Carbon Ion Irradiation Research Articles

Proton and Carbon Ion Radiation Therapy Decreased Severe Lymphopenia by Reducing Thoracic Vertebra and Aortic Doses in Non-Small Cell Lung Cancer Versus Intensity Modulated Radiation Therapy

Lymphopenia is a common adverse effect of radiotherapy (RT). Little is known about the difference in lymphopenia between intensity-modulated (photon) radiation therapy (IMRT) and proton and carbon ion radiotherapy (PCIRT). This study aimed to investigate lymphopenia differences between IMRT and PCIRT in non-small cell lung cancer (NSCLC). Clinical and dosimetric parameters were collected from 343 patients who received definitive IMRT or PCIRT for NSCLC. Severe lymphopenia (SRL) was defined as an absolute lymphocyte count (ALC) ≤0.5*103 cells/μL. Overall survival (OS) was analyzed using the Kaplan-Meier method. Propensity score matching was performed between the IMRT and PCIRT groups. LASSO analysis was used to select appropriate dosimetric parameters. Univariate and multivariate logistic regression analyses were conducted to identify the predictors of SRL. Compared to the IMRT group, the PCIRT group was less likely to develop SRL (p <0.001). Compared with non-SRL group, SRL group showed significant association with poorer OS, with median survival time of 29.2 vs. 15.0 months (p = 0.046). IMRT was an independent risk factor of SRL (p = 0.004). A lower ALC before RT (p = 0.030) and larger planning target volume (PTV) (p = 0.002) were also significant independent risk factors for SRL. Moreover, the majority of dosimetric parameters of organ at risks in PCIRT were lower than those in IMRT (p <0.001). Thoracic vertebra V5 (p =0.002) and aorta V5 (p =0.026) were identified as independent risk predictors of SRL after adding dosimetric parameters to the regression model. Compared with IMRT, PCIRT could reduce the SRL incidence, possibly by limiting thoracic vertebra and aortic doses, and SRL was associated with poor outcomes in NSCLC patients.

Weak ferromagnetism in thin fullerene films as a consequence of 600 keV carbon ion irradiation

Weak ferromagnetism in thin fullerene films as a consequence of 600 keV carbon ion irradiation

Dynamic interplay between thionine and DNA under carbon ion irradiation: a real-time first-principles study

Understanding the interactions between deoxyribonucleic acid (DNA) and photosensitizer under ion irradiation benefits the development of aptasensors, DNA biosensors and cancer diagnosis. Using real-time time-depended density functional theory, by simulating high-energy C ion passing through DNA with poly(dG)·poly(dC) sequence and that with embedded thionine (3,7-diamino-5-phenothiazinium, TH), we compared the electronic stopping power (ESP), evolution of the structure and charge, and absorption spectrum. TH inserting leads the increase in space charge density, a larger electron de-excitation and a larger ESP, but the speed corresponding to the maximum ESP is almost same. When C ion passes through TH–DNA, the structure of TH slightly changes and there still exists noncovalent interaction between TH and DNA, but the absorption coefficient depends on the electron occupied state of TH when the ion passes through. These results indicate that at low radiation doses, TH still can be a DNA detector, although its response wavelength and intensity have been slightly changed, and provide a theoretical reference to improve the possible application of phenothiazine dye in DNA biosensor under ion irradiation.

Functional imaging-guided carbon ion irradiation with simultaneous integrated boost for localized prostate cancer: study protocol for a phase II randomized controlled clinical trial

BackgroundDue to the physical dose distribution characteristic of “Bragg peak” and the biological effect as a kind of high linear energy transfer ray, heavy ion therapy has advantages over conventional photon therapy in both efficacy and safety. Based on the evidence that prostate cancer lesions before treatment are the most common sites of tumor residual or recurrence after treatment, simultaneous integrated boost radiation therapy for prostate cancer has been proven to have the advantage of improving efficacy without increasing toxicities.MethodsThis study is a prospective phase II randomized controlled clinical trial evaluating the efficacy and safety of functional imaging-guided carbon ion irradiation with simultaneous integrated boost for localized prostate cancer. One hundred and forty patients with localized prostate cancer will be randomized into carbon ion radiotherapy group and simultaneous integrated boost carbon ion radiotherapy group at a 1:1 ratio. The primary endpoint is to compare the incidence of treatment-related grade 2 and higher acute toxicities between the two groups according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 4.03. Secondary endpoints are late toxicities, biochemical relapse-free survival, overall survival, progression-free survival, and quality of life.DiscussionThis study adopts functional imaging-guided simultaneous integrated boost of carbon ion radiotherapy for localized prostate cancer, aiming to evaluate the differences in the severity and incidence of acute toxicities in patients with localized prostate cancer treated with carbon ion radiotherapy and simultaneous integrated boost carbon ion radiotherapy, in order to optimize the carbon ion treatment strategy for localized prostate cancer.Trial registrationClinicalTrials.gov NCT05010343. Retrospectively registered on 18 August 2021

A cross-sectional analysis of registered clinical trials on the use of particle beam radiation therapy in head and neck cancers

To present and analyze the current status of registered clinical trials on particle beam (including proton and carbon ion beam) radiation therapy (PBRT) for head and neck (H&N) malignancies, and to provide insights for future clinical research, we designed the cross-sectional analysis. We identified and analyzed all clinical trials of interest registered on ClinicalTrials.gov and PTCOG.ch until March 22, 2020. We identified 57 registered clinical trials related to the use of proton therapy or carbon ion radiation therapy (CIRT) in H&N malignancies. There were 20, 27, and 5 trials focused on CIRT, proton therapy, and both ions, respectively. The eligible trials were registered between 2007 and 2020, mainly focused on adenoid cystic carcinoma (ACC), squamous cell carcinoma (SCC), sinonasal malignancies (SNM), skull base tumors, locally advanced, and recurrent tumors. The nature of 23 (40%) trials were not stated and could not be identified. A total of 25 (44%) registered trials were phase II, including randomized controlled trials (RCTs). There were 14 RCTs (7 phase II, 2 phase II/III, 2 phase III, 1 phase I/II, and 2 phase not applicable), and 25 studies including RCTs were registered before the first enrolment. There were 11 completed clinical trials among the eligible trials, including 7 with published trial-related results. Less than 10% of the countries with PBRT treatment facilities in operation have initiated clinical trials on H&N cancer. Furthermore, among all registered trials, less than 10% have been completed with results published. More clinical trials, especially high quality trials, are needed for optimizing and standardizing treatment techniques of PBRT for H&N malignancies.

Carbon-Ion Therapy Patient-Specific QA: Preliminary Results Derived Using 3D Polymer Gel Dosimetry in Anthropomorphic Inhomogeneous Geometry

<h3>Purpose/Objective(s)</h3> Improved conformity in carbon-ion radiation therapy (CIRT) with respect to photon RT comes at the cost of a potential reduced delivery robustness due to patient setup uncertainties, approximations in dose calculations and carbon-ion range uncertainties. This work presents preliminary results of a study aiming to address these challenges using 3D polymer gel dosimetry in anthropomorphic and inhomogeneous geometry. <h3>Materials/Methods</h3> All irradiations were performed at a synchrotron facility, in one of the treatment rooms equipped with a horizontal fixed beam line and pencil beam scanning (PBS) modality. For basic dosimetric characterization, carbon pristine Bragg peaks (BP) (ranges 30, 70, 90 mm in water) and a spread-out BP (SOBP) (range 115 mm and modulation 40 mm) were delivered on a cylindrical PMMA container filled with VIPAR polymer gel. An anthropomorphic phantom equipped with a cylindrical polymer gel insert was used for the irradiation of a pseudo-clinical CIRT plan, following all the steps of the standard clinical workflow, from simulation CT to irradiation. Two contralateral beams were optimized with a TPS (v.8b) to deliver 15 Gy (RBE) on a target located approximately at the center of the brain, in proximity of critical OARs such as brainstem and optical pathways. The phantom was then MRI scanned post-irradiation to retrieve the irradiated brain volume in 3D. The measured irradiated volume was compared against corresponding TPS derived data. <h3>Results</h3> Carbon-ion range was spatially verified with an accuracy of < 1 mm. For both the pristine BP and the SOBP irradiations. A significant deviation of the polymer gels' response on high-LET has been observed, as expected from previous studies with proton irradiations. For the pseudo-clinical treatment plan, a qualitative comparison between doses measured in polymer gels, against the corresponding TPS calculations, revealed a satisfying geometric accuracy of dose delivery in 3D, thus showing a high 3D geometrical accuracy of dose delivery in a typical standard clinical workflow. <h3>Conclusion</h3> In this work, we showed that patient-specific 3D polymer gel dosimetry is applicable to CIRT, as a valid tool to evaluate dosimetric and spatial plan accuracy in the clinical environment. As expected, the LET dependence of polymer gel's response, especially in the high-LET region, poses severe limitations for accurate dose measurements. Nevertheless, the proposed methodology is a promising efficient and safe clinical way for verifying such a complex RT technique.

Intensity-modulated proton and carbon-ion radiation therapy in the management of major salivary gland carcinomas

Primary major salivary gland carcinomas (SGCs) present with diverse histological types that are known to be largely radioresistant with a high tendency to develop distant metastasis (DM). Photon-based radiotherapy (RT) is limited in terms of its therapeutic effect and toxicities. In view of the physical and biological advantages of intensity-modulated proton and/or carbon-ion radiation therapy, we aimed to evaluate the short-term therapeutic effect and toxicities in patients with major SGCs treated with this form of radiation therapy. Between August 2015 and November 2019, a total of 55 consecutive and non-selected major SGC patients who received particle RT at the Shanghai Proton and Heavy Ion Center (SPHIC) were retrospectively analyzed. The 2-year overall survival (OS), progression-free survival (PFS), local-regional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS) rates, as well as prognostic factors were analyzed. Additionally, acute and late toxicities were also analyzed. With a median follow-up time of 24 (range, 6-57) months, the 2-year OS, PFS, LRRFS, and DMFS rates were 91.6%, 78.6%, 94.2%, and 83.9%, respectively. At the time of this analysis, four patients had developed local or regional recurrence, and seven additional patients had developed DM. Three patients had died due to disease progression, and another patient with recurrence experienced a late Grade 5 event (hemorrhage) at 9 months after re-irradiation with carbon ion and subsequently died. Otherwise, none of the patients had grade 3 or higher treatment-induced acute or late adverse effects except one who developed grade 3 acute mucositis. Overall, intensity-modulated proton and/or carbon-ion radiation therapy provided satisfactory therapeutic effectiveness in our major SGCs patients with a low incidence of acute and late toxicities.

Carbon Ion Irradiation Downregulates Notch Signaling in Glioma Cell Lines, Impacting Cell Migration and Spheroid Formation.

Photon-based radiotherapy upregulates Notch signaling in cancer, leading to the acquisition of the stem cell phenotype and induction of invasion/migration, which contributes to the development of resistance to therapy. However, the effect of carbon ion radiotherapy (CIRT) on Notch signaling in glioma and its impact on stemness and migration is not explored yet. Human glioma cell lines (LN229 and U251), stable Notch1 intracellular domain (N1ICD) overexpressing phenotype of LN229 cells, and Notch inhibitor resistant LN229 cells (LN229R) were irradiated with either photon (X-rays) or (carbon ion irradiation) CII, and expressions of Notch signaling components were accessed by RT-PCR, Western blotting, and enzymatic assays and flow cytometry. Spheroid forming ability, cell migration, and clonogenic assay were used to evaluate the effect of modulated Notch signaling by irradiation. Our results show that X-ray irradiation induced the expression of Notch signaling components such as Notch receptors, target genes, and ADAM17 activity, while CII reduced it in glioma cell lines. The differential modulation of ADAM17 activity by CII and X-rays affected the cell surface levels of NOTCH1 and NOTCH2 receptors, as they were reduced by X-ray irradiation but increased in response to CII. Functionally, CII reduced the spheroid formation and migration of glioma cells, possibly by downregulating the N1ICD, as stable overexpression of N1ICD rescued these inhibitory effects of CII. Moreover, LN229R that are less reliant on Notch signaling for their survival showed less response to CII. Therefore, downregulation of Notch signaling resulting in the suppression of stemness and impaired cell migration by CII seen here may reduce tumor regrowth and disease dissemination, in addition to the well-established cytotoxic effects.

Dosimetric Analysis for Otitis Media With Effusion Due to Eustachian Tube Dysfunction After Carbon-ion Radiation Therapy for Head and Neck Cancers

PurposeThis study aimed to clarify the predictive factors for otitis media with effusion (OME) due to Eustachian tube dysfunction in patients treated with carbon-ion radiation therapy (CIRT) for head and neck cancers. Methods and MaterialsWe investigated patients with head and neck cancer whose Eustachian tube was irradiated by CIRT between October 2013 and December 2018 at our institution. OME severity was assessed by the proportion of mastoid cell opacification of magnetic resonance or computed tomography imaging (grade 0: <5% of volume of mastoid cell with opacification by fluid collection; grade 1: 6%-33%; grade 2: 34%-67%; and grade 3: 68%-100%). Clinical factors and dosimetric parameters affecting the development of grade 2 to 3 OME were analyzed using a log-rank test and Cox proportional hazards model. ResultsIn total, 141 patients were analyzed. The median follow-up period was 25.2 months. Grade 2 to 3 OME was observed in 65 patients, with a median incidence period of 6.5 months. According to the multivariate analysis, the mean dose of the cartilage part was a significant independent predictive parameter of grade 2 to 3 OME. The 2-year incidence rate of patients with a mean dose of the cartilage part of <40.59 Gy (relative biological effectiveness) and ≥40.59 Gy (relative biological effectiveness) was 24.2% (95% confidence interval, 15.1%-37.4%) and 66.4% (95% confidence interval, 54.5%-78.0%), respectively. ConclusionsOur findings may be useful to predict the risk of grade 2 to 3 OME due to Eustachian tube dysfunction before CIRT.

Ultra-High Dose-Rate Carbon-Ion Scanning Irradiation with a Compact Type Medical Synchrotron toward FLASH Research

<h3>Purpose/Objective(s)</h3> To establish an irradiation system to enable the ultra-high dose-rate (uHDR; FLASH) scanned carbon-ion irradiation with a compact type medical synchrotron. <h3>Materials/Methods</h3> After technical adjustments of the accelerator operation parameters, the medical synchrotron extracted ≥1.0 × 10⁹ carbon-ions (2.0 nC/spill) at 208.3 MeV/u (86 mm in range) within a maximum 100 ms. The uHDR carbon-ion beam delivery system was designed to prevent damage to monitors in the nozzle due to the uHDR beam by avoiding passage through the nozzle. The dose amount was adjusted by the extraction time of the total spill with a function generator. The carbon-ion beam was scanned once to create a field within the extraction time. Advanced Markus chamber and radiographic film were used to measure the absolute dose and the field size respectively, at a plateau depth. Operation voltage of the chamber was set to 400 V at the uHDR. <h3>Results</h3> The FLASH irradiation utilizing beam scanning was confirmed with a dose of 5.4 Gy (homogeneity of ±2%) for the beam in a volume of at least 16 mm × 16 mm in a square field and a corresponding dose-rate of 95 Gy/s (± 1%). The dose was changed to about 0.7, 1.5, 2.9 Gy for the dose-rate and the field size. Details of the results are shown in Table1. <h3>Conclusion</h3> The FLASH dose-rates >40 Gy/s at different dose levels were achieved in a useful field size for research created by the scanned carbon-ion beams with the compact type medical synchrotron. This study reported promising beam characteristics of uHDR scanned carbon-ion beams, at different dose levels, and can be used for further investigation of carbon-ion FLASH research. The dose and dose-rate established with the uHDR irradiation system can be applied in biological experiments.

Infrared LiF ridge waveguide fabricated by carbon ion irradiation

We report on the fabrication of an optical ridge waveguide in lithium fluoride crystal using the method of C5+ ion irradiation with precise diamond blade dicing. The guiding properties of the waveguide at the infrared wavelengths of 1064 nm, 2200 nm and 4000 nm are investigated in detail. All the near-field modal profiles exhibit single-mode guidance and the minimum propagation losses of the ridge waveguide after annealing are reduced to 0.7 dB cm−1 (λ = 1064 nm), 0.4 dB cm−1 (λ = 2200 nm) and 0.2 dB cm−1 (λ = 4000 nm), respectively. The Raman spectroscopy of the waveguide shows that the ion irradiation does not obviously change the lattice structure of the crystal.

FLASH with carbon ions: Tumor control, normal tissue sparing, and distal metastasis in a mouse osteosarcoma model.

The FLASH effect is a potential breakthrough in radiotherapy because ultra-high dose-rate irradiation can substantially widen the therapeutic window. While the normal tissue sparing at high doses and short irradiation times has been demonstrated with electrons, photons, and protons, so far evidence with heavy ions is limited to in vitro cell experiments. Here we present the first in vivo results with high-energy 12C-ions delivered at an ultra-high dose rate. LM8 osteosarcoma cells were subcutaneously injected in the posterior limb of female C3H/He mice 7days before radiation exposure. Both hind limbs of the animals were irradiated with 240MeV/n 12C-ions at ultra-high (18Gy in 150ms) or conventional dose rate (∼18Gy/min). Tumor size was measured until 28days post-exposure, when animals were sacrificed and lungs, limb muscles, and tumors were collected for further histological analysis. Irradiation with carbon ions was able to control the tumour both at conventional and ultra-high dose rate. FLASH decreases normal tissue toxicity as demonstrated by the reduced structural changes in muscle compared to conventional dose-rate irradiation. Carbon ion irradiation in FLASH conditions significantly reduced lung metastasis compared to conventional dose-rate irradiation and sham-irradiated animals. We demonstrated the FLASH effect in vivo with high-energy carbon ions. In addition to normal tissue sparing, we observed tumor control and a substantial reduction of lung metastasis in an osteosarcoma mouse model.

Label-Free Direct Mass Spectrometry Analysis of the Bystander Effects Induced in Chondrocytes by Chondrosarcoma Cells Irradiated with X-rays and Carbon Ions.

Radiation-induced bystander effects are induced changes in cells that were not themselves directly irradiated but were in the vicinity of a radiation path. Such effects, which occur in the microenvironment of an irradiated tumor, remain poorly understood and depend on the cell type and irradiation quality. This study aimed to evaluate bystander effects in non-irradiated chondrocytes that received conditioned medium from irradiated chondrosarcoma cells. SW1353 chondrosarcoma cells were irradiated with X-rays and carbon ions, each at 0.1 Gy and 2 Gy, and the conditioned media of the irradiated cells were transferred to T/C-28A2 chondrocytes and Human Umbilical Venous Endothelial Cells (HUVECs). The whole proteome of bystander chondrocytes was analyzed by label-free mass spectrometry, and a comparative study was performed by dose and irradiation quality. HUVECs were evaluated for inflammatory cytokine secretion. The bystander response of chondrocytes to X-ray irradiation primarily affected the protein translation pathway (DHX36, EIF3B, EIF3D, EIF3M, EIF5, RPL6, RPLP0, RPS24, SYNCRIP), IL-12 (AIP, BOLA2, MIF, GAS6, MIF, PDGFRB) and the oxidative stress pathway (MGST3, PRDX2, PXDN, SOD2, TXN, TXNL1). Following carbon-ion irradiation, the G1/S pathway (PCBP4, PSMD12, PSME, XIAP) and mitotic G2 DNA damage checkpoint pathway (MRE11, TAOK1, UIMC1) were engaged. Changes in the regulation of chromosome separation (BCL7C, BUB3, CENPF, DYNC1LI1, SMARCA4, SMC4) were associated with only low-dose X-ray and carbon-ion irradiation. Modification of the protein translation pathway represented at least 30% of bystander effects and could play a role, possibly along with stress granules, in reduction in cellular metabolism to protect proteins. Stress granules were significantly enriched according to an interaction map. All these accessions corresponded to a window of the proteins modulated in response to the bystander effect. Our chondrosarcoma model clarified the nature of the bystander response of chondrocytes and may suggest several interesting new mechanisms that are specific to particular irradiation doses and qualities.

Cellular and Molecular Biological Alterations after Photon, Proton, and Carbon Ions Irradiation in Human Chondrosarcoma Cells Linked with High-Quality Physics Data.

Chondrosarcomas are particularly difficult to treat due to their resistance to chemotherapy and radiotherapy. However, particle therapy can enhance local control and patient survival rates. To improve our understanding of the basic cellular radiation response, as a function of dose and linear energy transfer (LET), we developed a novel water phantom-based setup for cell culture experiments and characterized it dosimetrically. In a direct comparison, human chondrosarcoma cell lines were analyzed with regard to their viability, cell proliferation, cell cycle, and DNA repair behavior after irradiation with X-ray, proton, and carbon ions. Our results clearly showed that cell viability and proliferation were inhibited according to the increasing ionization density, i.e., LET, of the irradiation modes. Furthermore, a prominent G2/M arrest was shown. Gene expression profiling proved the upregulation of the senescence genes CDKN1A (p21), CDKN2A (p16NK4a), BMI1, and FOXO4 after particle irradiation. Both proton or C-ion irradiation caused a positive regulation of the repair genes ATM, NBN, ATXR, and XPC, and a highly significant increase in XRCC1/2/3, ERCC1, XPC, and PCNA expression, with C-ions appearing to activate DNA repair mechanisms more effectively. The link between the physical data and the cellular responses is an important contribution to the improvement of the treatment system.

Robust treatment planning in scanned carbon-ion radiotherapy for pancreatic cancer: Clinical verification using in-room computed tomography images.

PurposeCarbon-ion beam (C-beam) has a sharp dose distribution called the Bragg peak. Carbon-ion radiation therapy, such as stereotactic body radiotherapy in photon radiotherapy, can be completed in a short period by concentrating the radiation dose on the tumor while minimizing the dose to organs at-risk. However, the stopping position of C-beam is sensitive to density variations along the beam path and such variations can lower the tumor dose as well as cause the delivery of an unexpectedly high dose to the organs at risk. We evaluated the clinical efficacy of a robust planning technique considering gastrointestinal gas (G-gas) to deliver accurate radiation doses in carbon-ion radiotherapy for pancreatic cancer.Materials and methodsWe focused on the computed tomography (CT) value replacement method. Replacement signifies the overwriting of CT values in the CT images. The most effective replacement method for robust treatment planning was determined by verifying the effects of the three replacement patterns. We selected 10 consecutive patients. Pattern 1 replaces the CT value of the G-gas contours with the value of the region without G-gas (P1). This condition indicates a no-gas state. Pattern 2 replaces each gastrointestinal contour using the mean CT value of each contour (P2). The effect of G-gas was included in the replacement value. Pattern 3 indicates no replacement (P3). We analyzed variations in the target coverage (TC) and homogeneity index (HI) from the initial plan using in-room CT images. We then performed correlation analysis on the variations in G-gas, TC, and HI to evaluate the robustness against G-gas.ResultsAnalysis of variations in TC and HI revealed a significant difference between P1 and P3 and between P2 and P3. Although no statistically significant difference was observed between P1 and P2, variations, including the median, tended to be fewer in P2. The correlation analyses for G-gas, TC, and HI showed that P2 was less likely to be affected by G-gas.ConclusionFor a treatment plan that is robust to G-gas, P2 mean replacement method should be used. This method does not necessitate any particular software or equipment, and is convenient to implement in clinical practice.

A review of micro silica beads in radiation dosimetry applications

A recent development in the field of radiation measurement is the use of silica glass beads as high performance thermoluminescent detectors. The application of using doped silica glass jewellery beads as radiation detectors was first proposed by Jafari in 2014, on the basis that it held the potential to resolve long standing issues in dosimetry, could be cheaply implemented, and had yielded good results in initial experimental work. Today the body of literature concerned with glass bead dosimeters has grown extensively, covering their behaviour in various radiation fields, as well as their handling and storage properties. The purpose of this review is to summarise the results obtained in the literature so far. Paramount among these is the finding that beads could offer excellent performance in radiotherapy applications, particularly due to their small volume (1–3 mm3), measurement reproducibility of less than 3% (k = 2), chemical inertness and low fading rate (10% over the first 30 days after irradiation). The beads are energy independent over the MV photon and MeV electron energy ranges and exhibit good linearity in electron, proton, carbon ion and photon radiation (an R2 of 0.999 having been achieved from 1 cGy to 50 Gy in a 6 MV photon beam) as well as being dose-rate and angular independent. However, significant energy dependence in the lower energy range is apparent (<300 kV), thus careful calibration is required. Irradiation of beads with neutrons has also been studied, the reported results indicate their potential use as high spatial resolution alternatives to the gas detectors presently used in industrial and scientific fields. Published use cases of silica beads have been identified and summarised in this review, these include treatment plan verification, small field dosimetry, SABR audits and kV therapy all of which demonstrating the potential use for silica bead TLDs within Radiotherapy.

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.

Near-infrared single-mode optical waveguide fabrication in LiF crystal by carbon ion irradiation

In this study, a carbon-ion beam irradiation method with energy of 6.0 MeV was employed to prepare single-mode optical waveguide structures in LiF single crystal. The results of this study reveal that the visible light and near-infrared laser beams can be well-confined in the irradiated region that is influenced by the irradiation fluences. An end-face coupling system was used to estimate the propagation loss (1.3 dB cm−1) after annealing treatment. The surface damage of the irradiated regions in LiF was analysed based on the displacements per atom calculation using the stopping and range of ions in matter code.

Tunable structural colors in all-dielectric photonic crystals using energetic ion beams.

The modulation of structural color through various methods has attracted considerable attention. Herein, a new modulation method for the structural colors in all-dielectric photonic crystals (PCs) using energetic ion beams is proposed. One type of periodic PC and two different defective PCs were experimentally investigated. Under carbon-ion irradiation, the color variation primarily originated from the blue shift of the optical spectra. The varying degrees of both the reflection and transmission structural colors mainly depended on the carbon-ion fluences. Such nanostructures are promising for tunable color filters and double-sided chromatic displays based on PCs.

Carbon-ion radiotherapy for urological cancers.

Carbon-ions are charged particles with a high linear energy transfer, and therefore, they make a better dose distribution with greater biological effects on the tumors compared with photons and protons. Since prostate cancer, renal cell carcinoma, and retroperitoneal sarcomas such as liposarcoma and leiomyosarcoma are known to be radioresistant tumors, carbon-ion radiotherapy, which provides the advantageous radiobiological properties such as an increasing relative biological effectiveness toward the Bragg peak, a reduced oxygen enhancement ratio, and a reduced dependence on fractionation and cell-cycle stage, has been tested for these urological tumors at the National Institute for Radiological Sciences since 1994. To promote carbon-ion radiotherapy as a standard cancer therapy, the Japan Carbon-ion Radiation Oncology Study Group was established in 2015 to create a registry of all treated patients and conduct multi-institutional prospective studies in cooperation with all the Japanese institutes. Based on accumulating evidence of the efficacy and feasibility of carbon-ion therapy for prostate cancer and retroperitoneal sarcoma, it is now covered by the Japanese health insurance system. On the other hand, carbon-ion radiotherapy for renal cell cancer is not still covered by the insurance system, although the two previous studies showed the efficacy. In this review, we introduce the characteristics, clinical outcomes, and perspectives of carbon-ion radiotherapy and our efforts to disseminate the use of this new technology worldwide.