Absorbed dose in ion beams: comparison of ionisation- and fluence-based measurements.
A direct comparison measurement of fluorescent nuclear track detectors (FNTDs) and a thimble ionisation chamber is presented. Irradiations were performed using monoenergetic protons (142.66 MeV, ϕ=3×10(6) cm(-2)) and carbon ions (270.55 MeV u(-1), ϕ=3 × 10(6) cm(-2)). It was found that absorbed dose to water values as determined by fluence measurements using FNTDs are, in case of protons, in good agreement (2.4 %) with ionisation chamber measurements, if slower protons and Helium secondaries were accounted for by an effective stopping power. For carbon, however, a significant discrepancy of 4.5 % was seen, which could not be explained by fragmentation, uncertainties or experimental design. The results rather suggest a W-value of 32.10 eV ± 2.6 %. Additionally, the abundance of secondary protons expected from Monte-Carlo transport simulation was not observed.
Department of Radiation Oncology and Radiation Therapy, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany Division of Medical Physics in Radiooncology, German Cancer Research Center (dkfz), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany j.osinga@dkfz-heidelberg.de.
Julia-Maria
JM
Osinga
Heidelberg Ion-Beam Therapy Center, Im Neuenheimer Feld 450, 69120 Heidelberg, Germany.
Stephan
S
Brons
Oklahoma State University, Stillwater, OK 74074, USA Landauer, Inc., 723 1/2 Eastgate, Stillwater, OK 74074, USA.
James A
JA
Bartz
Landauer, Inc., 723 1/2 Eastgate, Stillwater, OK 74074, USA.
Mark S
MS
Akselrod
Department of Radiation Oncology and Radiation Therapy, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany Division of Medical Physics in Radiooncology, German Cancer Research Center (dkfz), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany Heidelberg Ion-Beam Therapy Center, Im Neuenheimer Feld 450, 69120 Heidelberg, Germany.
Oliver
O
Jäkel
Division of Medical Physics in Radiooncology, German Cancer Research Center (dkfz), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
Steffen
S
Greilich
D002151:Calorimetry; D002244:Carbon / Q000737:chemistry; D003198:Computer Simulation; D006371:Helium; D007091:Image Processing, Computer-Assisted; D007477:Ions; D018613:Microscopy, Confocal / Q000295:instrumentation / Q000379:methods; D015233:Models, Statistical; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011522:Protons; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012984:Software; D014867:Water
D007477:Ions; D011522:Protons; D014867:Water; D006371:Helium; D002244:Carbon