[Failure analysis of medical linear accelerator with reliability analyses].

We analyzed a number of cases about the Linac troubles in our hospital and have examined the effect of preventive maintenance with Weibull analysis and exponential distribution from April 2001 to March 2012. The total failure by irradiation disabled was 1, 192. (1) Medical linear accelerator (MLC) system was 24.

[Development of software for estimating exposure dose and radiation exposure region in cardiac catheterization inspection].

We developed software for estimating exposure doses and radiation exposure regions in cardiac catheterization inspection. In the software, the back of a thoracic phantom were divided into a total of 21 square blocks with a width of 30 degrees. Furthermore, we developed a system with which reference air kerma is distributed to each of the above blocks in accordance with the distribution ratio calculated from the data obtained by the system, and the calculation results are displayed.

Overlap of radiation field and radiation field shape in cardiac catheterization.

The radiation field shape for cardiac catheterization has changed from being circular to being rectangular with the spread of flat-panel detector systems. A rectangular radiation field provides a wide fluoroscopy field to the four corners of a subject area; however, in cardiac catheterization, there is not much usable information around the four corners at several angles, and this tends to be regarded as a meaningless radiation exposure. Hence, overlap of radiation fields has been of concern recently.

[A characteristic of angiographic cone-beam CT].

Angiographic cone-beam CT, called DynaCT by SIEMENS, is a 3D imaging tool reconstructed from projection data by a rotational C-arm with a flat panel detector. It can visualize low-contrast objects such as soft tissue or small vessels as well as high-contrast structures such as enhanced vessels or bone. We need to understand its image characteristics and dose distribution during 200 degree rotation around a patient.

[Creation of a crystalline lens radiation exposure defense cover and the effect of radiation exposure decrease on neuro-interventions].

A variety of radiation hazards resulting from interventional radiology (IVR) have been reported in recent years. Particularly affected are the skin and the crystalline lens, with their high radiation sensitivity. During neurological interventions, the radiological technologist should consider decreasing radiation exposure.

[Importance of an initial check-up for diagnostic radiology apparatus management].

The management of apparatus for diagnostic imaging is an important job for radiological technologists. In the last 10 years we have encountered 2227 malfunctions in 3652 days. We detected 163 cases at the initial check-up, which accounted for 7.