial resolutionSpatial resolution�� Pixel dimension 0.34 Pixel dimension 0.34 –– 0.042mm (720.042mm (72--600 dpi) 600 dpi)
�� Dynamic rangeDynamic range�� 0 to upper limit of 2.5 to 4.0 OD0 to upper limit of 2.5 to 4.0 OD
�� Scanner output Scanner output �� OD measurement (OD measurement (>> 12 bit ADC)12 bit ADC)�� Transmission measurement and then converted to OD Transmission measurement and then converted to OD
((>>14 bit ADC)14 bit ADC)
Dempsey et.al. Dempsey et.al. Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
��Optimal OD Optimal OD DigitizersDigitizers
ReinsteinReinstein et. al.et. al.
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
TG69 TG69 -- RADIOGRAPHIC FILM FOR RADIOGRAPHIC FILM FOR MEGAVOLTAGE BEAM DOSIMETRYMEGAVOLTAGE BEAM DOSIMETRY
Enhanced Dynamic WedgeEnhanced Dynamic Wedge��CommissioningCommissioning
�� EDW profiles are obtained in a single exposure EDW profiles are obtained in a single exposure using a multiple film loaded phantomusing a multiple film loaded phantom
��Concern: Energy Dependency of filmConcern: Energy Dependency of film�� Affects the measured wedge angle in EDW Affects the measured wedge angle in EDW
profiles for large field size and large depths.profiles for large field size and large depths.
Elder, et.al, Klein, et.al.Elder, et.al, Klein, et.al. Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
TG69 TG69 -- RADIOGRAPHIC FILM FOR RADIOGRAPHIC FILM FOR MEGAVOLTAGE BEAM DOSIMETRYMEGAVOLTAGE BEAM DOSIMETRY
Stereotactic RadiosurgeryStereotactic Radiosurgery��Energy DependencyEnergy Dependency
�� Overall error of 1%Overall error of 1%-- by using midby using mid--way calibration for F.S.way calibration for F.S.uptoupto 10x10 cm10x10 cm22 and depths of 2and depths of 2--10cm.10cm.
��Output FactorOutput Factor�� Small field output depends upon the spatial resolution.Small field output depends upon the spatial resolution.
��Penumbra DelineationPenumbra Delineation�� Detector size; TG 42 specificationDetector size; TG 42 specification-- detector dimension of detector dimension of
2mm or less is recommended.2mm or less is recommended.
��Concern: Optical ScatterConcern: Optical Scatter�� Light transmission artifacts of the scanner contaminating Light transmission artifacts of the scanner contaminating
the signal (penumbra broadening)the signal (penumbra broadening)
Dempsey, et.al.,Tsai, et.al.Dempsey, et.al.,Tsai, et.al.
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
TG69 TG69 -- RADIOGRAPHIC FILM FOR RADIOGRAPHIC FILM FOR MEGAVOLTAGE BEAM DOSIMETRYMEGAVOLTAGE BEAM DOSIMETRY
Intensity Modulated Radiation TreatmentIntensity Modulated Radiation Treatment��Film dosimetry Film dosimetry -- Best dosimeter to dateBest dosimeter to date�� Spatial resolutionSpatial resolution
�� Detector size; detector dimension of 2mm or less is Detector size; detector dimension of 2mm or less is recommended.recommended.
��Concerns: Energy DependencyConcerns: Energy Dependency�� Varying component of primary to scatter ratio within the Varying component of primary to scatter ratio within the
field poses a big problem .field poses a big problem .
��Concerns: Spatial Distortion and Optical ScatterConcerns: Spatial Distortion and Optical Scatter�� Scanner distortion which are most apparent in high dose Scanner distortion which are most apparent in high dose
gradient regions gradient regions –– throughout IMRT fieldthroughout IMRT field�� Optical scatter distorting the transmitted signalOptical scatter distorting the transmitted signal
ChuiChui, et. al. Low, et.al., et. al. Low, et.al. Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
Kodak’s New Kodak’s New Extended Dose Range Extended Dose Range (EDR2) Film(EDR2) Film
Each grain is Each grain is 10 times 10 times smallersmaller than XV grains,than XV grains,
Uniform cubic grains Uniform cubic grains ofof AgBrAgBr rather than rather than nonnon--uniform potato uniform potato shaped grains for XV.shaped grains for XV.
EDR2
XV2
Dose cGyCourtesy: Courtesy: OlchOlch, A., A.
EDR2 vs. XV2EDR2 vs. XV2
15
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
��No MU reduction is required for EDR2 film No MU reduction is required for EDR2 film IMRT QA.IMRT QA.
�� AvoidsAvoids LinacLinac delivery problems with small delivery problems with small number of MU per segmentnumber of MU per segment
�� Avoids round off errors for systems that can not Avoids round off errors for systems that can not deliver nondeliver non--integer MUinteger MU
�� IMRT QA can be performed on the IDENTICAL IMRT QA can be performed on the IDENTICAL plan that is used to treat the patient.plan that is used to treat the patient.
��EDR2 film is less sensitive to processor EDR2 film is less sensitive to processor variations than XV2 film.variations than XV2 film.
Courtesy: Courtesy: OlchOlch, A., A.
KODAK’S NEW EDR2 FILMKODAK’S NEW EDR2 FILM
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
TG69 TG69 -- RADIOGRAPHIC FILM FOR RADIOGRAPHIC FILM FOR MEGAVOLTAGE BEAM DOSIMETRYMEGAVOLTAGE BEAM DOSIMETRY
TG Chapters:TG Chapters:�� Introduction and Background Introduction and Background -------------------------- S. PaiS. Pai
�� Characteristics ofCharacteristics of AgHAgH films films -------------------------- I. DasI. Das
�� Film types and Processors Film types and Processors -------------------------- K. LamK. Lam
�� Detection Equipment Detection Equipment
�� Point Point Densitometers Densitometers -------------------------- A. Olch/L. E. ReinsteinA. Olch/L. E. Reinstein
�� 2D scanners 2D scanners -------------------------- J. Dempsey/J. WilliamsonJ. Dempsey/J. Williamson
�� Phantom considerations Phantom considerations andand -------------------------- E. GreinE. Grein
Film Calibration ProtocolFilm Calibration Protocol
�� Special ApplicationsSpecial Applications
�� QA of photon/Electron beams QA of photon/Electron beams -------------------------- J. J. PaltaPalta
�� IMRT/EDW/SRS IMRT/EDW/SRS -------------------------- T. LossasoT. Lossaso
Das/Cheng/Das/Cheng/PaiPai/AAPM//2002/AAPM//2002
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