In vivo isocenter dose in two hip prosthesis patients.

Hip prostheses may cause irradiation dose inhomogeneities in conventional four-field target volumes to the pelvis. Two patients, with bilateral and unilateral prostheses, were subjected to thermoluminescent dosimetry measurements in the prostatic urethra during 24 MV photon portal exposures. The results suggested a 13% decrease in absorbed dose only for conventional four-field beam geometry with bilateral prostheses, as compared to oblique four-field beam geometry or unilateral prosthesis. This supports the suggestion that beam technique modifications may be warranted for patients with hip prostheses.