Measurement of relative dose distributions in stereotactic radiosurgery by the polymer-gel dosimeter

The purpose of this study was to evaluate relative dose distributions in six various treatment plans (acoustic schwannoma, pituitary adenoma, meningioma, metastasis, Uveal melanoma and glaucoma) in the Leksell gamma knife stereotactic radiosurgery procedure by polymer-gel dosimeter. The presented experiment allowed a check of the entire stereotactic procedure including target stereotactic localization on MRI, treatment planning and irradiation. Relatively good agreement between dose profiles calculated and measured ill a special head phantom by polymer-gel dosimeter was observed. The maximum observed deviation in the spatial position of the center of measured and calculated dose profiles was 0.9 mm (median 0.3). Maximum observed difference in FWHM of measured and calculated profiles was 3.0 mm (median 1.4). No significant difference was observed in deviations between calculated and measured dose profiles related to different treatments simulated in this experiment. The use of the polymer-gel dosimeter for verification of stereotactic procedures has some unique advantages compared to other dosimetric systems which can be summarized as follows: (1) the dosimeter itself is tissue equivalent, (2) three-dimensional dose distributions can be measured, and (3) the dosimeter allows simulation of the patient's procedures without any limitations. Copyright (C) 2004 S. Karger AG, Basel.