|
KMID : 0384620110220040216
|
|
Korean Journal of Medical Physics
2011 Volume.22 No. 4 p.216 ~ p.223
|
|
|
A Study of Characteristics of MicroLion Liquid Ionization Chamber for 6 MV Photon Beam
|
|
Choi Sang-Hyoun
Huh Hyun-Do
Kim Seong-Hoon
Ji Young-Hoon
Kim Kum-Bae
Kim Woo-Chul
Kim Hun-Jeong
Shin Dong-Oh
Kim Chan-Hyeong
|
|
|
Abstract
|
|
|
|
Recently PTW developed a MicroLion liquid ionization chamber which is water_equivalent and has a small sensitive volume of 0.002㎤. The aim of this work is to investigate such dosimetric characteristics as dose linearity, dose rate dependency, spatial resolution, and output factors of the chamber for the external radiotherapy photon beam. The results were compared to those of Semiflex chamber, Pinpoint chamber and Diode chamber with the sensitive volumes of 0.125㎤,0.03㎤ and 0.0025㎤, respectively and evaluated to be suitable for small fields. This study was performed in the 6MV photon energy from a Varian 2300 C/D linac accelerator and the MP3 water phantom (PTW, Freiburg) was used. Penumbras in the varios field sizes ranged from 0.5×0.5㎠ to 10×10㎠ were used to evaluate the spatial resolution. Output factors were measured in the field sizes of 0.5×0.5㎠ to 40×40㎠. Readings of the chamber was linearly proportional to dose. Dose rate dependency was measured from 100 MU/min to 600 MU/min, showed a maximum difference of 5.0%, and outputs decreased with dose rates. The spatial resolutions determined with comparing profiles for the field sizes of 0.5×0.5㎠ to 10×10㎠ agreed between every detector except the Semiflex chamber to within 2%. Outputs of detectors were compared to that of Semiflex chamber and showed good agreements within 2% for every chamber. This study shows that MicroLion chamber characterized by a high signal-to-noise ratio and water equivalence could be suitable for the small field dosimetry.
|
|
|
KEYWORD
|
|
|
MicroLion liquid ionization chamber, Water equilibrium material, Small field
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
  
|