1) Identify and name the specific characteristics of a radiograph that determine quality and visibility of clinically significant features 2) Identify the design parameters and operating factors that determine ranges and values for each image characteristic. 3) Understand how changing the various image characteristics affects radiation dose to a patient. 4) Describe the general contrast sensitivity requirements for the various types of clinical procedures and how contrast is optimized. 5) Explain how each source of blurring in a radiographic procedure can be controlled and balanced to provide optimum visibility of detail. 6) Identify the primary source of visual noise in radiography and system factors that affect its appearance in an image.
Radiography is a complex imaging process that requires optimization of each procedure in order to maximize visibility of clinically significant structures and objects. Visibility of specific features is determined by a combination of individual characteristics, contrast sensitivity, blurring, and visual noise, with some potential effects from artifacts and the geometry of the imaging process. Each image characteristic is dependent on a combination of equipment design parameters and selectable operating factors. Many of the factors that are used to control image characteristics also have a significant effect on the radiation dose to the patient.
Am optimized procedure is one in which the factors have been selected and adjusted to provide the necessary visibility without unnecessary exposure to the patient. Factors for optimizing contrast sensitivity are heavily dependent on the anatomical environment of the objects being imaged. The relationship of blurring and noise is a significant issue in designing equipment that will have optimum characteristics for the different radiographic applications.
There are major differences between digital and film based radiography with respect to the factors affecting the image characteristics and the approach to optimizing procedures.
Sprawls, P,
Radiographic Image Formation and Characteristics. Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL.
http://archive.rsna.org/2006/4425857.html
