American Society of Radiologic Technologist (ASRT) Practice Exam

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Prepare for the American Society of Radiologic Technologist Exam. Utilize flashcards and multiple-choice questions, with hints and explanations for each. Boost your confidence and ensure success!

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Which factors affect the spatial resolution of an image?

mAs and object-to-image distance (OID)
Source-to-image distance (SID) and focal spot size
kVp and mAs
Tube angle and kVp

The correct answer is: Source-to-image distance (SID) and focal spot size

Spatial resolution refers to the clarity and detail within an image, which is crucial in diagnostic imaging. The correct factors that affect spatial resolution include source-to-image distance (SID) and focal spot size. When considering source-to-image distance, increasing the SID improves spatial resolution. This occurs because a greater distance minimizes the divergence of the x-ray beam, thereby reducing the geometric unsharpness or penumbra, which enhances image clarity. Focal spot size also plays a critical role. A smaller focal spot size increases spatial resolution because it produces less blurring in the image. This is due to the more concentrated x-ray beam that emanates from a smaller area, resulting in sharper images of structures being imaged. Other options present different combinations of factors, but they do not specifically target the elements that directly enhance spatial resolution. While mAs, kVp, tube angle, and object-to-image distance can influence other image characteristics such as contrast and exposure, they do not have the same direct relationship with spatial resolution as SID and focal spot size do.