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Prescription dose in permanent Cs 131 seed prostate implants
Author(s) -
Yue Ning,
Heron Dwight E.,
Komanduri Krishna,
Huq M. Saiful
Publication year - 2005
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 - 10.1118/1.1951062
Subject(s) - prostate , medicine , dosimetry , medical prescription , implant , prostate cancer , nuclear medicine , urology , surgery , pharmacology , cancer
Recently, Cs131 seeds have been introduced for prostate permanent seed implants. This type of seed has a relatively short half‐life of 9.7 days and has its most prominent emitted photon energy peaks in the 29–34 keV region. Traditionally, 145 and 125 Gy have been prescribed for I125 and Pd103 seed prostate implants, respectively. Since both the half‐life and dosimetry characteristics of Cs131 seed are quite different from those of I125 and Pd103 , the appropriate prescription dose for Cs131 seed prostate implant may well be different. This study was designed to use a linear quadratic radiobiological model to determine an appropriate dose prescription scheme for permanent Cs131 seed prostate implants. In this model, prostate edema was taken into consideration. Calculations were also performed for tumors of different doubling times and for other related radiobiological parameters of different values. As expected, the derived prescription dose values were dependent on type of tumors and types of edema. However, for prostate cancers in which tumor cells are relatively slow growing and are reported to have a mean potential doubling time of around 40 days, the appropriate prescription dose for permanent Cs131 seed prostate implants was determined to be:127 − 12 + 5 Gy if the experiences of I125 seed implants were followed and121 − 3 + 0 Gy if the experiences of Pd103 seed implants were followed.