Volumetric arc therapy and intensity-modulated radiotherapy for primary prostate radiotherapy with simultaneous integrated boost to intraprostatic lesion with 6 and 18 MV: a planning comparison study.
OBJECTIVE
The aim of the present study was to compare intensity-modulated radiotherapy (IMRT) with volumetric arc therapy (VMAT), in the treatment of prostate cancer with maximal dose escalation to the intraprostatic lesion (IPL), without violating the organ-at-risk constraints. Additionally, the use of 6-MV photons was compared with 18-MV photons for all techniques.


METHODS
A total of 12 consecutive prostate cancer patients with an IPL on magnetic resonance imaging were selected for the present study. Plans were made for three IMRT field setups (three, five, and seven fields) and one VMAT field setup (single arc). First, optimal plans were created for every technique using biologic and physical planning aims. Next, an additional escalation to the IPL was planned as high as possible without violating the planning aims of the first step.


RESULTS
No interaction between the technique and photon energy (p=.928) occurred. No differences were found between the 6- and 18-MV photon beams, except for a reduction in the number of monitor units needed for 18 MV (p<.05). All techniques, except for three-field IMRT, allowed for dose escalation to a median dose of ≥93±6 Gy (mean±standard deviation) to the IPL. VMAT was superior to IMRT for rectal volumes receiving 20-50 Gy (p<.05).


CONCLUSIONS
VMAT allowed for dose escalation to the IPL with better sparing of the rectum than static three-, five-, and seven-field IMRT setups. High-energy photons had no advantage over low-energy photons.
Ost
Piet
P
Department of Radiotherapy, Ghent University Hospital, Ghent, Belgium. piet.ost@ugent.be
Speleers
Bruno
B
De Meerleer
Gert
G
De Neve
Wilfried
W
Fonteyne
Valérie
V
Villeirs
Geert
G
De Gersem
Werner
W
D012809:Colon, Sigmoid / Q000000981:diagnostic imaging; D005270:Femur Head / Q000000981:diagnostic imaging; D006801:Humans; D007421:Intestine, Small / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D058958:Organs at Risk / Q000000981:diagnostic imaging / Q000528:radiation effects; D017785:Photons / Q000627:therapeutic use; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000295:instrumentation / Q000379:methods*; D012007:Rectum / Q000000981:diagnostic imaging / Q000528:radiation effects; D014057:Tomography, X-Ray Computed / Q000379:methods; D001743:Urinary Bladder / Q000000981:diagnostic imaging