Performance tests and comparison of microdosimetric measurements with four tissue-equivalent proportional counters in scanning proton therapy

Farah, Jad; Saint-Hubert, Marijke De; Mojżeszek, Natalia; Chiriotti, S.; Gryziński, M.; Ploc, Ondřej; Trompier, F.; Turek, K.; Vanhavere, F.; Olko, P.

doi:10.1016/j.radmeas.2016.12.005

Cited by 18 publications

(15 citation statements)

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“…TEPCs have been applied to measure single‐event distributions of many types of ionizing radiation, including photons, neutrons, and heavy charged particles. These detectors can and have been used to conduct measurements around proton and carbon therapy beams . The event‐size spectra obtained during measurements can range from around 0.1 keV/μm to > 1000 keV/μm.…”

Section: Measurement Approachesmentioning

confidence: 99%

“…These detectors can and have been used to conduct measurements around proton and carbon therapy beams. 163,241,242 The event-size spectra obtained during measurements can range from around 0.1 keV/lm to > 1000 keV/lm. The absorbed dose contributions from various types of secondary particles can be differentiated via the microdosimetric spectrum because different secondary particles have different lineal energies in the active volume.…”

Section: B2 Fast Neutron Detectorsmentioning

confidence: 99%

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AAPM TG158: Measurement and calculation of doses outside the treated volume from external‐beam radiation therapy

et al. 2017

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The introduction of advanced techniques and technology in radiotherapy has greatly improved our ability to deliver highly conformal tumor doses while minimizing the dose to adjacent organs at risk. Despite these tremendous improvements, there remains a general concern about doses to normal tissues that are not the target of the radiation treatment; any "nontarget" radiation should be minimized as it offers no therapeutic benefit. As patients live longer after treatment, there is increased opportunity for late effects including second cancers and cardiac toxicity to manifest. Complicating the management of these issues, there are unique challenges with measuring, calculating, reducing, and reporting nontarget doses that many medical physicists may have limited experience with. Treatment planning systems become dramatically inaccurate outside the treatment field, necessitating a measurement or some other means of assessing the dose. However, measurements are challenging because outside the treatment field, the radiation energy spectrum, dose rate, and general shape of the dose distribution (particularly the percent depth dose) are very different and often require special consideration. Neutron dosimetry is also particularly challenging, and common errors in methodology can easily manifest as errors of several orders of magnitude. Task Group 158 was, therefore, formed to provide guidance for physicists in terms of assessing and managing nontarget doses. In particular, the report: (a) highlights major concerns with nontarget radiation; (b) provides a rough estimate of doses associated with different treatment approaches in clinical practice; (c) discusses the uses of dosimeters for measuring photon, electron, and neutron doses; (d) discusses the use of calculation techniques for dosimetric evaluations; (e) highlights techniques that may be considered for reducing nontarget doses; (f) discusses dose reporting; and (g) makes recommendations for both clinical and research practice.

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Section: Measurement Approachesmentioning

confidence: 99%

Section: B2 Fast Neutron Detectorsmentioning

confidence: 99%

AAPM TG158: Measurement and calculation of doses outside the treated volume from external‐beam radiation therapy

et al. 2017

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“…Events encountering significant electronic noise below the so-called low energy threshold (0.3 keV·μm −1 for the HAWK used here) are not recorded. For data analysis, a simple coefficient (the average of correction factor determined for 60 Co and 137 Cs gamma-rays) was applied ( 46 ). No compensation of the counting loss due to dead time is included in the analysis software.…”

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confidence: 99%

Neutron Radiation Dose Measurements in a Scanning Proton Therapy Room: Can Parents Remain Near Their Children During Treatment?

et al. 2022

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PurposeThis study aims to characterize the neutron radiation field inside a scanning proton therapy treatment room including the impact of different pediatric patient sizes.Materials and MethodsWorking Group 9 of the European Radiation Dosimetry Group (EURADOS) has performed a comprehensive measurement campaign to measure neutron ambient dose equivalent, H*(10), at eight different positions around 1-, 5-, and 10-year-old pediatric anthropomorphic phantoms irradiated with a simulated brain tumor treatment. Several active detector systems were used.ResultsThe neutron dose mapping within the gantry room showed that H*(10) values significantly decreased with distance and angular deviation with respect to the beam axis. A maximum value of about 19.5 µSv/Gy was measured along the beam axis at 1 m from the isocenter for a 10-year-old pediatric phantom at 270° gantry angle. A minimum value of 0.1 µSv/Gy was measured at a distance of 2.25 m perpendicular to the beam axis for a 1-year-old pediatric phantom at 140° gantry angle.The H*(10) dependence on the size of the pediatric patient was observed. At 270° gantry position, the measured neutron H*(10) values for the 10-year-old pediatric phantom were up to 20% higher than those measured for the 5-year-old and up to 410% higher than for the 1-year-old phantom, respectively.ConclusionsUsing active neutron detectors, secondary neutron mapping was performed to characterize the neutron field generated during proton therapy of pediatric patients. It is shown that the neutron ambient dose equivalent H*(10) significantly decreases with distance and angle with respect to the beam axis. It is reported that the total neutron exposure of a person staying at a position perpendicular to the beam axis at a distance greater than 2 m from the isocenter remains well below the dose limit of 1 mSv per year for the general public (recommended by the International Commission on Radiological Protection) during the entire treatment course with a target dose of up to 60 Gy. This comprehensive analysis is key for general neutron shielding issues, for example, the safe operation of anesthetic equipment. However, it also enables the evaluation of whether it is safe for parents to remain near their children during treatment to bring them comfort. Currently, radiation protection protocols prohibit the occupancy of the treatment room during beam delivery.

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“…A dedicated experiment was organised for microdosimetric spectra measurements around a paediatric phantom (Farah et al 2017). Four different tissue-equivalent proportional counters (TEPC), first compared in standard neutron and gamma radiation fields, were used.…”

Section: One Of the Important Conclusion From This Work Comes From A ...mentioning

confidence: 99%

The European radiation dosimetry group – Review of recent scientific achievements

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Ainsbury

Breustedt

et al. 2020

Radiation Physics and Chemistry

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Performance tests and comparison of microdosimetric measurements with four tissue-equivalent proportional counters in scanning proton therapy

Cited by 18 publications

References 29 publications

AAPM TG158: Measurement and calculation of doses outside the treated volume from external‐beam radiation therapy

AAPM TG158: Measurement and calculation of doses outside the treated volume from external‐beam radiation therapy

Neutron Radiation Dose Measurements in a Scanning Proton Therapy Room: Can Parents Remain Near Their Children During Treatment?

The European radiation dosimetry group – Review of recent scientific achievements

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