Sequential comparison of seed loss and prostate dosimetry of stranded seeds with loose seeds in 125I permanent implant for low-risk prostate cancer.
OBJECTIVE
To compare stranded seeds (SSs) with loose seeds (LSs) in terms of prostate edema, dosimetry, and seed loss after (125)I brachytherapy.


METHODS
Two prospective cohorts of 20 men participated in an institutional review board-approved protocols to study postimplant prostate edema and its effect on dosimetry. The LS cohort underwent brachytherapy between September 2002 and July 2003 and the SS cohort between April 2006 and January 2007. Both cohorts were evaluated sequentially using computed tomography-magnetic resonance imaging fusion-based dosimetry on Days 0, 7, and 30. No hormonal therapy or supplemental beam radiotherapy was used.


RESULTS
Prostate edema was less in the SS cohort at all points (p = NS). On Day 0, all the prostate dosimetric factors were greater in the LS group than in the SS group (p = 0.003). However, by Days 7 and 30, the dosimetry was similar between the two cohorts. No seeds migrated to the lung in the SS cohort compared with a total of five seeds in 4 patients in the LS cohort. However, the overall seed loss was greater in the SS cohort (24 seeds in 6 patients; 1.1% of total vs. 0.6% for LSs), with most seeds lost through urine (22 seeds in 5 patients).


CONCLUSIONS
Despite elimination of venous seed migration, greater seed loss was observed with SSs compared with LSs, with the primary site of loss being the urinary tract. Modification of the technique might be necessary to minimize this. Prostate dosimetry on Days 7 and 30 was similar between the SS and LS cohorts.
Saibishkumar
Elantholi P
EP
Department of Radiation Oncology, Princess Margaret Hospital, Toronto, ON, Canada.
Borg
Jette
J
Yeung
Ivan
I
Cummins-Holder
Cheryl
C
Landon
Angela
A
Crook
Juanita
J
D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects* / Q000295:instrumentation*; D004487:Edema / Q000175:diagnosis / Q000209:etiology*; D005548:Foreign-Body Migration / Q000175:diagnosis / Q000209:etiology*; D006801:Humans; D007457:Iodine Radioisotopes / Q000009:adverse effects* / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000150:complications / Q000532:radiotherapy; D019736:Prostheses and Implants / Q000009:adverse effects*; D011832:Radiation Injuries / Q000175:diagnosis / Q000209:etiology*; D019275:Radiopharmaceuticals / Q000009:adverse effects / Q000627:therapeutic use; D018570:Risk Assessment; D012307:Risk Factors
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals