Effect of edema on the post-implant dosimetry of an I-125 prostate implant: a case study.
OBJECTIVE
To investigate the effect of post-implant edema on the CT-based calculation of the total dose delivered by an I-125 prostate implant.


METHODS
CT scans of a transperineal I-125 prostate implant were obtained 1 and 39-days post-implant. Changes in the prostate dimensions were determined from changes in the spatial distribution of the I-125 seeds. The total dose delivered to the target volume was computed from each CT scan, and the results compared.


RESULTS
The volume of the prostate decreased by approximately 17% during the 38-day interval between the first and second CT scans. As a result, the radiation dose computed from the second CT scan was 13% higher.


CONCLUSIONS
Post-implant edema can cause a significant underestimation of the radiation dose delivered by an I-125 prostate implant. Similar analysis should be carried out among a larger cohort of patients to confirm or refute these observations.
Waterman
F M
FM
Department of Radiation Oncology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
Yue
N
N
Reisinger
S
S
Dicker
A
A
Corn
B W
BW
D000368:Aged; D001918:Brachytherapy; D004487:Edema / Q000473:pathology*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D011467:Prostate / Q000000981:diagnostic imaging / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D011859:Radiography; D011879:Radiotherapy Dosage
D007457:Iodine Radioisotopes