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Purpose: Patients with head and neck cancer (HNC) who undergo dental procedures during radiotherapy (RT) face an increased risk of developing osteoradionecrosis (ORN). Accordingly, new tools must be developed to extract critical information regarding the dose delivered to the teeth and mandible. This article proposes a novel approach for visualizing 3-dimensional planned dose distributions on panoramic reconstruction computed tomography (pCT) images. Materials and Methods: Four patients with HNC who underwent volumetric modulated arc therapy were included. One patient experienced ORN and required the extraction of teeth after RT. In the study approach, the dental arch curve (DAC) was defined using an open-source platform. Subsequently, pCT images and dose distributions were generated based on the new coordinate system. All teeth and mandibles were delineated on both the original CT and pCT images. To evaluate the consistency of dose metrics, the Mann-Whitney U test and Student t-test were employed. Results: A total of 61 teeth and 4 mandibles were evaluated. The correlation coefficient between the 2 methods was 0.999, and no statistically significant difference was observed (P>0.05). This method facilitated a straightforward and intuitive understanding of the delivered dose. In 1 patient, ORN corresponded to the region of the root and the gum receiving a high dosage (approximately 70 Gy). Conclusion: The proposed method particularly benefits dentists involved in the management of patients with HNC. It enables the visualization of a 3-dimensional dose distribution in the teeth and mandible on pCT, enhancing the understanding of the dose delivered during RT.
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PURPOSE: This study aimed to clarify the dosimetric impact of the respiratory motion of the liver on stereotactic body radiation therapy (SBRT) for spine metastasis and examine the utility of introducing beam avoidance (beam-off at specific gantry angles). METHODS: A total of 112 consecutive patients who underwent SBRT for spine metastasis between 2018 and 2024 were examined. Overall, 15 patients who had lesions near the liver dome were included in this study. Retrospective treatment plans were generated using computed tomography (CT) images acquired during inhalation and exhalation to evaluate the dosimetric impact of respiratory motion of the liver. The dose difference (DD) and relative value (DD%) were evaluated using the dose-volume histogram (DVH) metrics, planning target volume Dmax, D95%, spinal cord D0.035 cc, and esophagus D2.5 cc. The magnitude of the liver movements was evaluated based on differences of liver size Lave at the isocentric axial plane between the inspiratory and expiratory CT images. RESULTS: The DD in almost all DVH metrics tended to increase when the liver moved away from the target during inhalation: For example, Mean ± $ \pm $ a standard deviation (SD) DD in PTV D95% for the treatment plan incorporating beam avoidance and those without beam avoidance was 0.5 ± $\pm$ 0.3 and 0.9 ± $ \pm $ 0.6 Gy, respectively. The spinal cord D0.035 cc for those shows 0.4 ± $ \pm $ 0.2 and 0.7 ± $ \pm $ 0.7 Gy, respectively. The treatment plans without beam avoidance also showed moderate or strong correlations between Lave and DD for almost all DVH metrics. No correlation was seen in the beam avoidance plan. The spinal cord D0.035 cc revealed approximately 1 Gy or +4% in DD when Lave was < -4 cm. CONCLUSIONS: Respiratory motion of the liver dome can cause substantial dosimetric discrepancies in the dose delivered to the spinal cord, although the extent depends on patient variables. Dose assessment should be performed for determining the appropriate means of respiratory management, such as breath-hold. Alternatively, beam avoidance effectively mitigates the impact.
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Accelerator-based boron neutron capture therapy (BNCT) systems employing a solid-state lithium target indicated the reduction of neutron flux over the lifetime of a target, and its reduction could represent the neutron flux model. This study proposes a novel compensatory approach for delivering the required neutron fluence and validates its clinical applicability. The proposed approach relies on the neutron flux model and the cumulative sum of real-time measurements of proton charges. The accuracy of delivering the required neutron fluence for BNCT using the proposed approach was examined in five Li targets. With the proposed approach, the required neutron fluence could be delivered within 3.0%, and within 1.0% in most cases. However, those without using the proposed approach exceeded 3.0% in some cases. The proposed approach can consider the neutron flux reduction adequately and decrease the effect of uncertainty in neutron measurements. Therefore, the proposed approach can improve the accuracy of delivering the required fluence for BNCT even if a neutron flux reduction is expected during treatment and over the lifetime of the Li target. Additionally, by adequately revising the approach, it may apply to other type of BNCT systems employing a Li target, furthering research in this direction.
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Terapia por Captura de Nêutron de Boro , Lítio , Nêutrons , Terapia por Captura de Nêutron de Boro/métodos , Lítio/química , Humanos , Aceleradores de Partículas , Dosagem RadioterapêuticaRESUMO
Objectives: Hydrogel spacer (HS) was developed to reduce rectal toxicities caused by radiotherapy, but has been reported to cause major adverse events. Our institute has attempted to introduce a hyaluronic acid (HA) as an alternative spacer. This study aimed to compare rectal doses and geometric distributions between the HS and HA implantation in prostate cancer. Methods: HS and HA were inserted in 20 and 18 patients undergoing high-dose brachytherapy, respectively. The rectum spacer volumes injected were 10 mL and 22 mL, respectively. In the treatment planning system, 13.5 Gy was administered with common catheter positions. The rectal dose indices were assessed between the spacer groups for dosimetry evaluation. Distances between the prostate and rectum and configurations of the spacers were compared. Results: The mean doses irradiated to 0.1 and 2 mL of the rectum were 10.45 Gy and 6.71 Gy for HS, and 6.73 Gy and 4.90 Gy for HA (p<0.001). The mean minimum distances between the prostate and rectum were 1.23 cm and 1.79 cm for HS and HA, respectively (p<0.05). Geometrical configuration comparisons revealed that HA has a higher ability to expand the space than HS. Conclusion: The rectal dose reduction ability of HA is significantly greater than that of HS, suggesting its potential as a new spacer.
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Previous plan competitions have largely focused on dose metric assessments. However, whether the submitted plans were realistic and reasonable from a quality assurance (QA) perspective remains unclear. This study aimed to investigate the relationship between aperture-based plan complexity metrics (PCM) in volumetric modulated arc therapy (VMAT) competition plans and clinical treatment plans verified through patient-specific QA (PSQA). In addition, the association of PCMs with plan quality was examined. A head and neck (HN) plan competition was held for Japanese institutions from June 2019 to July 2019, in which 210 competition plans were submitted. Dose distribution quality was quantified based on dose-volume histogram (DVH) metrics by calculating the dose distribution plan score (DDPS). Differences in PCMs between the two VMAT treatment plan groups (HN plan competitions held in Japan and clinically accepted HN VMAT plans through PSQA) were investigated. The mean (± standard deviation) DDPS for the 98 HN competition plans was 158.5 ± 20.6 (maximum DDPS: 200). DDPS showed a weak correlation with PCMs with a maximum r of 0.45 for monitor unit (MU); its correlation with some PCMs was "very weak." Significant differences were found in some PCMs between plans with the highest 20% DDPSs and the remaining plans. The clinical VMAT and competition plans revealed similar distributions for some PCMs. Deviations in PCMs for the two groups were comparable, indicating considerable variability among planners regarding planning skills. The plan complexity for HN VMAT competition plans increased for high-quality plans, as shown by the dose distribution. Direct comparison of PCMs between competition plans and clinically accepted plans showed that the submitted HN VMAT competition plans were realistic and reasonable from the QA perspective. This evaluation may provide a set of criteria for evaluating plan quality in plan competitions.
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Neoplasias de Cabeça e Pescoço , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade Modulada , Humanos , Radioterapia de Intensidade Modulada/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Neoplasias de Cabeça e Pescoço/radioterapia , Garantia da Qualidade dos Cuidados de SaúdeRESUMO
This study reports the first patient treatment for cutaneous malignant melanoma using a linear accelerator-based boron neutron capture therapy (BNCT) system. A single-center open-label phase I clinical trial had been conducted using the system since November 2019. A patient with a localized node-negative acral malignant melanoma and the largest diameter of the tumor ≤ 15 cm who refused primary surgery and chemotherapy was enrolled. After administering boronophenylalanine (BPA), a single treatment of BNCT with the maximum dose of 18 Gy-Eq delivered to the skin was performed. The safety and efficacy of the accelerator-based BNCT system for treating localized cutaneous malignant melanoma were evaluated. The first patient with cutaneous malignant melanoma in situ on the second finger of the left hand did not develop dose-limiting toxicity in the clinical trial. After BNCT, the treatment efficacy was gradually observed, and the patient achieved PR within 6 months and CR within 12 months. Moreover, during the follow-up period of 12 months after BNCT, the patient did not exhibit a recurrence without any treatment-related grade 2 or higher adverse events. Although grade 1 adverse events of dermatitis, dry skin, skin hyperpigmentation, edema, nausea, and aching pain were noted in the patient, those adverse events were relieved without any treatment. This case report shows that the accelerator-based BNCT may become a promising treatment modality for cutaneous malignant melanoma. We expect further clinical trials to reveal the efficacy and safety of the accelerator-based BNCT for cutaneous malignant melanoma.
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The uterus is known as one of the moving organs. We evaluated the movement of the uterus during irradiation and the effects of changes in the surrounding organs using a magnetic resonance (MR)-guided radiotherapy system. Seven patients with cervical cancer underwent pre- and posttreatment MR imaging to assess changes in the positioning of the uterus and cervix as well as the alterations in bladder and rectal volume. The study revealed that the movements of the uterus were greater than that of the cervix and showed a tendency to correlate with the bladder rather than the rectum. We also examined whether intrafractional motion could lead to insufficient dose coverage of the clinical target volume (CTV), specifically focusing on the D98% of the CTV in the uterine body and cervix. The impact of intrafractional motion on the D98% varied among patients, with one out of the seven patients experiencing an average dosimetric change of -2.6 Gy in the uterus, although larger planning target volume margins of 1.5 cm were applied, therefore, indicating the need for individualized optimal margins in each case. Online adaptive radiotherapy offers the advantage of modifying the treatment plan when irradiating moving organs, such as the uterus. However, it should be noted that this approach may result in longer overall treatment times compared with the traditional methods. Therefore, we must carefully consider the influence of intrafractional organ motions when opting for such a treatment.
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Radioterapia Guiada por Imagem , Radioterapia de Intensidade Modulada , Neoplasias do Colo do Útero , Feminino , Humanos , Colo do Útero/patologia , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Útero , Neoplasias do Colo do Útero/diagnóstico por imagem , Neoplasias do Colo do Útero/radioterapia , Neoplasias do Colo do Útero/patologia , Radioterapia Guiada por Imagem/métodos , Movimento (Física) , Dosagem RadioterapêuticaRESUMO
We present a 41-year-old man with idiopathic interstitial pneumonia and pulmonary hypertension (PH) in the setting of a non-autoimmune background whose clinical presentation masqueraded pulmonary veno-occlusive disease (PVOD). Because of no histological evidence of venous occlusion in his previous lung biopsy, phosphodiesterase type-5 inhibitor was given, resulting in sudden onset of pulmonary edema. At autopsy, there were histological features of interstitial fibrosis with occlusion of the lobular septal veins and venules. Clinical presentations of PH due to interstitial fibrosis with pulmonary venous lesions may simulate those of PVOD and careful diagnostic and therapeutic approaches are required.
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This study aimed to quantify the relative biological effectiveness (RBE) for epithermal neutron beam contaminated with fast neutrons in the accelerator-based boron neutron capture therapy (BNCT) system coupled to a solid-state lithium target. The experiments were performed in National Cancer Center Hospital (NCCH), Tokyo, Japan. Neutron irradiation with the system provided by Cancer Intelligence Care Systems (CICS), Inc. was performed. X-ray irradiation, which was assigned as the reference group, was also performed using a medical linear accelerator (LINAC) equipped in NCCH. The four cell lines (SAS, SCCVII, U87-MG and NB1RGB) were utilized to quantify RBE value for the neutron beam. Before both of those irradiations, all cells were collected and dispensed into vials. The doses of 10% cell surviving fraction (SF) (D10) were calculated by LQ model fitting. All cell experiments were conducted in triplicate at least. Because the system provides not only neutrons, but gamma-rays, the contribution from the gamma-rays to the survival fraction were subtracted in this study. D10 value of SAS, SCCVII, U87-MG and NB1RGB for the neutron beam was 4.26, 4.08, 5.81 and 2.72 Gy, respectively, while that acquired by the X-ray irradiation was 6.34, 7.21, 7.12 and 5.49 Gy, respectively. Comparison of both of the D10 values, RBE value of SAS, SCCVII, U87-MG and NB1RGB for the neutron beam was calculated as 1.7, 2.2, 1.3 and 2.5, respectively, and the average RBE value was 1.9. This study investigated RBE of the epithermal neutron beam contaminated with fast neutrons in the accelerator-based BNCT system coupled to a solid-state lithium target.
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Terapia por Captura de Nêutron de Boro , Nêutrons Rápidos , Lítio , Nêutrons , Aceleradores de Partículas , Eficiência Biológica RelativaRESUMO
PURPOSE: We measure the dose distribution of gated delivery for different target motions and estimate the gating latency in a magnetic resonance-guided radiotherapy (MRgRT) system. METHOD: The dose distribution accuracy of the gated MRgRT system (MRIdian, Viewray) was investigated using an in-house-developed phantom that was compatible with the magnetic field and gating method. This phantom contains a simulated tumor and a radiochromic film (EBT3, Ashland, Inc.). To investigate the effect of the number of beam switching and target velocity on the dose distribution, two types of target motions were applied. One is that the target was periodically moved at a constant velocity of 5 mm/s with different pause times (0, 1, 3, 10, and 20 s) between the motions. During different pause times, different numbers of beams were switched on/off. The other one is that the target was moved at velocities of 3, 5, 8, and 10 mm/s without any pause (i.e., continuous motion). The gated method was applied to these motions at MRIdian, and the dose distributions in each condition were measured using films. To investigate the relation between target motion and dose distribution in the gating method, we compared the results of the gamma analysis of the calculated and measured dose distributions. Moreover, we analytically estimated the gating latencies from the dose distributions measured using films and the gamma analysis results. RESULTS: The gamma pass rate linearly decreased with increasing beam switching and target velocity. The overall gating latencies of beam-hold and beam-on were 0.51 ± 0.17 and 0.35 ± 0.05 s, respectively. CONCLUSIONS: Film measurements highlighted the factors affecting the treatment accuracy of the gated MRgRT system. Our analytical approach, employing gamma analysis on films, can be used to estimate the overall latency of the gated MRgRT system.
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Planejamento da Radioterapia Assistida por Computador , Humanos , Movimento (Física) , Espectroscopia de Ressonância Magnética , Dosagem Radioterapêutica , Imagens de FantasmasRESUMO
INTRODUCTION: Concurrent chemoradiotherapy (CCRT) has been the standard of care for patients with locally advanced non-small cell lung cancer (LA-NSCLC). BACKGROUND AND PURPOSE: The results of the PACIFIC trial established the use of consolidative durvalumab after concurrent chemoradiotherapy (CCRT) as the standard of care for patients with locally advanced non-small cell lung cancer (LA-NSCLC). A subgroup analysis of the PACIFIC trial reported a better progression-free survival (PFS) in Asians. Although real-world data on LA-NSCLC patients who received CCRT plus durvalumab have been reported, there have been few large-scale reports on Asians. In this study, we investigated prognostic factors in the largest real-world data set in Asia of only Japanese LA-NSCLC patients treated with CCRT plus durvalumab. MATERIALS AND METHODS: One hundred and thirteen LA-NSCLC patients who received definitive CCRT and consolidative durvalumab at our institution between May 2018 and April 2021 were analyzed. Overall survival (OS), cause-specific survival (CSS), PFS, distant metastasis-free survival (DMFS), and in-field progression-free survival (IFPFS) were investigated as treatment outcomes using competing risk analyses. RESULTS: During a median follow-up of 24 months (range, 5-47) after the initiation of durvalumab therapy, 31 patients died, of whom 23 died of lung cancer. In the multivariate analysis, the pretreatment factors that correlated with OS were ILA scores, adenocarcinoma, and performance status at the initiation of durvalumab. Furthermore, ILA score and programmed cell death ligand 1 (PD-L1) tumor proportion score (TPS) ≥ 1 % were significantly correlated with CSS, and PD-L1 TPS ≥ 1 % was significantly correlated with PFS and IFPFS. CONCLUSION: Pretreatment ILA, adenocarcinoma, and performance status may have an impact on OS of LA-NSCLC patients receiving CCRT plus durvalumab.
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Adenocarcinoma , Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Antígeno B7-H1/metabolismo , Estadiamento de Neoplasias , Adenocarcinoma/patologia , Quimiorradioterapia/métodos , Pulmão/patologiaRESUMO
INTRODUCTION: Scalp angiosarcoma is a rare and aggressive cancer. Definitive radiotherapy is a treatment option for localised scalp angiosarcoma patients. Although definitive surgical resection reportedly prolongs overall survival (OS), whether initial local treatment effect affects OS when definitive radiotherapy is administered is unclear. Therefore, this study analysed whether local recurrence within 6 months of irradiation correlates with OS and cancer-specific survival (CSS). Furthermore, how local control affects patients' quality of life was investigated. MATERIALS AND METHODS: Thirty-one localised scalp angiosarcoma patients who had received definitive radiotherapy at our institution between October 2010 and July 2021 were analysed retrospectively. The most commonly used dose fractionation was 70 Gy in 35 fractions (83.9%). Local recurrence within 6 months of radiotherapy and other clinical factors were examined in univariate and subsequent multivariate analyses for correlation with OS and CSS. RESULTS: The median follow-up period was 16 months (range, 6-45 months). Local recurrence was detected in 16 patients (51.6%), 12 of whom had recurrence within 6 months. In multivariate analyses, the presence of local recurrence within 6 months of radiotherapy was significantly associated with OS and CSS (p = 0.003, 0.0001, respectively). Ten of the 16 patients with local recurrence had severe symptoms such as bleeding, pain, difficulty opening the eye and malodour. CONCLUSIONS: The initial local treatment effect was significantly associated with OS and CSS after definitive radiotherapy. Furthermore, local recurrence after radiotherapy resulted in a variety of symptoms, including bleeding and pain, which reduced the patient's quality of life.
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Hemangiossarcoma , Humanos , Hemangiossarcoma/radioterapia , Hemangiossarcoma/patologia , Couro Cabeludo/patologia , Estudos Retrospectivos , Relevância Clínica , Qualidade de Vida , DorRESUMO
BACKGROUND: Boron Neutron Capture Therapy (BNCT) has recently been used in clinical oncology thanks to recent developments of accelerator-based BNCT systems. Although there are some specific processes for BNCT, they have not yet been discussed in detail. PURPOSE: The aim of this study is to provide comprehensive data on the risk of accelerator-based BNCT system to institutions planning to implement an accelerator-based BNCT system. METHODS: In this study, failure mode and effects analysis (FMEA) was performed based on a treatment process map prepared for the accelerator-based BNCT system. A multidisciplinary team consisting of a medical doctor (MD), a registered nurse (RN), two medical physicists (MP), and three radiologic technologists (RT) identified the failure modes (FMs). Occurrence (O), severity (S), and detectability (D) were scored on a scale of 10, respectively. For each failure mode (FM), risk priority number (RPN) was calculated by multiplying the values of O, S, and D, and it was then categorized as high risk, very high risk, and other. Additionally, FMs were statistically compared in terms of countermeasures, associated occupations, and whether or not they were the patient-derived. RESULTS: The identified FMs for BNCT were 165 in which 30 and 17 FMs were classified as high risk and very high risk, respectively. Additionally, 71 FMs were accelerator-based BNCT-specific FMs in which 18 and 5 FMs were classified as high risk and very high risk, respectively. The FMs for which countermeasures were "Education" or "Confirmation" were statistically significantly higher for S than the others (p = 0.019). As the number of BNCT facilities is expected to increase, staff education is even more important. Comparing patient-derived and other FMs, O tended to be higher in patient-derived FMs. This could be because the non-patient-derived FMs included events that could be controlled by software, whereas the patient-derived FMs were impossible to prevent and might also depend on the patient's condition. Alternatively, there were non-patient-derived FMs with higher D, which were difficult to detect mechanically and were classified as more than high risk. In O, significantly higher values (p = 0.096) were found for FMs from MD and RN associated with much patient intervention compared to FMs from MP and RT less patient intervention. Comparing conventional radiotherapy and accelerator-based BNCT, although there were events with comparable risk in same FMs, there were also events with different risk in same FMs. They could be related to differences in the physical characteristics of the two modalities. CONCLUSIONS: This study is the first report for conducting a risk analysis for BNCT using FMEA. Thus, this study provides comprehensive data needed for quality assurance/quality control (QA/QC) in the treatment process for facilities considering the implementation of accelerator-based BNCT in the future. Because many BNCT-specific risks were discussed, it is important to understand the characteristics of BNCT and to take adequate measures in advance. If the effects of all FMs and countermeasures are discussed by multidisciplinary team, it will be possible to take countermeasures against individual FMs from many perspectives and provide BNCT more safely and effectively.
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Terapia por Captura de Nêutron de Boro , Análise do Modo e do Efeito de Falhas na Assistência à Saúde , Humanos , Medição de Risco , Controle de QualidadeRESUMO
This study aimed to clarify the differences in radiotherapy dose characteristics and delivery efficiency between the supine and prone positions in patients with prostate cancer using the CyberKnife. The planning computed tomography (CT) and delineations of the prone position were obtained by rotating the supine CT images with delineations of 180° using image processing software. The optimization parameters for planning target volume (PTV) and organs at risk (OARs) were based on the prone position. The optimization parameters determined for the prone position were applied to the supine position for optimization and dose calculation. The dosimetric characteristics of the PTV and OARs, and delivery efficiency were compared between the two different patient positions. The plans in the prone position resulted in better PTV conformity index (nCI), rectum V90%, V80%, V75%, V50% and bladder V50%. A significant difference was observed in treatment time and depth along the central axis (dCAX) between the two plans. The mean treatment time per fraction and dCAX for the supine and prone positions were 20.9 ± 1.7 min versus 19.8 ± 1.3 min (P = 0.019) and 151.1 ± 33.6 mm versus 233.2 ± 8.8 mm (P < 0.001), respectively. In this study the prone position was found to improve dosimetric characteristics and delivery efficiency compared with the supine position during prostate cancer treatment with the CyberKnife.
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Neoplasias da Próstata , Radiocirurgia , Radioterapia Conformacional , Radioterapia de Intensidade Modulada , Masculino , Humanos , Próstata , Radioterapia Conformacional/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Decúbito Dorsal , Dosagem Radioterapêutica , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/radioterapia , Órgãos em Risco , Decúbito VentralRESUMO
BACKGROUND: The setup of lung shield (LS) in total body irradiation (TBI) with the computed radiography (CR) system is a time-consuming task and has not been quantitatively evaluated. The TBI mobile imager (TBI-MI) can solve this problem through real-time monitoring. Therefore, this study aimed to perform commissioning and performance evaluation of TBI-MI to promote its use in clinical practice. METHODS: The source-axis distance in TBI treatment, TBI-MI (CNERGY TBI, Cablon Medical B.V.), and the LS position were set to 400, 450, and 358 cm, respectively. The evaluation items were as follows: accuracy of image scaling and measured displacement error of LS, image quality (linearity, signal-to-noise ratio, and modulation transfer function) using an EPID QC phantom, optimal thresholding to detect intra-fractional motion in the alert function, and the scatter radiation dose from TBI-MI. RESULTS: The accuracy of image scaling and the difference in measured displacement of the LS was <4 mm in any displacements and directions. The image quality of TBI imager was slightly inferior to the CR image but was visually acceptable in clinical practice. The signal-to-noise ratio was improved at high dose rate. The optimal thresholding value to detect a 10-mm body displacement was determined to be approximately 5.0%. The maximum fraction of scattering radiation to irradiated dose was 1.7% at patient surface. CONCLUSION: MI-TBI can quantitatively evaluate LS displacement with acceptable image quality. Furthermore, real-time monitoring with alert function to detect intrafraction patient displacement can contribute to safe TBI treatment.
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Planejamento da Radioterapia Assistida por Computador , Irradiação Corporal Total , Humanos , Imagens de Fantasmas , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodosRESUMO
BACKGROUND: 18F-FDG PET is often utilized to determine BNCT selection due to the limited availability of 18F-BPA PET, which is performed by synthesizing 18F into the boron drug used for BNCT, although the uptake mechanisms between those are different. Additionally, only a few non-spatial point parameters, such as maximum SUV (SUVmax), have reported a correlation between those in previous studies. This study aimed to investigate the spatial accumulation pattern between those PET images in tumors, which would be expected to either show higher uptake on 18F-BPA PET or be utilized in clinical, to verify whether 18F-FDG PET could be used as a selection indicator for BNCT. METHODS: A total of 27 patients with 30 lesions (11 squamous cell carcinoma, 9 melanoma, and 10 rhabdomyosarcoma) who received 18F-FDG and 18F-BPA PET within 2 weeks were enrolled in this study. The ratio of metabolic tumor volumes (MTVs) to GTV, histogram indices (skewness/kurtosis), and the correlation of total lesion activity (TLA) and non-spatial point parameters (SUVmax, SUVpeak, SUVmin, maximum tumor-to-normal tissue ratio (Tmax/N), and Tmin/N) were evaluated. After local rigid registration between those images, distances of locations at SUVmax and the center of mass with MTVs on each image and similarity indices were also assessed along its coordinate. RESULTS: In addition to SUVmax, SUVpeak, and Tmax/N, significant correlations were found in TLA. The mean distance in SUVmax was [Formula: see text] and significantly longer than that in the center of mass with MTVs. The ratio of MTVs to GTV, skewness, and kurtosis were not significantly different. However, the similarities of MTVs were considerably low. The similarity indices of Dice similarity coefficient, Jaccard coefficient, and mean distance to agreement for MTV40 were [Formula: see text], [Formula: see text], and [Formula: see text] cm, respectively. Furthermore, it was worse in MTV50. In addition, spatial accumulation patterns varied in cancer types. CONCLUSIONS: Spatial accumulation patterns in tumors showed low similarity between 18F-FDG and 18F-BPA PET, although the various non-spatial point parameters were correlated. In addition, the spatial accumulation patterns were considerably different in cancer types. Therefore, the selection for BNCT using 18F-FDG PET should be compared carefully with using 18F-FBPA PET.
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Submacular hemorrhage (SMH) can lead to devastating visual loss in patients with age-related macular degeneration. We retrospectively evaluated the surgical outcomes of vitrectomy with subretinal injection of tissue plasminogen activator, bevacizumab, and air in 13 cases. Visual prognosis, anatomical results obtained with optical coherence tomography (OCT), and their correlations were investigated. We analyzed OCT parameters including SMH height, pigment epithelial detachment (PED) height and width, and status of ellipsoid zone (EZ) line. Complete displacement of SMH was achieved in 12 eyes. At 3 months post-surgery, best-corrected visual acuity (BCVA) and SMH height exhibited significant improvements (P < 0.01). In eyes with preoperative SMH height < 300 µm and a detectable EZ line, BCVA was significantly improved at as early as 1 month, whereas the remaining eyes exhibited visual improvements only at 3 months. Postoperative BCVA positively correlated with preoperative BCVA (r = 0.86, P < 0.005), and negatively correlated with SMH size (r = 0.69, P < 0.01) and PED height (r = 0.58, P < 0.05) and width (r = 0.67, P < 0.05). Multivariate analyses confirmed preoperative BCVA as the predominant factor associated with postoperative BCVA (ß = 1.093, P < 0.05). In conclusion, significant improvements in BCVA and anatomical findings can be achieved with our reported surgical technique. Preoperative OCT findings may influence the duration required for visual improvements.
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Degeneração Macular , Descolamento Retiniano , Humanos , Ativador de Plasminogênio Tecidual/uso terapêutico , Fibrinolíticos/uso terapêutico , Estudos Retrospectivos , Resultado do Tratamento , Seguimentos , Hemorragia Retiniana/tratamento farmacológico , Hemorragia Retiniana/etiologia , Degeneração Macular/tratamento farmacológico , Descolamento Retiniano/cirurgia , Tomografia de Coerência Óptica , Vitrectomia/métodosRESUMO
Background and purpose: Online magnetic resonance-guided adaptive radiotherapy (MRgART) is a new technology of radiotherapy and requires a new quality control program in many aspects. This study aimed to gain a deeper understanding of risks in online MRgART through the application of failure mode and effect analysis (FMEA) for more enhanced and effective quality assurance (QA) programs. Materials and methods: We present an FMEA conducted by a multidisciplinary team with more than two years of experience. A process map describing the whole process of online MRgART was developed and potential failure modes were identified. High-risk failure modes and their potential causes and corrective measures were also identified. Failure modes were classified into three categories, MRgRT, online ART, and conventional RT, to investigate their features. A comparison with previous studies was also conducted to gain a general perspective. Results: In total, 153 failure modes and 49 high risks were identified. Among all failure modes, 51, 63, and 66 were related to MRgRT, online ART, and conventional RT, respectively. The hazardous processes were structure segmentation, treatment planning, and treatment beam delivery. Lists of failure modes identified in this study and previous studies were presented. Based on the results, characteristics and general aspects of the risks were discussed. Conclusion: Exploring the results of the FMEA enhanced our understanding of risk characteristics to improve QA program of online MRgART.
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PURPOSE: This study reports the first-in-human use of a linear accelerator-based boron neutron capture therapy (BNCT) system and the first treatment of patients with scalp-angiosarcoma with accelerator-based BNCT. PATIENTS AND METHODS: A single-center open-label phase I clinical trial has been conducted using the system since November 2019. Patients with a localized node-negative scalp-angiosarcoma along with the largest diameter of the tumor ≤ 15 cm who refused primary surgery and chemotherapy were enrolled. After administration of boronophenylalanine (BPA), a single treatment of BNCT with the maximum dose delivered to the skin being 12 Gy-Eq was performed. The safety and effectiveness of accelerator-based BNCT therapy for localized scalp angiosarcoma were evaluated. RESULTS: Scalp-angiosarcoma of the two patients did not develop the dose-limiting toxicity in the clinical trial. They reached CR within half a year and did not exhibit in-field failure 20 months after BNCT without any severe treatment-related adverse events. Although a grade 3 adverse event of an asymptomatic but increased serum amylase level was noted in both patients, it relieved without any treatment. Additionally, no severe acute dermatitis was observed for both patients, which is typically seen with conventional primary radiotherapy. CONCLUSIONS: It was suggested that BNCT would be a promising treatment modality for scalp-angiosarcoma, which is difficult to treat.
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Cutaneous angiosarcomas is a rare cancer with poor prognoses. The common radiotherapy techniques that have been reported so far are two pairs of lateral X-ray and electron fields. However, it is quite difficult to irradiate scalp angiosarcomas (SAs) homogeneously with this technique. In this study, safety, effectiveness, and risk factors were assessed for localized SAs ≥ 5 cm treated with intensity-modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) with boluses. Sixty-eight angiosarcoma patients who had received radiotherapy in our institution between January 2007 and November 2020 were retrieved from our radiotherapy database. Of these patients, 27 localized SA patients were included in the retrospective analysis. The 2-year overall survival, local progression-free rate, and distant metastases-free survival were 41.8%, 48.4%, and 33.1%. All the patients experienced acute radiation dermatitis ≥ grade 2, with18 (66.7%) ≥ grade 3. No nodule lesion was a significant unfavorable predictive factor of acute radiation dermatitis ≥ grade 3. Tumor bleeding at the initiation of radiotherapy and tumor invasion to the face were significant predictive factors of overall survival, and tumor bleeding at the initiation of radiotherapy was also a significant predictive factor of local progression-free rate.