Prostate motion during radiotherapy of prostate cancer patients with and without application of a hydrogel spacer: a comparative study.
OBJECTIVE
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
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.
Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, NSW, 2065, Australia. prabhjot@physics.usyd.edu.au.|Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, 2006, Australia. prabhjot@physics.usyd.edu.au.
Prabhjot
P
Juneja
Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, NSW, 2065, Australia. Andrew.Kneebone@health.nsw.gov.au.
Andrew
A
Kneebone
Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, NSW, 2065, Australia. Jeremy.Booth@health.nsw.gov.au.|Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, 2006, Australia. Jeremy.Booth@health.nsw.gov.au.
Jeremy T
JT
Booth
Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, 2006, Australia. david.thwaites@sydney.edu.au.
David I
DI
Thwaites
, 5/161A Willoughby Road, Naremburn, NSW, 2065, Australia. kaurramandeep@hotmail.co.uk.
Ramandeep
R
Kaur
Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, NSW, 2065, Australia. emma.colvill@sydney.edu.au.|Radiation Physics Laboratory, School of Medicine, University of Sydney, Sydney, NSW, 2006, Australia. emma.colvill@sydney.edu.au.
Emma
E
Colvill
Radiation Physics Laboratory, School of Medicine, University of Sydney, Sydney, NSW, 2006, Australia. jin.aun@sydney.edu.au.
Jin A
JA
Ng
Radiation Physics Laboratory, School of Medicine, University of Sydney, Sydney, NSW, 2006, Australia. paul.keall@sydney.edu.au.
Paul J
PJ
Keall
Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, NSW, 2065, Australia. Thomas.Eade@health.nsw.gov.au.
Thomas
T
Eade
D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008297:Male; D009038:Motion; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D015625:Tissue Expansion Devices
D020136:Hydrogel, Polyethylene Glycol Dimethacrylate