Fabrication of Head Phantom to Investigate the Effect of Heterogeneity on the Absorbed Dose in Radiotherapy

The validation of treatment planning systems is performed using phantoms. The accuracy of the results depends on the similarity of phantom and target organs. There are some vital organs in the head so each discrepancy between the absorbed dose delivered in planning target volume and the one predicted by the treatment planning system can be caused irreparable impairment. This research reports the methodology and materials used to fabricate a heterogeneous head phantom based on Snyder digital phantom use in dosimetry studies. This phantom includes an elliptical shell as a base, skull, eyes, maxillary sinuses, and brain equivalent material. The cow bone powdered and polyvinyl alcohol solution is used for the construction of skull, eyeballs, and maxillary sinuses. Also, water is selected as a brain and eye tissue-equivalent material. To evaluate the constructed phantom, Monte Carlo calculation and measurement have been compared. The results of the two methods are in good agreement, and the maximum difference between them is 2.6. Constructed phantom is easy to use, and it prepares all dosimetry purposes such as diagnosis, treatment, and investigation.