[en] Sequential subtraction processing of successive time frames acquired by conventional radionuclide angiography was evaluated fundamentally and clinically. The processing reduced efficiently blood back-ground, which resulted from mutual superimposition of vascular system, by means of subtracting a posterior component of the intravascular distribution of first-pass radioactivity. Upon phantom experiment, an appropriate method of the processing was established by evaluating signal-to-noise ratio of the image, quantitative accuracy of the time-activity curve and the consequential artifact. Upon clinical application, the processed time frames could demonstrated regional components of vascular system such as the left atrium or abnormal blood flow appearances such as shunt more distinctly than the original frames. And, time-activity curves obtained from the processed time frames revealed narrow dispersion of cardiac output values measured from the right ventricular, pulmonary and left ventricular curve in all cases with congestive heart failure, and described clear shunt curve providing reproducible and reasonable value of pulmonary-to-systemic flow ratio in all cases with left-to-right cardiac shunt

No abstract available

[en] Long-term observations were made for the development of secondary neoplasms following radiotherapy of animal tumors. Experimental tumors were 3rd generation isotransplants of a mammary carcinoma which arose spontaneously in a C3Hf/He mouse. A single dose of TCD20--TCD98 was followed by weekly observations. Most recurrences were observed in the first 150 days, while only a few were seen in the subsequent 150 days. Secondary neoplasms developed frequently following this period, i.e., 41 out of 67 animals surviving more than 300 days developed secondary neoplasms. They were osteogenic and soft tissue sarcomas, and half the new tumors were found within 490 days after radiotherapy. The results obtained were compared with literature reports of secondary neoplasms following postoperative radiotherapy for carcinoma of the breast and treatment of retinoblastomas. Most of these secondary human neoplasms were nonepithelial sarcomas as in the present study. Secondary carcinomas have been reported following radiotherapy of carcinoma in other locations, i.e., the cervix or head and neck; however, only a limited number of studies have been reported

[en] Tolerance of surgical portal vein anatomosis to intraoperative radiation therapy (IORT) was studied in dogs after single doses of zero, 10, 20 and 40 Gy (290 kVp X-rays). Portal venography was performed prior to IORT and before sacrificing. The dogs were sacrificed 3 and 12 months respectively after irradiation. Portal venography revealed no radiation induced anastomotic stenosis. Autopys disclosed macroscopic periportal fibrosis in all dogs, independent of radiation dose and observation periods. Microscopically, the three tunicas of the vein did not show any pathological changes after any dose level. (orig.)

[en] The authors report the results of internal irradiation with labeled chromic phosphate (32P) and gold-198 (198Au) colloid in eight cases of cystic craniopharyngiomas. They used a newly developed dosimetric formula, by which the radiation dose at the cyst wall and at any point far from the radioactive source can be calculated. Ten courses of irradiation in eight patients were carried out by injection of either 32P or 198Au colloid into the cyst through an Ommaya drainage system that had been placed at craniotomy. Follow-up studies ranging from 13 to 156 months revealed that all cysts were effectively treated, with elimination of fluid or collapse of the cyst. This was confirmed by Conray cystography and/or computerized tomography. Not only the dose delivered to the wall but also the thickness of the cyst wall and the location of the cyst are important factors in planning internal irradiation. A safe and adequate dose to the cyst wall could range between 9000 to 30,000 rads for craniopharyngioma. This treatment is suitable for large cysts that are thought to be difficult to remove radically, recurrent cysts resistant to previous treatment, or multiple cysts. Internal irradiation may also be applicable in other cystic intracranial tumors if dosimetry is calculated accurately

[en] A method for calculating the elastic constant of tissue is described. Length measurements obtained from Ultrasonograms (US) are different from those obtained from Computerized Tomograms (CT) when the velocity of sound is compared to standardized water measurements

[en] The heat-treated Zr-2.5Nb is a pressure tube alloy utilized in prototype advanced thermal reactor Fugen. Fugen surveillance specimens as well as three kinds of modified HT Zr-2.5Nb, i.e. as received, 200 ppm hydrogen enriched and radially hydride re orientated specimens, were prepared and irradiated in the special fuel assemblies of Fugen up to neutron exposure of 7 x 10²⁵ n/m² (E>1MeV) at around 560 K. A series of post irradiation examination including tensile test, bending fracture test, compact tension test and metallographies have been extensively conducted to investigate the effects of neutron irradiation on mechanical property changes of pressure tube. Tensile strength of pressure tube increases within the initial stage of 1 x 10²⁵ n/m², and thereafter takes saturation around 1000 MPa and 800 MPa at room temperature and at 573 K, respectively. The fracture toughness of the modified HT Zr-2.5Nb pressure tube is improved at both unirradiated and irradiated conditions. The fracture toughness is very sensitive to the orientation relationship between hydride platelets and crack extension axis. The radially re orientated hydride specimens degrades in fracture toughness, but satisfy the Fugen design value. Based on present results, the integrity of the Fugen pressure tube was appropriately demonstrated for 30 years operation. (author)

[en] SAR(specific adsorption rate) regulates the quantity of the heat caused by the RF radiation to human body. This SAR is dependent on the waveform of the RF-pulse and MR Pulse Sequence. Especially SAR become high value on T1W which images the wide distance by short TE and thin slice. We succeeded in reducing the SAR value on T1W by improving the RF-pulse waveform. The reduction of the SAR value also improve the T1W contrast in the multi- slice imaging

[en] For the future large application of superconducting RF cavities, one has to fabricate cheaply the cavities with high gradient. We propose to fabricate the seamless cavity out from Nb/Cu clad materials as unnecessary electron beam welding process and low fabrication cost. We made a fabrication study of 1.3 GHz Nb/Cu clad single cell cavity out of clad tube by HIP (Hot Isostatic Pressing) bonding. Two single cell Nb/Cu clad seamless cavities were fabricated by the collaboration with KEK/Toshiba Corporation. In this paper, the fabrication and cold test result of cavity of seamless type obtained by hydrostatic bulging will be presented. (author)

[en] Since several years, we are developing seamless niobium/copper clad cavities in order to reduce the fabrication cost. In FY 1999, we are carried out the studies for seamless cavities. They are: (1) Performance appraisal of bulk niobium cavities by spinning by the collaboration with KEK/INFN-LNL. (2) Fabrication of the Cu/Nb/Cu clad tubes by HIP (Hot Isostatic Pressing) bonding. (3) Fabrication of the Cu/Nb/Cu clad long pipes by tube drawing technique. (4) Fabrication of seamless niobium/copper clad cavities by hydrostatic bulging by the collaboration with KEK/Toshiba Corporation. In this paper, we report the trial fabrication of Cu/Nb/Cu clad tube and hydrostatic bulging clad cavities, and cold test results of clad cavities obtained by hydrostatic bulging and bulk niobium cavities by spinning will be presented. (author)