• Tibor Major, Peter Agoston, Georgina Fröhlich, Karoly Baricza, Zoltan Szabo, Kliton Jorgo, Andras Herein, and Csaba Polgar.
• Centre of Radiotherapy, National Institute of Oncology, 7-9. Rath Gy. u., H-1122 Budapest, Hungary. Electronic address: major@oncol.hu.
• Phys Med. 2014 Dec 1; 30 (8): 909-13.

PurposeTo compare target volume coverage and critical organ dosimetry of intraoperative treatment plans for loose seed (LS) and stranded seed (SS) (125)I permanent implants for low and intermediate risk prostate cancer.MethodsTwo hundred and five patients who underwent permanent seed brachytherapy were included in the study. For prostate dosimetry V90, V100, V150, V200, D90 and COIN were used. The dose to urethra and rectum was determined by the maximal dose and relative doses that cover specified volumes. Means and standard deviations were calculated and statistically compared.ResultsOn average, 54 (range, 30-78) and 48 (range, 31-67) seeds were implanted in the prostate with individual median activities of 0.62 U (range, 0.52-0.70 U) and 0.71 U (range, 0.65-0.71 U) for LS and SS technique, respectively. The target coverage was slightly better with SS (V100: 98% vs. 96%,p < 0.05; D90: 172 Gy vs. 166 Gy, p < 0.05), but more conformal dose distributions were observed with LS (COIN: 0.70 vs. 0.63, p < 0.05). The dose homogeneity did not differ significantly between the two groups. Regarding the dose to urethra and rectum all dose parameters were significantly lower with LS.ConclusionsLS resulted in less dose to the urethra and rectum compared to SS in intraoperative dosimetry. A slightly better target volume coverage with decreased conformity of dose distribution is reported with SS. More studies are necessary to determine how these results will affect postoperative dosimetry, and ultimately, clinical outcome.Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

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