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SU‐E‐T‐389: Energy Deposition Characteristics of Beta‐Emitter P‐32 and Photon Emitter Pd‐103
Author(s) -
Li Texin,
Tong Shidong,
Gong Jason,
Fountain Lynn,
Duffy Edward
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3612343
Subject(s) - common emitter , dosimetry , photon energy , photon , nuclear medicine , brachytherapy , volume (thermodynamics) , deposition (geology) , monte carlo method , beta particle , physics , atomic physics , beta (programming language) , energy (signal processing) , absorbed dose , analytical chemistry (journal) , materials science , radiochemistry , chemistry , optics , optoelectronics , radiation therapy , mathematics , medicine , statistics , biology , paleontology , chromatography , quantum mechanics , sediment , computer science , programming language
Purpose: Comparing the energy deposition characteristics of beta‐emitter P‐32 and photon emitter Pd‐103 to evaluate potential improvement in prostate brachytherapy dosimetry.Materials /Methods: Energy deposited by an activity A after total decay is calculated by 1.44T1/2AE, where E is the energy emitted by a single disintegration. The total energy deposited in the target will be 1.44T1/2AE F, where F is the absorbed fraction (AF). Absorbed fraction is defined as the fraction of emitted energy absorbed in the target. It increases monotonously with target volume. Monte Carlo calculated AF data for uniformly distributed spherical targets, 1 for P‐32 and clinically obtained AF, 2 from Pd‐103 permanent prostate brachytherapy are used in this study. Results: A unity activity (1 mCi) of P‐32 will deliver 7.38 joules, while the same activity of Pd‐103 will deliver 0.26 joules. The total energy deposited in a volume of 20 cc will be 6.90 joules for P‐32 and 0.11 joules for Pd‐103. As the volume of the target increases to 60 cc, the total energy deposited for P‐32 will be 7.06 joules, and 0.14 joules for Pd‐103 respectively. Conclusion: From the preliminary comparison, P‐32 is about 50 to 60 times more efficient in utilizing energy than Pd‐103. This high efficiency will reduce total activity needed to achieve desired dosage in the target. Also, the fact that most energy is absorbed locally in the target suggests that the dose to healthy tissue outside the target can be significantly reduced. Further study is needed in order to fully realize these potential dosimetric advantages.