9. Radiative Stopping Power

Berger, M. J.; Inokuti, Mitio; Anderson, Harold; Bichsel, H.; Dennis, J. A.; Powers, D.; Seltzer, S. M.; Turner, James

doi:10.1093/jicru/os19.2.45

Cited by 2 publications

(4 citation statements)

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“…Unfortunately, this is not the case for a large number of clinical beam qualities and ionization chambers. Additionally, in the past these coefficients have been evaluated theoretically using Bragg-Gray cavity theory together with ICRU 37 data (Berger et al 1984). Such approach relies on different approximations, particularly with regard to the procedures to obtain chamber perturbation correction factors, which increase the uncertainty of the k Q,Q0 values in TRS 398.…”

Section: Trs 398 Formalism and The Beam Quality Correction Factormentioning

confidence: 99%

Monte Carlo calculation of beam quality correction factors for PTW cylindrical ionization chambers in photon beams

et al. 2020

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The beam quality correction factor kQ for megavoltage photon beams has been calculated for eight PTW (Freiburg, Germany) ionization chambers (Farmer chambers PTW30010, PTW30011, PTW30012, and PTW30013, Semiflex 3D chambers PTW31021, PTW31010, and PTW31013, and the PinPoint 3D chamber PTW31016). Simulations performed on the widely used NE-2571 ionization chamber have been used to benchmark the results. The Monte Carlo code PENELOPE/penEasy was used to calculate the absorbed dose to a point in water and the absorbed dose to the active air volume of the chambers for photon beams in the range 4 to 24 MV. Of the nine ionization chambers analysed, only five are included in the current version of the International Code of Practice for dosimetry based on standards of absorbed dose to water (IAEA TRS 398). The values reported in this work agree with those in the literature within the uncertainty estimates and are to be included in the average values of the data obtained by different working groups for the forthcoming update of TRS 398.

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Section: Trs 398 Formalism and The Beam Quality Correction Factormentioning

confidence: 99%

Monte Carlo calculation of beam quality correction factors for PTW cylindrical ionization chambers in photon beams

et al. 2020

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“…W air is the mean energy to create an ion pair in air at the beam qualities Q and 60 Co. For electron and photon radiation fields W air can be assumed to be independent from energy (Burns et al 2014). The aim of this work was to compare Monte Carlo calculated k Q values according to the recommendations of the new ICRU Report 90 (Seltzer et al 2014) and the ICRU Report 37 (Berger et al 1984). For this purpose the ratio of Monte Carlo calculated k Q values according to the ICRU Report 90 and 37 were determined.…”

Section: W D Detmentioning

confidence: 99%

“…In this respect, the ICRU Report 37 (Berger et al 1984) recommends values for the mean excitation energy I and the density of elements and compounds. Based on newer measurements, recommendations for the I values for graphite I g and water I w have been revised in the recent published ICRU Report 90 (Seltzer et al 2014), i.e.…”

Section: Introductionmentioning

confidence: 99%

“…According to the investigations published by Andreo et al (2013), the impact of these new key data for clinical reference dosimetry was evaluated. Following the results of Andreo et al (2013), stopping-power ratios water to air for high energy photon and electron beams were calculated according to the recommendations of the ICRU Report 37 (Berger et al 1984) and 90 (Seltzer et al 2014). Extending the investigation of Andreo et al (2013), the impact on the beam quality correction factor k Q according to the IAEA dosimetry protocol TRS-398 (Andreo et al 2001) due to adoption of the new I values and using the grain density of graphite to evaluate density correction, was investigated by Monte Carlo simulations for high energy photon and electron beams.…”

Section: Introductionmentioning

confidence: 99%

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Impact of new ICRU Report 90 recommendations on calculated correction factors for reference dosimetry

Czarnecki¹,

Poppe

Zink

2018

Phys. Med. Biol.

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In 2016 the ICRU published a new report dealing with key data for ionizing radiation dosimetry (ICRU Report 90). New recommendations have been made for the mean excitation energies I for air, graphite and liquid water as well as for the graphite density to use when evaluating the density effect. In addition, the ICRU Report 90 discusses renormalized photoelectric cross sections, but refuses to give a recommendation on the use of renormalization factors. However, the Consultative Committee for Ionizing Radiation recommends to use renormalized photoeffect cross sections. Goal of the present work is to evaluate the impact of these new recommendations on clinical reference dosimetry for high energy photon and electron beams. The beam quality correction factor k was calculated by Monte Carlo simulations for compact and parallel plate ionization chambers. In case of photons seven phase space files from clinical accelerators and twelve spectra taken from literature from 4 MV to 24 MV and additionally aCo source were applied. As electron source thirteen electron spectra available in literature were used in the range of 4 MeV-21 MeV. The new ICRU recommendations have a small impact on Monte Carlo calculated k values for the chosen ionization chambers in the range of 0.1%-0.35% only-the difference increases for higher photon energies. The impact of the ICRU Report 90 recommendations on Monte Carlo calculated stopping power ratios s , perturbation factors p and beam quality correction factors k was investigated and confirmed a decrese of s by a fraction of a percent for photon and electron beams. This study indicates that the impact of the new ICRU recommendation is within 0.35%. The determined deviations should be taken into account, when widely published Monte Carlo calculated values are examined.

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9. Radiative Stopping Power

Cited by 2 publications

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Monte Carlo calculation of beam quality correction factors for PTW cylindrical ionization chambers in photon beams

Monte Carlo calculation of beam quality correction factors for PTW cylindrical ionization chambers in photon beams

Impact of new ICRU Report 90 recommendations on calculated correction factors for reference dosimetry

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