Involved-field high-dose chemoradiotherapy with respiratory motion management for esophageal squamous cell carcinoma.

BACKGROUND: We investigated the clinical outcomes of involved-field high-dose (≥66 Gy) chemoradiotherapy (CRT) combined with respiratory motion management for esophageal squamous cell carcinoma (ESCC). METHODS: Patients who underwent definitive CRT for histologically confirmed ESCC in our department between 2012 and 2018 were retrospectively analyzed. Respiratory motion management strategies included breath-holding (63%) and mask immobilization (29%) based on individual measurements of respiratory tumor motion using radiographic fluoroscopy with endoscopically placed clip markers as landmarks. We evaluated patient characteristics, treatment efficacy, failure patterns, and toxicities. RESULTS: We enrolled 35 patients with a prescribed dose of 66-70 Gy in 33-35 fractions. The overall response rate within 6 months post-CRT was 94.3%; the median follow-up period for survivors was 43 months. The 2-year overall survival (OS), progression-free survival, and locoregional failure-free survival rates were 51.4%, 42.9%, and 42.9%, respectively. A significant difference in OS was observed between patients with and without esophageal fistulas after CRT (p = 0.002, log-rank test). Disease failure occurred in 16 patients (45.7%), including one (2.9%) with out-of-field regional nodal failure. Major grade 3 or higher toxicities included decreased white blood cell count (48.6%), neutrophil count (34.3%), and esophageal stenosis (31.4%). No grade 3 or higher cardiopulmonary toxicities were observed. Bronchial/tracheal tumor compression and a higher radiotherapy dose (70 Gy) were significantly correlated with esophageal fistulas. CONCLUSION: Involved-field high-dose CRT with respiratory motion management may be a feasible treatment option for ESCC. However, a comprehensive assessment of esophageal fistula risk is required to identify suitable candidates.

Comparison and Significance of Contrast-Enhanced Computed Tomographic Findings of Large-Vessel Vasculitis Before and After Treatment: Differences Between Takayasu Arteritis and Giant Cell Arteritis.

Objective: Imaging is essential for diagnosing large-vessel vasculitis (LVV). During diagnostic imaging, assessing disease activity and vascular damage separately is important. Acute-phase findings represent disease activity, while chronic-phase findings represent vascular damage; however, whether the imaging findings are acute or chronic may be unclear. We investigated how vascular lesions change before and after treatment and whether they were acute- or chronic-phase findings. Methods: Fifty-one patients with LVV who had undergone contrast-enhanced computed tomography (CT) scans from the neck to the pelvis before treatment and 1-4 months after treatment were recruited. Wall thickening, wall contrast enhancement, stenosis, occlusion, dilation, aneurysm, and calcification were semi-quantitatively assessed in 21 vessels from the common carotid to the common iliac artery. Results: Twenty-four patients were diagnosed with Takayasu arteritis (TAK), and 27 with giant cell arteritis (GCA). Wall thickening and wall contrast enhancement improved after the treatment, which was especially significant in the GCA group. No significant differences in stenosis, occlusion, dilation, aneurysm, or calcification were observed before and after treatment. Stenosis and occlusion were more common with TAK, while calcification was more common with GCA. Conclusion: Wall thickening and wall contrast enhancement are acute-phase findings (activity), while stenosis, occlusion, dilation, aneurysm, and calcification are chronic-phase findings (damage). The frequencies of these findings differ between TAK and GCA.

Cost-Utility Analysis of Stereotactic Body Radiation Therapy Versus Surgery for Patients With Stage I Non-small Cell Lung Cancer in Japan.

PURPOSE: Stereotactic body radiation therapy (SBRT) for patients with operable stage I non-small cell lung cancer (NSCLC) is less invasive than surgery. However, differences in lifetime costs and patient outcomes remain unclear. In this study, a cost-utility analysis of SBRT compared with surgery for Japanese patients with operable stage I NSCLC was conducted. METHODS AND MATERIALS: A partitioned survival model was constructed using each treatment arm's overall survival (OS) and progression-free survival (PFS) data. The data for the SBRT arm were extracted from the Japanese multicenter cohort study, which enrolled 678 medically operable patients with stage I NSCLC, and patient registry data were used for the surgery arm. The 5-year OS rate was 78.2% for SBRT and 74.8% for surgery from both studies. The 5-year PFS rate was 57.0% for SBRT and 63.4% for surgery. The quality of life values of PFS and progressive disease were obtained from domestic and overseas literature (PFS: 0.74, progressive disease: 0.65). The time horizon was set to 10 years. The expected costs and quality-adjusted life years for each treatment group were calculated. All costs are expressed in Japanese yen converted to US dollars (USD). RESULTS: SBRT was the dominant strategy, reducing treatment costs by 4,443.8 USD and increasing quality-adjusted life years by 0.131 compared with surgery. According to probabilistic sensitivity analysis, the probability of SBRT being dominant and cost-effective was 50.6% and 72.4%, respectively. Under the budget impact analysis, the total savings for the patients with stage I NSCLC in Japan was 6,252,870.0 USD (n = 1,407). CONCLUSIONS: SBRT is a more cost-effective option than surgery in patients with medically operable stage I NSCLC in Japan. Large-scale epidemiologic studies that reflect the latest clinical realities, such as OS/PFS, will be needed to validate this study's robustness.

Evaluation of deep learning based dose prediction in head and neck cancer patients using two different types of input contours.

PURPOSE: This study evaluates deep learning (DL) based dose prediction methods in head and neck cancer (HNC) patients using two types of input contours. MATERIALS AND METHODS: Seventy-five HNC patients undergoing two-step volumetric-modulated arc therapy were included. Dose prediction was performed using the AIVOT prototype (AiRato.Inc, Sendai, Japan), a commercial software with an HD U-net-based dose distribution prediction system. Models were developed for the initial plan (46 Gy/23Fr) and boost plan (24 Gy/12Fr), trained with 65 cases and tested with 10 cases. The 8-channel model used one target (PTV) and seven organs at risk (OARs), while the 10-channel model added two dummy contours (PTV ring and spinal cord PRV). Predicted and deliverable doses, obtained through dose mimicking on another radiation treatment planning system, were evaluated using dose-volume indices for PTV and OARs. RESULTS: For the initial plan, both models achieved approximately 2% prediction accuracy for the target dose and maintained accuracy within 3.2 Gy for OARs. The 10-channel model outperformed the 8-channel model for certain dose indices. For the boost plan, both models exhibited prediction accuracies of approximately 2% for the target dose and 1 Gy for OARs. The 10-channel model showed significantly closer predictions to the ground truth for D50% and Dmean. Deliverable plans based on prediction doses showed little significant difference compared to the ground truth, especially for the boost plan. CONCLUSION: DL-based dose prediction using the AIVOT prototype software in HNC patients yielded promising results. While additional contours may enhance prediction accuracy, their impact on dose mimicking is relatively small.

A bone tumor-like chest wall mass lesion with pathological rib fractures observed 13 years after lung stereotactic body radiotherapy: A case report.

Although stereotactic body radiotherapy (SBRT) is a curative treatment option for stage I non-small cell lung cancer (NSCLC), limited data are available regarding chest wall (CW) toxicities during an extended follow-up of over 10 years. We report an unusual case of a bone tumor-like CW mass lesion with pathological rib fractures observed 13 years after SBRT for peripheral lung cancer. Despite the initial suspicion of radiation-induced sarcoma, a subsequent incisional biopsy revealed no evidence of malignancy, and a definitive diagnosis of osteonecrosis was made. Thus, long-term observation of over 10 years is required to identify late chronic complications following SBRT.

A national survey of medical staffs' required capability and workload for accelerator-based boron neutron capture therapy.

This study aimed to identify the required capabilities and workload of medical staff in accelerator-based boron neutron capture therapy (BNCT). From August to September 2022, a questionnaire related to the capabilities and workload in the accelerator-based BNCT was administered to 12 physicians, 7 medical physicists and 7 radiological technologists engaged in BNCT and 6 other medical physicists who were not engaged in BNCT to compare the results acquired by those engaged in BNCT. Only 6-21% of patients referred for BNCT received it. Furthermore, 30-75% of patients who received BNCT were treated at facilities located within their local district. The median required workload per treatment was 55 h. Considering additional workloads for ineligible patients, the required workload reached ~1.2 times longer than those for only eligible patients' treatment. With respect to capabilities, discrepancies were observed in treatment planning, quality assurance and quality control, and commissioning between medical physicists and radiological technologists. Furthermore, the specialized skills required by medical physicists are impossible to acquire from the experience of conventional radiotherapies as physicians engaged in BNCT were specialized not only in radiation oncology, but also in other fields. This study indicated the required workload and staff capabilities for conducting accelerator-based BNCT considering actual clinical conditions. The workload required for BNCT depends on the occupation. It is necessary to establish an educational program and certification system for the skills required to safely and effectively provide BNCT to patients.

Diagnostic efficacy of contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging in idiopathic cerebrospinal fluid rhinorrhea.

We report a case of a 50-year-old woman in which contrast-enhanced fluid-attenuated inversion recovery (FLAIR) was used for the diagnosis of idiopathic cerebrospinal fluid rhinorrhea. The pre- and postcontrast FLAIR subtraction images showed a contrasted protrusion of the right olfactory cleft canal, highlighting the potential practicality and effectiveness of using pre- and postcontrast FLAIR subtraction images in diagnosing idiopathic cerebrospinal fluid rhinorrhea, in conjunction with conventional high-resolution computed tomography and magnetic resonance cisternography. The successful diagnosis of cerebrospinal fluid rhinorrhea allowed for treatment through endoscopic nasal surgery to close the fistula with a positive clinical outcome.

Cost-effectiveness Analysis of Ranibizumab Biosimilar for Neovascular Age-Related Macular Degeneration and its Subtypes from the Societal and Patient Perspectives in Japan.

INTRODUCTION: This study evaluated the cost-effectiveness of anti-vascular endothelial growth factor (VEGF) therapies for subtypes of neovascular age-related macular degeneration (nAMD) from the societal perspective, and for any nAMD from the patient perspective in Japan. METHODS: A Markov model was developed to simulate the lifetime transitions of a cohort of patients with nAMD through various health states based on the involvement of nAMD, the treatment status, and decimal best-corrected visual acuity. Ranibizumab biosimilar was compared with aflibercept from the societal perspective regardless of treatment regimen for the analysis of three subtypes (typical nAMD, polypoidal choroidal vasculopathy (PCV), and retinal angiomatous proliferation (RAP)). Two analyses from the patient perspective focusing on the treat-and-extend regimens were performed, one with a cap on patients' copayments and one without. Ranibizumab biosimilar was compared with branded ranibizumab, aflibercept, aflibercept as the loading dose switching to ranibizumab biosimilar during maintenance (aflibercept switching to ranibizumab biosimilar), and best supportive care (BSC), for patients with any nAMD. RESULTS: In the subtype analyses, ranibizumab biosimilar when compared with aflibercept resulted in incremental quality-adjusted life years (QALYs) of - 0.015, 0.026, and 0.009, and the incremental costs of Japanese yen (JPY) - 50,447, JPY - 997,243, and JPY - 1,286,570 for typical nAMD, PCV, and RAP, respectively. From the patient perspective, ranibizumab biosimilar had incremental QALYs of 0.015, 0.009, and 0.307, compared with aflibercept, aflibercept switching to ranibizumab biosimilar, and BSC, respectively. The incremental costs for ranibizumab biosimilar over a patient lifetime excluding the cap on copayment were estimated to be JPY - 138,948, JPY - 391,935, JPY - 209,099, and JPY - 6,377,345, compared with branded ranibizumab, aflibercept, aflibercept switching to ranibizumab biosimilar, and BSC, respectively. CONCLUSIONS: Ranibizumab biosimilar was demonstrated as a cost-saving option compared to aflibercept across all subtypes of nAMD, irrespective of the perspectives considered.

Long-term Renal Function Outcomes After Stereotactic Ablative Body Radiotherapy for Primary Renal Cell Carcinoma Including Patients with a Solitary Kidney: A Report from the International Radiosurgery Oncology Consortium of the Kidney.

BACKGROUND AND OBJECTIVE: Renal function preservation is particularly important following nonoperative treatment of localized renal cell carcinoma (RCC) since patients are often older with medical comorbidities. Our objective was to report long-term renal function outcomes after stereotactic ablative radiotherapy (SABR) including patients with a solitary kidney. METHODS: Patients with primary RCC treated with SABR with ≥2 yr of follow-up at 12 International Radiosurgery Consortium for Kidney institutions were included. Renal function was measured by estimated glomerular filtration rate (eGFR). KEY FINDINGS AND LIMITATIONS: In total, 190 patients (56 with a solitary kidney) underwent SABR and were followed for a median of 5.0 yr (interquartile range [IQR]: 3.4-6.8). In patients with a solitary kidney versus bilateral kidneys, pre-SABR eGFR (mean [standard deviation]) was 61.1 (23.2) versus 58.0 (22.3) ml/min (p = 0.32) and the median tumor size was 3.65 cm (IQR: 2.59-4.50 cm) versus 4.00 cm (IQR: 3.00-5.00 cm; p = 0.026). At 5 yr after SABR, eGFR decreased by -14.5 (7.6) and -13.3 (15.9) ml/min (p = 0.67), respectively, and there were similar rates of post-SABR dialysis (3.6% [n = 2/56] vs 3.7% [n = 5/134]). A multivariable analysis demonstrated that increasing tumor size (odds ratio [OR] per 1 cm: 1.57; 95% confidence interval [CI]: 1.14-2.16, p = 0.0055) and baseline eGFR (OR per 10 ml/min: 1.30; 95% CI: 1.02-1.66, p = 0.034) were associated with an eGFR decline of ≥15 ml/min at 1 yr. CONCLUSIONS AND CLINICAL IMPLICATIONS: With long-term follow-up after SABR, kidney function decline remains moderate, with no observed difference between patients with a solitary kidney and bilateral kidneys. Tumor size and baseline eGFR are dominant factors predictive of long-term renal function decline. PATIENT SUMMARY: With long-term follow-up, stereotactic ablative radiotherapy (SABR) yields moderate long-term renal function decline and low dialysis rates even in patients with a solitary kidney. SABR thus represents a promising noninvasive, nephron-sparing option for patients with localized renal cell carcinoma.

Iodine-123-Iomazenil Single-Photon Emission Computed Tomography Revealed Recovery of Neuronal Viability in Association With Improvement of Cognitive Dysfunction After Revascularization in Moyamoya Disease.

BACKGROUND AND OBJECTIVES: Recent studies indicate that 123I-iomazenil (123I-IMZ) single-photon emission computed tomography (SPECT) can demonstrate neuronal viability. Although cognitive dysfunction has been recognized as an important issue in adult patients with moyamoya disease (MMD), no standard neuroradiological methods to define such conditions have been established. We examined the relationship between cognitive function and 123I-IMZ SPECT before and after revascularization in patients with MMD. METHODS: The study participants were 16 adult patients with MMD whose cerebrovascular reactivities were decreased only on the surgical sides of combined revascularization. Cognitive function was examined using the Mini-Mental State Examination (MMSE; cutoff: 27) and the Frontal Assessment Battery (FAB; cutoff: 16) before and at 3 to 6 months after surgery. 123I-iodoamphetamine (123I-IMP) SPECT with acetazolamide challenge and 123I-IMZ SPECT were performed concurrently while evaluating cognitive function. The radioreactivities of 123I-IMZ SPECT in regions with decreased cerebrovascular reactivities on 123I-IMP SPECT were investigated using affected-to-contralateral side asymmetry ratio (IMZ-ACR). RESULTS: Twelve patients showed normal cognitive function (MMSE: 29.8 ± 0.4, FAB: 18 ± 0) before surgery. No evident laterality of 123I-IMZ uptake was seen (IMZ-ACR: 0.98 ± 0.04). Neither cognitive function nor 123I-IMZ SPECT worsened after surgery (MMSE: 29.8 ± 0.3, FAB: 18 ± 0, IMZ-ACR: 1.00 ± 0.04). By contrast, 4 patients presented cognitive dysfunction (MMSE: 24.3 ± 3.9, FAB: 14.8 ± 2.7) before revascularization. Preoperative imaging of these patients showed decreased 123I-IMZ uptake, and their IMZ-ACRs (0.83 ± 0.08) were significantly lower than those of the normal group. After revascularization, cognitive functions and 123I-IMZ uptake tended to ameliorate (MMSE: 27.5 ± 1.7, FAB: 16.3 ± 2.2, IMZ-ACR: 0.94 ± 0.09). CONCLUSION: Preoperative cognitive function was associated with 123I-IMZ uptake in adult patients with MMD. After revascularization, cognitive function could be recovered in the viable areas of the brain, which is consistent with 123I-IMZ SPECT findings.

Multi-institutional questionnaire-based survey on online adaptive radiotherapy performed using commercial systems in Japan in 2023.

In this study, we aimed to conduct a survey on the current clinical practice of, staffing for, commissioning of, and staff training for online adaptive radiotherapy (oART) in the institutions that installed commercial oART systems in Japan, and to share the information with institutions that will implement oART systems in future. A web-based questionnaire, containing 107 questions, was distributed to nine institutions in Japan. Data were collected from November to December 2023. Three institutions each with the MRIdian (ViewRay, Oakwood Village, OH, USA), Unity (Elekta AB, Stockholm, Sweden), and Ethos (Varian Medical Systems, Palo Alto, CA, USA) systems completed the questionnaire. One institution (MRIdian) had not performed oART by the response deadline. Each institution had installed only one oART system. Hypofractionation, and moderate hypofractionation or conventional fractionation were employed in the MRIdian/Unity and Ethos systems, respectively. The elapsed time for the oART process was faster with the Ethos than with the other systems. All institutions added additional staff for oART. Commissioning periods differed among the oART systems owing to provision of beam data from the vendors. Chambers used during commissioning measurements differed among the institutions. Institutional training was provided by all nine institutions. To the best of our knowledge, this was the first survey about oART performed using commercial systems in Japan. We believe that this study will provide useful information to institutions that installed, are installing, or are planning to install oART systems.

The interface between ice and alcohols analyzed by atomic force microscopy.

This study investigates the interface between ice and organic solvents using atomic force microscopy (AFM). Atomically flat ice surfaces were prepared and observed by AFM in 1-octanol, 1-hexanol, and 1-butanol. The results show differences in surface roughness influenced by the interaction of ice and alcohols. Young's modulus of ice was analyzed by force curve measurements, providing valuable insights into the properties of ice in liquid environments. The results showed the characteristics of the ice surface in different solvents, suggesting potential applications in understanding surface and interface phenomena associated with ice under realistic conditions.

Quality of palliative radiotherapy assessed using quality indicators: a multicenter survey†.

We sought to identify potential evidence-practice gaps in palliative radiotherapy using quality indicators (QIs), previously developed using a modified Delphi method. Seven QIs were used to assess the quality of radiotherapy for bone metastases (BoM) and brain metastases (BrM). Compliance rate was calculated as the percentage of patients for whom recommended medical care was conducted. Random effects models were used to estimate the pooled compliance rates. Of the 39 invited radiation oncologists, 29 (74%) from 29 centers participated in the survey; 13 (45%) were academic and 16 (55%) were non-academic hospitals. For the QIs, except for BoM-4, the pooled compliance rates were higher than 80%; however, for at least some of the centers, the compliance rate was lower than these pooled rates. For BoM-4 regarding steroid use concurrent with radiotherapy for malignant spinal cord compression, the pooled compliance rate was as low as 32%. For BoM-1 regarding the choice of radiation schedule, the compliance rate was higher in academic hospitals than in non-academic hospitals (P = 0.021). For BrM-3 regarding the initiation of radiotherapy without delay, the compliance rate was lower in academic hospitals than in non-academic hospitals (P = 0.016). In conclusion, overall, compliance rates were high; however, for many QIs, practice remains to be improved in at least some centers. Steroids are infrequently used concurrently with radiotherapy for malignant spinal cord compression.

Development of a phantom for assessing the precision of setup in skin mark-less surface-guided radiotherapy.

BACKGROUND: Surface-guided radiotherapy (SGRT) is adopted by several institutions; however, reports on the phantoms used to assess the precision of the SGRT setup are limited. PURPOSE: The purpose of this study was to develop a phantom to verify the accuracy of the irradiation position during skin mark-less SGRT. METHODS: An acrylonitrile butadiene styrene (ABS) plastic cube phantom with a diameter of 150 mm on each side containing a dummy target of 15 mm and two types of body surface-shaped phantoms (breast/face shape) that could be attached to the cube phantom were fabricated. Films can be inserted on four sides of the cubic phantom (left, right, anterior and posterior), and the center of radiation can be calculated by irradiating the dummy target with orthogonal MV beams. Three types of SGRT using a VOXELAN-HEV600M (Electronics Research&Development Corporation, Okayama, Japan) were evaluated using this phantom: (i) SGRTCT-a SGRT set-up based solely on a computed tomography (CT)-reference image. (ii) SGRTCT + CBCT-a method where cone beam computed tomography (CBCT) matching was performed after SGRTCT. (iii) SGRTScan-a resetup technique using a scan reference image obtained after completing the (ii) step. RESULTS: Both the breast and face phantoms were recognized in the SGRT system without problems. SGRTScan ensure precision within 1 mm/1° for breast and face verification, respectively. All SGRT methods showed comparable rotational accuracies with no significant disparities. CONCLUSIONS: The developed phantom was useful for verifying the accuracy of skin mark-less SGRT position matching. The SGRTScan demonstrated the feasibility of achieving skin-mark less SGRT with high accuracy, with deviations of less than 1 mm. Additional research is necessary to evaluate the suitability of the developed phantoms for use in various facilities and systems. This phantom could be used for postal surveys in the future.

Evaluation of the performance of both machine learning models using PET and CT radiomics for predicting recurrence following lung stereotactic body radiation therapy: A single-institutional study.

PURPOSE: Predicting recurrence following stereotactic body radiotherapy (SBRT) for non-small cell lung cancer provides important information for the feasibility of the individualized radiotherapy and allows to select the appropriate treatment strategy based on the risk of recurrence. In this study, we evaluated the performance of both machine learning models using positron emission tomography (PET) and computed tomography (CT) radiomic features for predicting recurrence after SBRT. METHODS: Planning CT and PET images of 82 non-small cell lung cancer patients who performed SBRT at our hospital were used. First, tumors were delineated on each CT and PET of each patient, and 111 unique radiomic features were extracted, respectively. Next, the 10 features were selected using three different feature selection algorithms, respectively. Recurrence prediction models based on the selected features and four different machine learning algorithms were developed, respectively. Finally, we compared the predictive performance of each model for each recurrence pattern using the mean area under the curve (AUC) calculated following the 0.632+ bootstrap method. RESULTS: The highest performance for local recurrence, regional lymph node metastasis, and distant metastasis were observed in models using Support vector machine with PET features (mean AUC = 0.646), Naive Bayes with PET features (mean AUC = 0.611), and Support vector machine with CT features (mean AUC = 0.645), respectively. CONCLUSIONS: We comprehensively evaluated the performance of prediction model developed for recurrence following SBRT. The model in this study would provide information to predict the recurrence pattern and assist in making treatment strategies.

Evaluation of a New Method for CyberKnife Treatment for Central Lung and Mediastinal Tumors by Tracheobronchial Tracking.

BACKGROUND: CyberKnife treatment for central lung tumors and mediastinal tumors can be difficult to perform with marker less. PURPOSE: We aimed to evaluate a novel tracheobronchial-based method (ie, tracheobronchial tracking) for the purpose of minimally invasive CyberKnife treatment for central lung and mediastinal tumors. METHODS: Five verification plans were created using an in-house phantom. Each plan included five irradiation sessions. The reference plan irradiated and tracked the simulated tumor (using the target tracking volume, TTV). Trachea plans tracked the simulated tracheo-bronchus and irradiated the simulated tumor and included two types of subplans: correlated plans in which the displacement of the simulated tracheobronchial and the simulated tumor were correlated, and non-correlated plans in which these factors were not correlated. Moreover, 15 mm and 25 mm TTVs were evaluated for each plan. The sin waveform and the patient's respiratory waveform were prepared as the respiratory model. Evaluations were performed by calculating the dose difference between the radiophotoluminescent glass dosimeter (RPLD)-generated mean dose values (generated by the treatment planning system, TPS) and the actual absorbed RPLD dose. Statistical analyses were performed to evaluate findings for each plan. Correlation and prediction errors were calculated for each axis of each plan using log files to evaluate tracking accuracy. RESULTS: Dose differences were statistically significant only in comparisons with the non-correlated plan. When evaluated using the sin waveform, the mean values for correlation and prediction errors in each axis and for all plans were less than 0.6 mm and 0.1 mm, respectively. In the same manner, they were less than 1.1 mm and 0.2 mm when evaluated using the patient's respiratory waveform. CONCLUSION: Our newly-developed tracheobronchial tracking method would be useful in facilitating minimally invasive CyberKnife treatment in certain cases of central lung and mediastinal tumors.

Cycle-generative adversarial network-based bone suppression imaging for highly accurate markerless motion tracking of lung tumors for cyberknife irradiation therapy.

PURPOSE: Lung tumor tracking during stereotactic radiotherapy with the CyberKnife can misrecognize tumor location under conditions where similar patterns exist in the search area. This study aimed to develop a technique for bone signal suppression during kV-x-ray imaging. METHODS: Paired CT images were created with or without bony structures using a 4D extended cardiac-torso phantom (XCAT phantom) in 56 cases. Subsequently, 3020 2D x-ray images were generated. Images with bone were input into cycle-consistent adversarial network (CycleGAN) and the bone suppressed images on the XCAT phantom (BSIphantom ) were created. They were then compared to images without bone using the structural similarity index measure (SSIM) and peak signal-to-noise ratio (PSNR). Next, 1000 non-simulated treatment images from real cases were input into the training model, and bone-suppressed images of the patient (BSIpatient ) were created. Zero means normalized cross correlation (ZNCC) by template matching between each of the actual treatment images and BSIpatient were calculated. RESULTS: BSIphantom values were compared to their paired images without bone of the XCAT phantom test data; SSIM and PSNR were 0.90 ± 0.06 and 24.54 ± 4.48, respectively. It was visually confirmed that only bone was selectively suppressed without significantly affecting tumor visualization. The ZNCC values of the actual treatment images and BSIpatient were 0.763 ± 0.136 and 0.773 ± 0.143, respectively. The BSIpatient showed improved recognition accuracy over the actual treatment images. CONCLUSIONS: The proposed bone suppression imaging technique based on CycleGAN improves image recognition, making it possible to achieve highly accurate motion tracking irradiation.

Current status of remote radiotherapy treatment planning in Japan: findings from a national survey†.

The purpose of this study was to investigate the status of remote-radiotherapy treatment planning (RRTP) in Japan through a nationwide questionnaire survey. The survey was conducted between 29 June and 4 August 2022, at 834 facilities in Japan that were equipped with linear accelerators. The survey utilized a Google form that comprised 96 questions on facility information, information about the respondent, utilization of RRTP between facilities, usage for telework and the inclination to implement RRTPs in the respondent's facility. The survey analyzed the utilization of the RRTP system in four distinct implementation types: (i) utilization as a supportive facility, (ii) utilization as a treatment facility, (iii) utilization as a teleworker outside of the facility and (iv) utilization as a teleworker within the facility. The survey response rate was 58.4% (487 facilities responded). Among the facilities that responded, 10% (51 facilities) were implementing RRTP. 13 served as supportive facilities, 23 as treatment facilities, 17 as teleworkers outside of the facility and 5 as teleworkers within the facility. In terms of system usage between supportive and treatment facilities, 70-80% of the participants utilized the system for emergencies or as overtime work for external workers. A substantial number of facilities (38.8%) reported that they were unfamiliar with RRTP implementation. The survey showed that RRTP utilization in Japan is still limited, with a significant number of facilities unfamiliar with the technology. The study highlights the need for greater understanding and education about RRTP and financial funds of economical compensation.

Patterns of care for brachytherapy in Japan.

This study aimed to assess the current state of brachytherapy (BT) resources, practices and resident education in Japan. A nationwide survey was undertaken encompassing 177 establishments facilitating BT in 2022. Questionnaires were disseminated to each BT center, and feedback through online channels or postal correspondence was obtained. The questionnaire response rate was 90% (159/177), and every prefecture had a response in at least one center. The number of centers in each prefecture ranged from 0.6 to 3.6 (median: 1.3) per million population. The annual number of patients in each center ranged from 0 to 272 (median: 31). While most prefectures provided intracavitary (IC) BT for gynecological cancers and interstitial (IS) BT for prostate cancer, only one-third of the prefectures provided IS BT for cancer sites other than the prostate. The institutional image-guided BT implementation rate was 71%. IC and IS BT was performed for 15.4% of IC BT cases of gynecological cancer. Only 47% of the BT training centers answered that they could provide adequate training in BT for residents. The most common reason for this finding was the insufficient number of patients in each center. The results show that, although BT has achieved uniformity in terms of facility penetration, new technologies are not yet widespread enough. Furthermore, IS BT, which requires advanced skills, is limited to a few BT centers, and considerable number of BT training centers do not have sufficient caseloads to provide the necessary experience for their residents.

Unravelling the interfacial water structure at the photocatalyst strontium titanate by sum frequency generation spectroscopy.

The direct conversion of solar energy to hydrogen is considered as a possible method to produce carbon neutral hydrogen fuel. The mechanism of photocatalytic water splitting involves the chemical breakdown of water and re-assembly into hydrogen and oxygen at the interface of a photocatalyst. The selection rules of a suitable material are well established, but the fundamental understanding of the mechanisms, occurring at the interface between the catalyst and the water, remains missing. Using surface specific sum frequency generation spectroscopy, we present here characterisation of the interface between water and the photocatalyst strontium titanate (SrTiO3). We monitor the OH-stretching vibrations present at the interface. Their variations of intensities and frequencies as functions of isotopic dilution, pH and salt concentration provide information about the nature of the hydrogen bonding environment. We observe the presence of water molecules that flip their orientation at pH 5 indicating the point of zero charge of the SrTiO3 layer. These water molecules are oriented with their hydrogen away from the surface when the pH of the solutions is below 5 and pointing towards the surface when the pH is higher than 5. Besides, water molecules donating a H-bond to probably surface TiOH groups are observed at all pH.