Sources of uncertainty in therapy level alanine dosimetry

Response of l-alanine and 2-methylalanine minidosimeters for K-Band (24GHz) EPR dosimetry

“…Although 2MA is more sensitive than L-alanine, the uncertainty results are about the same order of magnitude for each corresponding dose value. As was established by Bartollota et al [46], the S/N for the EPR signal degrades as the dose diminishes because some of the sources of uncertainty, such as the baseline distortion, become more pronounced for low doses. The overall uncertainty could be improved by controlling and/or correcting for the contribution of the three above sources, but this will be limited by the particular experimental conditions.…”

“…6 and 7) represent the overall uncertainty in the minidosimeter reading, that is, the uncertainty in the determination of the peak-to-peak amplitude. This overall uncertainty is the combination of uncertainties from the contribution of three sources: (a) spectrometer instability and minidosimeter orientation effect, (b) variation in signal amplitude even for minidosimeters irradiated with the same dose due to a change in radiation sensitive material content in a minidosimeter, (c) baseline distortion effects [46]. This uncertainty diminishes as the dose increases, oscillating between 2.2% (22 Gy) to 28% (1 Gy) for L-alanine and 1.7% (20 Gy) to 35% (1 Gy) for 2MA.…”

“…LLD is defined as the dose value that provides signal amplitude that is statistically distinguishable from the background signal at least in three standard deviations [46]. Taking into account this definition, three non-irradiated minidosimeters for both dosimetric materials were used to determine the background signal.…”

Ionizing Radiation Induced Radicals

“…First results for dose values between 2 Gy and 10 Gy are presented as well (Mathias Anton, 2006). More methods of evaluation of uncertainties of alanine dosimetry can be found elsewhere (Bartolotta, A., et al, 1993, Bergstrand, S., et al, 1998, Kojima, T., et al, 1999, Nagy, V., et al, 2002.…”

Improvement of ESR dosimetry for thermal neutron beams through the addition of gadolinium

“…The lowest detectable dose (LDD), defined as the dose that produces an ESR signal equal to the mean value of the zero-dose signal plus three standard deviations (Bartolotta et al 1993), was also calculated for all blends. The zero-dose signals were obtained from background measurements of six unirradiated dosimeters for each type in the magnetic field range, wherein the ESR signal of the radiation-induced free radicals was expected to appear.…”