[Examination of Application to Radiation Protection Education by Four-dimensional Visualization of Scatter Distribution in Radiological Examination Using Virtual Reality].

PURPOSE: When working on fluoroscopy and patient assistance in a healthcare facility, workers need to understand how to properly protect scattered radiation. In this study, we examined a four-dimensional visualization method to make it easy to understand the spread of scattered radiation visually, and proposed its application to radiation protection education. METHODS: We constructed the X-ray room, X-ray CT room, and angiography room using Particle Heavy Ion Transport code System (PHITS), and calculated the scattered radiation distribution when the patient was irradiated with X-rays. The three-dimensional distribution of each moment was continuously displayed to create a four-dimensional distribution. Using the created data, we conducted radiation protection education including exercises to make the students confirm the scatter distribution from any direction. The effectiveness of the scattered radiation visualization data was evaluated by a questionnaire. RESULTS: The position of assistance for standing chest radiograph was less scattered radiation at the side and below the patient. As a result of the questionnaire, this education has confirmed the effect of attracting attention about radiation protection. The fourdimensional visualization allowed students to understand the behavior of radiation and the source of scattered radiation. CONCLUSION: Visualization of three- and four-dimensional scattered radiation distribution in the radiological examination room can intuitively enhance the understanding of the invisible radiation spread and appropriate aids.

One-month assessment of renal cell carcinoma treated by everolimus using FDG PET/CT predicts progression-free and overall survival.

PURPOSE: We evaluated 18F-2-fluoro-2-deoxyglucose positron emission tomography/computed tomography (FDG PET/CT) results as outcome predictors for patients with metastatic renal cell carcinoma (RCC) treated by everolimus (EVL), an inhibitor of mammalian target of rapamycin. METHODS: We retrospectively reviewed 30 patients who were treated with EVL for metastatic RCC between May 2010 and March 2015, by evaluating their FDG PET/CT result before and 1 month after starting EVL treatment. We examined the relationships between each patient's maximum standardized uptake value (max SUVmax) assessed by FDG PET/CT on progression-free survival (PFS) and overall survival (OS). RESULTS: Median PFS for all 30 patients was 3.77 months (range 0.72-24.56 months) and median OS after EVL treatment of all 30 patients was 11.67 months (range 1.0-62.98 months). Enrolled patients were divided into two groups by max SUVmax prior to EVL (median = 7.6) and at 1 month after EVL treatment (median = 5.7). PFS were significantly shorter in higher max SUVmax prior to EVL (<7.6, PFS 7.8 vs 3.5 months, log-rank P = 0.017) and at 1 month after EVL (<5.7, PFS 10.6 vs 2.7 months, log-rank P = 0.002) than lower max SUVmax. OS were also significantly shorter in higher max SUVmax prior to EVL (<7.6, OS 18.1 vs 7.5 months, log-rank P = 0.010) and at 1 month after EVL (<5.7, OS 17.2 vs 7.5 months, log-rank P = 0.009) than lower max SUVmax. Multivariate Cox hazard regression analysis indicated that max SUVmax at 1 month after EVL is an independent predictor of both PFS and OS in patients treated with EVL although univariate regression analysis showed max SUVmax before EVL is a possible predictor. CONCLUSIONS: Max SUVmax assessed by FDG PET/CT prior to EVL and at 1 month after EVL treatment can accurately predict PFS and can guide decisions on whether to continue or change treatments for patients with EVL-treated RCC who suffer from adverse events.

Early assessment by FDG-PET/CT of patients with advanced renal cell carcinoma treated with tyrosine kinase inhibitors is predictive of disease course.

BACKGROUND: We reported previously that (18)F-2-fluoro-2-deoxyglucose positron emission tomography/ computed tomography (FDG PET/CT) had potential for evaluating early response to treatment by tyrosine kinase inhibitors (TKIs) in advanced renal cell carcinoma (RCC). This time we investigated the relation of the early assessment by FDG PET/CT to long-term prognosis with an expanded number of patients and period of observation. METHODS: Patients for whom TKI treatment for advanced RCC was planned were enrolled. FDG PET/CT was performed before TKI treatment and after one month of TKI treatment. The relations of the FDGPET/CT assessment to progression free survival (PFS) and overall survival (OS) were investigated. RESULTS: Thirty-five patients were enrolled (sunitinib 19 cases, sorafenib 16 cases). The patients with RCC showing high SUVmax in pretreatment FDG PET/CT demonstrated short PFS (P =0.024, hazard ratio 1.137, 95% CI 1.017-1.271) and short OS (P =0.004, hazard ratio 1.210 95% CI 1.062-1.379). Thirty patients (sunitinib 16 cases, sorafenib 14 cases) were evaluated again after 1 month. The PFS of the patients whose SUVmax decreased<20% was shorter than that of the patients whose SUVmax decreased<20% (P = 0.027, hazard ratio 3.043, 95% CI 1.134-8.167). The PFS of patients whose tumor diameter sum increased was shorter than that of the patient with tumors whose diameter sum did not (P =0.006, hazard ratio 4.555, 95% CI 1.543-13.448). The patients were classified into three response groups: good responder (diameter sum did not increase, and SUVmax decreased ≥ 20%), intermediate responder (diameter sum did not increase, and SUVmax decreased<20%), and poor responder (diameter sum increased, or one or more new lesions appeared). The median PFS of good, intermediate, and poor responders were 458 ± 146 days, 131 ± 9 days, and 88 ± 26 days (good vs. intermediate P = 0.0366, intermediate vs. poor P = 0.0097, log-rank test). Additionally the mean OSs were 999 ± 70 days, 469 ± 34 days, and 374 ± 125 days, respectively (good vs. intermediate P = 0.0385, intermediate vs. poor P = 0.0305, log-rank test). CONCLUSIONS: The evaluation of RCC response to TKI by tumor size and FDG uptake using FDG PET/CT after 1 month can predict PFS and OS.