Evaluation of the clinical advantage of endo-rectal balloons (ERBs) for prostate treatments.

148 Background: The challenge of prostate and rectal motion during radiotherapy has been firmly established, both these problems are exacerbated by rectal instability. A number of different mechanical methods have been explored to see if the rectum can be stabilised. This study aimed to establish whether there is a clinical advantage in the use of ERB’s for the treatment of prostate patients, assessing inter-fractional prostate stability and dose to the rectum. Methods: This planning study was based on 10 patients with 2 sets of CT and Cone beam CT (CBCT) data with and without an ERB in situ. The ERB was a 100cc air filled RectalPro balloon. CBCT scan with and without the ERB were taken on the same day. The scans were contoured and planned using pinnacle version 9.8 with rotational arc therapy to a dose of 60Gy in 20 fractions, for an Elekta Agility treatment unit. An assumption was made that the prostate stability was directly related to the rectal stability. Based on this assumption, comparisons of the ...