[Visualization of Effectiveness of the Medical Safety Measures -Suggestion of the Evaluation Technique for Rare Medical Incident].

For events with a low occurrence rate, such as medical incidents, we were able to determine the evaluation before and after taking medical safety measures by statistical methods (testing for differences in population rate). The point of this method is that we evaluated the occurrence rate of incidents to the total number of examinations (number of incident occurrence real number plus number of examinations carried out without any problems). Our results suggest that this technique becomes the evaluation technique as the effective method of medical safety measures. The present studies demonstrated that the evaluation technique by the testing for differences in population rate become the indicator to judge the effectiveness of the medical safety measures in the following cases. (1) When we evaluate the decrease in incident for the long term before and after safety measures. (2) When we evaluate the effectiveness of measures in the middle evaluation after safety measures.

[Examination of Ability to Support the Interpreting of CT Images of Emergency Transport Patients by the Radiological Technologist─About the Factors That Influences Image Interpretation Assistance─].

The Japanese Ministry of Health, Labor and Welfare announced a revision of the law about the expansion of duties by the radiological technologist in team medical care in April, 2010. In that respect, the importance of reading images with support from the radiological technologist became higher. We compared the interpretation results of the radiologist with the image analysis by the radiological technologist of the CT images of emergency patients. And we checked for symptoms and diseases which were frequently overlooked by the technologists. Inexperienced radiological technologists overlooked considerably more than experienced radiological technologists. Our results showed that abdominal or chest image analysis differed more often than head scan analysis. The reasons given for the differences include a lack of clear indication for abdominal tumors, and we overlooked a lot of diseases such as pneumonia and enteritis. We also had several cases of abdominal and chest images over-reading by radiological technologists. To improve these, radiological technologists should deepen their knowledge of normal anatomy and work to improve recalling diseases that are inferred from the patient's symptoms. This will greatly improve the image interpretation support by the radiological technologists.

Optimization of dual-energy subtraction chest radiography by use of a direct-conversion flat-panel detector system.

We aimed to optimize the exposure conditions in the acquisition of soft-tissue images using dual-energy subtraction chest radiography with a direct-conversion flat-panel detector system. Two separate chest images were acquired at high- and low-energy exposures with standard or thick chest phantoms. The high-energy exposure was fixed at 120 kVp with the use of an auto-exposure control technique. For the low-energy exposure, the tube voltages and entrance surface doses ranged 40-80 kVp and 20-100 % of the dose required for high-energy exposure, respectively. Further, a repetitive processing algorithm was used for reduction of the image noise generated by the subtraction process. Seven radiology technicians ranked soft-tissue images, and these results were analyzed using the normalized-rank method. Images acquired at 60 kVp were of acceptable quality regardless of the entrance surface dose and phantom size. Using a repetitive processing algorithm, the minimum acceptable doses were reduced from 75 to 40 % for the standard phantom and to 50 % for the thick phantom. We determined that the optimum low-energy exposure was 60 kVp at 50 % of the dose required for the high-energy exposure. This allowed the simultaneous acquisition of standard radiographs and soft-tissue images at 1.5 times the dose required for a standard radiograph, which is significantly lower than the values reported previously.

[Difference in the level of patient treatment safety analysed by the years of experience of the radiological technologists].

According to the report of the reporting project of medical accidents (from July 2010 to March 2011) which was issued by the Ministry of Health, Labour, and Welfare, a lot of incidents involving radiological technologists occurred among young ages or experienced ages; therefore, we focused on this matter. We carried out questionnaires for the radiological technologists at the radiology department of our hospital to see how concerned they are about the patient treatment safety. We examined the causal relationship between years of their experience and their concerns about the patient treatment safety. As a result, we found that their concerns about the patient treatment safety are characteristically different depending on the years of experience. The results showed that the new technologists were on a low level of caring with a similar philosophy to the saying "To err is human". They also lack a positive attitude. Moreover, they stated that the causes of the errors were neither the devices nor the system of the devices. Mid-career technologists stated that the most common cause of errors is the liability of the person concerned. They are concerned that education to improve individual abilities is important. Experienced technologists stated that the cause of the error is excluding the person concerned, but due to the devices, patients, or advanced specialization of the examinations. However, they also had the positive attitude to promote the patient treatment safety.

[The effect of the surroundings to the apparent diffusion coefficient on diffusion weighted imaging].

Diffusion weighted imaging (DWI) is now widely used in magnetic resonance (MR) imaging of the head and body. Moreover, the Apparent diffusion coefficient (ADC) value is often used for the differential diagnosis of the tumor. However, the effect of the surroundings on the ADC value has not been reported. In this study, we used the phantom completely sealed up to measure the change in the ADC value depending on the surroundings material. The results showed that the ADC value decreased according to the density of superparamagnetic iron oxide (SPIO) in the surroundings. Clinically, hemorrhage or iron deposit around the tumor may affect the ADC value of the tumor and result in under-estimation.