Heavy Radiation Research Articles

Monitor of the single event upsets and linear energy transfer of space radiation on the Beidou navigation satellites

Abstract The single event effect caused by space heavy ion radiation is one of the important factors affecting the safety and operation of spacecraft on orbit. In the research and evaluation of the frequency, spatial distribution and time characteristics of single event effects, linear energy transfer (LET) spectra of space radiation play an important role. On the Beidou navigation M15 and M16 satellites, a single event upset (SEU) and LET monitor was developed to obtain the upsets of the memory device and the LET spectra of space radiation which passes through the device. Through the measurement results from this monitor, the correlation between the device’s SEUs and the LET spectra could be studied.

An overview of the antioxidant effects of silymarin and its role in reducing the harmful effects of some heavy metals, radiation and nicotine on sperm quality.

An overview of the antioxidant effects of silymarin and its role in reducing the harmful effects of some heavy metals, radiation and nicotine on sperm quality.

The Biological Implication of Semicarbazide-Sensitive Amine Oxidase (SSAO) Upregulation in Rat Systemic Inflammatory Response under Simulated Aerospace Environment.

The progress of space science and technology has ushered in a new era for humanity's exploration of outer space. Recent studies have indicated that the aerospace special environment including microgravity and space radiation poses a significant risk to the health of astronauts, which involves multiple pathophysiological effects on the human body as well on tissues and organs. It has been an important research topic to study the molecular mechanism of body damage and further explore countermeasures against the physiological and pathological changes caused by the space environment. In this study, we used the rat model to study the biological effects of the tissue damage and related molecular pathway under either simulated microgravity or heavy ion radiation or combined stimulation. Our study disclosed that ureaplasma-sensitive amino oxidase (SSAO) upregulation is closely related to the systematic inflammatory response (IL-6, TNF-α) in rats under a simulated aerospace environment. In particular, the space environment leads to significant changes in the level of inflammatory genes in heart tissues, thus altering the expression and activity of SSAO and causing inflammatory responses. The detailed molecular mechanisms have been further validated in the genetic engineering cell line model. Overall, this work clearly shows the biological implication of SSAO upregulation in microgravity and radiation-mediated inflammatory response, providing a scientific basis or potential target for further in-depth investigation of the pathological damage and protection strategy under a space environment.

Spermine oxidase induces DNA damage and sensitizes fusion negative rhabdomyosarcoma cells to irradiation.

Rhabdomyosarcoma (RMS) is a pediatric myogenic soft tissue sarcoma that includes fusion-positive (FP) and fusion-negative (FN) molecular subtypes. FP-RMS expresses PAX3-FOXO1 fusion protein and often shows dismal prognosis. FN-RMS shows cytogenetic abnormalities and frequently harbors RAS pathway mutations. Despite the multimodal heavy chemo and radiation therapeutic regimens, high risk metastatic/recurrent FN-RMS shows a 5-year survival less than 30% due to poor sensitivity to chemo-radiotherapy. Therefore, the identification of novel targets is needed. Polyamines (PAs) such as putrescine (PUT), spermidine (SPD) and spermine (SPM) are low-molecular-mass highly charged molecules whose intracellular levels are strictly modulated by specific enzymes. Among the latter, spermine oxidase (SMOX) regulates polyamine catabolism oxidizing SPM to SPD, which impacts cellular processes such as apoptosis and DNA damage response. Here we report that low SMOX levels are associated with a worse outcome in FN-RMS, but not in FP-RMS, patients. Consistently, SMOX expression is downregulated in FN-RMS cell lines as compared to normal myoblasts. Moreover, SMOX transcript levels are reduced FN-RMS cells differentiation, being indirectly downregulated by the muscle transcription factor MYOD. Noteworthy, forced expression of SMOX in two cell lines derived from high-risk FN-RMS: 1) reduces SPM and upregulates SPD levels; 2) induces G0/G1 cell cycle arrest followed by apoptosis; 3) impairs anchorage-independent and tumor spheroids growth; 4) inhibits cell migration; 5) increases γH2AX levels and foci formation indicative of DNA damage. In addition, forced expression of SMOX and irradiation synergize at activating ATM and DNA-PKCs, and at inducing γH2AX expression and foci formation, which suggests an enhancement in DNA damage response. Irradiated SMOX-overexpressing FN-RMS cells also show significant decrease in both colony formation capacity and spheroids growth with respect to single approaches. Thus, our results unveil a role for SMOX as inhibitor of tumorigenicity of FN-RMS cells in vitro. In conclusion, our in vitro results suggest that SMOX induction could be a potential combinatorial approach to sensitize FN-RMS to ionizing radiation and deserve further in-depth studies.

Heavy Ion-Responsive lncRNA EBLN3P Functions in the Radiosensitization of Non-Small Cell Lung Cancer Cells Mediated by TNPO1.

In recent decades, the rapid development of radiotherapy has dramatically increased the cure rate of malignant tumors. Heavy-ion radiotherapy, which is characterized by the "Bragg Peak" because of its excellent physical properties, induces extensive unrepairable DNA damage in tumor tissues, while normal tissues in the path of ion beams suffer less damage. However, there are few prognostic molecular biomarkers that can be used to assess the efficacy of heavy ion radiotherapy. In this study, we focus on non-small cell lung cancer (NSCLC) radiotherapy and use RNA sequencing and bioinformatic analysis to investigate the gene expression profiles of A549 cells exposed to X-ray or carbon ion irradiation to screen the key genes involved in the stronger tumor-killing effect induced by carbon ions. The potential ceRNA network was predicted and verified by polymerase chain amplification, western blotting analysis, colony formation assay, and apoptosis assay. The results of the experiments indicated that lncRNA EBLN3P plays a critical role in inhibiting carbon ion-induced cell proliferation and inducing apoptosis of NSCLC cells. These functions were achieved by the EBLN3P/miR-144-3p/TNPO1 (transportin-1) ceRNA network. In summary, the lncRNA EBLN3P functions as a ceRNA to mediate lung cancer inhibition induced by carbon ion irradiation by sponging miR-144-3p to regulate TNPO1 expression, indicating that EBLN3P may be a promising target for increasing the treatment efficacy of conventional radiotherapy for NSCLC.

Study on occupational exposure of medical staff caused by induced radioactivity in the treatment room of medical heavy-ion facility

Heavy-ion radiotherapy is currently recognized as the most advanced particle therapy method and is being vigorously promoted and applied worldwide. This method can rapidly generate radiation and induce radioactivity during treatment. However, the induced radioactivity, which is the primary source of exposure for medical staff, does not disappear following therapeutic application in the treatment room. In this study, we investigated the characteristics, dose rate distribution, and impact of this induced radioactivity on medical staff in the treatment room (uniform scanning mode) at Gansu Wuwei Tumor Hospital using experimental measurement and Monte Carlo simulation. We found that the exposure dose experienced by medical staff is predominantly related to the irradiated patients for single irradiation and the irradiated beam delivery system for long-term irradiation. The half-lives of the main radionuclides ranged from a few minutes to tens of minutes for single irradiation and from tens of days to hundreds of days for long-term irradiation. The primary radionuclide contributors are 15O, 11C, 176Ta, and 177W. We also estimated the personal dose experienced by the medical staff in the treatment room in relation to their working patterns. The results showed that the maximum annual exposure dose of medical staff in the horizontal treatment direction under the current model was 0.728 mSv. We hypothesized that an appropriate increase in the patient's treatment could reduce the annual exposure dose of medical staff to 0.650 mSv without changing the total treatment time per day. Finally, some suggestions were made to reduce the exposure of medical staff to unwanted radiation.

Experimental investigation on heat transfer and flow characteristics of TiO2-water nanofluid in a heavy vehicle radiator

Experimental investigation on heat transfer and flow characteristics of TiO2-water nanofluid in a heavy vehicle radiator

BT-5 LONG-TERM OUTCOME OF CLIVAL CHORDOMAS AT A SINGLE INSTITUTION

Abstract Purpose Chordoma is a rare malignant tumor, about 30% of which occurs in the clivus. The purpose of this study is to investigate the outcome after treatment of clival chordoma in our institute. Methods Nineteen patients {M/F=11/8, mean age: 50.4 (15-72) years} who were treated between 1987 and 2021 and followed for at least 6 months were retrospectively evaluated for survival and local control rate. Results The cumulative survival rate was 89.2% at 5 years, 82.3% at 10 years, and 54.9% at 25 years, and the median OS was 107 (6-359) months. 4 deaths: 2 tumor deaths (1 from poorly differentiated chordoma), 2 non-tumor deaths (1 from IC rupture after heavy ion radiotherapy). The cumulative local control rate was 47.3% at 5 years and 35.5% at 10 years, with a median progression-free survival (PFS) of 41 (0-278) months. There was no difference in OS (p=0.85) or PFS (p=0.90) between the two groups, with 6 cases of gross total resection, GTR (all transsphenoidal) and 13 cases of non-GTR (9 transsphenoidal, 4 transcranial) at first surgery. In the 4 patients without irradiation (1 GTR, 3 non-GTR), no disease progression (PD) was observed, and the mean OS was 170 (69-278) months. Of the 15 patients irradiated, 6 were irradiated before PD and 9 were irradiated after PD, and there was no difference in OS or PFS between the two groups, i.e., the timing of irradiation. One patient with refractory chordoma was found to have elevated TMB levels by cancer genome testing and is currently receiving pembrolizumab, which has resulted in significant tumor shrinkage. Conclusion The patients with clival chordoma have a varied course, which may be due to differences in molecular biology. Cancer genome testing may provide new treatment options, such as molecularly targeted drugs and immune checkpoint inhibitors, for refractory cases.

A Fast 3D/3D Registration Method Based on Water Equivalent Path Length for Heavy-Ion Radiotherapy

<h3>Purpose/Objective(s)</h3> The accuracy of patient setup needs to be high in heavy-ion radiotherapy. Accordingly, there is an increasing demand for three-dimensional (3D) image-guided systems because of the limitations of the present two-dimensional imaging registration technology. One of the limitations is the inability to directly compare with planning computed tomography (CT) images. Due to this uncertainty in conformation, high dose per fraction radiotherapy is difficult. This study proposes a fast 3D/3D registration method comparing with water equivalent path length (WEPL) that uses planning and treatment CT images to minimize range variations by using the Lucas-Kanade (LK) algorithm. <h3>Materials/Methods</h3> A six-degrees-of-freedom (6DOF) couch correction was simulated for patient positioning at our center by performing automatic rigid image registration (RIR) and using the resultant translation/rotation. Our automatic RIR algorithm was used to align the planning CT and treatment CT images, simulating 6DOF. The alignment values (Δ<i>V</i>), which represents a six-dimensional vector of the amounts of 6DOF couch movement, were calculated by minimizing the following error function: E(<i>ΔV</i>)=Σ <i>_i</i>_∈Ω [<i>T_i</i> (<i>V+ΔV</i>)-<i>P_i</i> (<i>V</i>)]², where <i>V</i> is a six-dimensional vector that denotes a CT position and rotation in a treatment room; <i>T_i</i> (<i>V</i>) and <i>P_i</i> (<i>V</i>) are treatment and planning CT images respectively, whose position in the room is represented by <i>V; i</i> is a 3D vector which denotes a point in the room; and Ω is a set of calculation points, which was assigned a planning target volume (PTV) of Ω in this study. We minimized the error function by using the LK algorithm. To minimize the range variations, each pixel value of the CT images was changed into WEPL values and the alignment values were calculated in the same manner as the above algorithm. The method was evaluated using a dataset containing eight prostate cancer patient images, including a planning CT image with PTV and treatment CT images of four fraction with a fan-beam CT. The range variations were measured by calculating WEPL variations between the planning CT and treatment CT at (1) before registration and after registration based on (2) CT pixel values and (3) WEPL values, respectively. In addition, the calculation time was measured on a workstation with a single GPU. <h3>Results</h3> The mean WEL variation across the 32 cases (eight patients of four fractions) was (1) 1.8 ± 1.16 mm, (2) 1.08 ± 0.52 mm, and (3) 0.22 ± 0.17 mm. The worst WEPL variation were (1) 6.23 mm, (2) 3.06 mm, and (3) 1.17 mm. The mean calculation time were (2) 89 ms and (3) 1066 ms. <h3>Conclusion</h3> We developed a fast 3D/3D RIR method for reducing range variations to realize more accurate heavy-ion radiotherapy. We performed experiments involving eight prostate cancer patients, and our proposed method obtained high accuracy and short computation time.

The high toxicity of DSB-clusters modelling high-LET-DNA damage derives from inhibition of c-NHEJ and promotion of alt-EJ and SSA despite increases in HR.

Heavy-ion radiotherapy utilizing high linear energy transfer (high-LET) ionizing radiation (IR) is a promising cancer treatment modality owing to advantageous physical properties of energy deposition and associated toxicity over X-rays. Therapies utilizing high-LET radiation will benefit from a better understanding of the molecular mechanisms underpinning their increased biological efficacy. Towards this goal, we investigate here the biological consequences of well-defined clusters of DNA double-strand breaks (DSBs), a form of DNA damage, which on theoretical counts, has often been considered central to the enhanced toxicity of high-LET IR. We test clonal cell lines harboring in their genomes constructs with appropriately engineered I-SceI recognition sites that convert upon I-SceI expression to individual DSBs, or DSB-clusters comprising known numbers of DSBs with defined DNA-ends. We find that, similarly to high-LET IR, DSB-clusters of increasing complexity, i.e. increasing numbers of DSBs, with compatible or incompatible ends, compromise classical non-homologous end-joining, favor DNA end-resection and promote resection-dependent DSB-processing. Analysis of RAD51 foci shows increased engagement of error-free homologous recombination on DSB-clusters. Multicolor fluorescence in situ hybridization analysis shows that complex DSB-clusters markedly increase the incidence of structural chromosomal abnormalities (SCAs). Since RAD51-knockdown further increases SCAs-incidence, we conclude that homologous recombination suppresses SCAs-formation. Strikingly, CtIP-depletion inhibits SCAs-formation, suggesting that it relies on alternative end-joining or single-strand annealing. Indeed, ablation of RAD52 causes a marked reduction in SCAs, as does also inhibition of PARP1. We conclude that increased DSB-cluster formation that accompanies LET-increases, enhances IR-effectiveness by promoting DNA end-resection, which suppresses c-NHEJ and enhances utilization of alt-EJ or SSA. Although increased resection also favors HR, on balance, error-prone processing dominates, causing the generally observed increased toxicity of high-LET radiation. These findings offer new mechanistic insights into high-LET IR-toxicity and have translational potential in the clinical setting that may be harnessed by combining high-LET IR with inhibitors of PARP1 or RAD52.

Development and Application of the First Carbon Ion Therapy System in China

At present, heavy ion is an ideal radiation for cancer treatment, and carbon ion is used in the treatment of many kinds of cancer due to its higher relative biological effect value. In 2019, Wuwei heavy ion center built the first medical heavy ion accelerator-carbon ion radiotherapy system in China, and obtained the registration license from the National Medical Products Administration, and officially received cancer patients in March 2020. This study introduced the development and application of the first carbon ion radiotherapy system in China.

Structural and Electrical Response of Emerging Memories Exposed to Heavy Ion Radiation.

Hafnium oxide- and GeSbTe-based functional layers are promising candidates in material systems for emerging memory technologies. They are also discussed as contenders for radiation-harsh environment applications. Testing the resilience against ion radiation is of high importance to identify materials that are feasible for future applications of emerging memory technologies like oxide-based, ferroelectric, and phase-change random-access memory. Induced changes of the crystalline and microscopic structure have to be considered as they are directly related to the memory states and failure mechanisms of the emerging memory technologies. Therefore, we present heavy ion irradiation-induced effects in emerging memories based on different memory materials, in particular, HfO2-, HfZrO2-, as well as GeSbTe-based thin films. This study reveals that the initial crystallinity, composition, and microstructure of the memory materials have a fundamental influence on their interaction with Au swift heavy ions. With this, we provide a test protocol for irradiation experiments of hafnium oxide- and GeSbTe-based emerging memories, combining structural investigations by X-ray diffraction on a macroscopic, scanning transmission electron microscopy on a microscopic scale, and electrical characterization of real devices. Such fundamental studies can be also of importance for future applications, considering the transition of digital to analog memories with a multitude of resistance states.

Depth dose measurements in water for 11C and 10C beams with therapy relevant energies

Owing to the favorable depth-dose distribution and the radiobiological properties of heavy ion radiation, ion beam therapy shows an improved success/toxicity ratio compared to conventional radiotherapy. The sharp dose gradients and very high doses in the Bragg peak region, which represent the larger physical advantage of ion beam therapy, make it also extremely sensitive to range uncertainties. The use of β+-radioactive ion beams would be ideal for simultaneous treatment and accurate online range monitoring through PET imaging. Since all the unfragmented primary ions are potentially contributing to the PET signal, these beams offer an improved image quality while preserving the physical and radiobiological advantages of the stable counterparts. The challenging production of radioactive ion beams and the difficulties in reaching high intensities, have discouraged their clinical application. In this context, the project Biomedical Applications of Radioactive ion Beams (BARB) started at GSI (Helmholtzzentrum für Schwerionenforschung GmbH) with the main goal to assess the technical feasibility and investigate possible advantages of radioactive ion beams on the pre-clinical level. During the first experimental campaign 11C and 10C beams were produced and isotopically separated with the FRagment Separator (FRS) at GSI. The β+-radioactive ion beams were produced with a beam purity of 99% for all the beam investigated (except one case where it was 94%) and intensities potentially sufficient to treat a small animal tumors within few minutes of irradiation time, ∼106 particle per spill for the 10C and ∼107 particle per spill for the 11C beam, respectively. The impact of different ion optical parameters on the depth dose distribution was studied with a precision water column system. In this work, the measured depth dose distributions are presented together with results from Monte Carlo simulations using the FLUKA software.

Thermal Design and Test Results of the Superconducting Magnet for a Compact Heavy-Ion Synchrotron

A project to develop a next-generation small facility for heavy-ion radiotherapy called Quantum Scalpel is underway at the National Institutes for Quantum Science and Technology (QST), having started in 2016. One of the aims of this project is to downsize the synchrotron by applying superconducting technology. With a view to accomplishing this, we have been developing a superconducting magnet for a compact heavy-ion synchrotron in collaboration with QST. This superconducting magnet can generate a dipole field of 3.5 T at an operating current of 265 A. It adopts conduction cooling with GM cryocoolers and is designed to be able to raise the magnetic field from 0.3 T to 3.5 T in 5 seconds. Such high-speed excitation causes large AC loss in the superconducting coil. In this paper, the thermal design result, including countermeasures for this AC loss, is described. In addition, a short model with the same cross section as the designed coil was fabricated and an excitation test was carried out. As a result of the test, it was confirmed that the magnet can generate the designed maximum field of 3.5 T in 5 seconds without quench. And it was also confirmed that there was a difference of about 0.5 K between the measurement results and the thermal calculation results of the pattern test. The design of a full-scale magnet is almost completed, and the results of the present work shows that the conduction-cooling method using 4K GM cryocoolers is applicable to the superconducting magnet for the synchrotron.

The influence of helium and heavy ion irradiations on radiation responses of single crystal Cu with nanovoids: An in situ TEM study

Helium is a common nuclear reaction product, and it plays an important role in radiation-induced void swelling. Although extensive studies have been conducted to investigate the helium effects in metals and alloys, most of them were based on the post-irradiation analyses or computer simulations. Conclusive evidence that can demonstrate how voids evolve in the presence of He under high-temperature radiation remains limited. In this work, we performed in situ heavy ion radiation studies in a transmission electron microscope to compare the radiation response of the preexisting nanovoids in single crystal copper subjected to a single beam of 1 MeV Kr ions and a sequential dual beam of 14 keV He ion and 1 MeV Kr ion at 350 °C. Our studies revealed that the nanovoids would contract continuously until being eliminated when irradiated by a single beam of Kr ions. In comparison, the nanovoids in helium-injected Cu could reach a stable state and eventually stopped shrinking. Moreover, the influence of helium on the kinetics of void/bubble evolution under heavy ion irradiation was discussed within the framework of a proposed critical bubble model and bubble coarsening model.

Bats and pollution: Genetic approaches in ecotoxicology

Environmental pollution drives the decline of species and, as flying mammals, bats can be considered to be excellent indicators of environmental quality, and the analysis of genetic biomarkers in these animals can provide important parameters for the assessment of environmental health. This review verifies the trends in pollution research, in particular, the use of genetic markers in the study of bats, based on a literature search of the Web of Science and Scopus platforms. Sixteen publications were identified during the search, which focused on the timeframe between 1996 and March 2022, including investigations of the effects of heavy metals, agricultural pesticides, and radiation. The studies were based primarily on the application of biomarkers for genotoxic analysis, including the comet assay, micronucleus test, and the Polymerase Chain Reaction (PCR). Only 55 bat species have been investigated up to now, that is, 4% of the 1447 currently recognized. In general, bats exposed to polluted environments presented a higher frequency of genotoxic and mutagenic damage than those sampled in clean environments. Given the importance of the diverse ecological functions provided by bats, including pest control, pollination, and seed dispersal, it is increasingly necessary to investigate the damage caused to the health of these animals exposed to areas with high concentrations of contaminants. Although genetic biomarkers have been used to investigate physiological parameters in bats for more than two decades, then, many knowledge gaps remain, worldwide, in terms of the number of species and localities investigated.

Investigation on the activity distribution of positron products in PMMA target irradiated by carbon ion beam

In the heavy ion radiotherapy, the dose distribution is an important index to ensure the therapeutic effect. But it can not be directly measured during a treatment. Positron-emitting radionuclides (10 C, 11 C, and 15 O et al.) produced in the treatment process are deposited along the path and the end of the beam trajectory, so the positron activity distribution can be used to monitor the dose distribution of carbon ions. In this paper, we present results of measurements of positron activity distributions with a developed scanner system. Then the relationship between the activity distribution of positrons and the dose distribution of carbon ions is studied. The research shows that the activity distribution of positrons is quite similar to that of carbon ions in the direction of penetration depth. The activity peak position of positrons is smaller than the dose peak position of carbon ions, and this difference increases along with the increase of carbon ion beam energy. These experimental results are consistent with the GATE simulation results. It is found that the detector system can distinguish shift of peak position of 3 mm that corresponds change of a particle energy of 4 MeV/u. This indicates that the positron scanner system had been successfully developed for heavy ion therapy equipment.

Physiological and Differential Proteomic Analysis at Seedling Stage by Induction of Heavy-Ion Beam Radiation in Wheat Seeds.

Novel genetic variations can be obtained by inducing mutations in the plant which help to achieve novel traits. The useful mutant can be obtained through radiation mutation in a short period which can be used as a new material to produce new varieties with high yield and good quality wheat. In this paper, the proteomic analysis of wheat treated with different doses of 12C and 7Li ion beam radiation at the seedling stage was carried out through a Tandem Mass Tag (TMT) tagging quantitative proteomic analysis platform based on high-resolution liquid chromatography-mass spectrometry, and the traditional 60Co-γ-ray radiation treatment for reference. A total of 4,764 up-regulated and 5,542 down-regulated differentially expressed proteins were identified. These proteins were mainly enriched in the KEGG pathway associated with amino acid metabolism, fatty acid metabolism, carbon metabolism, photosynthesis, signal transduction, protein synthesis, and DNA replication. Functional analysis of the differentially expressed proteins showed that the oxidative defense system in the plant defense system was fully involved in the defense response after 12C ion beam and 7Li ion beam radiation treatments. Photosynthesis and photorespiration were inhibited after 12C ion beam and 60Co-γ-ray irradiation treatments, while there was no effect on the plant with 7Li ion beam treatment. In addition, the synthesis of biomolecules such as proteins, as well as multiple signal transduction pathways also respond to radiations. Some selected differentially expressed proteins were verified by Parallel Reaction Monitoring (PRM) and qPCR, and the experimental results were consistent with the quantitative results of TMT. The present study shows that the physiological effect of 12C ion beam radiation treatment is different as compared to the 7Li ion beam, but its similar to the 60Co-γ ray depicting a significant effect on the plant by using the same dose. The results of this study will provide a theoretical basis for the application of 12C and 7Li ion beam radiation in the mutation breeding of wheat and other major crops and promote the development of heavy ion beam radiation mutation breeding technology.

DR-only Carbon-ion radiotherapy treatment planning via deep learning

PurposeTo evaluate the feasibility of patient-specific digital radiography (DR)-only treatment planning for carbon ion radiotherapy in anthropomorphic thorax-and-abdomen phantom and head-and-neck patients. MethodsThe study was conducted on the anthropomorphic phantom and head-and-neck patients. We collected computed tomography (CT) and DR images of the phantom and cone beam CT (CBCT) and DR images of the patients, respectively. Two different deep neural networks were established to correlate the relationships between DR and digitally reconstructed radiograph (DRR) images, as well as DRR and CT images. The similarity between CT and predicted CT images was evaluated by computing the mean absolute error (MAE), root mean square error (RMSE), peak signal-to-noise ratio (PSNR) and structural similarity (SSIM), respectively. Dose calculations on the predicted CT images were compared against the true CT-based dose distributions for carbon-ion radiotherapy treatment planning with intensity-modulated pencil-beam spot scanning. Relative dose differences in the target volumes and organ-at-risks were computed and three-dimensional gamma analyses (3 mm, 3%) were performed. ResultsThe average MAE, RMSE, PSNR and SSIM of the framework were 0.007, 0.144, 37.496 and 0.973, respectively. The average relative dose differences between the predicted CT- and CT-based dose distributions at the same carbon-ion irradiation settings for the phantom and the patients were <2% and ≤4%, respectively. The average gamma pass-rates were >98% for the predicted CT-based versus CT-based carbon ion plans of the phantom and the patients. ConclusionWe have demonstrated the feasibility of a patient-specific DR-only treatment planning workflow for heavy ion radiotherapy by using deep learning approach.

The methodology for validation of cross sections in quasi monoenergetic neutron field

Dosimetry cross sections are fundamental quantities for proper determination of the neutron fluences in points of interest under heavy radiation load. One of the critical applications is the Reactor Pressure Vessel aging management, related to the correct estimation of its residual lifetime or for many non-reactor applications including neutron dosimetry of accelerator-based fields or space applications. The neutron flux of neutrons above 12 MeV in reference to fission spectra is below 1%. Therefore, new reference neutron fields with average energy above 5 MeV should be developed for the validation of neutron dosimetry cross sections up to 60 MeV. This paper presents the testing of a new methodology for the use of quasi monoenergetic neutron fields, where different sensitivity allows validations of the dosimetry cross section at energies much higher than the average energy of around 2 MeV typical of fission spectra. The exact shape of the neutron spectrum in the tested fields is measured by stilbene spectrometry. The total flux is determined from Ni and Al flux monitors. The developed methodology was applied to the validation of selected reactions from the IRDFF-II library showing satisfactory agreement.