In diagnostic radiology, routine tests are recommended to ensure that the image quality (IQ) level assessed at the equipment installation keeps substantially unchanged over time. Current guidelines suggest that digital radiographic performance reproducibility can be evaluated by exposing daily/weekly/monthly phantoms containing several details regarding different aspects of image quality. The total number of details and their types vary between phantoms, but they often include series of low- and high-contrast details, different in size and shape, spatial resolution patterns, and step wedges for dynamic range and contrast resolution evaluation.
Digital images produced by modern equipments support the development of appropriate algorithms capable to automatically analyse phantom images and measure one or more objective image quality indices (IQI) from details available in the phantom. The evolution of IQIs over time can be used for monitoring long-term reproducibility of a radiological unit and detecting possible meaningful variations, which could be interpreted as “abnormal” over the normal statistical fluctuations of the imaging system. Traditionally, this is done by comparing the current value of each IQI with a reference level (baseline), by means of control charts, a graphical method introduced by Walter Shewhart to improve the quality of manufacturing processed by reducing their variability. Using multiple control charts to describe changes in image quality over time is extremely useful to
- assess the reproducibility of an imaging modality
- distinguish "abnormal" changes from the normal, inherent process variations.
AutoPIA Cloud is a web-based service that supports experts in monitoring the performance of radiological equipments without the need of being physically present.