Chapter 6 External Photon Beams: Physical Aspects - IRSN

746.12 CLARKSON SEGMENTAL INTEGRATIONClarkson segmental integration is based on circular fielddata and used in determination of equivalent square fieldas well as various dose functions for a given irregular field.Clarkson method resolvesthe irregular field into sectorsof circular fields centred atthe point of interest Q in thephantom or patient.• For manual calculations sectorangular width is 10 o .• For computer driven calculationssector angular width is 5 o or less.IAEA Radiation Oncology Physics: A Handbook for Teachers and Students - 6.12 Slide 2 (147/170)6.12 CLARKSON SEGMENTAL INTEGRATION An assumption is made that asector with a given fieldradius contributes 1/N of thetotal circular field value to thevalue of a given function F forirregular field at point Q. N is number of sectors in afull circular field of 360 o .• N = 36 for manual calculations.• N = 72 for computer calculations.IAEA Radiation Oncology Physics: A Handbook for Teachers and Students - 6.12 Slide 3 (148/170)