Chapter 6 External Photon Beams: Physical Aspects - IRSN

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766.12 CLARKSON SEGMENTAL INTEGRATIONOnce the value of a dose function for a given irregularfield is determined through the Clarkson integrationmethod, the equivalent square for the given irregularfield can be determined by finding, in tabulated squarefield data, the square field that will give the same valuefor the dose function.This square field is then defined as the equivalentsquare for the given irregular field.IAEA Radiation Oncology Physics: A Handbook for Teachers and Students - 6.12 Slide 6 (151/170)6.12 CLARKSON SEGMENTAL INTEGRATIONThe segmental integration technique was originallyproposed by Clarkson in the 1940s and developedfurther by Johns and Cunningham in the 1960s fordetermining the scatter component of the dose at anarbitrary point of interest in the patient, either inside oroutside the direct radiation field.• Originally, the Clarkson integration method was used with flatradiation beams (orthovoltage and cobalt-60).• When used with linac beams, the dependence of primarybeam flatness on depth in patient for off axis points must beaccounted for.IAEA Radiation Oncology Physics: A Handbook for Teachers and Students - 6.12 Slide 7 (152/170)
776.13 RELATIVE DOSE MEASUREMENTS WITH IONIZATIONCHAMBERSDose parameters for radiotherapy treatment are mostcommonly measured with ionization chambers thatcome in many sizes and geometrical shapes.• Usually each task of dose determination is carried out withionization chambers designed for the specific task at hand.• In many situations the measured chamber signal must becorrected with correction factors that depend upon influencequantities, such as chamber air temperature and pressure,chamber polarity and applied voltage, and photon beamenergy.IAEA Radiation Oncology Physics: A Handbook for Teachers and Students - 6.13 Slide 1 (153/170)6.13 RELATIVE DOSE MEASUREMENTS WITH IONIZATIONCHAMBERSIAEA Radiation Oncology Physics: A Handbook for Teachers and Students - 6.13 Slide 2 (154/170)
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26.1 INTRODUCTIONRadiotherapy (also
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46.2 QUANTITIES USED IN DESCRIBING
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106.3 PHOTON SOURCES FOR EXTERNAL B
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126.4 INVERSE SQUARE LAW We assume
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146.5 PENETRATION OF PHOTON BEAMS I
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166.5 PENETRATION OF PHOTON BEAMS I
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186.6 RADIATION TREATMENT PARAMETER
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Chapter 6 External Photon Beams: Physical Aspects - IRSN

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