Final answer:
The early practice involving the variable kVp system in radiology required adjusting the kVp level based on the thickness of the area being imaged in order to optimize the contrast and quality of x-ray images.
Step-by-step explanation:
The early practice involving changing kVp (kilovoltage peak) based on thickness using a variable kVp system has its roots in the field of radiology. This method was used for improving the quality of x-ray images. The practice entails adjusting the kVp level based on the thickness of the area being imaged, with the understanding that a thicker part of the body, such as a torso, requires a higher kVp to penetrate the tissue effectively, compared to a thinner part, like a limb. This adjustment was believed to optimize the contrast and detail of the radiograph.
The guideline often followed was to increase kVp by 2 for each centimeter of tissue thickness after the first few centimeters. However, as technology improved, this method was largely replaced by a fixed kVp technique, which provides consistency, reduces radiation exposure, and simplifies the imaging process.