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Background/aim To evaluate the incidence and grade of radiation pneumonitis after volumetric modulated arc therapy (VMAT) performed for the treatment of non-small cell cancer (NSCLC). Patients and methods Fifty consecutive non-surgical candidates with NSCLC underwent VMAT. Thirty-five patients had stage-III tumors and 15 had recurrent tumors. The prescribed radiation dose for the gross tumor and the elective nodal area was 69 Gy in 30 fractions and 51 Gy in 30 fractions, respectively. Results Radiation pneumonitis developed in 38 patients (76%, 38/50), and grade ≥2 radiation pneumonitis developed in 11 patients (22%, 11/50). The percentage of lung volume that received a dose in excess of 5 Gy (V5), V10, V20, V30, and the mean lung dose (MLD) in the bilateral and ipsilateral lung were significantly associated with the development of grade ≥2 radiation pneumonitis. Conclusion The incidence and degree of radiation pneumonitis are acceptable following treatment of NSCLC with VMAT.

Aim This study aimed to assess the utility and stability of intraoral stent during intensity-modulated radiation therapy (IMRT). Background The benefits of intraoral stents in radiotherapy are unclear. Materials and methods We analyzed 386 setup errors in 12 patients who received IMRT for head and neck cancers without intraoral stents (intraoral stent [−]) and 183 setup errors in 6 patients who received IMRT with intraoral stents (intraoral stent [+]). All patients were matched according to the immobilization method (masks and boards). Setup errors were measured as the distance from the initial setup based on the marking on the skin and mask to the corrected position based on bone matching on cone beam computed tomography. Results The mean interfractional setup errors in the right–left, craniocaudal, anterior–posterior (AP), and three-dimensional (3D) directions were −0.33, 0.08, −0.25, and 2.75 mm in the intraoral stent (−) group and −0.37, 0.24, −0.63, and 2.42 mm in the intraoral stent (+) group, respectively ( P = 0.50, 0.65, 0.01, and 0.02, respectively). The systematic errors for the same directions were 0.89, 1.46, 1.15, and 0.88 mm in the intraoral stent (−) group and 0.62, 1.69, 0.68, and 0.56 mm in the intraoral stents (+) group, respectively. The random errors were 1.43, 1.43, 1.44, and 1.22 mm in the intraoral stent (−) group and 1.06, 1.11, 1.05, and 0.92 mm in the intraoral stents (+) group, respectively. Conclusion Setup errors can be significantly reduced in the AP and 3D-directions by using intraoral stents.

Deformable image registration (DIR) has been an important component in adaptive radiotherapy (ART). Our goal was to examine the accuracy of ART using the dice similarity coefficient (DSC) and to determine the optimal timing of replanning. A total of 22 patients who underwent volume modulated arc therapy (VMAT) for head and neck (H&N) cancers were prospectively analyzed. The planning target volume (PTV) was to receive a total of 70 Gy in 33 fractions. A second planning CT scan (rescan) was performed at the 15th fraction. The DSC was calculated for each structure on both CT scans. The continuous variables to predict the need for replanning were assessed. The optimal cut-off value was determined using receiver operating characteristic (ROC) curve analysis. In the correlation between body weight loss and DSC of each structure, weight loss correlated negatively with DSC of the whole face (rs = -0.45) and the face surface (rs = -0.51). Patients who required replanning tended to have experienced rapid weight loss. The threshold DSC was 0.98 and 0.60 in the whole face and the face surface, respectively. Patients who showed low DSC in the whole face and the face surface required replanning at a significantly high rate (P < 0.05 and P < 0.01). Weight loss correlated with DSC in both the whole face and the face surface (P < 0.05 and P < 0.05). The DSC values in the face predicted the need for replanning. In addition, weight loss tended to correlate with DSC. DIR during ART was found to be a useful tool for replanning.

Background: Visit-to-visit variability (VVV) in blood pressure (BP) has been shown to be a strong predictor of cardiovascular disease (CVD). However, the long-term effect of comprehensive cardiac rehabilitation (CR) with exercise training on VVV in BP has not yet been established. Therefore, we evaluated the long-term effects of CR on VVV in BP in patients with CVD. Methods: Twenty-two CVD patients in a 12-month CR program who had at least six clinic visits per month to measure BP were enrolled. We determined VVV in BP expressed as the standard deviation of average BP every month for 12 months. Results: The mean age was 70 ± 8 years and the body mass index was 24.4 ± 4.9 kg/m 2 . In addition, the percentage (%) of males, % heart failure and % ischemic heart disease were 77%, 55% and 27%, respectively. Patients who had uncontrolled BP at baseline showed a significant reduction of both systolic BP (SBP) and diastolic BP (DBP). VVV in SBP in the first month was significantly less than that in the last month, although there was no difference in VVV in DBP. Patients were divided into larger (L-) and smaller (S-) VVV in SBP groups according to the average value of VVV in SBP as a cut-off. The L-VVV in SBP group, but not the S-VVV in SBP group, showed a significant reduction of VVV in SBP. Conclusion: Comprehensive CR may improve VVV in SBP in CVD patients who have larger VVV in SBP. J Clin Med Res. 2017;9(4):345-352 doi: https://doi.org/10.14740/jocmr2915w

Cardiac rehabilitation (CR) improves cardiac function and exercise capacity in patients with cardiovascular disease (CVD). Simpler techniques are needed for use by physicians in the examination room to assess the usefulness of CR. We enrolled 46 consecutive CVD patients in a CR program (CR group) and prospectively followed them for 3months. We compared them to 18 age-, gender- and body mass index-matched CVD patients without CR (non-CR group). Various parameters were measured at baseline and after 3months using 3 simple non-invasive tests: severity of atherosclerosis [arterial velocity pulse index and arterial pressure volume index (API)] were determined using PASESA®, an autonomic nerve total activity amount index and a coefficient of variation of the R–R interval (CVRR) were determined using eHEART®, and peripheral resistance index, pressure rate product, stroke volume and cardiac index were determined using nico®]. There were no significant differences in patient characteristics including percentages (%) of ischemic heart disease and heart failure between the non-CR and CR groups. Systolic blood pressure (SBP), diastolic BP, heart rate and API at baseline significantly decreased and CVRR at baseline significantly increased after 3months in the CR group, but not in the non-CR group. In addition, ΔAPI (Δ=the value after 3months minus the value at baseline) was positively associated with ΔSBP in the CR group. In conclusion, CR significantly decreased BP and improved atherosclerosis and sympathetic nerve activity. These findings suggest that simple non-invasive tests may be useful for assessing the effects of CR.

Visit-to-visit variability (VVV) in blood pressure (BP) has been shown to be a predictor of cardiovascular events. It is unknown whether CR can improve VVV in BP as well as reducing BP. We enrolled 84 patients who had cardiovascular disease (CVD) and participated in a 3-month CR program. We measured systolic and diastolic BP (SBP and DBP), pulse pressure (PP), and heart rate (HR) before exercise training at each visit and determined VVV in BP or HR expressed as the standard deviation of the average BP or HR. Patients who had uncontrolled BP at baseline and who did not change their antihypertensive drugs throughout the study period showed a significant reduction of both SBP and DBP with a decrease in PP after 3 months. Patients who did not change their antihypertensive drugs were divided into larger (L-) and smaller (S-) VVV in the SBP groups and L- and S-VVV in the DBP groups according to the average value of VVV in SBP or DBP. In the L-VVV in the SBP and DBP groups, VVV in SBP and DBP in the 1st month was significantly decreased after the 3rd month in both groups. HR at baseline was significantly decreased after 3 months. In addition, CR induced a significant increase in the level of high-density lipoprotein cholesterol (HDL-C) in blood. In conclusion, CR improved VVV in BP in patients with L-VVV in BP and evoked a significant reduction in HR and an increase in HDL-C. These effects due to the CR program may be cardioprotective.

The purpose of this paper is to study the core performance of passive safety small reactor for distributed energy supply by changing the heavy water (D2O) concentration in the mixed coolant together with the fuel pitch. The long core life with conditions of the excessive reactivity of 2 %Δk/k, the reactivity shutdown margin of 1 %Δk/k and the negative coolant temperature reactivity coefficient is attained for the case of D2O concentration of 60% with 10% enrichment gadolinia (Gd2O3) doped fuel rods. This D2O core has a shorter core life 4.14 years than the original light water (H2O) core 4.76 years, while it needs a larger core size. However, changing the D2O concentration on the way during the burn-up shows a possibility of extending more the core life than that of the original H2O core.

A steam-water separator with the help of the Coulomb force generated by the Corona discharge, has the merits of being a simple structure, one capable of separating very small quantities of water droplets while decreasing the flow pressure resistance in the system under development. while the principle behind this separator is the same as that of the electrostatic precipitator, used for the separation of particulate pollutants, the characteristics of an electric field in a mist flow, the water droplet is different from that of the air flow, which is without the water droplets. A calculating method to predict the water droplet collecting efficiency of this separator has been developed on the basis of this experimental data. This was conducted using water-air under conditions of room temperature and atmospheric pressure.

A highly reliable control rod drive mechanism driven by an electric motor installed inside the reactor vessel (INV- CRDM) for a very small reactor has been designed. The INV-CRDM contributes to the compactness and simplicity of the reactor system, and can eliminate the possibility of a rod ejection accident. In the design, a new type of latch mechanism using an electromagnetic force to directly connect both of the shafts, one of which was the motor driven shaft and the other the control rod driving shaft, was applied so as to make the INV-CRDM very compact. The cable supplying current remained stationary, even when both of the shafts was moving. The required functions of the latch mechanism are to maintain an adequate latching force for the control rod shaft to move within a stroke of 370 mm, and to release the shafts in a shorter time than 0.2 s after a scram signal is received. A functional test with a model that approximately simulated the design was conducted to test the latching force and de-latching...

Compactness and light weight are of importance for a reactor plant used for ship propulsion. An advanced marine reactor, MRX, which has been designed by Japan Atomic Energy Research Institute, has accomplished a passively safe, compact and light weight design by adoption of an integral PWR and a water filled containment vessel. Dose equivalent rates in all areas inside and outside a ship are required to be reduced below design criteria without any bulk shield outside the containment vessel. In this paper, a shielding design for installation of the steam generator in the vicinity of the reactor core to achieve a compact plant by reducing fast neutrons in the steam generator and to enable the engine room, where pipes of the secondary loop are installed, to be classified as surveillance area, not controlled area, is described. The main purpose to classify the engine room as the surveillance area is the improvement of working efficiency of crew. To accomplish the design goal, a relatively thick core barrel an...

A simple method is presented to calculate radiation streaming through cylindrical ducts in a concrete shield. It includes neutron and gamma-ray calculations and can be applied to the problems of practical slant incidence. The method is essentially one of summing the axial dose rates from the different neutron and gamma components which are functions of energy and angle of incident radiation, duct diameter, bend angle, etc. Axial dose rates are calculated by the MCNP Monte Carlo code for straight and bent ducts having diameters of 5,10,20,30 and 40 cm. Radiation sources are plane mono-directional fission neutrons, intermediate neutrons, thermal neutrons and 1.25-MeV gamma rays. Incident angles are 0, 15, 30, 45 and 60 deg for straight ducts. For bent ducts, an isotropic plane source is placed inside the duct mouth to reduce computation time. Bend angles are 30,45,60 and 90 deg. Reliability of the Monte Carlo calculations are assessed by comparison with a 60Co experiment and calculations by the one-dimensio...

Japan Atomic Energy Research Institute has studied a highly compact reactor DRX for deep-sea research. The DRX has no purification system to achieve compact and light weight design by simplification of the system. The DRX is designed to operate for one month without purification of the primary coolant water. To quantitatively evaluate the validity of reactor operation without a purification system, a computer code CTAM-II has been developed to calculate accumulation of the activated corrosion products during and after reactor operation. The code is an improved and modified version of CTAM, which was developed for the shield modification project of the nuclear ship Mutsu. Validity of CTAM-II and parameters used in the code has been confirmed by comparison of the calculated data and experimental ones for measurement of the concentrations of radioactive materials in the primary coolant water. Estimation of buildup of the corrosion products for DRX using CTAM-II has been carried out and shielding calculations...

Japan Atomic Energy Research Institute has been conducting a design study of an advanced marine reactor MRX. MRX employs a water-filled containment vessel. In a case of loss of coolant accident (LOCA), the discharge of water from the reactor vessel almost stops when the pressures of reactor vessel and containment vessel become equal. The core flooding can be maintained passively. The MRX, therefore, does not adopt a safety injection system which the conventional reactors have.The purpose of this study is to investigate the thermal hydraulic behavior in the water-filled containment vessel during the LOCA. This report describes the fundamental experimental study focused on pressure increase of the containment vessel. The experiment was carried out by using a small scale apparatus. The pressures and temperatures in the vessels were measured. According to our observation, the vapor bubbles at nozzle exit contracted or expanded caused by flashing due to pressure reduction or condensation in the containment water. The pressure increase in the containment vessel was revealed to be the sum of compressed nitrogen gas pressure and saturated steam pressure. One-volume thermal equivalent model can predict well the pressure increase in the containment vessel in this experiment.

This paper describes the experiments of the first Japanese nuclear ship ‘Mutsu’, to investigate the effects of sea wave on the thermal hydraulics of marine reactor system while cruising through various sea conditions. The experimental data were analyzed in time-domain by RETRAN-02/GRAV code. This code was modified so as to simulate the ship motion effect on reactor thermal hydraulics. The data were also analyzed in frequency domain by Blackman Turkey method for the calculation of the spectrum and response function. The experiments involving ship maneuvering were performed by cruising on different wave heights, as well as wave directions in the northern Pacific ocean. From the experiments, vertical acceleration due to ship motion was found to induce direct variation of water levels in the SGs and the pressurizer. The water level variations were largest in the head wave, but smallest in the following wave. On the other hand, the following wave caused greater variation of the reactor power when the feed back...

The transient characteristics of single- phase natural circulation flow caused by pump tripping are investigated experimentally and analytically for five different cooling configurations in loop-type PWRs for marine applications. The loop consists of a heater box, a cooler, and connecting bent pipes with inverse U shapes. The cooler Jacket is designed to provide five different cooling configurations; three inverse U-shaped and two straight tube types. The experiments are carried out using water as the working fluid at atmospheric pressure by holding the heater input constant ( Q = 0.25kW to 4.0kW) . Under a certain condition, an unstable flow, which developes a reverse flow with a periodic oscillation, occurs. The flow stability maps are obtained for the heat input Q vs the heater height ELhfor five cooling configurations. Furthermore, a one-dimensional nonlinear analysis is carried out. The analytical results agree well with the experimental results.