A study on fluoroscopic images in exposure reduction techniques - Focusing on the image quality of fluoroscopic images and exposure images.

The quality of the present day fluoroscopic images is sufficiently high for use as exposure images depending on the environment where the fluoroscopic images are recorded. In some facilities which use fluoroscopic images as exposure images they are recorded with a radiological x-ray diagnostic device equipped with a fluoroscopic storage function. There are, however, cases where fluoroscopic images cannot be used as exposure images because the quality of the fluoroscopic image cannot be assured in the environment where the fluoroscopic images are recorded. This poses problems when stored fluoroscopic images are used in place of exposure images without any clearly established standard. In the present study, we establish that stored fluoroscopic images can be used as exposure images by using gray values obtained from profile curves. This study finds that replacement of stored fluoroscopic images with exposure images requires 20.1 or higher gray scale value differences between the background and signal, using a 20 cm thick acrylic phantom (here an adult abdomen as representing the human body) as the specific geometry. This suggests the conclusion that the gray value can be considered a useful index when using stored fluoroscopic images as exposure images.

[Proposal for an auxiliary tool designed to reduce retake rates for lateral radiography of the knee joint].

The reproducibility of lateral radiography of the knee joint in the lateral position is low because patient positioning can be easily affected by passive rotation of the knee joint. We calculated the correction angle of the femoral external rotation and the lower leg elevation and developed our own auxiliary tool for obtaining a lateral view image. We were able to obtain, in a single attempt, an image with misalignment of the condyle limited to less than 7 mm. Our tool also contributed to the reduction of the re-imaging rate, suggesting its usefulness in contributing to a lower re-imaging rate for lateral radiography of the knee joint.

[Survey on scanning pediatric patients' heads with CT].

Pediatric patients are especially sensitive to radiation, and when scanning their heads with CT, it is necessary to do so with a low dose and pay very close attention. However, there are many problems when scanning pediatric patients, and it is often confusing to set the conditions for scanning. To do a survey and comparison, we issued a questionnaire to 23 pediatric hospitals and 89 university hospitals, asking about their usage of sedation, studied disorders, as well as how and under what conditions they scan their patients. The percentage of response was 40% in total. Based on the questionnaire results, we could not see much difference in the conditions for scanning. However, there was a significant difference in the usage of sedation and studied disorders between pediatric hospitals and university hospitals. The most studied disorders at pediatric hospitals were convulsion and consciousness disorders, and low-contrast areas such as the albocinereous, which requires images without movement artifacts. In order to obtain clear images, the patient was put under sedation. On the other hand, university hospitals often deal with external injuries, which usually involve danger in using sedation, and patients are usually examined without it. In addition, the usage of sedation is rare because bleeding brings up high-contrast images, and it is easy to make a diagnosis even if there is some movement artifact. Also to aim at setting a standard for medical technology, from here on, guidelines of examining methods and setting conditions should be made depending on how the different disorders should be treated.