Chapter 6 External Photon Beams: Physical Aspects - IRSN

326.7 CENTRAL AXIS DEPTH DOSES IN WATER: SSD SETUP6.7.1 Percentage depth dose For a constant z, A, and h , PDD(z,A,f, h) increases withincreasing f because of a decreasing effect of depth zon the inverse square factor, which governs the primarycomponent of the photon beam.IAEA Radiation Oncology Physics: A Handbook for Teachers and Students - 6.7.1 Slide 9 (63/170)6.7 CENTRAL AXIS DEPTH DOSES IN WATER: SSD SETUP6.7.1 Percentage depth doseFor a constantz, A, and f,PDD(z,A,f, h)beyond z maxincreases withbeam energy hbecause of adecrease in beamattenuation, i.e.,increase in beampenetrating power.IAEA Radiation Oncology Physics: A Handbook for Teachers and Students - 6.7.1 Slide 10 (64/170)