Scintillation dosimetry: Review, new innovations and ...aapm.org/meetings/amos2/pdf/35-9838-52729-634.pdf · Scintillation dosimetry: ... Professor Department of Radiation Physics,

Scintillation dosimetry: Scintillation dosimetry: Review, new innovations and Review, new innovations and

applicationsapplications

Sam Beddar, Ph.D., Sam Beddar, Ph.D., ProfessorProfessor

Department of Radiation Physics, UT MD Anderson Cancer Center Department of Radiation Physics, UT MD Anderson Cancer Center & UT Graduate School of Biomedical Sciences& UT Graduate School of Biomedical Sciences

&&

Luc Beaulieu, Ph.D., Luc Beaulieu, Ph.D., Associate Professor Associate Professor

Department of Physics, Department of Physics, UniversitUniversitéé Laval & Laval & Department of Radiation Department of Radiation Oncology, CHU de QuebecOncology, CHU de Quebec

OOUTLINEUTLINE

•• IntroductionIntroduction

•• Properties of plastic Properties of plastic scintillation detectorsscintillation detectors

•• ApplicationsApplications–– Daily QADaily QA–– RadiosurgeryRadiosurgery–– Clinical prototypeClinical prototype–– Proton therapyProton therapy–– Works in progressWorks in progress

•• ConclusionsConclusions

IINTRODUCTIONNTRODUCTION • Introduction• Properties• Applications• Conclusion

•• In the last 20 years, significant advances have been made In the last 20 years, significant advances have been made in scintillation dosimetryin scintillation dosimetry

•• They have a unique set of advantagesThey have a unique set of advantages

•• With the increasing complexity of radiotherapy treatments, With the increasing complexity of radiotherapy treatments, scintillation detectors could be used for quick and accurate scintillation detectors could be used for quick and accurate dose measurements even in complex geometriesdose measurements even in complex geometries

The purpose of this presentation is to show the advantages The purpose of this presentation is to show the advantages of of scintillatonscintillaton dosimetry and to explain how it can be used dosimetry and to explain how it can be used in modern radiotherapyin modern radiotherapy

INTRODUCTION • Introduction• Properties• Applications• Conclusion

•• In scintillation detectors:In scintillation detectors:

•• Impinging particles or photons will excite atoms or Impinging particles or photons will excite atoms or molecules of the scintillating medium.molecules of the scintillating medium.

•• Electron beams: Interacting electrons are not the same as Electron beams: Interacting electrons are not the same as the ionization electronsthe ionization electrons

•• The decay of these excited states will produce The decay of these excited states will produce photons in the visible part of the spectrum.photons in the visible part of the spectrum.

•• Photon beams: Interacting photons are not the same as the Photon beams: Interacting photons are not the same as the detected photonsdetected photons

•• These photons will be guided to a These photons will be guided to a photodetectorphotodetector and and then converted in an electric signal.then converted in an electric signal.

IINTRODUCTIONNTRODUCTION • Introduction• Properties• Applications• Conclusion

•• Two types of scintillators:Two types of scintillators:

A.A. Inorganic materialsInorganic materials-- NaINaI, , NaI(TlNaI(Tl), ), CsICsI, , CsI(TlCsI(Tl), ), CsI(NaCsI(Na), ), CsFCsF, BaF, BaF22, ,

CdWOCdWO44, , ……-- Advantages for stopping particles: high Z and Advantages for stopping particles: high Z and

high density (up to 8high density (up to 8--9 g/cm9 g/cm33))•• Disadvantage for dosimetryDisadvantage for dosimetry

-- Need an activator: Need an activator: e.g. e.g. TlTl ((ThaliumThalium))•• NaINaI: 330 nm: 330 nm•• NaI(TlNaI(Tl): 410 nm): 410 nm

INTRODUCTION • Introduction• Properties• Applications• Conclusion

•• Two types of scintillators:Two types of scintillators:

B.B. Organic materials (e.g. plastics) Organic materials (e.g. plastics)

-- Lower density Lower density …… and!!! nearly equivalent to waterand!!! nearly equivalent to water•• Density on the order of 1.03Density on the order of 1.03--1.06 g/cm1.06 g/cm33

•• (Generally) No high Z materials content.(Generally) No high Z materials content.

-- Excitation and emission spectra are similar in Excitation and emission spectra are similar in solid, liquid or vapor statessolid, liquid or vapor states

•• Core (bulk solvent)Core (bulk solvent)–– PolyvinyltoluenePolyvinyltoluene ((plastic scintillatorsplastic scintillators))–– Polystyrene (Polystyrene (plastic scintillating fibersplastic scintillating fibers))

•• Cladding (scintillating fibers)Cladding (scintillating fibers)–– PolymethylacrylatePolymethylacrylate (PMMA)(PMMA)–– Improves transmission of light to optical fiberImproves transmission of light to optical fiber

PPLASTICLASTIC SSCINTILLATINGCINTILLATING MMATERIALSATERIALS • Introduction• Properties• Applications• Conclusion

Dose deposition and scintillation

C.P. Interactions(keV to MeV)

De-excitation Processes

Energy Absorption

Energy Deposition

Ionization - Excitation

Light Emission(a few eV)

SSCINTILLATION CINTILLATION PPROCESSROCESS • Introduction• Properties• Applications• Conclusion

• Prompt fluorescence following excitation (10-9 – 10-7 s) important for radiation detection

• Introduction• Properties• Applications• Conclusion

SSCINTILLATION CINTILLATION PPROCESSROCESS

SCINTILLATION PROCESS • Introduction• Properties• Applications• Conclusion

• At room temperature, e- almost all in S00

– ΔE S1-S0 about 3-4 eV>> 0.025 eV

• S1 band (about 0.15 eV apart) decay radiation-less to the S1 base state

– Photon emitted only to S0 states

• T1 band: lower energy and longer process


• Aromatic molecules– Large number of “shared”

electrons (π-electrons)» 4n+2» Anthracene has 14 of

such electrons.

– Excitation of π-electrons in S states = fast fluorescence.

– Ionization of π-electrons = mostly T states.

– Excitation or ionization of other electrons (σ-electrons) = no fluo or temporary / permanent damage


• Since all photons come from the S10

– Shift in the emission spectrum to lower energy than the excitation (absorption) spectrum

– Mostly transparent to its own emitted photons!

From Knoll

• Organic fluors (scintillating materials) are used with a bulk solvent: two components system

– BC400: >97% PVT, < 3% organic fluors» e.g. p-TERPHENYL (C6H5 C6H4 C6H5)

– Energy deposited in the solvent is transfered to the organic fluor molecules

» Emission is typically peaked in the violet-blue region.

• “Wavelength shifters” or three component system– A third (organic) component can also be used to absorb

the organics fluors emitted photons and re-emit at a longer wavelength

» POPOP [1,4-bis(5-phenyloxazol-2-yl) benzene] to get scintillators emitting in the green or yellow region.

FLUORS • Introduction• Properties• Applications• Conclusion

SCINTILLATOR SPECTRA

Scintillators with Scintillators with longer wavelengths longer wavelengths have lower light have lower light emission emission

Archambault L, Arsenault J, Archambault L, Arsenault J, GingrasGingras L, Beddar A S, Roy R, Beaulieu L, "Plastic scintillation L, Beddar A S, Roy R, Beaulieu L, "Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintildosimetry: Optimal selection of scintillating fibers and scintillatorslators““, Med. Phys 32: 2271, Med. Phys 32: 2271--2278, 2278, 2005.2005.


• Only a small portion of the incident kinetic energy lost is converted in fluorescent energy

– For plastic scintillating fibers like BCF-12 about 8000 photons/MeV

This means about 125 eV / scintillation photon.The total energy of visible light produced (at 430 nm or ~ 2.9 eV) represents an efficiency of 2.4% (97.6% goes in phonons!)

– The light output depends on the LET (i.e. CP type)

SCINTILLATION EFFICIENCY • Introduction• Properties• Applications• Conclusion

• A decrease from the optimal scintillation efficiency, or quenching, can occur under various conditions

– For organic scintillators, little thermal quenching• Constant between -60 ºC and +20 ºC• 5% variation max between +20 ºC and +60 ºC

– Radiation damage can decrease the efficiency(Ionizations lead to temporary and/or permanent molecular damage)

• Increased absorption due to defects (plastics turn yellow)• Need > kGy accumulated doses (104 to 105 Gy)

QUENCHING EFFECT • Introduction• Properties• Applications• Conclusion

• Quenching also occurs for highly ionizing radiation

– Overlapping excitation sites and molecule damages.

– Provides alternate radiationless de-excitation processes.

– Non-linearity of Light (L) to Energy (E) response.

QUENCHING EFFECT • Introduction• Properties• Applications• Conclusion

• The relationship between the specific energy loss (ionization density) and the light output is given by the Birks’ formula:

S: Scintillation efficiencyB(dE/dx): Density of damaged

molecules along the particle trackk: fraction of damage contributing to

quenching

– For electrons above 125 keV: dL/dx = S dE/dx» Thus L = SE !

– For large dE/dx, saturation can occurs along the track» dL/dx = S / (kB) (usualy for ion particles)

BIRKS’ FORMULA • Introduction• Properties• Applications• Conclusion

dLdx

=S dEdx

1+ kB dEdx

Archambault L, Beddar S, Sahoo N, Archambault L, Beddar S, Sahoo N, PoensichPoensich F, Gillin M, Mohan R, " Experimental Proof and F, Gillin M, Mohan R, " Experimental Proof and Feasibility of a 3D RealFeasibility of a 3D Real--Time Detector System for Therapeutic Proton Beams Time Detector System for Therapeutic Proton Beams ““, Med. Phys. 35: , Med. Phys. 35: 2905, 2008. (Abstract).2905, 2008. (Abstract).

• Organic (plastic) scintillators are:– Made of low Z materials.

– Light output is directly proportional to the exciting energy.» Linear with deposited energy for e-,γ.» …for electron above 100-125 keV.

– (Mostly) Transparent to its emitted photons.

– The gap is wide enough to be insensitive to a wide range of temperatures.

– Fast time response (physics of orbital transitions).


SCINTILLATION PROCESS: SUMMARY

• Scintillation efficiency is not the collection efficiency.

» These photons must be detected.

» Linearity must be preserved throughout the complete detection chain

» Light must be calibrated to Dose.


SCINTILLATION PROCESS: SUMMARY

• JB Birks, The Theory and Practice of Scintillation Counting, Pergamon Press Book, MacMillan, New York, 1964. [Chapters 3 and 6]

• GF Knoll, Radiation Detection and Measurement, 3rd Edition, John Wiley and Sons, 2000. [Chapter 8]

• WR Leo, Techniques for Nuclear and Particle Physics Experiments, 2nd edition, Springer-Verlag, 1992. [Chapter 7]

• FH Attix, Introduction to Radiological Physics and Radiation Dosimetry, John Wiley and Sons, 1986. [Chapter 15]


SCINTILLATION PROCESS: REFERENCES

• Linear response to dose

• Dose rate independence

• Energy independence

• Temperature independence

• Spatial resolution

ADVANTAGES OF PLASTIC SCINTILLATORS


WATER EQUIVALENCE• W-E is achieved by:

– Media-matching (walls and sensitive volume)– Density state of the sensitive volume (gaseous vs.

condensed)

• W-E depends on:– Mass energy-absorption coefficients– Mass collision stopping powers– Size of the sensitive volume (according to Burlin

cavity theory)

H: 11.19O: 88.81

H: 7.74C: 92.26

H: 8.47C: 91.53

Composition (by weight %)

3.3433.2383.272Electron density(1023 e-/g)

1.0001.0601.032Density (g/cm3)WaterPolystyreneScintillatorParameter


WATER EQUIVALENCE

0.005 0.980 ±=med

sci

DD

According to Burlin cavity theory, above 125 keV:

Beddar A S, Mackie T R, Beddar A S, Mackie T R, AttixAttix F H, "WaterF H, "Water--equivalent plastic scintillation detectors for highequivalent plastic scintillation detectors for high--energy beam dosimetry: I. energy beam dosimetry: I. Physical characteristics and theoretical considerationsPhysical characteristics and theoretical considerations““, Phys. Med. Biol. 37: 1883, Phys. Med. Biol. 37: 1883--1900, 1992. 1900, 1992.


Scintillator Fiber light guide Photodetector

εacceptεcouple1

εtransmitεcouple2


DETECTOR CONFIGURATION

Plastic scintillating fibers offer a good alternative to regular plastic scintillators:

• Increased light capture due to cladding (>internal reflection) • The cladding is also water-equivalent/ no perturbation

ORIGINAL PROTOTYPE

• High sensitivity (PMT)• Remove Cerenkov with background subtraction

Beddar, A S, Mackie, T R, and Attix, F H, "WaterBeddar, A S, Mackie, T R, and Attix, F H, "Water--equivalent plastic scintillation detectors for highequivalent plastic scintillation detectors for high--energy energy beam dosimetry: I. Physical characteristics and theoretical consbeam dosimetry: I. Physical characteristics and theoretical considerations," Phys. Med. Biol. 37: 1883iderations," Phys. Med. Biol. 37: 1883--1900, 1992. 1900, 1992.


LINEARITY

Light production is proportional to the dose deposited


DOSE RATE INDEPENDENCE

Not affected by dose rate variations


ENERGY DEPENDENCE

• Detecting volumes: intermediate cavities• Best energy dependence relative to other dosimeters

used in radiotherapy


Beddar A S, Mackie T R, Beddar A S, Mackie T R, AttixAttix F H, "WaterF H, "Water--equivalent plastic scintillation detectors for highequivalent plastic scintillation detectors for high--energy beam dosimetry: I. energy beam dosimetry: I. Physical characteristics and theoretical considerationsPhysical characteristics and theoretical considerations““, Phys. Med. Biol. 37: 1883, Phys. Med. Biol. 37: 1883--1900, 1992. 1900, 1992.

TEMPERATURE

No temperature dependence between 18ºC and 30ºC


CERENKOV EMISSION

Although the light spectrum due to Cerenkov emission is differenAlthough the light spectrum due to Cerenkov emission is different t from the scintillation spectrum, de Boer et al have shown that sfrom the scintillation spectrum, de Boer et al have shown that spectral pectral filtration is not sufficient to remove completely the Cerenkov lfiltration is not sufficient to remove completely the Cerenkov light.ight.

• In plastics like polystyrene, electrons with energies 146 keV and higher produce a blue light due to Cerenkov emission

• This light is superposed on the scintillation signal• If a large amount of clear optical fiber is in the radiation

field, Cerenkov emission can be significant (>15 %)

de Boer S F, Beddar A S Rawlinson J F "Optical filtering and spde Boer S F, Beddar A S Rawlinson J F "Optical filtering and spectral measurement of radiationectral measurement of radiation--induced light in plastic scintillator dosimetryinduced light in plastic scintillator dosimetry““, Phys Med , Phys Med BiolBiol 38: 94538: 945--958, 1993. 958, 1993.


CERENKOV EMISSIONTechniques to remove the Cerenkov effect:

Background subtraction

Dsci ∝M −Mcrkv

Simple filtering

Find the optimal S(λ)that max. N(λ) and min. 1/λ2

Chromatic filtration

Note: requires 2 optical fibers

With 2 different wavelength filter S1(λ) and S2(λ),

mi = kDsciN(λ) +Cλ2

⎛ ⎝ ⎜

⎞ ⎠ ⎟ e−x / l(λ)

0

∞∫ Si(λ)dλ i = 1,2

⇒ Dsci = Am1 + Bm2

Where A and B are fixed by calibration under 2 different conditions

FontbonneFontbonne J M, J M, IltisIltis G, Ban G, G, Ban G, BattalaBattala A, A, VernhesVernhes J C, J C, TillierTillier J, J, BellaizeBellaize N, le N, le BrunBrun C, C, TamainTamain B, B, Mercier K, Mercier K, MotinMotin J C, "Scintillating fiber dosimeter for radiation therapy J C, "Scintillating fiber dosimeter for radiation therapy accleratoracclerator““, IEEE Trans. , IEEE Trans. NuclNucl. . Sci. 49: 2223Sci. 49: 2223--2227, 2002. 2227, 2002.


• Commercialized product• Rugged and simple to construct• Good stability and reproducibility• Independent of temperature and pressure• No high-voltage bias• Remote operation and reset• Easily used by trained technical staff• Cost effective

Beddar S, Beddar S, ““A new scintillator detector system for the quality assurance of A new scintillator detector system for the quality assurance of 6060Co and highCo and high--energy therapy energy therapy machinesmachines””. Phys Med . Phys Med BiolBiol 39: 25339: 253––263, 1994. 263, 1994.

A DAILY QA DETECTOR SYSTEM • Introduction• Properties• Applications• Conclusion

Stability of the QA device over time

Beddar A S, Beddar A S, ““A new scintillator detector system for the quality assurance of A new scintillator detector system for the quality assurance of 60Co and high60Co and high--energy energy therapy machinestherapy machines””, Phys Med , Phys Med BiolBiol 39: 25339: 253––263, 1994. 263, 1994.

A DAILY QA DETECTOR SYSTEM • Introduction• Properties• Applications• Conclusion

SCINTILLATION FIBER ARRAYPROTOTYPE

• Alta U2000c• Interline• Color• Cooled @ -20º

• Fixed focal• f/# = 1.4

• PMMA

• BCF12 (blue)

• Subtract Cerenkov contamination with chromatic removalArchambault L, Beddar S, Archambault L, Beddar S, GingrasGingras L, Roy R, Beaulieu L, "Measurement accuracy and Cerenkov L, Roy R, Beaulieu L, "Measurement accuracy and Cerenkov removal for high performance, high spatial resolution scintillatremoval for high performance, high spatial resolution scintillation dosimetryion dosimetry““, Med. Phys. 33: 128, Med. Phys. 33: 128--135, 135, 2006. 2006.


LacroixLacroix F, Archambault L, F, Archambault L, GingrasGingras L, Beddar AS, and Beaulieu L. Clinical prototype of a plastic wL, Beddar AS, and Beaulieu L. Clinical prototype of a plastic waterater--equivalent scintillating fiber dosimeter matrix for IMRT QA applequivalent scintillating fiber dosimeter matrix for IMRT QA applications, Med Phys 35 (2008) 3682ications, Med Phys 35 (2008) 3682--3690.3690.


SCINTILLATION FIBER ARRAYDETECTOR FOR QA

30

50

70

90

110

130

150

0 25 50 75 100 125 150 175 200 225 250 275 300

Depth (mm)

Rel

ativ

e D

ose

Scint. 10x10CC13 10x10


DEPTH DOSE

1.6%



BEAM PROFILE


0

20

40

60

80

100

-175 -125 -75 -25 25 75 125 175Position (mm)

Rel

ativ

e D

ose

CC13 20x20 CC13 10x10CC13 4x4Scint. 20x20Scint. 10x10Scint. 4x4

EBRT

Accurate for electron measurements:


Depth in Water (cm)

Dep

th D

ose

(%)

Depth in Water (cm)

6 MeV 18 MeV

Beddar, A. S., Mackie, T. R., and Attix, F. H., "WaterBeddar, A. S., Mackie, T. R., and Attix, F. H., "Water--equivalent plastic scintillation detectors for highequivalent plastic scintillation detectors for high--energy beam dosimetry: II. Properties and measurements," Phys. Menergy beam dosimetry: II. Properties and measurements," Phys. Med. Biol. 37, 1901ed. Biol. 37, 1901--1913 (1992) c1913 (1992) c

SPATIAL RESOLUTION • Introduction• Properties• Applications• Conclusion

Beddar, A. S., Mackie, T. R., and Attix, F. H., "WaterBeddar, A. S., Mackie, T. R., and Attix, F. H., "Water--equivalent plastic scintillation detectors for highequivalent plastic scintillation detectors for high--energy beam dosimetry: II. Properties and measurements," Phys. Menergy beam dosimetry: II. Properties and measurements," Phys. Med. Biol. 37, 1901ed. Biol. 37, 1901--1913 (1992) c1913 (1992) c

SPATIAL RESOLUTION • Introduction• Properties• Applications• Conclusion

Archambault L, Beddar S, Archambault L, Beddar S, GingrasGingras L, Lacroix F, Roy R, Beaulieu L, Lacroix F, Roy R, Beaulieu L, "L, "WaterWater--equivalentequivalentdosimeterdosimeter arrayarray for for smallsmall--fieldfield externalexternal beambeam radiotherapyradiotherapy", Med ", Med PhysPhys 34: 158334: 1583––1592, 1592, 2007.2007.

A12A16Scint Diode

DOSIMETRY FOR STEREOTACTICRADIOSURGERY


DOSIMETRY FOR STEREOTACTICRADIOSURGERY


Beddar S, Beddar S, KinsellaKinsella T J, T J, IkhlefIkhlef A, Sibata C H, A, Sibata C H, ““Miniature 'ScintillatorMiniature 'Scintillator--FiberopticFiberoptic--PMT' detector PMT' detector system for the dosimetry of small fields in stereotactic system for the dosimetry of small fields in stereotactic radiosurgeryradiosurgery””, IEEE Trans. Nucl. Sci. 48: , IEEE Trans. Nucl. Sci. 48: 924924--928, 2001.928, 2001.

MONTE CARLO SIMULATIONS FOR PROTON BEAMS• Use Geant4 for a complete simulation

– Electromagnetic and hadronic processes– Production and tracking of visible light (scintillation and

Cerenkov)• Understand the behavior of a plastic scintillator

irradiated with protons• Optimize light collection efficiency


MONTE CARLO SIMULATIONS OF PROTON BEAMS

Water equivalence preserved for most clinical proton energies


Archambault L, Archambault L, PolfPolf J C, Beaulieu L, Beddar S, J C, Beaulieu L, Beddar S, ““Characterizing the response of miniature Characterizing the response of miniature scintillation detectors when irradiated with proton beamsscintillation detectors when irradiated with proton beams””, Phys Med , Phys Med BiolBiol 53: 186553: 1865--1876, 2008.1876, 2008.

Monte Carlo accurately predicts quenching and can therefore be used for determining correction factors

0.0

0.2

0.4

0.6

0.8

1.0

Rel

ativ

e D

ose

-10 -8 -6 -4 -2 0 2

Unquenched – ion chambermeasurements & simulation

Quenched – scintillationmeasurements & simulation

Depth (cm)

QUENCHING (PROTONS ONLY) • Introduction• Properties• Applications• Conclusion

SCINTILLATION SCREEN

• Rapid, but requires correction for light propagation• Similar to a-Si dosimetry, but takes advantage of the

water equivalence of the plastic scintillator• Not as accurate as point-like scintillation dosimeters• See Petric et al. for more information

PetricPetric M P, M P, RobarRobar J L, Clark B G, J L, Clark B G, ““Development Development and characterization of a tissue equivalent plastic and characterization of a tissue equivalent plastic scintillator based dosimetry system,scintillator based dosimetry system,”” Med Phys 33: Med Phys 33: 9696--105, 2006.105, 2006.


BRACHYTHERAPY

• Scintillator irradiated with low energy (< 125 keV) photons is less water equivalent than megavoltage photons

• Chemical composition of plastic scintillator may be changed for a better response (Williamson et al., Kirov et al.)

• Kirov et al. have developed a 3D scintillation detector for the characterization of Ru-106 eye plaques

Kirov A S, Kirov A S, PiaoPiao J Z, J Z, MathurMathur N K, Miller T R, N K, Miller T R, DevicDevic S, S, trichtertrichter S, S, ZaiderZaider M, M, SoaresSoares C G, C G, LoSassoLoSasso T, T, ““ThreeThree--dimensional scintillation dimensional scintillation dosimetry method: test for a 106Ru plaque dosimetry method: test for a 106Ru plaque applicatorapplicator””, Phys Med , Phys Med BiolBiol 50: 306350: 3063--3081, 3081, 2005.2005.

see also Williamson J F, Dempsey J F, Kirov A S, Monroe J I, see also Williamson J F, Dempsey J F, Kirov A S, Monroe J I, BinnsBinns W R, W R, HedtjHedtjäärnrn, , ““Plastic scintillator Plastic scintillator response to lowresponse to low--energy photonsenergy photons””, Phys Med , Phys Med BiolBiol 44: 85744: 857--871, 1999.871, 1999.


IN VIVO DOSIMETRYFOR PROSTATE RADIOTHERAPY

• Direct measurement of the dose delivered to organs, critical structures, and within the vicinity of a tumor is feasible and can be used to verify treatment plan delivery.

• We believe this can be done using an in vivoscintillation detector composed of multiple probes arranged in an application-specific design that can monitor true in vivo dose in real time.

NCI Grant No. 1R01CA120198-01A2


Adam Melancon (MDACC)

INTRAFRACTIONAL MOTION • Introduction• Properties• Applications• Conclusion

Adam Melancon (MDACC)

INTRAFRACTIONAL MOTIONGASEOUS BUILDUP


Before Before TxTx After After TxTx

OUR GOAL: ACCURACY & PRECISION

Prostate

Detector


RECTAL DETECTOR

Rectal balloons are part of the standard treatment for radiation therapy at MDACC

Capillaries where scintillation probescan be inserted


URETHRAL DETECTOR

Foley Catheter

Urethral detector consisting of a capillary containing line and point probes for measurement of dose at the urethra. The outer diameter of the catheter is 2 mm (6F).


CLINICAL INNOVATION: REAL-TIME HDR DOSIMETRY


#1 #2#3

#4 #5 #6

#7#8 #9

#10

#11#12

A single PSD is placed in an empty standard prostate plastic catheter. The remaining 12 catheters are used for planning and delivery The PSD is read in real-time to monitor the treatment delivery.

CLINICAL INNOVATION: REAL-TIME HDR DOSIMETRY


13.7±274.54Scintillator*274.5PLATOcGy

* Results of 5 measurements

SUMMARY

• Scintillation dosimeters possess a unique set of advantages

– Water equivalence, linear dose response, energy and temperature independence, spatial resolution, etc…

• Several types of scintillation detectors have been developed in the last 15 years

• Main applications:– Conventional EBRT (photons and electrons)– Quality assurance device (daily and IMRT)– Radiosurgery– Protons– Brachytherapy


CONCLUSIONS

• Scintillation dosimetry will be increasingly used in radiotherapy.

• Their advantages make them ideal for measuring complex dose distributions such as those produced by IMRT.

• They can compete with other dosimeters in terms of measurement accuracy, convenience and can be economical.


ACKNOWLEDGEMENTS

L. Archambault L. Archambault F.H. AttixF.H. AttixS.F. de BoerS.F. de BoerT.M. BriereT.M. BriereL. Gingras L. Gingras M. M. GuillotGuillotA. Ikhlef A. Ikhlef T.J. T.J. KinsellaKinsellaF. F. LacroixLacroix

T.R. MackieJ.F. RawlinsonJ.F. RawlinsonR. RoyR. RoyC.H. SibataC.H. SibataJ.V. J.V. SiebersSiebersF. F. ThThéériaultriault--ProulxProulxM. VilleneuveM. VilleneuveN. N. SuchowerskaSuchowerskaS. LawS. Law

…… and all others who have contributed to the field of and all others who have contributed to the field of scintillation dosimetryscintillation dosimetry

CoCo--authorsauthors

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Scintillation dosimetry: Review, new innovations and ...aapm.org/meetings/amos2/pdf/35-9838-52729-634.pdf · Scintillation dosimetry: ... Professor Department of Radiation Physics,