The baseplate available in carbon fiber and acrylic, is suitable in positioning the pelvic area with thermoplastic masks. The radiation absorption of the carbon fiber sample would be less than one percent of the input radiation and can be disregarded in the calculations of treatment design. The acrylic sample of the plate has a higher radiation absorption at 6 mega volts energy (absorbing around 2.5 % of the input radiation). To precisely measure the absorption for posterior and posterior oblique fields is of great importance in the calculations of treatment design. Acrylic plates can be used to position the patient’s pelvis during CT simulation while their radiation absorption is not a concern.
