Radiotherapy treatment plans with RapidArc for prostate cancer involving seminal vesicles and lymph nodes.
OBJECTIVE
Dosimetric results and treatment delivery efficiency of RapidArc plans to those of conventional intensity-modulated radiotherapy (IMRT) plans were compared using the Eclipse treatment planning system for high-risk prostate cancer.


METHODS
This study included 10 patients. The primary planning target volume (PTV(P)) contained prostate, seminal vesicles, and pelvic lymph nodes with a margin. The boost PTV (PTV(B)) contained prostate and seminal vesicles with a margin. The total prescription dose was 75.6 Gy (46.8 Gy to PTV(P) and an additional 28.8 Gy to PTV(B); 1.8 Gy/fraction). Three plans were generated for each PTV: Multiple-field IMRT, one-arc RapidArc (1ARC), and two-arc RapidArc (2ARC).


RESULTS
In the primary IMRT with PTV(P), average mean doses to bladder, rectum and small bowel were lower by 5.9%, 7.7% and 4.3%, respectively, than in the primary 1ARC and by 3.6%, 4.8% and 3.1%, respectively, than in the primary 2ARC. In the boost IMRT with PTV(B), average mean doses to bladder and rectum were lower by 2.6% and 4.8% than with the boost 1ARC and were higher by 0.6% and 0.2% than with the boost 2ARC. Integral doses were 7% to 9% higher with RapidArc than with IMRT for both primary and boost plans. Treatment delivery time was reduced by 2-7 minutes using RapidArc.


CONCLUSIONS
For PTVs including prostate, seminal vesicles, and lymph nodes, IMRT performed better in dose sparing for bladder, rectum, and small bowel than did RapidArc. For PTVs including prostate and seminal vesicles, RapidArc with two arcs provided plans comparable to those for IMRT. The treatment delivery is more efficient with RapidArc.
Yoo
Sua
S
Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA. sua.yoo@duke.edu
Wu
Q Jackie
QJ
Lee
W Robert
WR
Yin
Fang-Fang
FF
D000465:Algorithms; D006801:Humans; D007421:Intestine, Small / Q000000981:diagnostic imaging; D008198:Lymph Nodes / Q000000981:diagnostic imaging; D008297:Male; D010388:Pelvis; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum / Q000000981:diagnostic imaging; D012669:Seminal Vesicles / Q000000981:diagnostic imaging; D001743:Urinary Bladder / Q000000981:diagnostic imaging