Measurement of the Heat Defect in Water and A-150 Plastic for High-Energy Protons, Deuterons, and alpha-Particles

Brede, H.J.; Hecker, O.; Hollnagel, R.

doi:10.1093/oxfordjournals.rpd.a032007

Cited by 9 publications

(17 citation statements)

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“…In the wake of those recommendations, numerous applications of calorimeters to reference dosimetry in clinical beams have been reported. This comprised the use of water calorimeters for scattered proton beams, scanned proton beams and carbon ion beams, the use of graphite calorimeters for scattered proton beams and carbon ion beams and the use of an A‐150 tissue‐equivalent calorimeter in a scattered proton beam …”

Section: Detectors For Measurements Of Absorbed Dose In Reference Conmentioning

confidence: 99%

“…For high‐energy (low‐LET) protons, pure water saturated with a chemically inert gas like argon or nitrogen exhibits a small initial chemical heat defect and a steady state is reached after pre‐irradiation . For high‐LET ions, experiments comparing the heat defect of water with that of aluminum in a dual‐component water/aluminum absorber indicate a nonzero endothermic heat defect that increases with LET . Simulations of the entire chemical reaction chain assign this effect to a higher production of hydrogen peroxide than what is decomposed .…”

Section: Detectors For Measurements Of Absorbed Dose In Reference Conmentioning

confidence: 99%

“…[4][5][6][7] In the wake of those recommendations, numerous applications of calorimeters to reference dosimetry in clinical beams have been reported. This comprised the use of water calorimeters for scattered proton beams, [8][9][10][11][12][13][14][15][16] scanned proton beams [17][18][19][20] and carbon ion beams, 12,14,16,21 the use of graphite calorimeters for scattered proton beams 22,23 and carbon ion beams 24 and the use of an A-150 tissue-equivalent calorimeter in a scattered proton beam. 25 Preceding these applications, however, a number of experiments were setup to measure the heat defect of certain media.…”

Section: A1 Dose Based: Calorimetry (Water and Graphite)mentioning

confidence: 99%

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Dose detectors, sensors, and their applications

Giordanengo

2018

Medical Physics

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This article is intended to present the different types of particle and radiation detectors available for applications in particle therapy. Several types of detectors and sensors exist for measurements of absorbed dose in reference and nonreference conditions and the ones in use for beam monitoring. Therefore, this manuscript focuses on the following applications: (a) primary methods for dosimetry in ion beams, (b) measurements of absorbed dose in realistic patient‐specific scenarios with different dose delivery configurations, and (c) beam monitoring. Water and graphite calorimeters, Faraday cups, ionization based gas detectors are described first, followed by the description of the protocols for proton and ion dosimetry. Then films, scintillator and solid‐state detectors are reviewed. Finally, several types of ionization chambers (large, pinpoint, arrays of chambers arranged in regular 1D or 2D pattern, parallel‐plate configuration with large integral electrodes or with anode segmented in strips or pixels, multi‐wire, and the multi‐gap prototype) have been considered. New beam monitors to deal with a wide range of intensity and pulsed beams expected from new accelerators, different dose fractionation and advanced delivery techniques are presented. The existing detectors available for particle therapy have been described taking into account the different requirements for devices used in reference and nonreference conditions and the ones designed for beam monitoring.

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Section: Detectors For Measurements Of Absorbed Dose In Reference Conmentioning

confidence: 99%

Section: Detectors For Measurements Of Absorbed Dose In Reference Conmentioning

confidence: 99%

Section: A1 Dose Based: Calorimetry (Water and Graphite)mentioning

confidence: 99%

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Dose detectors, sensors, and their applications

Giordanengo

2018

Medical Physics

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“…The heat defect h was determined from the linear energy transfer ͑LET͒ distribution in water at the measurement position with the h(LET) values published by Brede et al, 14 yielding in an LET-averaged mean h value of (0.0143 Ϯ0.0070). The LET spectrum was derived by using a tissue equivalent proportional counter ͑TEPC͒.…”

Section: Resultsmentioning

confidence: 99%

“…The heat defect is that part of the energy deposited that does not occur as heat but serves to produce chemical and physical changes in the absorber. For this study, the heat defect of water in the calorimeter core was derived by measurements using the values published by Brede et al 14 The ionization chamber which is used to adapt the absorbed dose-to-water to the calibration conditions of the UK-Essen must be small and water-tight. No specific wall mate-rial and operating gas-such as a tissue-equivalent chamber made from A150 plastics-is required.…”

Section: Iib the Measuring Devicesmentioning

confidence: 99%

Absolute dosimetry in a fast neutron beam

et al. 2004

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Since 1978, the Universitätsklinikum in Essen operates a d(14 MeV) + Be fast neutron beam for patient treatment. Dosimetric studies were performed in a rectangular 40 x 40 mm2 neutron/photon field using a transportable water calorimeter, which had been developed at the Physikalisch-Technische Bundesanstalt. The water calorimeter allowed small dosimeters to be directly calibrated in units of absorbed dose-to-water in a cylindrical phantom of 50 mm in diameter. Also, the twin detector method was applied in order to determine the photon and the neutron dose separately. By making use of a calibrated ionization chamber, the absorbed dose-to-water calibration in the cylindrical water phantom was transferred to a water phantom, a cube 300 mm on a side. Experiments and Monte Carlo calculations covering the neutron producing target, the collimator and the influence of the water calorimeter on the spectral neutron fluence at the measurement position allow the relative uncertainty of the absorbed dose-to-water determination to be reduced to 2.6% (1 SD). This direct absorbed dose-to-water determination by calorimetry has shown that the treatment planning system underestimates the physical dose to tissue by 9%. For clinical purposes, the statement of the prescribed dose had to be increased by 9% in order that the absolute absorbed dose remains constant and that the same biological endpoints are reached.

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