CAMRT Radiography Practice Exam

In medical imaging, the relationship between slice thickness, image noise, and radiation dose is essential to understand for optimizing image quality while minimizing patient exposure. When the slice thickness is decreased by a factor of two, the amount of tissue being irradiated reduces, which in turn can lead to an increase in image noise. Noise is the random variation in the image that can obscure the structures of interest, and in radiography, it is often related to the amount of radiation exposure. To maintain constant noise when slice thickness is halved, the technologist must compensate for the reduction in the amount of radiation reaching the detector. Since the noise level is connected to the amount of radiation used, traditionally, halving the slice thickness will require a proportional increase in dose to maintain the same image quality. Specifically, the relationship dictates that to keep the signal-to-noise ratio constant, the dose must be increased by a factor of four. This is based on the principle that the noise is proportional to the square root of the number of photons detected. Therefore, if the area being imaged is reduced to a quarter (due to halving the thickness), the dose needs to be increased by four times to maintain the same level of noise. Thus, the correct factor