2011 - Multi Channel Film Dosimetry With Non Uniformity Correction (1)
Basic Film Dosimetry - American Association of Physicists ... · Basic Film Dosimetry Indra J. Das,...
Transcript of Basic Film Dosimetry - American Association of Physicists ... · Basic Film Dosimetry Indra J. Das,...
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
Basic Film DosimetryIndra J. Das,Indra J. Das, PhPh.D..D.
Department of Radiation OncologyUniversity of Pennsylvania
Philadelphia, PA
CheeChee--WaiWai Cheng, Ph.D.Cheng, Ph.D.Department of Radiation Oncology
Morristown General HospitalMorristown General HospitalMorristown, NJMorristown, NJ
&&
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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 HurterHurter &&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
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Film Film DosimetryDosimetrykk Silver halides Silver halides
vv 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
kk Self DevelopingSelf Developingvv 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)
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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, 55, MedMed. Phys. 25(11), 2093. Phys. 25(11), 2093--2115, 19982115, 1998
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FilmFilmkk Base (Cellulose nitrate or Polyester) (typically 200 Base (Cellulose nitrate or Polyester) (typically 200 µµm)m)
kk Emulsion (10Emulsion (10--20 20 µµm; 2m; 2--5 mg/cm5 mg/cm33))
vv Gelatin (derivative from bone)Gelatin (derivative from bone)
vv grain (size: 0.1grain (size: 0.1 --3 3 µµm diameter)m diameter)uu AgBrAgBr (cubic crystal with lattice distance of 28(cubic crystal with lattice distance of 28 nmnm
uu AgIAgI
uu KIKI
�� There are 10There are 1099--10101212 grains/cmgrains/cm22 in xin x--ray filmsray films
kk CoatingCoating
vv Very sensitive which may determine X & Y Very sensitive which may determine X & Y direction uniformitydirection uniformity
BaseBaseEmulsionEmulsion
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Photographic ProcessPhotographic Process
kk Silver halides (Silver halides (AgBrAgBr,, AgClAgCl,, AgIAgI) ) are sensitive to radiation.are sensitive to radiation.
kk 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.
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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
vv it keeps grains well dispersedit keeps grains well dispersed
vv it prevents clumping and it prevents clumping and sedimentation of grains sedimentation of grains
vv it protects the unexposed grains it protects the unexposed grains from reduction by a developerfrom reduction by a developer
vv it allows easy processing of it allows easy processing of exposed grainsexposed grains
vv 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
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Film ProcessingFilm Processingkk Developing Developing [([(MetolMetol; methyl; methyl--pp--aminophenol sulphateaminophenol sulphate oror
PhenidonePhenidone; 1phenol 3pyrazolidone)]; 1phenol 3pyrazolidone)]
vv Converts allConverts all AgAg++ atoms toatoms to AgAg. The latent . The latent image image AgAg ++ are developed much more are developed much more rapidly.rapidly.
kk Stop BathStop Bath
vv dilute acetic acid stops all reaction and dilute acetic acid stops all reaction and further developmentfurther development
kk Fixer, Hypo Fixer, Hypo (Sodium(Sodium ThiosulphateThiosulphate))
vv it dissolves all undeveloped grains.it dissolves all undeveloped grains.
kk WashingWashing
kk DryingDrying
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Latent imageLatent imagekk 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.
kk 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).
kk On average 1000On average 1000 AgAg atoms are formed per xatoms are formed per x--ray quantum absorbed in a grain. ray quantum absorbed in a grain.
kk Gurney &Gurney & MottMott provided a clear picture of provided a clear picture of latent imagelatent image
Ref.Ref. HerzHerz, 1969, 1969
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GrainGrain
SilverSilver
SpeckSpeck
XX--rayray
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HurterHurter && DriffieldDriffield (1890)(1890)Optical Density (OD)Optical Density (OD)
OD= logOD= log1010((IoIo/I)/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..
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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
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Den
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Opt
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Den
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basebase
slopeslope
shouldershoulder
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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
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Den
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Opt
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Den
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Log Relative ExposureLog Relative Exposure
Haus Haus et al 1997et al 1997
Characteristic curves of various filmCharacteristic curves of various film
DxDx
RxRx
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Characteristics of Commercially Available Radiographic FilmsCharacteristics of Commercially Available Radiographic Films
FilmFilm Optimum DoseOptimum Dose GammaGamma LatitudeLatitudeCEA CEA TVSTVS 6060 4.44.4 0.350.35
CEA TLFCEA TLF 1919 3.63.6 0.40.4
Agfa Ortho Agfa Ortho STG2STG2 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 Kodak OrthoOrtho 4.54.5 2.32.3 0.40.4
Konica MGHKonica MGH 5.05.0 2.72.7 0.40.4
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TabularTabular
CubicCubic
3D3D
Eastman Kodak Company, 2001Eastman Kodak Company, 2001
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Kodak, XV CEA, TVS
Cheng & Das, Cheng & Das, MedMed. Phys. 23, 1225, 1996. Phys. 23, 1225, 1996
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Kodak MinKodak Min--RR Kodak ECLKodak ECL
Unusual silver halide grain morphologiesUnusual silver halide grain morphologiesHausHaus, 2001, 2001
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Developed grain showing filamentary silver
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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
7.07.0C
ontr
ast
Con
tras
t
RangeRange
Optimum Optical DensityOptimum Optical Density
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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
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Den
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Opt
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Den
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DupontDupontKodak MRMKodak MRMFujiFujiKodak MR5Kodak MR5
Temperature Dependence of Various FilmsTemperature Dependence of Various Films
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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
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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
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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
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Various types of plots for film responseVarious types of plots for film response
Opt
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Opt
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Den
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Den
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Log (exposure)Log (exposure)
(a)(a)
Opt
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Opt
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Den
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Den
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Exposure, DoseExposure, Dose
(c)(c)
Log
(Opt
ical
Log
(Opt
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Den
sity
)D
ensi
ty)
Log (exposure, dose)Log (exposure, dose)
(b)(b)
OpticalOptical DensityDensity
Exp
osur
e, D
ose
Exp
osur
e, D
ose
(d)(d)
DXDX
TxTx
H&
DH
&D
Con
tras
tC
ontr
ast
Sens
itom
etri
cSe
nsito
met
ric
Cal
ibra
tion
Cal
ibra
tion
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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))
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Film Film Dosimetry Dosimetry in therapyin therapy
kk 1954,1954, GrankeGranke et al; tissue dose studies with 2 MV xet al; tissue dose studies with 2 MV x--raysrays
kk 1969,1969, DutreixDutreix et al; highlights of the problems in film et al; highlights of the problems in film dosimetrydosimetry
kk 1981, Williamson et al; Provided solution to the film 1981, Williamson et al; Provided solution to the film dosimetry problemsdosimetry problems
kk 1996, Cheng & Das; CEA film, better film for 1996, Cheng & Das; CEA film, better film for dosimetrydosimetry
kk 1997, Burch et al & 1997, Burch et al & YeoYeo et al; lateral scatter filteringet al; lateral scatter filtering
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Optimum propertiesOptimum properties
kk Linear with dose (dose dependence)Linear with dose (dose dependence)
kk Linear with dose rate (dose rate Linear with dose rate (dose rate independence)independence)
kk Radiation type (independent of photon and Radiation type (independent of photon and electron)electron)
kk Energy independentEnergy independent
kk Uniformity in x & y (coating artifact)Uniformity in x & y (coating artifact)
kk Processing conditionProcessing conditionvv FadingFadingvv Delayed processingDelayed processingvv Atmospheric condition, temperature, humidityAtmospheric condition, temperature, humidity
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Exposure, RExposure, R
Opt
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Opt
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Den
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Den
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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
EhrlichEhrlich, J.Opt., J.Opt.SocSoc.Am. 46,801, 1956.Am. 46,801, 1956
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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
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Den
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Net
Opt
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28 28 keVkeV 44 44 keVkeV
79 79 keVkeV
97 97 keVkeV
142 142 keVkeV
1.711.71 MeVMeV
Muench Muench et al, et al, MedMed. Phys. 18, 769, 1991. Phys. 18, 769, 1991
Kodak XV FilmKodak XV Film
Energy Dependence of Radiographic FilmEnergy Dependence of Radiographic Film
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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
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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
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Den
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Opt
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Den
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Energy Dependence of CEA Energy Dependence of CEA TVS TVS filmfilm
CsCs--137137CoCo--60604 MV4 MV6 MV6 MV10 MV10 MV18 MV18 MV
Cheng & Das, Cheng & Das, MedMed. Phys. 23, 1225, 1996. Phys. 23, 1225, 1996
Gamma raysGamma rays XX--raysrays
ODODγγ = 0.054 Dose= 0.054 Dose
ODODxx = 0.047 Dose= 0.047 Dose
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0055 1010
5050
100100
Depth (cm)Depth (cm)
Dos
e (%
)D
ose
(%)
Air gapAir gapFilmFilm
00
0.250.25
0.500.50
0.75 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, 1969
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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
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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
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Methods to eliminate problems with FilmMethods to eliminate problems with Film
kk 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).
kk To keep identical position and pressure, RMI To keep identical position and pressure, RMI sells film cassettes for dosimetry.sells film cassettes for dosimetry.
kk Use film in water as suggested by van Use film in water as suggested by van Battum Battum et al, et al, RadiotherRadiother..OncolOncol. 34, 152, 1995. 34, 152, 1995
kk Special phantom; Special phantom; BovaBova, , MedMed. Dos. 15, 83, 1990. Dos. 15, 83, 1990
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CEA Films (TLF, CEA Films (TLF, TVSTVS))
00 2020 4040 6060 8080 100100
Dose (cGy)Dose (cGy)
Opt
ical
Den
sity
Opt
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Den
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00
11
22
33
44Kodak TLKodak TL
120120
CEA TLFCEA TLFCEA CEA TVSTVS
Kodak XVKodak XV
Cheng & Das, Cheng & Das, MedMed. Phys. 23, 1225, 1996. Phys. 23, 1225, 1996
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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 , Williamson et al , MedMed. Phys. 8, 94, 1981. Phys. 8, 94, 1981
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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 , Williamson et al , MedMed. Phys. 8, 94, 1981. Phys. 8, 94, 1981
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001Williamson et al , Williamson et al , MedMed. Phys. 8, 94, 1981. Phys. 8, 94, 1981
3030
4040
5050
6060
7070
8080
9090100100
110110120120
FilmFilmIon ChamberIon Chamber
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3030
4040
5050
6060
7070
9595100100
9090
8080 FilmFilmIon ChamberIon Chamber
Williamson et al , Williamson et al , MedMed. Phys. 8, 94, 1981. Phys. 8, 94, 1981
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Sensitivity of film to scatterSensitivity of film to scatterkk Depth and field size dependence of ODDepth and field size dependence of OD
kk Van Van Battum Battum et al, film in wateret al, film in water
kk Burch et al, lead filterBurch et al, lead filter
kk Yeo Yeo et al , Lead filteret al , Lead filter
kk Skyes Skyes et al, against filter methodet al, against filter method
vv “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”
kk Suchowerska Suchowerska et al MC simulation to prove scatter as et al MC simulation to prove scatter as a problema problem
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
00 55 1010 1515 2020 2525
9494
9696
9898
100100
102102
104104
106106
108108
4x44x4
10x1010x10
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/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
2
34
5
6
23 4
56
Scattered photon, hν’
Primary Photon, hν
Scattered electrons
Compton Scattering
11
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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. et al, Phys. MedMed. . BiolBiol. 44, 1755, 1999. 44, 1755, 1999
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
00 55 1010 1515 2020 2525 3030 3535 404000
2020
4040
6060
8080
100100
120120
140140
160160
180180
200200
Dos
e (
Dos
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/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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 4040
00
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/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001Danciu Danciu et al, et al, MedMed. Phys. 28, 972, 2001. 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
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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, et al, MedMed. Phys. 28, 972, 2001. Phys. 28, 972, 2001
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
eewweewweeww
PP PP
eewweeww
eeff
filmfilm# # eeww<< #<< # eef f
ODODperpendicular perpendicular << ODODparallelparallel
PerpendicularPerpendicular ParallelParallel
PhotonsPhotons
electronselectrons
((eeww))nn ((eeww))nn+(+(eeff))mm
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
Gantry AngleGantry Angle
8080 8282 8484 8686 8888 9090
Nor
mal
ized
Res
pons
eN
orm
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. . MedMed. . BiolBiol. 46, 1391, 2001. 46, 1391, 2001
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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, 2000
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
Electron beam film & isodoseElectron beam film & isodose
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
Densitometer: Densitometer: Device that measures Device that measures optical densityoptical density
kk Visual type densitometer (Visual type densitometer (DobsonDobson, Griffith & , Griffith & Harrison, 1926)Harrison, 1926)
kk Photoelectric typePhotoelectric type
vv light densitometer (wide spectrum)light densitometer (wide spectrum)�� Standard:Standard: McBethMcBeth,, XriteXrite, Nuclear Associate etc, Nuclear Associate etc
�� VidarVidar scanning systemscanning system
vv laser densitometer (single wavelength)laser densitometer (single wavelength)�� LumysisLumysis scanning systemscanning system
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
Film
Incident light
Transmitted light
Diffuse
Specular
Double diffuse
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
Disadvantage of film dosimetryDisadvantage of film dosimetrykk Chemical processing (except Gafchromic films)Chemical processing (except Gafchromic films)
vv OD depends on:OD depends on:�� developer temperaturedeveloper temperature�� drying conditionsdrying conditions
kk 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))
kk Sensitivity to environmentsSensitivity to environmentsvv high temperature and humidity crating fadinghigh temperature and humidity crating fading
vv 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 et al MedMed. . PhyPhy. 22, 1691, 1995). 22, 1691, 1995)
kk Microbiological growth in gelatinMicrobiological growth in gelatin
kk SolarizationSolarization: at extremely higher doses, OD decreases: at extremely higher doses, OD decreases
kk Absolute dosimetry is difficultAbsolute dosimetry is difficult
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
Advantage of film dosimetryAdvantage of film dosimetrykk Unrivaled spatial distribution of dose or energy Unrivaled spatial distribution of dose or energy
imparted.imparted.
kk Repeated reading of same film: permanent Repeated reading of same film: permanent recordrecord
kk Wide availability: Kodak,Wide availability: Kodak, AgfaAgfa, Fuji,, Fuji, DupontDupont, , CEA etc.CEA etc.
kk Large area dosimetry: Especially for electron Large area dosimetry: Especially for electron beambeam
kk 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)
kk Dose rate independenceDose rate independence
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
ConclusionsConclusionskk Film is ideal for spatial dose mapping and relative Film is ideal for spatial dose mapping and relative
dose measurementsdose measurements
kk Proper storage is neededProper storage is needed
kk Proper processing is needed: QA on processorProper processing is needed: QA on processor
kk Use calibration factor (Use calibration factor (Sensitometric Sensitometric curve) from curve) from same batch of filmsame batch of film
kk Note for energy and dose rate dependenceNote for energy and dose rate dependence
kk Use same optical densitometer that has been used Use same optical densitometer that has been used for for sensitometric sensitometric curvecurve
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
--ConclusionsConclusionskk When exposing film; use proper methods to When exposing film; use proper methods to
eliminate air trapped in the jacket if vacuum packed eliminate air trapped in the jacket if vacuum packed films are not availablefilms are not available
vv Use identical pressure on film (invest in Use identical pressure on film (invest in pressure gauge)pressure gauge)
vv Use 2Use 2--3 degree angle when exposing parallel 3 degree angle when exposing parallel filmfilm
kk Keep film orientation sameKeep film orientation same
vv Parallel films gives higher OD than Parallel films gives higher OD than perpendicular orientationperpendicular orientation
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
--ConclusionsConclusionskk Select proper film for a dosimetric applicationSelect proper film for a dosimetric application
kk Be aware of differences in electron and photon OD Be aware of differences in electron and photon OD for same dosefor same dose
kk Keep identical exposure, processing and reading Keep identical exposure, processing and reading conditionsconditions
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
--Conclusions:Conclusions:
Accuracy in film dosimetryAccuracy in film dosimetry
2% 2% On the same filmOn the same film
3%3% Films processed simultaneouslyFilms processed simultaneously
5%5% Films processed separately but Films processed separately but identical processing conditionsidentical processing conditions
10%10% On films of different batches On films of different batches
Das/Cheng/AAPM/SLC/2001Das/Cheng/AAPM/SLC/2001
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