Journal of Medical Physics

Year
: 2003  |  Volume : 28  |  Issue : 1  |  Page : 20--22

Measurements Of Radiation Absorbed Doses In High Energy Radiotherapy Beams : A Comparison Of Different Calibration Protocols


S Sathiyan1, R Ravichandran2, M RaviKumar3 
1 
2 
3 

Correspondence Address:
S Sathiyan


The radiation output calibration of external beam radiotherapy machines based on the ionization chamber measurement is an important task of the medical physicists. Earlier, an in-air calibration measurement was practiced for 60Co beam and the water calibration methods were limited to linear accelerators only. In order to have a trace ability of dosimetry between calibration laboratories and users, various protocols were introduced over two decades. The absorbed dose to air calibration) factor was explained in TG-21 and TRS-277 protocols which were later replaced by absorbed dose to water calibration (ND,w)in TG-51 and TRS-398 protocols. In this context, we have compared in-air measurements with in-water measurements using above protocols for the 60Co and I37Cs beams, and the results agree within &2%. The photon beam output values measured using TRS-277 and TRS-398 formalisms were within +2% for the 60Cob beam, 6 MV and 18 MV x-ray photon beams. The measurements using a cylindrical chamber (TRS-277) and parallel plate chamber (TRS-381) have shown good agreement for high energy photons and electrons. The TLD audit carried out for all the photon beams and the results are within &5%.


How to cite this article:
Sathiyan S, Ravichandran R, RaviKumar M. Measurements Of Radiation Absorbed Doses In High Energy Radiotherapy Beams : A Comparison Of Different Calibration Protocols.J Med Phys 2003;28:20-22


How to cite this URL:
Sathiyan S, Ravichandran R, RaviKumar M. Measurements Of Radiation Absorbed Doses In High Energy Radiotherapy Beams : A Comparison Of Different Calibration Protocols. J Med Phys [serial online] 2003 [cited 2022 May 25 ];28:20-22
Available from: https://www.jmp.org.in/article.asp?issn=0971-6203;year=2003;volume=28;issue=1;spage=20;epage=22;aulast=Sathiyan;type=0