Efficiency-corrected dose verification with thermoluminescence dosemeters in heavy-ion beams.
One of the most essential difficulties in heavy-ion dosimetry by means of thermoluminescence dosemeters (TLDs)--often seen as a serious disadvantage of TLD utilisation--regards the changing TL-efficiency with increasing linear energy transfer (LET) of the particle. This behaviour leads to a falsification of absorbed dose that can be significant for many applications, e.g. in space or radiotherapeutic dosimetry. The high-temperature TL emission of LiF:Mg,Ti TL detectors can be exploited to obtain information about the LET of the heavy-ion radiation field under study. The high-temperature ratio (HTR) is used as a parameter to determine average LET. To correct the absorbed dose according to the TL-efficiency, the detailed dependence of HTR- and TL-efficiency on LET was recorded. These investigations were accomplished at the Heavy Ion Medical Accelerator (HIMAC) in Chiba, Japan, with a variety of high-energy ion beams (helium, carbon, neon, silicon and iron) ranging in LET from 2.2 to 393 keV microm(-1). The obtained relationships HTR vs. LET and TL-efficiency vs. LET were combined into a TL efficieny vs. HTR relationship. This enables correction of the absorbed dose (HTR-B method). The methodology is demonstrated by means of TLD 700 ((7)LiF:Mg,Ti) measurements in carbon beams of 290 and 400 MeV n(-1) available from HIMAC.
Berger
Thomas
T
Atomic Institute of the Austrian Universities (ATI), Stadionallee 2, 1020 Vienna, Austria. thomas.berger@dlr.de
Hajek
Michael
M
Fugger
Mamfred
M
Vana
Norbert
N
D000465:Algorithms; D016477:Artifacts; D004307:Dose-Response Relationship, Radiation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D020450:Heavy Ions; D008422:Materials Testing; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000379:methods*