Proton Irradiation Research Articles

Evaluating optimal quality assurance and quality control conditions of activation measurements at the accelerator-based boron neutron capture therapy system employing a lithium target.

Evaluating neutron output is important to ensure proper dose delivery for patients in boron neutron capture therapy (BNCT). It requires efficient quality assurance (QA) and quality control (QC) to maintain measurement accuracy. This study investigated the optimal measurement conditions for QA/QC of activation measurements using a high-purity germanium (HP-Ge) detector in an accelerator-based boron neutron capture therapy (AB-BNCT) system employing a lithium target. The QA/QC uncertainty of the activation measurement was evaluated based on counts, reproducibility, and standard radiation source uncertainties. Measurements in a polymethyl methacrylate (PMMA) cylindrical phantom using aluminum-manganese (Al-Mn) foils and aluminum-gold (Al-Au) foils and measurements in a water phantom using gold wire with and without cadmium cover were performed to determine the optimal measurement conditions. The QA/QC uncertainties of the activation measurements were 4.5% for Au and 4.6% for Mn. The optimum irradiation proton charge and measurement time were determined to be 36 C and 900 s for measurements in a PMMA cylindrical phantom, 7.0 C and 900 s for gold wire measurements in a water phantom, and 54 C and 900 s at 0-2.2 cm depth and 3,600 s at deeper depths for gold wire measurements with cadmium cover. Our results serve as a reference for determining measurement conditions when performing QA/QC of activation measurements using HP-Ge detectors at an AB-BNCT employing a lithium target.

Proton therapy in pediatric neuro-oncology. Potential advantages and the relationship between cost and results

The aim of study: to analyze the accumulated experience and try to identify those clinical situations in which the use of protons will be economically and clinically more effective than photon radiation therapy. Material and methods. The articles devoted to the study of the evaluation and comparison of the effectiveness of proton and photon radiation beams in the treatment of tumors of the central nervous system and published over the past 25 years were searched in the Medline, Embase and the Cochrane Library databases. Results. the analysis of available publications has shown that accelerated protons do not improve survival rates and disease-free rates in all forms of brain tumors compared with photon therapy. However, protons can significantly increase the level of dose distribution conformity and reduce the dose to critical structures (pituitary gland, cochlea, eye lenses, hypothalamus), thus reducing the risk of hearing and visual impairment as well as hormonal and cognitive disorders. All this is critically important for potentially curable malignant tumors, such as medulloblastoma and germinoma, for low malignant potential tumors (grade 1–2 glioma) or tumors with decreased metastatic potential, since proton therapy compared to photon therapy reduces the risk of late side effects that worsen the quality of life of cured children. Conclusion. central nervous system tumors are one of the most common solid malignant neoplasms in children. Radiation therapy (RT) is recognized as an important therapeutic component of treatment and is often used in strategies for multimodal therapy of tumors of the central nervous system in children. Proton radiation therapy is one of the attractive methods of radiotherapy with minimal dose distribution to normal tissues and a decrease in the absorbed dose. The precision of protons reduces the risk of long-term side effects associated with this type of treatment and the induction of secondary malignancies, which is of particular importance for the quality of life.

Bismuth Nanoparticles Increase Effectiveness of Proton Therapy of Ehrlich Carcinoma.

We studied the antitumor activity of the combined use of local proton irradiation in two modes (10 and 31 Gy) with preliminary intra-tumoral injection of two types of bismuth nanoparticles differing in surface coating: coated with the amphiphilic molecule Pluronic-F127 or Silane-PEG (5 kDa)-COOH polymer. Nanoparticles were used in doses of 0.75 and 1.5 mg/mouse. In two independent series on experimental tumor model (solid Ehrlich carcinoma), bismuth nanoparticles of both modifications injected directly into the tumor enhanced the antitumor effects of proton therapy. Moreover, the radiosensitizing effect of bismuth nanoparticles administered via this route increased with the increasing the doses of nanoparticles and the doses of radiation exposure. In our opinion, these promising data obtained for the first time extend the possibilities of treating malignant neoplasms.

A review and bibliometric analysis of global research on proton radiotherapy.

Proton beam therapy (PBT) has great advantages as tumor radiotherapy and is progressively becoming a more prevalent choice for individuals undergoing radiation therapy. The objective of this review is to pinpoint collaborative efforts among countries and institutions, while also exploring the hot topics and future outlook in the field of PBT. Data from publications were downloaded from the Web of Science Core Collection. CiteSpace and Excel 2016 were used to conduct the bibliometric and knowledge map analysis. A total of 6516 publications were identified, with the total number of articles steadily increasing and the United States being the most productive country. Harvard University took the lead in contributing the highest number of publications. Paganetti Harald published the most articles and had the most cocitations. PHYS MED BIOL published the greatest number of PBT-related articles, while INT J RADIAT ONCOL received the most citations. Paganetti Harald, 2012, PHYS MED BIOL can be classified as classic literature due to its high citation rate. We believe that research on technology development, dose calculation and relative biological effectiveness were the knowledge bases in this field. Future research hotspots may include clinical trials, flash radiotherapy, and immunotherapy.

Model Parameters and Degradation Mechanism Analysis of Indium Phosphide Hetero-Junction Bipolar Transistors Exposed to Proton Irradiation

The degradation properties of Indium phosphide hetero-junction bipolar transistors (InP HBTs) under proton irradiation are studied and modelled using a compact model for pre-irradiation, post-irradiation, and post-annealing. The variation rates of the model parameters, such as the base–emitter saturation current (ISE) and ideality factor in the ideal region (NE) in the forward Gummel characteristics, the zero-biased capacitance (Cje) and the grading factor (Mjer) in the BE junction capacitance, and the transit time parameter in the base region (Tfb), are analysed to delve into the degradation mechanism induced by proton irradiation. The displacement damage, induced by proton irradiation in the space charge region of the base–emitter junction and in the quasi-neutral bulk base region, is found to be responsible for the decrease in current gain and cut-off frequency. After annealing, the variation rates of the parameters decrease significantly compared to post-irradiation. This suggests that the recombination of unstable defects leads to a slight recovery in the degradation characteristics of InP HBTs after a period of annealing.

A high-resolution large-area detector for quality assurance in radiotherapy

Hadron therapy is an advanced radiation modality for treating cancer, which currently uses protons and carbon ions. Hadrons allow for a highly conformal dose distribution to the tumour, minimising the detrimental side-effects due to radiation received by healthy tissues. Treatment with hadrons requires sub-millimetre spatial resolution and high dosimetric accuracy. This paper discusses the design, fabrication and performance tests of a detector based on Gas Electron Multipliers (GEM) coupled to a matrix of thin-film transistors (TFT), with an active area of 60 × 80 mm2 and 200 ppi resolution. The experimental results show that this novel detector is able to detect low-energy (40 kVp X-rays), high-energy (6 MeV) photons used in conventional radiation therapy and protons and carbon ions of clinical energies used in hadron therapy. The GEM-TFT is a compact, fully scalable, radiation-hard detector that measures secondary electrons produced by the GEMs with sub-millimetre spatial resolution and a linear response for proton currents from 18 pA to 0.7 nA. Correcting known detector defects may aid in future studies on dose uniformity, LET dependence, and different gas mixture evaluation, improving the accuracy of QA in radiotherapy.

Alanine dosimeters for LET measurement in proton radiotherapy

Proton radiotherapy enables highly conformal dose delivery to the tumor while minimizing exposure to healthy tissues surrounding the target. However, to achieve the most optimal treatment plan, it is necessary to consider various parameters, including variable relative biological effectiveness (RBE) and linear energy transfer (LET) within the target and in the normal tissues. The proton treatment planning systems (TPS) currently under development incorporate both of these parameters. However, before introducing biologically guided treatment planning into the clinic, commissioning and end-to-end tests must be conducted. These procedures require specific tools to verify the planned LET distribution. The same tools will also be necessary for subsequent patient-specific quality assurance (QA).The objective of this work was to evaluate the alanine/EPR dosimetry system developed at the Cyclotron Center Bronowice at the Institute of Nuclear Physics (CCB IFJ PAN) for verifying LET values in therapeutic proton fields. The change in the shape of the EPR spectra of alanine irradiated in proton fields of different LETs, described by the ratio of the intensities of the satellite and central lines (x/y ratio), was used to discriminate LET values. The method does not provide absolute LET values. However, as demonstrated, it can verify the LET values calculated in the TPS after calibration using Monte Carlo (MC) simulation.

Abstract PO3-12-12: Axial Neuropathy in Two Breast Cancer Patients receiving Fam-trastuzumab deruxtecan: A Case Report

Abstract Introduction. Fam-trastuzumab deruxtecan (T-DXd) is FDA approved for metastatic HER2-positive (HER2+) and HER2-low breast cancer (BC). Peripheral neuropathy is a side effect of T-DXd, with an incidence of 13%. Here we discuss two BC patients (pts) who presented with paresthesias of the trunk after receiving T-DXd. Case 1. A 51-year-old female with Stage IIIB cT4N2M0 left BC, estrogen receptor positive (ER+), progesterone receptor positive (PR+) and HER2+ was treated with neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab (TCHP), followed by mastectomy and axillary lymph node dissection, with downstaging to ypT3N2a disease. She was enrolled on a clinical trial comparing T-DXd with standard treatment for HER2+ BC with residual disease after neoadjuvant therapy, and was randomized to T-DXd arm. She also received adjuvant proton radiation therapy to the chest wall. One week after her third cycle of T-DXd she developed Grade 3 paresthesias on her trunk and proximal upper and lower extremities, stating she could not bend over or perform activities of daily living. She did not experience associated weakness or peripheral neuropathy. Symptoms improved to Grade 1 after initiation of gabapentin and delay of cycle 4 T-DXd by one week. She resumed T-DXd with dose reduction per protocol, and increase in gabapentin dose. She was seen by neurology who localized her sensory findings to T5-T9. She was recommended to undergo MRI spine, but was unable to do so, due to presence of tissue expander. Paresthesias have been controlled on dose reduced T-DXd and continued gabapentin. Case 2. A 56-year-old female with ER+, PR+, HER2-negative BC initially diagnosed in 1990, with local recurrence in 2005, treated with mastectomy, adjuvant chemotherapy, and adjuvant endocrine therapy, followed by development of metastatic disease to lung, liver, bone and skin in 2017. She received multiple lines of endocrine therapy, including aromatase inhibitors and fulvestrant, with cdk4/6 inhibitors and everolimus, but either progressed or was intolerant to all treatments. Skin biopsy in 2022 confirmed metastatic BC, which was ER+, PR+, and HER2 low (IHC2+, FISH nonamplified). She then received T-DXd, with clinical and radiographic response to treatment. After cycle 8 T-DXd, the patient was hospitalized for severe burning pain of her trunk and skin. Radiologic evaluation, including CT chest, abdomen, pelvis, and MRI spine, did not show an etiology of her pain, and showed stable metastatic disease to liver and bones, without evidence of cord or nerve root compression. Symptoms improved on pregabalin. She received an additional cycle of T-DXd with dose reduction, but ultimately declined further treatment. Symptoms resolved within 5 months of discontinuation of T-DXd. Discussion. These cases represent unusual events of axial neuropathy in two BC patients receiving T-DXd. Given the similarity of their symptoms, these findings may represent an unusual adverse effect of T-DXd. As the indications for T-DXd continue to expand, clinicians should be aware of this uncommon potential toxicity. Citation Format: Lauren Botero, Katharine McNeill, Della Makower. Axial Neuropathy in Two Breast Cancer Patients receiving Fam-trastuzumab deruxtecan: A Case Report [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-12-12.

Long-term outcome of primary clival chordomas: a single-center retrospective study with an emphasis on the timing of recurrences based on the primary treatment.

This study aimed to provide data on extended outcomes in primary clival chordomas, focusing on progression-free survival (PFS) and overall survival (OS). A retrospective single-center analysis was conducted on patients with clival chordoma treated between 1987 and 2022 using surgery, stereotactic radiosurgery, or proton radiation therapy (PRT). The study included 100 patients (median age 44 years, 51% male). Surgery was performed using the endoscopic endonasal approach in 71 patients (71%). Gross-total resection (GTR) or near-total resection (NTR) was attained in 39 patients (39%). Postoperatively, new cranial nerve deficits occurred in 7%, CSF leak in 4%, and meningitis in none of the patients. Radiation therapy was performed in 79 patients (79%), with PRT in 50 patients (50%) as the primary treatment. During the median follow-up period of 73 (interquartile range [IQR] 38-132) months, 41 recurrences (41%) and 31 deaths (31%) were confirmed. Patients with GTR/NTR had a median PFS of 41 (IQR 24-70) months. Patients with subtotal resection or biopsy had a median PFS of 38 (IQR 16-97) months. The median PFS of patients who received radiation therapy was 43 (IQR 26-86) months, while that of patients who did not receive radiation therapy was 18 (IQR 5-62) months. The Kaplan-Meier method showed that patients with GTR/NTR (p = 0.007) and those who received radiation therapy (p < 0.001) had longer PFS than their counterparts. The PFS rates following primary treatment at 5, 10, 15, and 20 years were 51%, 25%, 17%, and 7%, respectively. The OS rates at the same intervals were 84%, 60%, 42%, and 34%, respectively. Multivariate Cox regression analysis showed that age < 44 years (p = 0.02), greater extent of resection (EOR; p = 0.03), and radiation therapy (p < 0.001) were associated with lower recurrence rates. Another multivariate analysis showed that age < 44 years (p = 0.01), greater EOR (p = 0.04), and freedom from recurrence (p = 0.02) were associated with lower mortality rates. Regarding pathology data, brachyury was positive in 98%, pan-cytokeratin in 93%, epithelial membrane antigen in 85%, and S100 in 74%. No immunohistochemical markers were associated with recurrence. In this study, younger age, maximal safe resection, and radiation therapy were important factors for longer PFS in patients with primary clival chordomas. Preventing recurrences played a crucial role in achieving longer OS.

Proton versus photon adjuvant radiotherapy: a multicenter comparative evaluation of recurrence following spinal chordoma resection.

Chordomas are rare tumors of the skull base and spine believed to arise from the vestiges of the embryonic notochord. These tumors are locally aggressive and frequently recur following resection and adjuvant radiotherapy. Proton therapy has been introduced as a tissue-sparing option because of the higher level of precision that proton-beam techniques offer compared with traditional photon radiotherapy. This study aimed to compare recurrence in patients with chordomas receiving proton versus photon radiotherapy following resection by applying tree-based machine learning models. The clinical records of all patients treated with resection followed by adjuvant proton or photon radiotherapy for chordoma at Mayo Clinic were reviewed. Patient demographics, type of surgery and radiotherapy, tumor recurrence, and other variables were extracted. Decision tree classifiers were trained and tested to predict long-term recurrence based on unseen data using an 80/20 split. Fifty-three patients with a mean ± SD age of 55.2 ± 13.4 years receiving surgery and adjuvant proton or photon therapy to treat chordoma were identified; most patients were male. Gross-total resection was achieved in 54.7% of cases. Proton therapy was the most common adjuvant radiotherapy (84.9%), followed by conventional or external-beam radiation therapy (9.4%) and stereotactic radiosurgery (5.7%). Patients receiving proton therapy exhibited a 40% likelihood of having recurrence, significantly lower than the 88% likelihood observed in those treated with nonproton therapy. This was confirmed on logistic regression analysis adjusted for extent of tumor resection and tumor location, which revealed that proton adjuvant radiotherapy was associated with a decreased risk of recurrence (OR 0.1, 95% CI 0.01-0.71; p = 0.047) compared with photon therapy. The decision tree algorithm predicted recurrence with an accuracy of 90% (95% CI 55.5%-99.8%), with the lowest risk of recurrence observed in patients receiving gross-total resection with adjuvant proton therapy (23%). Following resection, adjuvant proton therapy was associated with a lower risk of chordoma recurrence compared with photon therapy. The described machine learning models were able to predict tumor progression based on the extent of tumor resection and adjuvant radiotherapy modality used.

Radiation shielding properties of composites of TiZrNbHfTa refractory high entropy alloy reinforced with TiZrNbHfTaOx high-entropy oxide

Radiation shielding materials play a critical role in advancing the next generation of nuclear reactors. Among these, high-entropy materials with refractory properties emerge as a new category for radiation shielding applications. This study introduces TiZrNbHfTa-TiZrNbHfTaOx composites tailored for such purposes. Initially, a TiZrNbHfTa refractory high-entropy alloy (RHEA) is synthesized via mechanical alloying, followed by the oxidation of the alloy to obtain its refractory high-entropy oxide (RHEO), TiZrNbHfTaOx. Composites are then prepared by blending 5%, 10%, and 20% weight fractions of RHEO with RHEA using mechanical alloying. Comparative analysis of shielding properties reveals a decrease in mass attenuation coefficient and effective atomic number with increasing RHEO content. While RHEA exhibits superior shielding performance against gamma photons and neutrons, the composite containing 20% RHEO emerges as the optimal shield against alpha and proton irradiations. The equivalent neutron dose rate and removal cross-section values are obtained 49.8% and 0.142 for the composite with 20% RHEO, respectively. These findings, supported by computational simulations in this study, contribute valuable insights for the advancement of novel shielding materials crucial for future nuclear reactor technologies.

P8. Comparative Outcomes of Proton versus Photon Post-Mastectomy Radiation Therapy in Pre-pectoral Implant Based Breast Reconstruction

P8. Comparative Outcomes of Proton versus Photon Post-Mastectomy Radiation Therapy in Pre-pectoral Implant Based Breast Reconstruction

Apatite–Wollastonite (AW) glass ceramic doped with B2O3: Synthesis, structure, SEM, hardness, XRD, and neutron/charged particle attenuation properties

In the study, the influence of doping apatite-wollastonite (AW) glass-ceramics (GCs) with B2O3 on the structural, physical, microstructural, and light and heavy particle interaction properties is presented. Using the solid-state reaction and the cold isostatic press method, pristine AW, 10 wt% (AW-B10), and 20 wt% (AW-B20) B2O3-doped AW GCs were prepared. The prepared GCs were subject to structural, chemical compositional, and surface morphological investigation through standard experimental processes. Furthermore, the neutron (fast and thermal) and charged radiation (electron, proton, alpha, and carbon ion) interactional parameters of the GCs were obtained through standard theoretical models and software. The density of AW (2.91 gcm-3) increases to about 2.957 and 2.986 gcm-3 as B2O3 increases to 10 and 20 wt%, respectively. The presence of boron oxide supported the wollastonite phase to remain glass and suppressed crystallisation in the AW GCs. Doping AW with B2O3 improved the interaction probabilities of the GCs with fast and thermal neutrons, electrons, protons, alpha particles, and carbon ions. B-rich AW is thus potentially useful as a target material in human tissues for boron neutron capture therapy for the management of cancer and tumours, isolating or shielding specific tissues in ion beam therapy processes, and other techniques that require the exposure of human tissues to irradiation.

Comparative study on responses of three candidate materials for ADS beam/target windows to proton irradiation: T91, SIMP and Ti-6Al-4V

Accelerator-Driven System (ADS) represents an advanced nuclear energy system designed for the purpose of transmuting and eliminating nuclear waste. The irradiation tolerance of a material stands out as a critical factor in determining its availability for ADS beam/target windows. This study delves into the response of three promising candidates (T91, SIMP, and Ti-6Al-4V) for ADS beam/target windows to proton irradiation, as investigated by a 1.4 MeV H2+ irradiation experiment to dose of 1.5 peak dpa at 460 °C. Their cavity swelling and hardening behavior were estimated using Transmission Electron Microscope (TEM) and Nanoindentation, respectively. It was demonstrated that SIMP steel shows lower cavity swelling but slightly higher irradiation hardening compared to T91. Notably, no cavity swelling is observed in Ti-6Al-4V, but it experiences a higher level of irradiation hardening. The nucleation and evolution mechanisms of irradiation-induced defects (including cavities, dislocation loops, and precipitates) and their contributions to the proton irradiation response are discussed. Furthermore, a summary of the advantages and disadvantages of the three materials as candidates for proton beam/target windows is provided.

Controversies in neuro-oncology: focal proton versus photon radiation therapy for adult brain tumors

Abstract Radiation therapy (RT) plays a fundamental role in the treatment of malignant and benign brain tumors. Current state of the art photon- and proton-based RT combines more conformal dose distribution of target volumes and accurate dose delivery while limiting the adverse radiation effects. Several studies have demonstrated that proton therapy (PT) provides reduced dose to healthy brain parenchyma compared with photon-based (xRT) radiation techniques. However, whether dosimetric advantages translate into superior clinical outcomes for different adult brain tumors remains an open question. This review aims at critically reviewing the recent studies on PT in adult patients with brain tumors, including glioma, meningiomas and chordomas, to explore its potential benefits compared with xRT.

Influence of electrical field on the susceptibility of gallium nitride transistors to proton irradiation

Radiation susceptibility of electronic devices is commonly studied as a function of radiation energetics and device physics. Often overlooked is the presence or magnitude of the electrical field, which we hypothesize to play an influential role in low energy radiation. Accordingly, we present a comprehensive study of low-energy proton irradiation on gallium nitride high electron mobility transistors (HEMTs), turning the transistor ON or OFF during irradiation. Commercially available GaN HEMTs were exposed to 300 keV proton irradiation at fluences varying from 3.76 × 1012 to 3.76 × 1014 cm2, and the electrical performance was evaluated in terms of forward saturation current, transconductance, and threshold voltage. The results demonstrate that the presence of an electrical field makes it more susceptible to proton irradiation. The decrease of 12.4% in forward saturation and 19% in transconductance at the lowest fluence in ON mode suggests that both carrier density and mobility are reduced after irradiation. Additionally, a positive shift in threshold voltage (0.32 V and 0.09 V in ON and OFF mode, respectively) indicates the generation of acceptor-like traps due to proton bombardment. high-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy analysis reveal significant defects introduction and atom intermixing near AlGaN/GaN interfaces and within the GaN layer after the highest irradiation dose employed in this study. According to in-situ Raman spectroscopy, defects caused by irradiation can lead to a rise in self-heating and a considerable increase in (∼750 times) thermoelastic stress in the GaN layer during device operation. The findings indicate device engineering or electrical biasing protocol must be employed to compensate for radiation-induced defects formed during proton irradiation to improve device durability and reliability.

SAPPHIRE —establishment of small animal proton and photon image-guided radiation experiments

The in vivo evolution of radiotherapy necessitates innovative platforms for preclinical investigation, bridging the gap between bench research and clinical applications. Understanding the nuances of radiation response, specifically tailored to proton and photon therapies, is critical for optimizing treatment outcomes. Within this context, preclinical in vivo experimental setups incorporating image guidance for both photon and proton therapies are pivotal, enabling the translation of findings from small animal models to clinical settings. The SAPPHIRE project represents a milestone in this pursuit, presenting the installation of the small animal radiation therapy integrated beamline (SmART+ IB, Precision X-Ray Inc., Madison, Connecticut, USA) designed for preclinical image-guided proton and photon therapy experiments at University Proton Therapy Dresden. Through Monte Carlo simulations, low-dose on-site cone beam computed tomography imaging and quality assurance alignment protocols, the project ensures the safe and precise application of radiation, crucial for replicating clinical scenarios in small animal models. The creation of Hounsfield lookup tables and comprehensive proton and photon beam characterizations within this system enable accurate dose calculations, allowing for targeted and controlled comparison experiments. By integrating these capabilities, SAPPHIRE bridges preclinical investigations and potential clinical applications, offering a platform for translational radiobiology research and cancer therapy advancements.

Prompt gamma timing for proton range verification with TlBr and TlCl as pure Cherenkov emitters.

Objective.Prompt gamma timing (PGT) uses the detection time of prompt gammas emitted along the proton track in proton radiotherapy to verify Bragg peak positioning. Cherenkov detectors offer the possibility of enhanced signal-to-noise ratio (SNR) due to Cherenkov physics which enhances detection of high energy prompt gamma rays relative to other induced uncorrelated signals. In this work, the PGT technique was applied to 3 semiconductor materials that emit only Cherenkov light: a 3x3x20 mm3TlBr, a 12x12x12 mm3TlBr, and a 5x5x5 mm3 TlCl.Approach.A polymethyl methacrylate (PMMA) target was exposed to a 67.5 MeV, 0.5-nA proton beam and shifted in 3-mm increments at the Crocker Nuclear Laboratory (CNL) in Davis, CA, USA. A fast plastic scintillator coupled to a PMT provided the start reference for the proton time of flight (TOF). TOF distributions were generated using this reference and the gamma ray timestamp in the Cherenkov detector.Main results.The SNR of the proton correlated peaks relative to the background was 20, 29, and 30 for each of the three samples, respectively. The upper limit of the position resolutions with the TlCl sample were 2 mm, 3 mm, and 5 mm for 30k, 10k, and 5k detected events, respectively. The time distribution of events with respect to the reference reproduced with clarity the periodicity of the beam, implying a very high SNR of the Cherenkov crystals to detect prompt-gammas. Background presence from the neutron-induced continuum, prompt-gammas from deuterium, or positron activation were not observed. Material choice and crystal dimensions did not seem to affect significantly the outcome of the results.Significance.These results show the high SNR of the pure Cherenkov emitters TlBr and TlCl for the detection of prompt-gammas in a proton beam with current of clinical significance and their potential for verifying the proton range.

Reliability evaluation of spacecraft power generation performance with competitive failure processes under irradiation

AbstractThe performance of space power systems is crucial for space products as it determines the operational capabilities, endurance, and efficiency of satellites, spacecraft, and other extraterrestrial devices. Unlike reliability analysis in aerospace systems, studying spacecraft power generation performance requires consideration of both hardware and software aspects. Existing failure models do not fully capture the self‐recovery process of control programs. Therefore, this study presents an impact degradation model for space power systems that incorporates competitive failures under irradiation conditions. The model analyzes solar arrays and power controllers to derive a performance degradation model by considering the defect formation mechanism of amorphous semiconductor materials. Additionally, two shock types are defined based on redundancy backup in power controllers and scrubbing frequency in field‐programmable gate array (FPGA) units. Within the case analysis section, the research meticulously investigates and elucidates the correlation probabilities among varying proton irradiation doses, scrubbing frequencies, and the aforementioned shock types.

Positron annihilation spectroscopy evaluation of using proton irradiation as a surrogate for early neutron radiation damage

A positron annihilation spectroscopy investigation of early stages of radiation-induced damage in Chinese f/m (ferritic/martensitic) steel SIMP and strengthened variant of f/m steel ODS (oxide dispersion strengthened) EUROFER was conducted. Studied materials were irradiated by neutrons at the LVR-15 research reactor to 0.12 dpa at an average temperature of 260 ± 20 °C, and implanted by protons at the 6 MV Tandetron Accelerator of the Slovak University of Technology, to 0.0196 dpa at room temperature (RT) and 300 °C. The potential of using proton irradiation as a surrogate for early neutron radiation damage was investigated. A lifetime spectrometer and Doppler spectrometer was used to obtain simultaneously positron lifetime (PALS) and Doppler broadening spectra (DBS), which provided experimental data used to characterize the vacancy-type defect and their interaction with H atoms in the studied materials. The obtained results show an increase of mean positron lifetime (MLT) in the proton-implanted samples at RT when compared with high temperature irradiation. Similar trend was observed when comparing vacancy concentration of different irradiation conditions. The impact of temperature on mobility and recombination of defects, as well as effect of vacancy stabilization by H atoms, has been addressed. The effect of ODS microstructure on results has been examined. A methodology of comparing various irradiation conditions has been proposed, where the vacancy concentrations have been normalized by the dpa values. The potential application of proton implantation for evaluation of early stages of neutron damage was found to be promising.