نتایج جستجو برای: flattening filter free beams
تعداد نتایج: 665364 فیلتر نتایج به سال:
Analyzing the performance of URT treatment planning system and URT-Linac 506C for flattening filter (FF) free (FFF) photon beams Monte Carlo algorithm by use AAPM TG 119 test cases
Basic dosimetric properties of 6 MV and 18 MV photon beams from a Varian Clinac 21EX accelerator operating without the flattening filter have been measured. These include dose rate data, depth dose dependencies and lateral profiles in a water phantom, total scatter factors and transmission factors of a multileaf collimator. The data are reviewed and compared with measurements for the flattened ...
Flattening filter-free radiation beams have higher dose rates that significantly increase the ion recombination rate in an ion chamber's volume and lower the signal read by the chamber-electrometer pair. The ion collection efficiency correction (P(ion)) accounts for the loss of signal and subsequently changes dosimetric quantities when applied. We seek to characterize the changes to the percent...
Dosimetry protocols for external beam radiotherapy currently in use, such as the IAEA TRS-398 and AAPM TG-51, were written for conventional linear accelerators. In these accelerators, a flattening filter is used to produce a beam which is uniform at water depths where the ionization chamber is used to measure the absorbed dose. Recently, clinical linacs have been implemented without the flatten...
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