Monte Carlo dosimetry for /sup 125/I and /sup 60/Co in eye plaque therapy

Journal Article · Mon Sep 01 04:00:00 EDT 1986 · Med. Phys.; (United States)

OSTI ID:5080865

Chiu-Tsao, S; O'Brien, K; Sanna, R; Tsao, H; Vialotti, C; Chang, Y; Rotman, M; Packer, S

Monte Carlo calculations of radiation dosimetry using m-smcapso-smcapsr-smcapss-smcapse-smcaps code are performed for /sup 125/I and /sup 60/Co point sources in a cylindrical head phantom that simulates the geometry of eye plaque therapy for choroidal melanoma. We obtain the dose variation in the eye at submillimeter intervals over distances as close as 1 mm and up to 2.5 cm from the source. The calculations for /sup 125/I are performed for the phantom media of water, protein, and a homogenized protein--water mixture simulating the composition of the eye. Relative dose functions for /sup 125/I for these phantom media are fitted to second-degree polynomials. Agreement is found with published results. The relative dose function for /sup 60/Co at eye position in the water head phantom is fitted to a third-degree polynomial and compared with that for /sup 60/Co at the center of a large water sphere. A boundary effect due to the head phantom--air interface on the dose distribution for /sup 60/Co is demonstrated. The dose falloff with distance is faster for the eye geometry compared with the bulk geometry. We also show that the relative dose distributions within the tumor are comparable for /sup 125/I and /sup 60/Co by comparing their relative dose functions. This result is consistent with the success of clinical trials of large melanoma treatments with /sup 125/I plaques.

• Research Organization: Department of Medical Physics, Hackensack Medical Center, Hackensack, New Jersey 07601
• OSTI ID: 5080865
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 13:5; ISSN MPHYA
• Country of Publication: United States
• Language: English

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61 RADIATION PROTECTION AND DOSIMETRY
655003* -- Medical Physics-- Dosimetry
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
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COBALT 60
COBALT ISOTOPES
DAYS LIVING RADIOISOTOPES
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MONTE CARLO METHOD
NEOPLASMS
NUCLEAR MEDICINE
NUCLEI
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