Survey of high-dose-rate prostate brachytherapy practice in Australia and New Zealand, 2010-2011.

INTRODUCTION: A survey was designed to establish a baseline data set for the current routine practice of high-dose-rate prostate brachytherapy (HDR-PB) in Australia and New Zealand. Existing treatment protocols and clinical implementations are not generally known. METHODS: The survey, for the 2010 and 2011 calendar years, collected data including number of patients treated; equipment used; imaging modalities; applicator verification and correction methods; dose prescriptions and normal tissue dose constraints. The number of HDR-PB patients treated was compared with the most recently published prostate cancer incidence data in Australia and in New Zealand. Total biologically equivalent doses in 2.0 Gy fractions (EQD2) were calculated for each prescription regime reported. RESULTS: There were reductions, of 25-60%, in patients treated with HDR-PB from 2010 to 2011 in four departments. Prostate cancer patients are two to six times more likely to be prescribed HDR-PB in Western Australia than elsewhere in the region. There were 12 different treatment prescriptions, with EQD2 doses ranging from 73.5 to 97.6 Gy, among the 18 reported by survey respondents. Normal tissue definition methodology and dose constraints varied, and 13 of 15 departments reported that no particular published external guidelines were followed in full. CONCLUSION: The high survey response rate, 15 of 17 departments, has provided a representative baseline data set of contemporary HDR-PB practice in Australia and New Zealand that may assist government and professional bodies, such as the Australasian Brachytherapy Group, in formulating recommendations, setting standards and future planning.

A small tolerance for catheter displacement in high-dose rate prostate brachytherapy is necessary and feasible.

PURPOSE: We examined catheter displacement in patients treated with fractionated high-dose rate (HDR) brachytherapy boost for prostate cancer and the impact this had on tumor control probability (TCP). These data were used to make conclusions on an acceptable amount of displacement. METHODS AND MATERIALS: The last 20 patients treated with HDR brachytherapy boost for prostate cancer at our center in 2007 were replanned using simulated interstitial catheter displacements of 3, 6, 9, and 12 mm with originally planned dwell times. The computer-modeled dose-volume histograms for the clinical target volumes were exported and used to calculate the TCP of plans with displaced needles relative to the original plan. Actual catheter displacements were also measured before and after manual adjustment in all patients treated in 2007. RESULTS: In the 20 patients who were replanned for caudal catheter displacements of 3, 6, 9, and 12 mm, the median relative TCP was 0.998, 0.964, 0.797, and 0.265, respectively (p < 0.01 when all medians were compared). All patients replanned with a 3-mm displacement, compared with only 75% with a 6-mm displacement, had a relative TCP greater than 0.950. In the 91 patients treated in 2007, before adjustment, 82.3% of fractions had a displacement greater than 3 mm compared with 12.2% of fractions after adjustment. CONCLUSIONS: Catheter displacement in HDR brachytherapy significantly compromises the TCP. The tolerance for these movements should be small (< or =3 mm). Correcting these displacements to within acceptable limits is feasible.