|
KMID : 0384620030140040249
|
|
Korean Journal of Medical Physics
2003 Volume.14 No. 4 p.249 ~ p.258
|
|
|
Comparison of Air Kerma-based and Absorbed Dose to Water-based Protocols in the Dosimetry of High Energy Electron Beams
|
|
Park Sung-Yong
|
|
|
Abstract
|
|
|
|
A few years ago, a proposal was made to change the dosimetry from the air kerma-based reference dosimetry to the absorbed dose-based reference dosimetry for all radiotherapy beams of ionizing radiation to improve the accuracy of dosimetry. Here, we present a dosimetry study in which the two most widespread absorbed dosebased protocols (IAEA TRS398 and AAPM TG51) were compared with an air kermabased protocol (IAEA TRS-277) by measuring the absorbed dose in the same reference depth. Measurements were performed in three clinical electron beam energies using a PTW 30002 cylindrical chamber, and Markus and Roos planeparallel chambers. /sup 60/Co calibration factors were obtained from the KFDA. The absorbed dose differences between the air kermabased and absorbed dosebased protocols were within 2.0％ for all chambers in all beams. The results thus show that the obtained absolute dose values will be not significantly altered by changing from the air kermabased dosimetry to the absorbed dosebased dosimetry. It was also shown that absorbed dose values between the absorbed dosebased protocols agreed by deviations of less than 0.5％ for a cylindrical chamber and less than 0.7％ for planeparallel chambers using crosscalibration factors. Although the use of a cylindrical chamber and planeparallel chambers resulted in a difference of less than 2％ for all situations investigated here, to reduce errors, the planeparallel chambers are recommended for electron energies in which the use of cylindrical chamber is not permitted in each protocol.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
  
|