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Prostate motion during radiotherapy of prostate cancer patients with and without application of a hydrogel spacer: a
Prabhjot Juneja1,2, Andrew Kneebone3, Jeremy T Booth4,5
1Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, NSW, 2065, Australia. prabhjot@physics.usyd.edu.au.
Background And Purpose:
The use of a tissue expander (hydrogel) for sparing of the rectum from increased irradiation during prostate radiotherapy is becoming popular. The goal of this study is to investigate the effect of a tissue expander (hydrogel) on the intrafraction prostate motion during radiotherapy.
Methods And Material:
Real time prostate motion was analysed for 26 patients and 742 fractions; 12 patients with and 14 patients without hydrogel (SpaceOAR™). The intra-fraction motion was quantified and compared between the two groups.
Results:
The average (±standard deviation) of the mean motion during the treatment for patients with and without hydrogel was 1.5 (±0.8 mm) and 1.1 (±0.9 mm) respectively (p < 0.05). The average time of motion >3 mm for patients with and without hydrogel was 7.7 % (±1.1 %) and 4.5 % (±0.9 %) respectively (p > 0.05). The hydrogel age, fraction number and treatment time were found to have no effect (R (2) < 0.05) on the prostate motion.
Conclusions:
Differences in intrafraction motion in patients with hydrogel and without hydrogel were within measurement uncertainty (<1 mm). This result confirms that the addition of a spacer does not negate the need for intrafraction motion management if clinically indicated.
