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Intensity-modulated proton therapy (IMPT) is expected to improve treatment results with fewer side effects than other proton therapies. The purpose of this study was to evaluate the tumor sites for which IMPT was effective under the same beam calculation conditions by planning IMPT for typical cases treated with passive scattering proton therapy (PSPT). We selected 16 cases of nasal cavity, lung, liver or prostate cancers as typical tumor sites receiving PSPT. The dose distributions and dose volume histograms optimized by the IMPT were compared with those optimized by the PSPT. We took particular note of the doses to the skin and organs at risk (OAR) when PSPT was replaced by IMPT. Furthermore, an improvement of the beam angles was also performed to obtain better dose distributions in the IMPT. The IMPT with the same beam angles resulted in near-maximum doses to the skin of average 78%, 64%, 84% and 99% of the PSPT doses for nasal cavity, lung, liver, and prostate cancers, respectively. However, it was difficult to improve the dose homogeneity of the target volume. The change of the IMPT beam angles could reduce the doses to OARs and skin in the case of the nasal cavity, while it had limited effect in the other cases. We concluded that IMPT was effective for reducing the doses to some OARs when treating nasal cavity, lung, liver and prostate cancers. The selection of beam angles was important in the IMPT optimization, especially for nasal cavity cancers.

To investigate the amount that radiation-induced secondary cancer would be reduced by using proton beam therapy (PBT) in place of intensity-modulated X-ray therapy (IMXT) in pediatric patients, we analyzed lifetime attributable risk (LAR) as an in silico surrogate marker of the secondary cancer after these treatments. From 242 pediatric patients with cancers who were treated with PBT, 26 patients were selected by random sampling after stratification into four categories: (i) brain, head and neck, (ii) thoracic, (iii) abdominal, and (iv) whole craniospinal (WCNS) irradiation. IMXT was replanned using the same computed tomography and region of interest. Using the dose–volume histograms (DVHs) of PBT and IMXT, the LARs of Schneider et al. were calculated for the same patient. All the published dose–response models were tested for the organs at risk. Calculation of the LARs of PBT and IMXT based on the DVHs was feasible for all patients. The means ± standard deviations of the cumulative LAR difference between PBT and IMXT for the four categories were (i) 1.02 ± 0.52% (n = 7, P = 0.0021), (ii) 23.3 ± 17.2% (n = 8, P = 0.0065), (iii) 16.6 ± 19.9% (n = 8, P = 0.0497) and (iv) 50.0 ± 21.1% (n = 3, P = 0.0274), respectively (one tailed t-test). The numbers needed to treat (NNT) were (i) 98.0, (ii) 4.3, (iii) 6.0 and (iv) 2.0 for WCNS, respectively. In pediatric patients who had undergone PBT, the LAR of PBT was significantly lower than the LAR of IMXT estimated by in silico modeling. Although a validation study is required, it is suggested that the LAR would be useful as an in silico surrogate marker of secondary cancer induced by different radiotherapy techniques.

The authors attempt to establish the relative biological effectiveness (RBE) calculation for designing therapeutic proton beams on the basis of microdosimetry. The tissue-equivalent proportional counter (TEPC) was used to measure microdosimetric lineal energy spectra for proton beams at various depths in a water phantom. An RBE-weighted absorbed dose is defined as an absorbed dose multiplied by an RBE for cell death of human salivary gland (HSG) tumor cells in this study. The RBE values were calculated by a modified microdosimetric kinetic model using the biological parameters for HSG tumor cells. The calculated RBE distributions showed a gradual increase to about 1cm short of a beam range and a steep increase around the beam range for both the mono-energetic and spread-out Bragg peak (SOBP) proton beams. The calculated RBE values were partially compared with a biological experiment in which the HSG tumor cells were irradiated by the SOBP beam except around the distal end. The RBE-weighted absorbed dose distribution for the SOBP beam was derived from the measured spectra for the mono-energetic beam by a mixing calculation, and it was confirmed that it agreed well with that directly derived from the microdosimetric spectra measured in the SOBP beam. The absorbed dose distributions to planarize the RBE-weighted absorbed dose were calculated in consideration of the RBE dependence on the prescribed absorbed dose and cellular radio-sensitivity. The results show that the microdosimetric measurement for the mono-energetic proton beam is also useful for designing RBE-weighted absorbed dose distributions for range-modulated proton beams.

The purpose of this study is to determine the recommended dose (RD) of proton beam therapy (PBT) for inoperable stage III non‐small cell lung cancer (NSCLC). We tested two prescribed doses of PBT: 66 Gy (relative biological effectiveness [RBE]) in 33 fractions and 74 Gy (RBE) in 37 fractions in arms 1 and 2, respectively. The planning target volume (PTV) included the primary tumor and metastatic lymph nodes with adequate margins. Concurrent chemotherapy included intravenous cisplatin (60 mg/m2, day 1) and oral S‐1 (80, 100 or 120 mg based on body surface area, days 1–14), repeated as four cycles every 4 weeks. Dose‐limiting toxicity (DLT) was defined as grade 3 or severe toxicities related to PBT during days 1–90. Each dose level was performed in three patients, and then escalated to the next level if no DLT occurred. When one patient developed a DLT, three additional patients were enrolled. Overall, nine patients (five men, four women; median age, 72 years) were enrolled, including six in arm 1 and three in arm 2. The median follow‐up time was 43 months, and the median progression‐free survival was 15 months. In arm 1, grade 3 infection occurred in one of six patients, but no other DLT was reported. Similarly, no DLT occurred in arm 2. However, one patient in arm 2 developed grade 3 esophageal fistula at 9 months after the initiation of PBT. Therefore, we determined that 66 Gy (RBE) is the RD from a clinical viewpoints. (Clinical trial registration no. UMIN000005585) This is a dose‐finding study for locally advanced non‐small cell lung cancer using proton beam therapy and concurrent chemotherapy. We tested two doses of proton beam therapy, namely 66 Gy(RBE) and 74 Gy (RBE). From overall clinical viewpoints, 66 Gy (RBE) was determined as the recommended dose for future clinical trials.

Objective: In Japan, MRI-based thrombolysis after CT screening is the most common imaging strategy prior to intravenous thrombolysis (IVT) with tissue plasminogen activator (tPA) within 3 h after ischemic stroke. A choice of MRI with MR angiography (MRA) provides a higher diagnostic accuracy, but may delay an initiation of thrombolysis. Methods: In our neuro-unit, brain CT is the first screening image for suspected stroke. We retrospectively examined a delay to thrombolysis, imaging modality, diagnostic accuracy, and clinical outcomes at 3 months by the modified Rankin Scale in patients receiving IVT within 3 h. Results: Among 67 patients receiving IVT with tPA, brain imaging prior to IVT was solely CT in 10 (15%) patients and CT + MRI/MRA in 57 (85%) patients. Final diagnosis of brain ischemia was 100%. Patients receiving CT + MRI had significantly shorter pre-hospital delay (mean 54 vs. 83 min; p = 0.012), but longer door-to-needle time (mean 90 vs. 57 min; p = 0.019) than those receiving CT only. Finally, time from onset to thrombolysis was not different between the two groups and clinical outcomes were also comparable. The earlier patients arrived, the longer door-to-needle times were (p < 0.001). Conclusions: The imaging strategy of initial CT screening with optional MRI/MRA scans prior to IVT was feasible. However, it resulted in an additional 30 min in-hospital delay of tPA administration, which may affect clinical outcomes.

Purpose Rectal volume variation has a crucial effect on prostate localization during external beam radiotherapy for prostate cancer. This study investigated the effect of rectal volume reduction by a rectum-emptying tube (RET) on prostate immobilization. Materials and methods The study group comprised 21 patients who underwent proton beam treatment for prostate cancer. Sigmoid-shaped flexible plastic RETs were used to drain gases from the rectum. Computed tomography (CT) was performed before and after RET placement at the treatment planning stage and at the beginning of treatment. Prostate displacement and changes in rectal volume were measured on the CT images. The feasibility of RET placement was evaluated during and after the procedure. Results All 21 patients tolerated the procedure. The rectal volume was significantly lower with a RET than without a RET. The differences in rectal volume between the treatment planning stage and the beginning of treatment were significantly lower with a RET than without. RET placement significantly decreased prostate displacement in the anteroposterior and superoinferior directions but not in the left-right direction. Conclusion RET placement reduced both rectal volume and variation in rectal volume. The procedure reduced displacement of the prostate. RET placement thus appears to be an effective technique for immobilizing the prostate.

We report two cases having a similar clinical profile of systemic lupus erythematosus (SLE) complicated by hydronephrosis that developed concurrently with a similar pathological recognition of numerous unique microspherical and microtubular structures in the glomerular basement membrane (GBM). Case 1 refers to a 29-year-old woman with SLE. An increase in the level of proteinuria had been triggered by hydronephrosis. The pathological findings of the kidney revealed “bubbling” of the GBM, microspherical and microtubular structures in the GBM, and a suspicion of podocytic infolding into the GBM. Case 2 refers to a 46-year-old woman with SLE complicated with hydronephrosis. The level of proteinuria had increased, which was followed by renal biopsy. Similar pathological findings detected in Case 1 were also recognized in Case 2. The renal disorder of the two cases exhibited pathological abnormality atypical of lupus nephritis. Histopathological abnormality similar to that detected in the two cases has rarely been reported until recently. The pathogenesis of the GBM lesions of the two cases has not yet been elucidated, but we believe that there is a possibility the persistent mild autoimmune disorder and the concurrence of an obstructive state of the urinary tract may facilitate the occurrence of the pathological abnormality, because the clinical feature of the two cases are conspicuously similar to each other.

Background To compare proton beam therapy (PBT) and intensity-modulated radiation therapy (IMRT) with conformal radiation therapy (CRT) in terms of their organ doses and ability to cause secondary cancer in normal organs. Methods Five patients (median age, 4 years; range, 2–11 years) who underwent PBT for retroperitoneal neuroblastoma were selected for treatment planning simulation. Four patients had stage 4 tumors and one had stage 2A tumor, according to the International Neuroblastoma Staging System. Two patients received 36 Gy, two received 21.6 Gy, and one received 41.4 Gy of radiation. The volume structures of these patients were used for simulations of CRT and IMRT treatment. Dose–volume analyses of liver, stomach, colon, small intestine, pancreas, and bone were performed for the simulations. Secondary cancer risks in these organs were calculated using the organ equivalent dose (OED) model, which took into account the rates of cell killing, repopulation, and the neutron dose from the treatment machine. Results In all evaluated organs, the mean dose in PBT was 20–80% of that in CRT. IMRT also showed lower mean doses than CRT for two organs (20% and 65%), but higher mean doses for the other four organs (110–120%). The risk of secondary cancer in PBT was 24–83% of that in CRT for five organs, but 121% of that in CRT for pancreas. The risk of secondary cancer in IMRT was equal to or higher than CRT for four organs (range 100–124%). Conclusion Low radiation doses in normal organs are more frequently observed in PBT than in IMRT. Assessments of secondary cancer risk showed that PBT reduces the risk of secondary cancer in most organs, whereas IMRT is associated with a higher risk than CRT.