Читать книгу A Comprehensive Guide to Radiographic Sciences and Technology - Euclid Seeram - Страница 29

The ICRP optimization framework refers to optimization as keeping the dose ALARA and not compromise the diagnostic quality of the image. Therefore, optimization includes image quality and radiation dose.

The journal Radiation Protection Dosimetry dedicated a special issue to optimization strategies in medical imaging for fluoroscopy, radiography, mammography, and CT. Several studies identified at least four important requirements for dose and image‐quality optimization research. First, patient safety must be a priority in any study. Second, the level of image quality needed for a particular diagnostic task must be determined. The third requirement involves acquiring images at various exposure levels from high to low and in such a manner that accurate diagnosis can still be made, and finally, use reliable and valid methodologies for the dosimetry, image acquisition, and evaluation of image quality using human observers, keeping in mind the nature of the detection task.

An interesting study utilizing these elements of dose optimization is one by Seeram and colleagues published in Radiologic Technology in 2016. The purpose was to investigate a technique for optimizing radiation dose and image quality for a CR system. The researchers measure the entrance skin doses for phantom models of the pelvis and lumbar spine imaged using the vendor's recommended exposure settings (i.e. the reference doses) as well as doses above and below the vendor's recommended settings for both body parts. Images were assessed using visual grading analysis (VGA). The phantom dosimetry results revealed strong positive linear relationships between dose and milliampere seconds (mAs), mAs and inverse EI, and dose and inverse EI for both body parts. The VGA showed that optimized values of 16 mAs/EI = 136 for the anteroposterior (AP) pelvis and 32 mAs/EI = 139 for the AP lumbar spine did not compromise image quality. Selecting optimized mAs reduced dose by 36% compared with the vendor's recommended mAs (dose) values. The study concluded that optimizing the mAs and associated EIs can be an ED management strategy.