Dosimetric Verification of the ADAC Pinnacle3 Pencil Beam Algorithm For Clinical Electrons In Presence of Cerrobend Blocking

by Chan, Philip

The purpose of this study was to commission planning electrons in the ADAC Pinnacle3 treatment planning system and to verify its accuracy with clinical Cerrobend blocked fields. Pinnacle utilizes the Hogstrom electron pencil beam algorithm to perform its electron dose calculation. Complete set of measurement beam data in water phantom was first acquired and verified for consistency. The data was then entered into the planning system to develop a measurement and parameter-based model per beam. After the system was commissioned for clinical use, additional verification measurements were performed with unique field blocking. Comparisons between measured and computed dose from Pinnacle demonstrated the calculation was accurate and within clinical tolerance for all field blocking at standard treatment distance. For extended distance, relative depth dose prediction was poor only in the case with very high percentage field blocking. Relative cross-beam dose results were also poorer but were still acceptable for clinical use.