Measurement of microdosimetric spectra with a wall-less tissue-equivalent proportional counter for a 290 MeV/u 12C beam.
The frequency distribution of the lineal energy, y, of a 290 MeV/u carbon beam was measured to obtain the dose-weighted mean of y and compare it with the linear energy transfer (LET). In the experiment, a wall-less tissue-equivalent proportional counter (TEPC) in a cylindrical volume with a simulated diameter of 0.72 microm was used. The measured frequency distribution of y as well as its dose-mean value agrees within 10% uncertainty with the corresponding data from microdosimetric calculations using the PHITS code. The ratio of the measured dose-mean lineal energy to the LET of the 290 MeV/u carbon beam is 0.73, which is much smaller than the corresponding data obtained by a wall TEPC. This result demonstrates that a wall-less TEPC is necessary to precisely measure the dose-mean of y for energetic heavy ion beams.
Tsuda
Shuichi
S
Research Group of Radiation Protection, Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan. tsuda.shuichi@jaea.go.jp
Sato
Tatsuhiko
T
Takahashi
Fumiaki
F
Satoh
Daiki
D
Endo
Akira
A
Sasaki
Shinichi
S
Namito
Yoshihito
Y
Iwase
Hiroshi
H
Ban
Shuichi
S
Takada
Masashi
M
D000465:Algorithms; D002244:Carbon / Q000737:chemistry*; D020450:Heavy Ions; D018499:Linear Energy Transfer; D008954:Models, Biological; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D011879:Radiotherapy Dosage
D002244:Carbon