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Many radiotherapy centers don’t pay attention to effect of ionization champers type on accuracy of quality control measurements. They use any available ionization champers in all quality control and data entry measurements (1,2) . Many studies were carried out in this field to compare different ionization champers in small fields but large fields were not completely compared before (3.4). The aim of this work is to compare output factor in large field using two different sizes ionization champers connected to electrometer. Final out put were obtained from the farmer and smidflex dosimeter irradiated with 6 MV photon beams. Important field side ranging from 20 cm to 70 cm side field is measured in whole body radiation (5, 6).
For all examined large field sizes a difference ranging from 1% to 5 % was found when added to other calibration errors it will exceeds the acceptable margin. The largest difference was found in field side 70 cm this may be due to large scattering radiation
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2- Olding T, Holmes O, Dejean P, McAuley KB, Nkongchu K, Santyr G, Schreiner LJ (2011) Small field dose deliveryevalua_ons using cone beam op_cal computed tomography-based polymer gel dosimetry. J Med Phys,36:3-14.
3- Van Dyk J. The modern Technology of Radiation Oncology. Madison: Medical Physics Publishing; 1999. p. 641-62.
4- Vrtar M. Fizikalni aspekti tehnike ozraèenja cijelog tijela (TBI). (Physical aspects of total body irradiation technique (TBI). Zbornik predavanja dru¹tvaza mernu tehniku Srbije - Sekcija za merenja u radioterapiji. Belgrade: 1988. p. 209-30.
5- INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA), “Calibration of Dosimeters used in Radiotherapy: A manual sponsored by the IAEA and WHO”, IAEA Technical Report Series, TRS-374, IAEA, Vienna, Austria (1994).
6- INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA), “The use of plane parallel ionisation chambers in high energy electron and photon beams”, IAEA Technical Report Series, TRS-381, IAEA, Vienna, Austria (1997).
7- INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA), “Absorbed dose determination in external beam radiotherapy: An international code of practice for dosimetry based on standards of absorbed dose to water”, IAEA Technical Report Series, TRS-398, IAEA, Vienna, Austria (2000)
8- INTERNATIONAL ORGANIZATION FOR STANDARDIZATION (ISO), “Guide to expression of uncertainty in measurement”, ISO, Geneva, Switzerland (1992).
9- KHAN, F.M., “The physics of radiation therapy”, Williams and Wilkins, Baltimore, Mary-land, U.S.A. (1994).
10- KLEVENHAGEN, S.C., “Physics and dosimetry of therapy electron beams”, Medical Physics Publishing, Madison, Wisconsin, U.S.A. (1993).
11- VAN DYK, J. (editor), “Modern technology of radiation oncology: A compendium for medical physicists and radiation oncologists”, Medical Physics Publishing, Madison, Wisconsin, U.S.A. (1999). Forman, G. 2003. An extensive empirical study of feature selection metrics for text classification. J. Mach. Learn. Res. 3 (Mar. 2003), 1289-1305.