High-dose-rate prostate brachytherapy consistently results in high quality dosimetry.
OBJECTIVE
We performed a dosimetry analysis to determine how well the goals for clinical target volume coverage, dose homogeneity, and normal tissue dose constraints were achieved with high-dose-rate (HDR) prostate brachytherapy.


METHODS
Cumulative dose-volume histograms for 208 consecutively treated HDR prostate brachytherapy implants were analyzed. Planning was based on ultrasound-guided catheter insertion and postoperative CT imaging; the contoured clinical target volume (CTV) was the prostate, a small margin, and the proximal seminal vesicles. Dosimetric parameters analyzed for the CTV were D90, V90, V100, V150, and V200. Dose to the urethra, bladder, bladder balloon, and rectum were evaluated by the dose to 0.1 cm(3), 1 cm(3), and 2 cm(3) of each organ, expressed as a percentage of the prescribed dose. Analysis was stratified according to prostate size.


RESULTS
The mean prostate ultrasound volume was 38.7 ± 13.4 cm(3) (range: 11.7-108.6 cm(3)). The mean CTV was 75.1 ± 20.6 cm(3) (range: 33.4-156.5 cm(3)). The mean D90 was 109.2% ± 2.6% (range: 102.3%-118.4%). Ninety-three percent of observed D90 values were between 105 and 115%. The mean V90, V100, V150, and V200 were 99.9% ± 0.05%, 99.5% ± 0.8%, 25.4% ± 4.2%, and 7.8% ± 1.4%. The mean dose to 0.1 cm(3), 1 cm(3), and 2 cm(3) for organs at risk were: Urethra: 107.3% ± 3.0%, 101.1% ± 14.6%, and 47.9% ± 34.8%; bladder wall: 79.5% ± 5.1%, 69.8% ± 4.9%, and 64.3% ± 5.0%; bladder balloon: 70.3% ± 6.8%, 59.1% ± 6.6%, and 52.3% ± 6.2%; rectum: 76.3% ± 2.5%, 70.2% ± 3.3%, and 66.3% ± 3.8%. There was no significant difference between D90 and V100 when stratified by prostate size.


CONCLUSIONS
HDR brachytherapy allows the physician to consistently achieve complete prostate target coverage and maintain normal tissue dose constraints for organs at risk over a wide range of target volumes.
California Endocurietherapy at UCLA, Department of Radiation Oncology, David Geffen School of Medicine of the University of California at Los Angeles, Los Angeles, California 90095, USA.
Evan C
EC
White
Mitchell R
MR
Kamrava
John
J
Demarco
Sang-June
SJ
Park
Pin-Chieh
PC
Wang
Oluwatosin
O
Kayode
Michael L
ML
Steinberg
D Jeffrey
DJ
Demanes
D001918:Brachytherapy / Q000379:methods* / Q000592:standards; D006801:Humans; D008297:Male; D009929:Organ Size; D058958:Organs at Risk / Q000528:radiation effects; D011467:Prostate / Q000000981:diagnostic imaging / Q000473:pathology / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011829:Radiation Dosage; D011879:Radiotherapy Dosage / Q000592:standards; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012007:Rectum / Q000528:radiation effects; D012306:Risk; D012669:Seminal Vesicles / Q000528:radiation effects; D047368:Tumor Burden; D018084:Ultrasonography, Interventional; D014521:Urethra / Q000528:radiation effects