If kVp is too high the image will be over exposed and too dark. If kVp is too low, the image will lack density resulting in a whitewashed or sooty appearance. Increasing kVp increases the penetrating power of the x-ray beam. The correct kVp will produce differential x-ray absorption of soft and dense anatomic structures. The major way to depict these is in the selection of the kVp used to image the area of interest. For example, you want to display the differences between the bone cortex, the bone marrow cavity and the surrounding muscle or display the difference between the liver, the falciform fat, the intestinal wall and the intestinal lumen or display the difference between the air filled region of the lung, the pulmonary vessels and the heart. The type of tissue in the region of interest constitutes the subject contrast which is what you want to display. The type of film or screen system being used.The type of x-ray machine (specifically the type of.The type of tissue in the region of interest.In order to take a quality radiograph that details as much diagnostic information as possible the following factors must be considered: The mAs (milliampere seconds) determines the number of x-rays produced per unit time and the number of x-rays reaching the film determines the degree of blackening of the film. In the previous issue “Physics of Radiology” we discussed that kVp (kilovolt peak/kilovolt potential) gives variable “speed” to the electrons determining the penetration of the x-ray beam, which affects the efficiency of x-ray production, and determines the scale of contrast in the image. Through quality assurance and equipment care, these faults can be avoided, or rectified quickly preventing unnecessary repeat radiographs and extended anesthesia for the patient. The most common cause of poor contrast in radiographs is inappropriate exposure factors. DRĪ number of faults can occur that are detrimental to the diagnostic value of a radiograph, which is why it is important to understand the exposure factors that affect radiograph quality. Choosing the Appropriate Exposure FactorsĬourse 2 – Choosing the Appropriate Exposure FactorsĬourse 4 – Poor Quality Films-Causes and CorrectionsĬourse 5 – Radiation Safety-Importance and ProceduresĬourse 6 – Pros and Cons of Digital Radiography-CR vs.
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