Response Investigations of a TEPC in High Energy Proton and Neutron Beams using the Variance Method

Kyllönen, J.-E.; Grinborg, J. E.; Lindborg, L.

doi:10.1093/oxfordjournals.rpd.a006807

Cited by 1 publication

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“…( 19 ), Lillhök ( 18 ), and Kyllönen et al. ( 21 ). Simulated conversion coefficients to ambient absorbed dose from Ferrari and Pelliccioni ( 29 ) and Leuthold et al.…”

Section: Resultsmentioning

confidence: 99%

“…Included are also measured values, using the same detectors, for neutrons, photons, and protons from Lillhök ( 18 ), Kyllönen et al. ( 19 , 21 ), and Kyllönen and Mayer ( 28 ), as well as conversion coefficients to ambient absorbed doses from Ferrari and Pelliccioni ( 29 ) and Leuthold et al. ( 30 ).…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, Kyllönen et al. measured dose-mean lineal energies in proton beams between 68 and 174 MeV with the Sievert detectors and reported

values between 6.2 and 7.3 keV/μm ( 21 ).…”

Section: Methodsmentioning

confidence: 99%

“…From the equation, it is clear that a change in any of the component contributions will be reflected as a change in the measured y D value. As previously mentioned, the dose-mean lineal energies for the radiation components are energy dependent and can be estimated by using their simulated fluence distributions for the stray field and a known response function determined in monoenergetic beams (18,19). The simulated response function and comparisons with measurements are described in the following sections.…”

Section: Experimental Methods and Equipmentmentioning

confidence: 99%

“…where a = 0.73 and b = 0.17 mm/keV. (19). For this article, only total H* values were determined, but it is possible to estimate the H* values for the high-and low-LET components by using the relative dose contribution for each radiation component and the respective y D value in Equation 3.…”

Section: Experimental Methods and Equipmentmentioning

confidence: 99%

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Range-shifter effects on the stray field in proton therapy measured with the variance–covariance method

et al. 2022

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Measurements in the stray radiation field from a proton therapy pencil beam at energies 70 and 146 MeV were performed using microdosimetric tissue-equivalent proportional counters (TEPCs). The detector volumes were filled with a propane-based tissue-equivalent gas at low pressure simulating a mean chord length of 2 μm in tissue. Investigations were performed with and without a beam range shifter, and with different air gaps between the range shifter and a solid water phantom. The absorbed dose, the dose-mean lineal energy, and the dose equivalent were determined for different detector positions using the variance–covariance method. The influence from beam energy, detector- and range-shifter positions on absorbed dose, LET, and dose equivalent were investigated. Monte Carlo simulations of the fluence, detector response, and absorbed dose contribution from different particles were performed with MCNP 6.2. The simulated dose response for protons, neutrons, and photons were compared with, and showed good agreement with, previously published experimental data. The simulations also showed that the TEPC absorbed dose agrees well with the ambient absorbed dose for neutron energies above 20 MeV. The results illustrate that changes in both dose and LET variations in the stray radiation field can be identified from TEPC measurements using the variance–covariance method. The results are in line with the changes seen in the simulated relative dose contributions from different particles associated with different proton energies and range-shifter settings. It is shown that the proton contribution scattered directly from the range shifter dominates in some situations, and although the LET of the radiation is decreased, the ambient dose equivalent is increased up to a factor of 3.

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“…( 19 ), Lillhök ( 18 ), and Kyllönen et al. ( 21 ). Simulated conversion coefficients to ambient absorbed dose from Ferrari and Pelliccioni ( 29 ) and Leuthold et al.…”

Section: Resultsmentioning

confidence: 99%