ICDA-5

Performance evaluation of different active neutron detectors measuring H*(10) in a proton therapy facility

Jun 10, 2026, 3:00 PM

15m

Auditorium 103

Oral Presentation Radiation detection and spectrometry Radiation detection and spectrometry

Speakers

Josep M Martí-Climent (Clínica Universidad de Navarra) Carles Domingo (Universitat Autonoma de Barcelona)

Description

Neutron detector performance is usually assessed below 10 MeV, well under the 230 MeV maximum used in proton therapy. This study evaluated five active neutron H(10) detectors in a proton therapy facility.
Methods
Irradiations were performed with the gantry at 270° in pencil-beam-scanning mode, simulating a treatment layer plan (10×10cm²) in a solid-water phantom.
H(10) was measured using extended-energy-range (LUPIN, WENDI-II, NECH) and non-extended-energy-range (LB6411, Digipig-2222A) detectors. Measurements were performed at four angular directions relative to the beam (45°, 90°,135°, 270°) at 1.1m from the isocenter.
Parameters evaluated included dose linearity using monitor units (MU) to achieve H(10) from 0.1 to 100 μSv at 70 MeV, and from 1 to 1000 μSv at 150 and 229 MeV. The mean of four measurements was used, and linearity was assessed using the ratio R between measured and expected doses, scaling from the highest MU value. Reproducibility was evaluated by calculating the coefficient of variation (CV) of four repeated linearity measurements. Angular response was assessed by irradiating detectors at 0°, 90°, 180°, and 270°. Relative response was evaluated respect to the Lupin detector.
Results
Reproducibility: The highest CV was observed mainly under the lowest dose irradiation condition (0.05 μSv, 70 MeV): 18, 19, 16, 9, and 17 % for LB6411, Digipig, WENDI-II, LUPIN, and NECH, respectively.
Angular response: Averaging the values at each angular position, the highest CVs observed were 5.3, 2.2, 2.1, 1.1, and 2.4 % for LB6411, Digipig, WENDI-II, LUPIN, and NECH.
R values were within [0.86-1.04], [0.96-1.04], [0.84-1.00], [0.98-1.06] and [0.81-1.04] for LB6411, Digipig, WENDI-II, LUPIN, and NECH.
Relative response depends on the energy and the measurement point, being within 20% only for the WENDI-II detector.
Conclusions*
All detectors showed good reproducibility, angular response, and dose linearity. However, the relative response depends on neutron spectrum (beam energy and measurement point).