Keywords:
Interventional non-vascular, Oncology, Urinary Tract / Bladder, CT, MR, Dosimetry, Radiation therapy / Oncology, VMAT and Tomotherapy, Dosimetric comparison, Radiotherapy techniques
Authors:
M. Chao1, D. Lim Joon2, Y. Chan2, A. Tan3, M. Cokelek1, H. Ho1, P. Manohar4, M. Tacey2, K. McMillan5, T. Pham4, G. Koufogiannis6, M. Guerrieri1; 1Ringwood East, VIC/AU, 2Heidelberg, VIC/AU, 3Mornington, VIC/AU, 4Clayton, VIC/AU, 5Box Hill, VIC/AU, 6Knox, VIC/AU
DOI:
10.26044/ranzcr2021/R-0436
Results
Patient characteristics can be found in Table 1. The median age was 74 years. HA was inserted by new [11, (10.8%)], competent [4, (3.9%)] and experienced users [87, (85.3%)]. HA insertion was completed with a 100% success rate. This was rated as ‘easy’ to ‘very easy’ 100% of the time. When compared to experienced and competent users, new users were less likely to rate the insertion as ‘very easy’ (95% vs 75% vs 36% respectively). Nevertheless, all other insertions were rated as ‘easy’. There were no device related problems, rectal perforation, serious bleeding, infections or allergic reactions.
The median prostate size was 43.5cc (IQR 32-57). The mean recto-prostatic separation for all patients at the base, mid gland and apex were 12mm (SD 2mm), 11 mm (SD 2mm) and 9 mm (SD 1mm) respectively (see Table 2). The saggital length of the implant was 43mm (SD 5mm). The implant was rated as symmetrical in 98% of cases. When compared to experienced and competent users, new users achieved slightly less recto-prostatic separation at the base and midgland. Although this was statistically significant it had minimal dosimetric impact as the separation achieved was excellent. Notably, when compared to experienced and competent users, new users were able to achieve excellent separation at the apex (10mm vs 9mm vs 9mm respectively) with no statistical difference. This is critical as new users typically achieved inferior apical separation (3) with the use of hydrogel spacers with a significant learning curve reported (4).
The mean rV70 was 1.6% (IQR 0.8-3.3%) for patients receiving 78-80Gy. The mean rV70 in the pivotal hydrogel study was 3.3% with rectal spacing and 12.4% without rectal spacing. The mean rV53 was 2.8% (IQR 1.2-4.8%) for patients receiving 60-62Gy. The mean rV53 was 9.8% for a similar cohort of patients without rectal spacing. When compared to experienced and competent users, new users achieved similar rV70 and rV53 dosimetry (see Table 3). The length of follow up does not permit adequate assessment of late toxicity.