Which tissue or material corresponds to the highest signal intensity at the image receptor?

Which tissue or material corresponds to the highest signal intensity at the image receptor?

• A. Soft tissue
• B. Bowel gas
• C. Bone
• D. Fat

Answer: (B)

In X-ray imaging, the signal the image receptor receives depends on how much of the X-ray beam is transmitted through the tissue. The more the beam is attenuated, the fewer photons reach the receptor, and the lower the detected signal. Gas in the bowels has extremely low density and imparts very little attenuation, so most of the X-ray photons pass through and reach the receptor, giving the highest transmitted signal. In contrast, bone attenuates X-rays strongly, so only a small fraction reaches the receptor, producing a weaker signal. Fat and soft tissue fall in between in terms of attenuation, giving intermediate receptor signals.

In X-ray imaging, the signal the image receptor receives depends on how much of the X-ray beam is transmitted through the tissue. The more the beam is attenuated, the fewer photons reach the receptor, and the lower the detected signal. Gas in the bowels has extremely low density and imparts very little attenuation, so most of the X-ray photons pass through and reach the receptor, giving the highest transmitted signal. In contrast, bone attenuates X-rays strongly, so only a small fraction reaches the receptor, producing a weaker signal. Fat and soft tissue fall in between in terms of attenuation, giving intermediate receptor signals.