4 minute read.
Researchers from the National Physical Laboratory (NPL), Heidelberg University Hospital and the German Cancer Research Center (DKFZ) have published new findings that improve understanding of secondary neutron exposure during paediatric ion beam therapy, an important area of study for enhancing the safety of advanced cancer treatments for children.
The study, “Ambient dose equivalent and secondary neutron spectrometry during radiotherapy of a head tumour in a paediatric phantom with protons, helium ions and carbon ions”, was recently published in Physics in Medicine & Biology.
Ion beam therapy is increasingly recognised as a highly effective form of cancer treatment, particularly for complex tumours located close to critical organs. By using charged particles such as protons, helium ions and carbon ions, clinicians can deliver radiation doses with exceptional precision, limiting damage to surrounding healthy tissue. However, the treatment process also generates secondary neutrons, which can travel beyond the intended treatment area and contribute to unwanted radiation exposure.
Understanding and quantifying this exposure is particularly important for children, whose developing tissues are more sensitive to radiation and who may live long enough to experience potential long-term effects.
The research team conducted detailed measurements using a 10-year-old paediatric phantom containing a simulated brain tumour. The work formed part of a wider measurement campaign organised by Working Group 9 of the European Radiation Dosimetry Group (EURADOS), bringing together experts focused on improving radiation protection and dosimetry.
The study compared neutron fields produced during treatments delivered with three different ion species: protons, helium ions and carbon ions. Researchers employed advanced neutron detection technologies, including the NPL Extended Range Bonner Sphere Spectrometer and an extended range rem counter, together with sophisticated Monte Carlo simulations to characterise radiation exposure outside the treatment field.
By combining experimental measurements with computational modelling, the team was able to gain deeper insight into neutron energy spectra and the levels of out-of-field radiation associated with each treatment modality. The findings provide valuable new data on how the choice of ion species influences secondary neutron production and the resulting dose received beyond the target area.
The results contribute to ongoing efforts to improve treatment planning, strengthen radiation protection assessments and support the development of safer particle therapy techniques. Accurate characterisation of secondary neutron exposure is essential for validating clinical models and ensuring that the benefits of ion beam therapy are delivered with the highest possible levels of patient safety.
The research highlights the importance of multidisciplinary collaboration, bringing together expertise in radiation oncology, neutron metrology, detector development and computational modelling to address a key challenge in modern cancer treatment.
The publication also reinforces the critical role of measurement science in supporting advances in healthcare. By providing robust data and improved understanding of complex radiation environments, studies such as this help underpin innovations that enhance patient outcomes and contribute to the continued evolution of cancer therapy.
As ion beam therapy becomes more widely adopted around the world, the findings are expected to support future research and clinical practice aimed at further reducing unintended radiation exposure, particularly for young patients who stand to benefit most from advances in precision cancer treatment.
13 Jul 2026