Prostate dosimetry in an anthropomorphic phantom.
Four field prostate treatments are a standard treatment procedure in radiotherapy. Dose in the prostate and rectum region were calculated for 6MV and 18MV photon beams on an anthropomorphic phantom with a collapsed cone convolution method using a 3-D planning system. Validation has been performed with radiographic film and thermoluminescent dosimeters. Results have shown that the pinnacle planning system has accurately modelled doses delivered to a heterogeneous phantom with calculations and measurements agreeing within +/-3% over most areas. When treating clinically, considerations such as the volume of bowel gas should be taken into account when planning. A sample of patient CT scans showed that in the absence of a heterogeneity correction, the error in estimated dose through the rectum could be as high as 8% in the presence of large volumes of rectal gas. Considerations, such as whether the patient undergoes another CT scan, the bowel gas volume ignored or assigned a specific density needs to be taken into account and brought to the attention of the radiation oncologists for accurate treatment.
Yu
P K N
PK
City University of Hong Kong, Department of Physics and Materials Science, Kowloon Tong, Hong Kong.
Cheung
T
T
Butson
M J
MJ
D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control; D011874:Radiometry / Q000295:instrumentation / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods*; D012007:Rectum / Q000528:radiation effects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods