Answer to Question #4362 Submitted to "Ask the Experts"

As long as I have been a technologist I have always been taught to shield patients, whether it is general radiography or CT, etc. The basic rule has always been to shield a patient whenever the part of interest is not in the way of the lead to reduce the patient exposure and to reduce risk. This goes against everything I have been taught; however, when you calculate patient exposures they are always minimal, if none. So, it is being discussed and argued among my colleagues with newer beam restricting devices and close/fine collimation. Do we still need to shield our patients? Do we just shield patients within childbearing age?

Your questions are interesting as there are both health physics and sociological components to the answer. Let's approach the issue scientifically to start. Patient shielding is typically placed around the abdomen, presumably to protect the gonads. Here are gonadal doses from some typical procedures:

Reference: RADAR Medical Procedure Radiation Dose Calculator Web site

As you can see, any exposure outside of the general abdominal area results in very little exposure to the gonads. Clearly for chest, head, neck, and extremities exposures, dose reduction is not an issue. So the next question is whether shielding will help when the exposed area is near the gonads. Most scatter originates from the skin surface that the primary x rays hit and just below the skin surface. Since the lead drape is above the skin surface, it is not intercepting the source of most scatter (unless the patient is concave). It does intercept scatter in air and tube leakage radiation, but this is a small fraction of x rays scattered by the patient. 

If the gonads are in the primary beam and can be shielded, it is appropriate to do so if it does not interfere with the diagnostic quality of the image. This is confirmed by the Suggested State Regulations issued by the Conference of Radiation Control Program Directors (CRCPD), which states, "Gonad shielding of not less than 0.5 millimeter lead equivalent material shall be used for human patients, who have not passed the reproductive age, during radiographic procedures in which the gonads are in the useful beam, except for cases in which this would interfere with the diagnostic procedure." That the requirement to shield the patient is limited to procedures where the gonads are in the beam is, I think, evidence that the radiation protection basis for shielding in all cases is trivial. The American Society of Radiologic Technologists (ASRT) concurs, stating that radiosensitive organs (the thyroid gland and the male and female reproductive organs) are usually shielded when they are in the path of the x-ray beam.

But, there are reasons to shield the patient. Because lead drapes have been placed on patients receiving x rays for so long, they have come to expect it and are comforted by it. So, if you do not provide the lead drape, the patient's perception of you may be of a health care worker who does not care about his/her health and welfare. This does not help your hospital's patient satisfaction score. Further, in spite of its ineffectiveness, this is standard industry practice and failure to provide shielding to the patient may be considered a failure to follow appropriate safety procedures/precautions. 

Of course, providing the shielding perpetuates the exaggeration of risks associated with radiation exposure. Sorry. You can't win. 

Kent Lambert, MS, CHP