Dose Course 2018_Flipping book

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Input data – “general” to PB electron calculations

❑ Measured Depth–Dose Distributions o Depth dose distributions for electron beams of a given E 0 are extremely dependent on the particular beam transport system (scattering foils or scanning system, applicator design. etc.) of the user’s accelerator. The Fermi–Eyges model requires central-axis depth– dose distributions for a number of different rectangular field sizes – g ( z ) ❑ Dose Profiles o A dose profile is required in order to derive the weighting factor W (x,y). This should be measured at or near d max in a principal plane across the larger field dimension for each field for which the CAXD (z ) is required. ❑ Mean Energy at the Surface, E 0 ❑ The Initial Angular Spread o This parameter can be determined from in-air measurements of the penumbra at different distances from the collimator using film (Hogstrom et al. 1981).

Dublin 2018