Diamond DosimetryDiamond Dosimetry

Indra J Das PhD FACRIndra J Das PhD FACRIndra J. Das, PhD, FACRIndra J. Das, PhD, FACRDepartment of Radiation OncologyIndiana University of School of M di i & Mid t P t Medicine & Midwest Proton Radiation Therapy Institute (MPRI)Indianapolis, IN

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Diamond Facts Natural diamond consists of carbon atoms arranged in a

face centered cubic crystal structure called diamond latticelattice

Diamond is the most stable form of carbon which originates from the strong covalent bond between its g gatoms.

Diamond has remarkable optical characteristics. C bi d ith th id t ( di Combined with the wide transparency (corresponding to the wide band gap of 5.5 eV), this results in clear, colorless appearance of most natural diamondspp

Small amounts of defects or impurities creates the color of diamond: blue (boron), yellow (nitrogen), brown (lattice defect) green purple pink orange or red This

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(lattice defect), green, purple, pink, orange or red. This makes them semiconductor

Origin of Diamonds

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Understanding Solid State Dosimetry

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Depletion Region & Signal

ID/SS/diamond-09Fowler, in Radiation Dosimetry F. H. Attix and W. C. Roesch (Eds.) 1966

An ideal DosimeterAn ideal Dosimeter

Stable Linear with dose Linear with dose rate Linear with dose rate Energy independent Independent of type of radiation (x,,E) Direction independencep Rugged with thermal and humidity Direct read out

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Direct read out Minimal correction

Diamond Usage in DosimetryDiamond Usage in Dosimetry

Luminescent Chemical Vapor Deposition (CVD)

S i d Semiconductor

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Stopping-power Ratio of Detectors in Electron Beam

1.25

1.30

tio

1.15

1.20

wer

Rat

Water/Si

W t /C

1.05

1.10

ng-p

ow Water/C

0.95

1.00

Stop

pi

Water/air

0.1 1.0 10.0 50.0

0.90

El t E M VID/SS/diamond-09

Electron Energy, MeVData from Rogers et al, Appendix A, 2009

Stopping Power and Response in Photon Beam

ID/SS/diamond-09Laub et al, Med Phys, 24, 535, 1997

Schematic of PTW Diamond Detector

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Pre-Irradiation Condition

ID/SS/diamond-09De Angelis, et al. Med Phys 29:248-254, 2002

Applied Voltage to Diamond

ID/SS/diamond-09De Angelis et al, Med Phys 29:248-254, 2002

Angular Dependence of Diamond Detector

Natural diamond, NDDouble Diode, DDSingle Diode SDSingle Diode, SD

ID/SS/diamond-09Westermark et al, PMB, 45, 685, 2000

Dose Rate Dependence

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Hoban et al, PMB, 39, 1219-1229, 1994Westermark, et al, PMB, 45, 685-702, 2000

Depth Dose, Photon Beamp

ID/SS/diamond-09Haryanto et al Phys Med Biol 47:N133-N143, 2002

Profiles in Standard & SRS Photon Beams

Das et al J Radiosurg 3:177-185 (2000)

Haryanto et al Phys Med Biol 47:N133-N143, 2002

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Das et al J Radiosurg 3:177 185 (2000).

Depth Dose, Electron Beam

6 MeV15 MeV

ID/SS/diamond-09Heydrian et al Phys Med Biol 38, 1035, 1993

Radial Dose, Brachytherapy

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Rustgi Phys Med Biol 43:2085-2094, 1998.

Energy Dependence of DiamondEnergy Dependence of Diamond

ID/SS/diamond-09Rodriguez, et al. Med Phys 34:215-220, 2007

SummarySummaryyy

Diamond detectors have suitable characteristics for being an ideal detector

Radiological properties are similar to the Radiological properties are similar to the tissue

It is relatively independent of energy It is relatively independent of energy Slight dose rate effect

ll d f ll f ld Well suited for small fields, SRS etc Due to manufacturing difficulty, it is

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g yexpensive and availability is hard

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