[en] Mass screening of lung cancer has been widely performed using indirect chest X-ray method in Japan. However reduction of the mortality for lung cancer is questioned. We have proposed that recently developed spiral CT should be adopted for the screening of lung cancer, since CT has an excellent detectability for small nodule. Lung Cancer Screening CT (LSCT) has been developed by author's group using spiral CT with low dose and light weight in order to make a mobile unit. In this paper risk-benefit analysis and cost-effectiveness analysis are described for the LSCT screening of lung cancer. As a risk, radiation carcinogenesis due to exposure from LSCT are compared with gain of life-expectancy by screening and men of 40 years or more and women of 45 years or more are justified. The cost per person-year is estimated for LSCT screening which is better than that of present method, although total cost is higher. The LSCT screening could be recommended if total cost is affordable. (author)

No abstract available

[en] The principles of X-ray computed tomography (XCT) and of the high-speed XCT for cardiac imaging, i.e., the dynamic spatial reconstructer, and the diagnostic system using these methods were explained. Then, the three new medical imaging methods were introduced. One is the digital X-ray imaging method, and examples were given of image reconstruction using subtraction of digital images. The second method was positron XCT. The principles, imaging methods and usages of NMR imaging were discussed briefly. Finally, it was emphasized that by using digital imaging, images can be stored without film, and the images of certain patients taken several years ago can later be retrieved immediately by computer. (Kaihara, S.)

[en] Equations for theoretical calculation of cost efficacy of PACS (Picture Archiving and Communication System for Medical Application) are formulated, in order to get paypoint for scale merit in comparison between or among system such as X-ray film digitalized archiving system, micro-film system and traditional X-ray film library. The equations are expressed by linear function where redemption of initial capital cost and other allied parameters are taken as fixed cost and where human cost, floor rental charge, memory media cost, maintenance cost and others are taken as variable running cost. Accommodation ability per unit floor space, speed of image delivery, throughput, frequency of retrieving requests, and other paramaters are involved. (author)

[en] At present many medical images are used for diagnostics and treatment. After the advent of X-ray computer tomography (XCT), the violent development of medical images has continued. Medical imaging technology can be defined as the field of technology that deals with the production, processing, display, transmission, evaluation and so on of medical images, and it can be said that the present development of medical imaging diagnostics has been led by medical imaging technology. In this report, the most advanced technology of medical imaging is explained. The principle of XCT is shown. The feature of XCT is that it can image the delicate difference in the X-ray absorption factor of the cross section being measured. The technical development has been advanced to reduce the time for imaging and to heighten the resolution. The technology which brings about a large impact to future imaging diagnostics is computed radiography. Magnetic resonance imaging is the method of imaging the distribution of protons in human bodies. Positron CT is the method of measurement by injecting a positron-emitting RI. These methods are explained. (K.I.)

No abstract available

[en] Principles and equipments of positron CT were reviewed. Features of scintillators, NaI(Tl), BGO, and CsF were discussed. The commercially available equipments made by AECL, Scanditronix, Cyclotron Co., and EG and G-Ortec, and radiopharmaceuticals for imaging the heart were listed. A new positron CT with fine homogeneous scanning space controlled by a computer was developed in the author's laboratory. Application of positron CT to the investigation of the heart was shortly reviewed. (Nakanishi, T.)

[en] The risk of radiation exposure associated with mammography in breast cancer screening must be considered. In this study, we re-evaluated the benefit vs. risk of the mammographic procedure used for breast cancer screening in Japan, assuming a screening interval of 2 years with 2 mammography views for women aged 40-49 years and 1 view for those aged 50 years or more. We also used a new breast tissue weighting factor defined by ICRP2007 and the life-time mortality coefficient defined by BEIR. The effective radiation dose used in mammography was assumed to be 0.72 mSv and 0.36 mSv for women aged 40-49 and 50 years or more respectively. The risk was expressed as loss of life expectancy (person-day) due to a single screening test. On the other hand, the benefit of screening was calculated on the basis of the number of lives saved by a stage shift of breast cancer detected by screening and then multiplying by the average life expectancy. Thus the benefit was expressed as the gain of life expectancy (person-day) due to a single screening. Finally, the benefit/risk ratio was obtained as: gain of life expectancy/loss of life expectancy as a function of age at which the benefit/risk ratio exceeded 1.0. In this study we showed that the benefit/risk ratio exceeds 1.0 from age of 25 years old or more in Japanese breast cancer screening, and so our screening is justified because the lowest age for the screenee is set at 40 years old. (author)

[en] Scintigraphy in nuclear medicine is an important aspect of the in vivo examination of organs of the human body. The RI distribution in tissues is obtained both stationarily and dynamically for diagnosis by this method. RI-imaging device is the photographic apparatus used for the scintigraphy. Historical development in the field and the future prospect are reviewed. Originating with so-called scanners, the device has developed to two-dimensional scanning now, and then to the fixed type such as Anger's scintillation camera. However, a three-dimensional RI-imaging device is necessary from the nature of diagnosis. As a new type of detector, there is semiconductor detector. For the future, the utilization of computers for processing image information is expected. (K. Mori)

[en] The aim of ultrafast XCT is to obtain transverse images of the heart. Thus, the XCT system must have no mechanically moving parts. One method would be to sandwich the patient in between many x-ray tubes and many detectors to catch the x-rays. The design and data processing system of the dynamic spatial reconstructor, an instrument based on this principle were introduced. Experiments have been done on animals. The other method by which the x-ray target is scanned with electron beams so it is irradiated from many directions was introduced. (Kaihara, S.)