A comparison of multileaf collimator with conformal blocks for the boost phase of dose-escalated conformal prostate radiotherapy.
A multileaf collimator (MLC) is compared with conformal blocks for delivering the boost phase of dose-escalated conformal prostate radiotherapy. When using conformal blocks, the volume of rectum irradiated to 90% (V90) is lower (1.4+/-1.3%, 1 SD) for a three-field plan with gantry angles 0 degree, 90 degrees, 270 degrees than for a six-field plan with gantry angles 50 degrees, 90 degrees, 130 degrees, 230 degrees, 270 degrees, 310 degrees (2.1 +/- 1.3%, P = 0.002). However, when using an MLC in which the leaves and wedge are oriented at right angles, V90 is higher (4.7 +/- 3.0%) for a three-field plan than for a six-field plan (2.7 +/- 1.6%, P=0.05). The larger increase in V90 for the three-field plan when changing from conformal blocks to MLC is mainly due to the limitation imposed upon the MLC orientation by the use of wedges.
Bedford
J L
JL
Joint Department of Physics, The Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Surrey SM2 5PT, Sutton, UK.
Khoo
V S
VS
Warrington
A P
AP
Bidmead
A M
AM
Webb
S
S
Deamaley
D P
DP
D004307:Dose-Response Relationship, Radiation; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000532:radiotherapy*; D011829:Radiation Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome