Introduction
Medical professionals need a high-quality radiographic imitation of the patient region under examination to make an appropriate diagnosis. The placement and cooperation of the patient, exposure employed, and other variables must all be taken into account when evaluating the quality of an image. The photographic characteristics that influence image quality are density and contrast.
Spatial resolution and distortion are both parts of the geometric quality criteria. Together, these elements might offer a technical quality assessment method for radiography images. Despite the importance of the photographic and geometric quality factors, the diagnostic value is only successful when the right amount of each factor is present.
Density/IR Exposure
Among the two photographic characteristics that make up the visibility of detail is density, or IR exposure. The term “visibility of detail” relates to the idea that only in the presence of adequate IR exposure can the human eye detect the skeletal intricacies of a radiography image. The apparent clarity of the image has always been the outcome of the right amount of IR exposure, whether it is on a film screen or in digital photography (Carver et al., 2021).
However, nowadays, printing on film is less prevalent with digital imaging, yet in both scenarios, obtaining the right IR exposure is crucial for producing a viewable result. The ensuing density/IR exposure will decrease as mAs is reduced, and the reverse will occur (Carver et al., 2021). The quality of the image depends on the amount of density. The greater the density, the darker the image will be, and vice versa (Carver et al., 2021). Therefore, if the density is too high or too low, the results will be compromised.
Contrast Resolution
The variation in radiological density between adjacent areas of the image is referred to as contrast, a photographic feature. Sufficient contrast also greatly influences the visibility of detail. KVp is the main factor controlling contrast, and increased contrast results from decreased kVp, while decreased kVp results from increased kVp. Contrast renders the structure of the body more obvious (Long et al., 2020).
There is minimal variation in density between the structures of the body in images with insufficient contrast. They seem flat and gray, and the imaging densities of the details may be so identical that it is challenging to tell them apart (Long et al., 2020). Conversely, too much contrast will make the image too dark, which will compromise the quality of the image and make it unusable. In such instances, there will be places in images that are both exceptionally dark and exceptionally luminous, and it will be challenging to see small details. Therefore, an ideal contrast offers enough density differences to distinguish details across the whole image clearly.
Spatial Resolution/Detail
As for geometric quality factors, one of the factors is spatial resolution. Prior to the advent of digital imaging, it was known as recorded detail. Spatial resolution, often known as sharpness, definition, or just detail, describes the clarity of the image (Long et al., 2020). Whether an image seems clear or blurry depends on how sharp the outer edges of all its components are. The edges of components in an image are sharp and precisely depicted when the resolution is at its best (Adler et al., 2022).
When the resolution is low, the image often appears “fuzzy” or indistinct. Patient movement and the focal spot are crucial variables that influence spatial resolution (Adler et al., 2022). Therefore, a number of factors must be considered for the optimal quality of the image, and it involves the work of both the patient and the healthcare professional.
Distortion
Lastly, variations between the actual patient and its radiographic image are referred to as distortion, another geometric factor. All radiography images are distorted to some extent since the subject in question is three-dimensional, and the image is flattened, meaning that it is two-dimensional (Long et al., 2020). Distortion is an incorrect portrayal of the details under examination.
Radiographic distortion can be classified according to how much it mainly impacts an object’s size or shape. Uneven enlargement of the structure’s real shape leads to shape distortion. Occasionally, to avoid structures being superimposed or placed on top of one another, tube angulation or positioning is used (Carver et al., 2021). Nevertheless, superimposition may hide information in the primary topic, which is why distortion is occasionally accepted (Carver et al., 2021). Similarly, to the other mentioned factors, distortion must be of an optimal amount as well, since too high a value can lead to poor results.
Conclusion
Hence, the diagnostic value is only effective when the proper amount of each factor is present, notwithstanding the relevance of the photographic and geometric quality factors. Density—also referred to as IR exposure—represents one of the primary traits in photography that make up the visibility of detail. As mAs is decreased, the resulting density/IR exposure will decrease, and vice versa. Contrast is a photographic attribute that refers to the difference in radiological density between neighboring portions of the image.
A suitable amount of contrast also significantly impacts the visibility of detail. The spatial resolution might be one of the geometric features. When the resolution is high, the edges of image components are clearly visible and sharp, but they become blurry when the resolution is low. Distortion is the difference between the real patient and its radiological image. Shape distortion results from an uneven enlargement of the structure’s actual shape.
References
Adler, A. M., Stewart, K. L., & Carlton, R. R. (2022). Introduction to radiologic and imaging sciences and patient care. Elsevier Health Sciences.
Carver, E., Carver, B., & Knapp, K. (2021). Medical imaging. Elsevier Health Sciences.
Long, B. W., Frank, E. D., & Ehrlich, R. A. (2020). Radiography essentials for limited practice. Elsevier Health Sciences.