BACKGROUND Intensity-modulated proton therapy (IMPT) has shown promise in reducing toxicityfor patients with oropharyngeal squamous cell carcinoma (OPSCC), while maintaining comparable tumor control to intensity-modulated radiation therapy (IMRT). However, technical, logistical and economic factors have limited widespread implementation. METHODS We conducted the first Italian multicenter in-silico comparative study of photon and proton plans in 100 patients with HPV-related OPSCC, involving seven radiation oncology departments. Clinical photon-based plans (mostly using Volumetric Modulated Arc Therapy (VMAT)) were compared with robustly optimized IMPT plans generated using the CNAO beamline. Dosimetric endpoints and normal tissue complication probability (NTCP) values for xerostomia and dysphagia were assessed. Eligibility for IMPT was retrospectively estimated using the Dutch model-based selection (MBS)criteria. RESULTS Target coverage was comparable between modalities, although IMPT plans showed slightly lower conformity indices. IMPT significantly reduced the dose bath to healthy tissues, with lower mean doses to the parotids, submandibular glands, pharyngeal constrictors, oral cavity, brainstem, and spinal cord (p < 0.01). NTCP analyses predicted clinically relevant reductions in xerostomia and dysphagia with IMPT. Applying the MBS approach, 36 % of patients were deemed eligible for PT, consistent with previous reports. Inter-center variability in eligibility reflected differences in delineation practices and clinical protocols. CONCLUSIONS This study tested the feasibility of a multicenter model-based evaluation for IMPT in Italy. A substantial proportion of OPSCC patients could benefit from IMPT, though results likely represent a conservative estimate due to protocol choices. Standardized delineation, robust optimization, and integration of NTCP models are essential for consistent patient selection.
Background: Gamma spectrometry with high-resolution High-Purity Germanium detectors is a widely adopted technique, valued for its excellent energy resolution. It is applied across a range of Radiation Protection activities, including the measurement of low-activity concentrations in environmental samples containing natural and artificial radionuclides, as well as quality assurance assessments of radiopharmaceuticals used in diagnostic imaging. Methods: This work presents an inter-comparison between software for Efficiency Transfer calculations, including three semi-empirical (EFFTRAN, ETNA, and ANGLE) and two Monte Carlo based codes (GESPECOR and LabSOCS/ISOCS). The calculations considered sample geometries of increasing complexity, ranging from a Marinelli beaker to a vial and wipe test. A verification test (IAEA-TERC-2022-01/02) was conducted to assess the accuracy of the simulations by validating the results against a Verification Sample with well-known low activity radionuclide concentrations. Results: Calculations performed for the different sample geometries yielded consistent Efficiency Transfer coefficients across all the software tested. The largest relative bias was observed at a low photon energy (59keV from 241Am), which exceeded the 20% acceptability limit for the more complex sample under investigation. A similar trend was observed in the activity concentration results obtained from the verification test. Conclusions: A comprehensive evaluation of the most used Efficiency Transfer software was conducted to assess their performance in gamma-ray spectrometry. This work aims to enhance the accuracy of activity concentration estimates, for samples with non-standard geometries, thus enabling rapid and reliable responses in potential radiological emergencies.
BACKGROUND This work presents an extended-updated dataset of S-values for radionuclides commonly used in nuclear medicine: Y-90, Ho-166, Lu-177, Re-188, Sm-153, Cu-67, In-111, Ga-68, and Re-186. S-value, defined as the mean absorbed dose to target-region per unit of activity in source-region. Accurate estimation of S-values is essential for quantifying irradiation to radiosensitive structures during therapeutic and diagnostic procedures, particularly considering biokinetic clearance through kidneys, liver, and urinary bladder. METHODS In this work, S-values were calculated using DoseCalcs with ICRP145 mesh-type phantoms, which can provide a higher-resolution anatomical representation than most voxel-based models. The resulting values were then compared with ICRP110 voxel-based datasets to assess the impact of the improved anatomical representation. RESULTS The resulting database includes S-values for 27 radiosensitive target regions in two ICRP145 computational phantoms. The most pronounced self-irradiation contributions (between 10-4 and 10-3 mGy/(MBq s)) arise from Y-90, Ga-68, Re-188, and Ho-166, primarily due to their higher beta emission energies and yields. Substantial cross-organ energy deposition (S-values between 10-5 and 10-4 mGy/(MBq s)) was observed for Ga-68 and In-111, attributed to their penetrating photon emissions. Most source ← combinations showed agreement with voxel-based data, although deviations were observed for female, with mean ratios (DoseCalcs/OpenDose) of 0.80 for Ho-166 and 0.85 for Y-90. CONCLUSION These differences can be attributed to the different anatomical representation of the adopted mesh-type phantoms, that in principle have an enhanced realism with respect to the voxel-based phantoms used for reference, including smoother organ boundaries, refined tissue interfaces, and updated material composition for blood and bone regions.
