Electron beam energy QA — a note on measurement tolerances

• DOI: 10.1120/jacmp.v17i2.6049
• Publication Date: 2017-02-28T00:27:51Z
• Authors: Juergen Meyer; Matthew J. Nyflot; Wade P. Smith; Landon S. Wootton; Lori Young; Fei Yang; Minsun Kim; Kristi R. G. Hend...; Eric Ford; Alan M. Kalet; Ning Cao; Claire Dempsey; George A. Sandison
• Keywords: Beam energy

Monthly QA is recommended to verify the constancy of high-energy electron beams generated for clinical use by linear accelerators. The tolerances are defined as 2%/2 mm in beam penetration according AAPM task group report 142. practical implementation typically achieved measuring ratio readings at two different depths, preferably near depth maximum dose and corresponding half maximum. Based on commissioning data, we show that relationship between ranges energy ratios energies highly nonlinear. We provide a formalism translates measurement deviations reference into change six Elekta (6-18 MeV) eight Varian (6-22 beams. Experimental checks were conducted each compare calculated values with measurements, it was shown they agreement. For example, 6 MeV deviation measured ionization ± 15% might still be acceptable (i.e., within 2 mm), whereas an 18 tolerance 6%. These strongly depend initial chosen. In summary, differences derived. findings can translated monthly energies.