CAMRT Radiography Practice Exam

Which factor does NOT affect resolution in radiography?

1. OID (Magnification distortion)

2. SID (Magnification distortion)

3. Film speed

4. Focal spot size

The correct answer is: Film speed

Film speed refers to the sensitivity of the imaging receptor to ionizing radiation. While it has significant implications for image exposure times and overall image quality, it does not directly affect spatial resolution. Spatial resolution is the ability of an imaging system to distinguish between small objects that are close together, and it is influenced by factors such as object to image distance (OID), source to image distance (SID), and focal spot size. OID can introduce magnification and distortion, affecting the clarity and sharpness of the image. Similarly, SID impacts the degree of magnification, with increased distance generally improving resolution by minimizing divergence of the x-ray beam. Focal spot size, which refers to the size of the x-ray tube's focal point, plays a critical role in determining the sharpness of the image; smaller focal spots produce sharper images. In contrast, while film speed can enhance or diminish the overall quality of an image due to exposure efficiency, it does not specifically relate to the resolution capabilities in terms of sharpness and detail.