A questionnaire about radiation safety management of the draining-water system at nuclear medicine facilities

We conducted a questionnaire survey about radiation-safety management condition in Japanese nuclear medicine facilities to make materials of proposition for more reasonable management of medical radioactive waste. We distributed a questionnaire to institutions equipped with Nuclear Medicine facilities. Of 1,125 institutions, 642 institutes (52.8%) returned effective answers. The questionnaire covered the following areas: 1) scale of an institution, 2) presence of enforcement of radiotherapy, 3) system of a tank, 4) size and number of each tank, 5) a form of draining-water system, 6) a displacement in a radioactive rays management area, 7) a measurement method of the concentration of medical radioactive waste in draining water system, 8) planned and used quantity of radioisotopes for medical examination and treatment, 9) an average displacement of hospital for one month. In most institutions, a ratio of dose limitation of radioisotope in draining-water system was less than 1.0, defined as an upper limitation in ordinance. In 499 hospitals without facilities of hospitalization for unsealed radioisotope therapy, 473 hospitals reported that sum of ratios of dose limits in a draining-water system was less than 1.0. It was calculated by used dose of radioisotope and monthly displacement from hospital, on the premise that all used radioisotope entered in the general draining-water system. When a drainage including radioactivity from a controlled area join with that from other area before it flows out of a institution, it may be diluted and its radioactive concentration should be less than its upper limitation defined in the rule. Especially, in all institutions with a monthly displacement of more than 25,000 m3, the sum of ratio of the concentration of each radionuclide to the concentration limit dose calculated by used dose of radioisotope, indicated less than 1.0.     

Risk factors for postoperative pneumonia in elderly patients with colorectal cancer: a sub-analysis of a large,multicenter, case-control study in Japan

Surgery Today - Postoperative pneumonia affects the length of stay and mortality after surgery in elderly patients with colorectal cancer (CRC). We aimed to determine the risk factors of...     

Numerical Analysis of Physical Characteristics and Heat Transfer Decoupling Behavior in Bypass Coupling Variable Polarity Plasma Arc

A novel bypass coupling variable polarity plasma arc was proposed to achieve the accurate adjusting of heat and mass transfer in the welding and additive manufacturing of aluminum alloy. However, the physical characteristics and decoupled transfer behavior remain unclear, restricting its application and development. A three-dimensional model of the bypass coupling variable polarity plasma arc was built based on Kirchhoff’s law, the main arc and the bypass arc are coupled by an electromagnetic field. The model of current attachment on the tungsten electrode surface is included for simulating different heating processes of the EP and EN phases in the coupling arc. The distribution of temperature field, flow field, and current density of the bypass coupling variable polarity plasma arc was studied by the three-dimensional numerical model. The heat input on the base metal under different current conditions is quantified. To verify the model, the arc voltages are compared and the results in simulation and experiment agree with each other well. The results show that the radius of the bypass coupling arc with or without bypass current action on the base metal is different, and the flow vector of the bypass coupling arc plasma with bypass current is larger than the arc without bypass current. By comparing the heat transfer on the electrodes’ boundary under different current conditions, it is found that increasing the bypass current results in the rise in heat input on the base metal. Therefore, it is concluded that using bypass current is unable to completely decouple the wire melting and the heat input of the base metal. The decoupled degree of heat transfer is one of the important factors for accurate control in the manufacturing process with this coupling arc.     

Laparoscopic adrenalectomy for pheochromocytoma: morbidity compared with adrenalectomy for tumors of other pathology

PURPOSE: We report our experience with laparoscopic adrenalectomy in nine patients with pheochromocytoma and compare the morbidity with that of laparoscopic adrenalectomy for tumors of other pathology. PATIENTS AND METHODS: Between January 1997 and November 1999, nine patients underwent laparoscopic surgery for pheochromocytoma via a transperitoneal approach. Of the patients, eight had solitary tumors, and one presented with bilateral pheochromocytomas. The mean size of the tumors was 5.4 cm. The surgical outcomes of the 9 patients were compared with those of 28 patients with adrenal tumors of other pathology (primary aldosteronism in 15 patients, Cushing syndrome in 6, and nonfunctioning adenoma in 7) who underwent transperitoneal laparoscopic adrenalectomy during the same period. The mean size of the adrenal tumors of other pathology was 2.4 cm. RESULTS: In eight of the nine patients with pheochromocytoma, laparoscopic adrenalectomy was successful. The procedure was converted to open surgery in the patient with bilateral tumors because of uncontrollable hemorrhage. A hypertensive crisis with the systolic blood pressure >200 mm Hg occurred in 6 patients (67%), but the episode could be controlled by temporary discontinuation of tumor manipulation, administration of drugs, or both. In adrenalectomy for pheochromocytoma, the mean operative time was longer (199 v 177 minutes) and the mean estimated blood loss was greater (360 v 54 mL) than for tumors of other pathology. Blood transfusion was given to two patients with pheochromocytoma but to no patient with tumors of other pathology. The patients with adrenal tumors of other pathology could resume normal activity earlier (mean 18 v 26 days) than those with pheochromocytoma. CONCLUSION: The operation is more difficult and the morbidity is higher in laparoscopic adrenalectomy for pheochromocytoma than that for tumors of other pathology. An experienced team of surgeons with advanced laparoscopic skills and anesthesiologists is mandatory. In large tumors, great caution should be taken for intraoperative complications. Nevertheless, laparoscopic adrenalectomy is not contraindicated for pheochromocytoma and can be performed safely.     

Total aortic arch aneurysm repair using a stent graft without cardiac or cerebral ischemia

A 74-year-old man with an aortic arch aneurysm and a chronic type IIIb aortic dissection underwent total aortic arch repair without cerebral or cardiac ischemia. After confirming no atheromatous change in the ascending aortic wall, a custom-designed 4-limbed graft, prepared for both arterial return of cardiopulmonary bypass and reconstruction of the arch vessels, was anastomosed onto the right side of the ascending aorta. The 3 arch vessels were then bypassed sequentially during systemic cooling and monitoring cerebral perfusion with near-infrared oxymetry. After aortic cross-clamping, a stent graft was inserted into the distal arch from the distal ascending aorta, maintaining cerebral and cardiac perfusion. This procedure is indicated especially in a high-risk patient who has an aortic arch aneurysm without severe atheromatous change in the ascending aorta and the arch vessels.