What is the difference between receptor exposure and patient dose?

• A. Receptor exposure is the amount of X-ray energy reaching the receptor; patient dose is the energy absorbed by patient tissues.
• B. Receptor exposure is energy absorbed by tissues; patient dose is energy reaching the receptor.
• C. They are the same measurement.
• D. Receptor exposure measures radiation scattered by patient.

Answer: (A)

Receptor exposure refers to the X-ray energy that reaches and is available at the image receptor to form the image, essentially the incident energy at the detector. Patient dose is the energy actually absorbed by the patient’s tissues, expressed as absorbed dose in gray (Gy) and related metrics. So they describe different things: one is about what hits the detector, the other about what the patient’s tissues absorb. The energy that reaches the receptor may include transmitted and scattered photons, but it is not the same as the energy deposited in patient tissues.