Edema‐induced changes in tumor cell surviving fraction and tumor control probability in [Formula: see text] permanent prostate brachytherapy implant patients

The study is designed to investigate the effect of edema on the delivered dose, tumor cell surviving fraction (SF), and tumor control probability (TCP) in the patients of prostate cancer who underwent [Formula: see text] permanent seed implantation. The dose reduction, the SF, and the TCP for edematous prostate implants were calculated for 31 patients who underwent real‐time [Formula: see text] permanent seed implantation for edema half‐lives (EHL), ranging from 4 days to 34 days and for edema magnitudes ([Formula: see text]) varying from 5% to 60% of the actual prostate volume. A dose reduction in [Formula: see text] implants varied from 1.1% (for [Formula: see text] and [Formula: see text]) to 32.3% (for [Formula: see text] and [Formula: see text]). These are higher than the dose reduction in [Formula: see text] implants, which vary from 0.3% (for [Formula: see text] and [Formula: see text]) to 17.5% (for [Formula: see text] and [Formula: see text]). As EHL increased from 4 days to 34 days and edema magnitude increased from 5% to 60%, the natural logarithmic value of SF increased by 4.57 and the TCP decreased by 0.80. Edema induced increase in the SF and decrease in the TCP in [Formula: see text] seed implants, is significantly more pronounced in a combination of higher edema magnitude and larger edema half‐lives than for less edema magnitude and lower edema half‐lives, as compared for [Formula: see text] and [Formula: see text] , and [Formula: see text] and [Formula: see text]. PACS number: 87.53.Jw