Oral & Poster Presentation – Physics Abstracts Archive

UK & Ireland Prostate Brachytherapy Conference 2016

Abstract number 4

Global and sector based dosimetric comparison of plugged vs plug-free needles in permanent prostate brachytherapy 

Sarri L*; Crockett C*; Badusha A*; Workman G*; Mitchell D*; Jain S*
*Northern Ireland Cancer Centre, Belfast City Hospital

AIMS/INTRODUCTION: The goal of permanent prostate brachytherapy is to achieve adequate tumour and gland coverage with minimal toxicity. Previous studies have identified relative underdosing at the anterior prostate base. One potential cause for this is the effect of the deadspace created by the bio-absorbable plug in plugged needles. Plug-free needles have the potential of improving dose to this area by removing the dead-space created by the plug. We wished to compare the post implant CT global and multi-sector dosimetry of patients treated using plugged and plug-free needles. 

MATERIALS/METHODS: 58 consecutive cases were identified with Group 1 (n=28) treated with plugged needles and Group 2 (n=30) treated using plug-free needles. Dosimetric analysis was performed for the whole prostate and 12 individual sectors1, including minimum dose to 90% of the prostate or sector (D90) and dose to 0.1 cm3 of the rectum (D0.1cc), as well as the number of needles per unit volume (N/V) and seed loss. 

RESULTS: Global dosimetry was similar for both groups, but fewer needles were required per unit volume in Group 2 (0.58±0.10 cm-3 vs 0.66±0.15 cm-3; p<0.05). Seed loss was significantly reduced in Group 2 (p<0.05). Furthermore, sector analysis indicated improvements in D90 in a number of sectors of the prostate (p<0.05), except for the anterior gland. The rectal D0.1cc was higher in Group 2 than Group 1 (114% vs 100%, p<0.02) but well within recommended tolerances2. 

CONCLUSION: Our results indicate that plug-free needles have the potential to improve implant quality via better spatial dose distribution within the prostate using fewer needles and reducing the number of seeds lost. While there was a trend towards improved anterior base dosimetry this was not significant. 

References:
1. AB Mohamed Yoosuf, DM Mitchell, G Workman et al. Brachytherapy 2015; 14(5):703-10.
2. C Salembier, P Lavagnini, P Nickers et al. Radiat. Oncol. 2007; 83: 3-10.