Comparison between PHITS and GEANT4 Simulations of the Heavy Ion Beams at the BEVALAC at LBNL and the Booster Accelerator at BNL

Heavy charged particles have been discussed for clinical use due to their superior dose-depth distribution compared to conventional radiation such as X-rays. In addition, high-charge and energy (HZE) ions in galactic cosmic rays (GCR) present important health risks for crewed space missions to the Earth's moon or Mars. Experiments at heavy ion accelerators are used in radiobiology studies; however, numerical simulations of track segment or Bragg peak irradiations are complicated by the details of the beam-line and dosimetry systems. The goal of the present work is in support of biophysics modeling of historical radiobiology data at Lawrence Berkeley National Laboratory (LBNL) and more recent results from the Brookhaven National Lab (BNL) facility (NASA Space Radiation Lab (NSRL)). In this work, the Spread-Out Bragg Peak (SOBP) of 4He, 12C, and 20Ne particles, and a Bragg curve of 56Fe ion have been simulated numerically in the geometries of LBNL and BNL using the Monte-Carlo based PHITS and GEANT4 simulation toolkits. The dose contributions of primary particles and secondary particles, including neutrons and photons, in the target material are computed and discussed as well. Comparisons suggest more contributions of secondaries in GEANT4 simulations compared to PHITS simulations, and less statistical fluctuation and better prediction of neutrons in PHITS simulations. Neutrons and gamma-rays are estimated to make minor contributions to absorbed doses for these beams.

Rapid Sorting of Fucoxanthin-Producing Phaeodactylum tricornutum Mutants by Flow Cytometry

Fucoxanthin, which is widely found in seaweeds and diatoms, has many benefits to human health, such as anti-diabetes, anti-obesity, and anti-inflammatory physiological activities. However, the low content of fucoxanthin in brown algae and diatoms limits the commercialization of this product. In this study, we introduced an excitation light at 488 nm to analyze the emitted fluorescence of Phaeodactylum tricornutum, a diatom model organism rich in fucoxanthin. We observed a unique spectrum peak at 710 nm and found a linear correlation between fucoxanthin content and the mean fluorescence intensity. We subsequently used flow cytometry to screen high-fucoxanthin-content mutants created by heavy ion irradiation. After 20 days of cultivation, the fucoxanthin content of sorted cells was 25.5% higher than in the wild type. This method provides an efficient, rapid, and high-throughput approach to screen fucoxanthin-overproducing mutants.

Hyaluronic acid/polyethyleneimine nanoparticles loaded with copper ion and disulfiram for esophageal cancer

In the clinical treatment of cancer, improving the effectiveness and targeting of drugs has always been a bottleneck problem that needs to be solved. In this contribution, inspired by the targeted inhibition on cancer from combination application of disulfiram and divalent copper ion (Cu²⁺), we optimized the concentration of disulfiram and Cu²⁺ ion for inhibiting esophageal cancer cells, and loaded them in hyaluronic acid (HA)/polyethyleneimine (PEI) nanoparticles with specific scales, in order to improve the effectiveness and targeting of drugs. The in vitro cell experiments demonstrated that more drug loaded HA/PEI nanoparticles accumulated to the esophageal squamous cell carcinoma (Eca109) and promoted higher apoptosis ratio of Eca109. Both in vitro and in vivo biological assessment verified that the disulfiram/Cu²⁺ loaded HA/PEI nanoparticles promoted the apoptosis of cancer cells and inhibited the tumor proliferation, but had no toxicity on other normal organs.

[Medical application of particle and heavy ion transport code system PHITS]

This is a review on medical application of particle and heavy ion transport code system PHITS by JSRT and JSMP (https://www.jsmp.org/en).

[Analysis of Key Points of Radiation Sources in Proton and Carbon Ion Radiotherapy Facilities in Shanghai]

Compared with conventional high energy X-ray radiotherapy, proton/carbon ion has obvious advantages because of its Bragg peak dose distribution. However, proton heavy ion facility has complex structure, high energy and various radiation types due to various nuclear reaction processes, the radiation protection safety brought by the operation of facilities has gradually attracted attention. Taking the proton/carbon ion radiotherapy facility of Shanghai Proton and Heavy Ion Center as an example, the author mainly analyzed the operation principle of proton/carbon ion treatment facility, the basis of radiation protection, analysis of key radiation source points, etc., so as to provide theoretical support and experience for radiation protection.

Dual aspect of radioenhancers and free radical scavengers

Combining an external beam of ionizing particles with agents to augment the dose effects of cell damages for therapeutic purpose is an important goal of radiotherapy. This last decade intensive works have focused on metal compounds or metal nanoparticles as radiosensitizers to increase the oxidative damages under irradiation. In principle the nanoparticles can be coated with a functionalized shell, to achieve a specific targeting of the tissues, making such approach attractive. The functionalized coating is made of polymers. These molecules are able to scavenge the free radicals, thus, the coating can decrease the overall efficacy of the radiation. The purpose of the present model is to analyse the role of free hydroxyl radicals in the dual behaviour of the added agent. Consideration of the efficiency of the added agents versus the Linear Energy Transfer - LET - of the ionizing particles is made. It is shown that an efficient agent combined with a low-LET particle beams might become less efficient when high-LET particles like heavy-ions are used. These general considerations should be useful to optimize the design of the nanoparticles to be combined with the different kind of ionizing particles.

Heavy ion radiation-induced DNA damage mediates apoptosis via the Rpl27a-Rpl5-MDM2-p53/E2F1 signaling pathway in mouse spermatogonia

The risk of exposure to ionizing radiation (IR) environments has increased with the development of nuclear technology. IR exposure induces excessive apoptosis of the spermatogonia, which leads to male infertility. Spermatogonia apoptosis may be involved in ribosomal stress triggered by DNA damage following exposure to IR because ribosomal proteins (RPs) directly interact with mouse double minute 2 homolog (MDM2) to induce apoptosis. This study aimed to use comparative proteomics and transcriptomics approach to screen the differential RPs and ribosomal mRNAs in mouse testes following high linear energy transfer (LET) carbon ion radiation (CIR). The expression of ribosomal large subunit protein 27a (Rpl27a) decreased at both protein and mRNA levels in the spermatogonia in vivo. After 6 h of CIR, the immunofluorescence signal of 8-oxo-dG and phosphorylated ataxia-telangiectasia-mutated protein (ATM)/histone H2Ax increased, but that of Rpl27a decreased in the spermatogonia of p53 wild-type and knockout mouse testes. Moreover, the nucleolin was scattered throughout the nucleoplasm after CIR. These results suggested that CIR-induced DNA damage might trigger ribosomal stress, and the reduction in the expression of Rpl27a was associated with DNA damage in the spermatogonia. Similarly, in vitro, the immunofluorescence signal of 8-oxo-dG increased in the GC-1 cells after CIR. Moreover, the expression of Rpl27a was regulated by DNA damage because the co-transfection of ATM and Rpl27a or inhibition of ATM-treated CIR could restore the expression of Rpl27a. Furthermore, the reduction in the expression of Rpl27a led to weakened binding of E2F transcription factor 1 (E2F1) and p53 to MDM2, causing p53 activation and E2F1 degradation in p53 wild-type and knockdown GC-1 cells. This study proposed that heavy ion radiation-induced DNA damage mediated spermatogonia apoptosis via the Rpl27a-Rpl5-MDM2-p53/E2F1 signaling pathway. The results provided the underlying molecular mechanisms of spermatogonia apoptosis following exposure to high LET radiation.

Internal exposure rate conversion coefficients and absorbed fractions of mouse for 137Cs, 134Cs and 90Sr contamination in body

The aim of this study was to determine parameters for estimating the internal exposure of all organs in mouse experiments from the radioactivity concentration in organs. The estimation of internal exposure rate conversion coefficients and absorbed fractions for 137Cs, 134Cs and 90Sr by the Particle and Heavy Ion Transport code System (PHITS) with a voxel-based mouse phantom is presented. The geometry of the voxel phantom is constructed from computer tomography images of a mouse 9 cm in length weighing 23.9 g. The voxel-based mouse phantom has the following organs: brain, skull, heart, lungs, liver, stomach, spleen, kidneys, bladder, testis and tissue (tissue and other organs). Gamma- and beta-rays from 137Cs, 134Cs and 90Sr sources in each source organ are generated and scored for every target organ. The internal exposure rate conversion coefficients and absorbed fractions are calculated from deposition energies in each target organ from each source organ and are used to generate an internal exposure rate conversion coefficient matrix and an absorbed fraction matrix. The absorbed fractions of beta-rays in the source organs are roughly 0.5-0.8 for 137Cs and 134Cs, and the absorbed fractions of gamma-rays are <0.04 for 137Cs and <0.03 for 134Cs. The internal exposure rate conversion coefficient matrix is defined using the absorbed fractions. The calculated internal exposure rate coefficient matrix is tested under a uniform radioactivity concentration of 1 Bq/kg for 137Cs, 134Cs and 90Sr. The estimated internal exposure rates in the mouse whole body for 137Cs, 134Cs and 90Sr are 3.28 × 10-3, 2.55 × 10-3 and 1.20 × 10-2 μGy/d, respectively. These values are very similar to those for an ellipsoid frog (31.4 g) and an ellipsoid crab egg mass (12.6 g) reported in ICRP Publication 108.

Phy-X/ZeXTRa: a software for robust calculation of effective atomic numbers for photon, electron, proton, alpha particle, and carbon ion interactions

The purpose of the present work is robust calculation of effective atomic numbers ([Formula: see text]s) for photon, electron, proton, alpha particle and carbon ion interactions through the newly developed software, Phy-X/ZeXTRa (Z_eff of materials for X-Type Radiation attenuation). A pool of total mass attenuation and energy absorption coefficients (for photons) and total mass stopping powers (for charged particles) for elements was constructed first. Then, a matrix of interaction cross sections for elements Z = 1-92 was constructed. Finally, effective atomic numbers were calculated for any material by interpolating adjacent cross sections through a linear logarithmic interpolation formula. The results for [Formula: see text] for photon interaction were compared with those calculated through Mayneord's formula, which suggests a single-valued [Formula: see text] for any material for low-energy photons for which photoelectric absorption is the dominant interaction process. The single-valued [Formula: see text] was found to agree well with that obtained by other methods, in the low-energy region. In addition, [Formula: see text] values of various materials of biological interest were compared with those obtained experimentally at 59.54 keV. In general, the agreement between values calculated with Phy-X/ZeXTRa and Auto-Zeff and those measured were satisfactory. A comparison of [Formula: see text] values for photon energy absorption calculated with Phy-X/ZeXTRa and literature values for a nucleotide base, adenine, was made, and the relative difference (RD) in [Formula: see text] between Phy-X/ZeXTRa and literature values was found to be 2% < RD < 11%, at low photon energies (1-100 keV), while it was less than 1% at energies higher than 100 keV. Highest [Formula: see text] values were observed at low photon energies, where photoelectric absorption dominates photon interaction. For electrons, corresponding RD(%) values in [Formula: see text] were found to be in the range 0.4 ≤ RD(%) ≤ 1.7, while for heavy charged particle interactions it was 2.4 ≤ RD(%) ≤ 4.2 for total proton interaction and 0 ≤ RD(%) ≤ 8 for total alpha particle interaction. In view of the importance of [Formula: see text] for identifying and differentiating tissues in diagnostic imaging as well as for estimating accurate dose in radiotherapy and particle-beam therapy, Phy-X/ZeXTRa could be used for fast and accurate calculation of [Formula: see text] in a wide energy range for both photon and charged particle (electrons, protons, alpha particles and C ions) interactions.

Comparison of signaling profiles in the low dose range following low and high LET radiation

During space travel astronauts will be exposed to a very low, mixed field of radiation containing different high LET particles of varying energies, over an extended period. Thus, defining how human cells respond to these complex low dose exposures is important in ascertaining risk. In the current study, we have chosen to investigate how low doses of three different ion's at various energies uniquely change the kinetics of three different phospho-proteins. A normal hTERT immortalized fibroblast cell line, 82-6, was exposed to a range of lower doses (0.05-0.5 Gy) of radiation of different qualities and energies (Si 1000 MeV/u, Si 300 MeV/u, Si 173 MeV/u, Si 93 MeV/u, Fe 1000 MeV/u, Fe 600 MeV/u, Fe 300 MeV/u, Ti 300 MeV/u, Ti 326 MeV/u, Ti 386 MeV/u), covering a wide span of LET's. Exposed samples were analyzed for the average intensity of signal as a fold over the geometric mean level of the sham controls. Three phospho-proteins known to localize to DNA DSBs following radiation (γH2AX, pATF2, pSMC1) were studied. The kinetics of their response was quantified by flow cytometery at 2 and 24 h post exposure. These studies reveal unique kinetic patterns based on the ion, energy, fluence and time following exposure. In addition, γH2AX phosphorylation patterns are uniquely different from phospho-proteins known to be primarily phosphorylated by ATM. This latter finding suggests that the activating kinase(s), or the phosphatases deactivating these proteins, exhibit differences in their response to various radiation qualities and/ or doses of exposure. Further studies will be needed to better define what the differing kinetics for the kinases activated by the unique radiation qualities plays in the biological effectiveness of the particle.

Heavy metal ions removed from imitating acid mine drainages with a thermoacidophilic archaea: Acidianus manzaensis YN25

Metals in acid mine drainages (AMD) have posed a great threat to environment, and in situ economic environment-friendly remediation technologies need to be developed. Moreover, the effects of acidophiles on biosorption and migrating behaviors of metals in AMD have not been previously reported. In this study, the extremely thermoacidophilic Archaea, Acidianus manzaensis YN25 (A. manzaensis YN25) was used as a bio-adsorbent to adsorb metals (Cu²⁺, Ni²⁺, Cd²⁺ and Zn²⁺) from acidic solutions which were taken to imitate AMD. The values of their maximum biosorption capacities at both high (1 mM) and low (0.1 mM) metal concentrations followed the order: Cu²⁺ > Ni²⁺ > Cd²⁺ > Zn²⁺. With the elevations of temperature and pH value, the adsorption amounts of metals increased. The results also indicated that A. manzaensis YN25 had the highest adsorption affinity to Cu²⁺ in coexisting system of quaternary metals. Acid-base titration data revealed that carboxyl and phosphoryl groups provided adsorption sites for metals via deprotonation. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) further corroborated that amino played an important role in the biosorption process. The fitted Langmuir model illustrated monolayer adsorption occurring on cell surface. The possible adsorption mechanism of A. manzaensis YN25 mainly involved in electrostatic attraction and complexes formation. This study gives a profound insight into the biosorption behavior of heavy metals in acidic solution by thermoacidophilic Archaea and provides a probable novel strategy for in situ remediation of heavy metals pollution in AMD.

Intense carbon beams production with an all permanent magnet electron cyclotron resonance ion source for heavy ion medical machine

LAPECR3 (Lanzhou All Permanent magnet Electron cyclotron Resonance ion source No. 3) had been developed as an ion injector of Heavy Ion Medical Machine (HIMM) accelerator facility since 2009. The first HIMM accelerator facility was built in Wuwei city in 2015, and the LAPCER3 ion source has delivered C⁵⁺ ion beam to HIMM for more than 1000 days in the past four years. In order to improve the performance of the LAPECR3 ion source for intense carbon beams production, continuous research and development work has been made. The recently developed LAPECR3 ion source together with the new low-energy beam transportation can provide better performance in terms of both beam intensity and quality. This paper will generally review the LAPECR3 ion source operation status for HIMM, and the recent improvement will be presented, especially the stable beams production of C⁴⁺ and C⁵⁺.

RADIATION-INDUCED PLASMID DNA DAMAGE: EFFECT OF CONCENTRATION AND LENGTH

Plasmid DNA is commonly used as a simpler substitute for a cell in studies of early effects of ionizing radiation because it allows to determine yields of primary DNA lesions. Experimental studies often employ plasmids of different lengths, in different concentrations in the aqueous solution. Influence of these parameters on the heavy-ion induced yields of primary DNA damage has been studied, using plasmids pUC19 (2686 bp), pBR322 (4361 bp) and pKLAC2 (9107 bp) in 10 and 50 ng/μl concentration. Results demonstrate the impact of plasmid length, while no significant difference was observed between the two concentrations. The uncertainty of the results is discussed.

ANGULAR DEPENDENCE OF TRACK-ETCH DETECTOR HARZLAS TD-1

Track-etched detectors are commonly used also for radiation monitoring onboard International Space Station. To be registered in track-etched detectors, the particle needs to meet several criteria-it must have linear energy transfer above the detection threshold and strike the detector's surface under an angle higher than the so-called critical angle. Linear energy transfer is then estimated from calibration curve from the etch rate ratio V that is calculated from parameters of individual tracks appearing on the detector's surface after chemical etching. It has been observed that V can depend on the incident angle and this dependence can vary for different detector materials, etching and evaluating conditions. To investigate angular dependence, detectors (Harzlas TD-1) were irradiated at HIMAC by several ions under angles from 0° to 90°. The correction accounting not only for critical angle but also for dependence of V on the incident angle is introduced and applied to spectra measured onboard International Space Station.

PRELIMINARY EVALUATION OF A HAND-MADE RADIATION MONITOR'S POTENTIAL FOR PROVIDING ENERGY INFORMATION AS AN ADDITIONAL FEATURE FOR SECONDARY LEVEL RADIATION EDUCATION

A hand-made air GM counter was developed using simple, low-cost and easily available materials. The detector was successful in demonstrating the inverse square law, shielding effect, and determining the half-life of thoron gas. The possibility of using the tube design as a simple proportional counter to provide energy information has been explored and preliminary experiment and simulation results appear to agree at low energy. The energy deposition characteristics for an internally placed alpha-emitting Rn-220 were simulated using Particle and Heavy Ion Transport code System (PHITS).

Nitric Oxide Is Involved in Heavy Ion-Induced Non-Targeted Effects in Human Fibroblasts

Previously, we investigated the dose response for chromosomal aberration (CA) for exposures corresponding to less than one particle traversal per cell nucleus by high energy and charge (HZE) particles, and showed that the dose responses for simple exchanges for human fibroblast irradiated under confluent culture conditions were best fit by non-linear models motivated by a non-targeted effect (NTE). Our results suggested that the simple exchanges in normal human fibroblasts have an important NTE contribution at low particle fluence. Nitric oxide (NO) has been reported as a candidate for intercellular signaling for NTE in many studies. In order to estimate the contribution of NTE components in induced CA, we measured CA with and without an NO scavenger in normal skin fibroblasts cells after exposure to 600 MeV/u and 1 GeV/u 56Fe ions, less than one direct particle traversal per cell nucleus. Yields of CA were significantly lower in fibroblasts exposed to the NO scavenger compared to controls, suggesting involvement of NO in cell signaling for induction of CA. Media transferred from irradiated cells induced CA in non-irradiated cells, and this effect was abrogated with NO scavengers. Our results strongly support the importance of NTE contributions in the formation of CA at low-particle fluence in fibroblasts.

Analysis of the Stay Time of Patients in Gunma University Heavy Ion Medical Center (GHMC) Using RFID Technology

We observed the stay time of patients and staff in Gunma University Heavy Ion Medical Center. The stay time of patients with the prostatic cancer and the facing time with radiotherapy technicians in treatment rooms were significantly reduced as times goes by. This decreasing in time has an implication in scheduling algorithm development: for patients. RFID technology can be a potential method to track both staff and patients and thereby to assess the resource utilization efficiency.

Suitability of Solanum lycopersicum L. 'Microtom' for growth in Bioregenerative Life Support Systems: exploring the effect of high-LET ionising radiation on photosynthesis, leaf structure and fruit traits

The realisation of manned space exploration requires the development of Bioregenerative Life Support Systems (BLSS). In such self-sufficient closed habitats, higher plants have a fundamental role in air regeneration, water recovery, food production and waste recycling. In the space environment, ionising radiation represents one of the main constraints to plant growth. In this study, we explore whether low doses of heavy ions, namely Ca 25 Gy, delivered at the seed stage, may induce positive outcomes on growth and functional traits in plants of Solanum lycopersicum L. 'Microtom'. After irradiation of seed, plant growth was monitored during the whole plant life cycle, from germination to fruit ripening. Morphological parameters, photosynthetic efficiency, leaf anatomical functional traits and antioxidant production in leaves and fruits were analysed. Our data demonstrate that irradiation of seeds with 25 Gy Ca ions does not prevent achievement of the seed-to-seed cycle in 'Microtom', and induces a more compact plant size compared to the control. Plants germinated from irradiated seeds show better photochemical efficiency than controls, likely due to the higher amount of D1 protein and photosynthetic pigment content. Leaves of these plants also had smaller cells with a lower number of chloroplasts. The dose of 25 Gy Ca ions is also responsible for positive outcomes in fruits: although developing a lower number of berries, plants germinated from irradiated seeds produce larger berries, richer in carotenoids, ascorbic acid and anthocyanins than controls. These specific traits may be useful for 'Microtom' cultivation in BLSS in space, in so far as the crew members could benefit from fresh food richer in functional compounds that can be directly produced on board.

STUDY OF NEUTRON RADIATION FIELD AT THE FIRST RADIOACTIVE ION BEAM LINE IN LANZHOU

The first Radioactive Ion Beam Line in Lanzhou was a projectile fragment separator located in the HIRFL. The process of production and separation of radioactive ion beams can induce a strong and complex radiation field. The neutron dose equivalent rates were measured in four positions with a 70 MeV/u 40Ar18+ beam. The results were compared with that simulated by the FLUKA code. New shielding walls were installed to reduce the neutron background for spectroscopy measurement in the experimental terminal. In addition, the induced radioactivity of accelerator components and corresponding residual dose rates were analyzed for the radiation safety of accelerator workers. The airborne radioactivity as well as occupational exposure due to immersion in and inhalation of activated air were also estimated. This work aims to provide a valuable experience for the radiation study in the future fragment separator HFRS at HIAF.

ESTIMATION OF RBE VALUES FOR CARBON-ION BEAMS IN THE WIDE DOSE RANGE USING MULTICELLULAR SPHEROIDS

Hypofractionated carbon-ion therapy has been applied to treatment of several tumours. In this case, relative biological effectiveness (RBE) at high dose region must be considered, however, the RBE calculated physically has been not verified biologically. In this study, spheroid technique was adopted to estimate RBE in wide dose range. Cells were irradiated with X-rays and heavy-ions with LET of 13, 35, 100 and 300 keV/μm with monolayer and spheroid condition. Surviving fractions in wide dose range (0-15 Gy) were obtained to combined monolayer with spheroid survival data. The linear-quadratic and multi-target single-hit equation fitted well in survival data at low dose, and high dose region, respectively. A multi-process equation showed best fitting for survival data in wide dose range. RBE values of heavy-ions could be estimated by combination of monolayer and spheroid data. The values converged at 1.1-1.4 and varied by LET values at high and low dose region, respectively.

THE ROLE OF PARTICLE SPECTRA IN MODELING THE RELATIVE BIOLOGICAL EFFECTIVENESS OF PROTON RADIOTHERAPY BEAMS

Radiotherapy beams of protons or heavier ions generate secondary particles through nuclear interactions over different patient tissues. The resulting particle spectra depend on the tissue composition and on charge and energy of the primary beam ions. In proton radiotherapy, predictive radiobiological models usually apply dose-averaged linear energy transfer (LET). Microdosimetry-based models for proton or heavier ion primary beams also rely on dose-averaged quantities, the values of which depend on whether the produced secondaries are included or excluded in the calculation. In turn, this will affect the results of calculations of the relative biological effectiveness (RBE) of these beams. In this brief note, we study quantitatively the influence of the secondary radiation spectra on the averaged expectation values of LET and their impact on predictions of RBE. It is noted that for microdosimetry-based quantities and for corresponding LET-based parameters the trends are similar and that fluence-averaged quantities should be studied more closely.