Q/A with Tony Friedman (BIDMC HAEMR 2004)

The first entry (actually, the first three entries) will be taken from an earlier iteration of "B.I.T.C.H.E.S" - a previous graduate of the program, Tony Friedman, used to do a similar thing, which he (more politically correctly) named " Question Box". Some of the older residents in the program had saved a couple of these, which were all useful and interesting.

The first is on a topic that all ED residents know and love....(NOTE that these are copied directly from Tony's excellent work.

Total Resident Irradiation

THE QUESTION:

I've noticed that in a trauma, as soon as I hear someone yell "X-RAY!" I see a similar effect as if they had yelled "GRENADE!". Suddenly a huge flux of residents, nurses, and techs rushes for the door save for the unlucky few crushed underneath the horde. Foleys are left half inserted, laryngoscopes dangle from mouths, and syringes implanted in the femoral artery wiggle suggestively. After the danger has passed, everyone surges back into the room and tries to recall what was going on before the thermonuclear assault. Is all this really necessary? How dangerous are x-rays in a trauma?
THE ANSWER: This question has indeed been addressed in several studies. The most relevant, from 1994, assessed radiation exposure in surgical residents, ER attendings, and ER nurses according to dosimeters clipped outside of protective garments [1]. In one year, surgical residents were exposed to an average of 780 radiographs while ER attendings and nurses were exposed to 347 and 86 radiographs respectively. The average yearly exposure for surgical residents was 20 mrem, while ED attendings and nurses had average yearly exposures of about 3.5 mrem. Exposure per radiograph appeared to be approximately .03 mrem (lower for ER attendings, who presumably were watching safely from the corner of the room).
Much higher levels of exposure were found in a study from 1990 [2]. Residents were exposed to 481 radiographs over 3 months and sustained average monthly whole body exposure of 120 mrem, which extrapolates to a yearly exposure of approximately 1500 mrem. Average whole body exposure per radiograph was about 1.3 mrem, more than 40 times the average exposure seen in the first study described. I think this level is much less reflective of our exposure at BIDMC because their residents removed the cervical collar and manually stabilized the cervical spine during C-spine radiographs (duh!). Furthermore, at BIDMC plain radiographs of the cervical spine are rarely performed in trauma resuscitation. However, it would be useful to repeat the study due to the large discrepancy in average exposure per radiograph.
For the purposes of comparison, annual background radiation that we are all exposed to averages 100 mrem per year. In the 1994 study, even the most heavily exposed personnel received only an additional 20% exposure on top of background radiation. The National Council of Radiation Protection (NCRP) permits an annual occupational exposure of 5000 mrem, which further emphasizes the negligible exposure received during trauma resuscitations. Even assuming the exposure levels of the 1990 study, a worker would have to be exposed to several thousand films annually to exceed the NCRP recommendations.
Even for pregnant personnel, radiation exposure is not clinically significant. The NCRP permits occupational exposure of 500 mrem over the course of the pregnancy, which dwarfs the 20 mrem maximal annual exposure from trauma resuscitations.
This data suggests that it is not appropriate to interrupt a resuscitation, especially in the middle of procedures, in order to avoid radiation exposure. In addition, it is important to remember that these exposures were derived from dosimeters placed outside of protective aprons. Therefore, even the practice of wearing lead aprons in resuscitations owes more to superstition than it does to actual science.
References _1. Ciraulo et al. (1994) J Trauma 36:703 _2. Weiss et al. (199) Ann Emerg Med 19:134

(Reply from One of our attendings)

Tony
As usual great discussion but a few quick things. Your underlying premise is absolutely correct: We need not worry so much about incidental radiation exposure when in the room for X-rays, etc. However, you made a couple of mistakes with units. An "exposure" is not measured in Rem, it is measured as below:
Exposure:Roentgens (Common Units), Coulomb/Kg (SI units)
Radioactivity: Curie (CU), Becquerel (SI)
Absorbed dose: Rad (CU), Gray (SI)
Dose Equivalent: Rem (CU), Sievert (SI)
There are easy conversions between Common Units and SI units
Also, The Biologic Effects of Ionizing Radiation (BIER V) Committee of the National Research Council found if 100,000 people were exposed to a one-time absorbed dose of 10 rem (10,000 mrem) and were followed over their lifetime, about 790 more would die of cancer. A one-time dose of 10 rem is substantially more deleterious than a chronic exposure of much smaller units over time equaling 10 rem. As per your discussion this makes our exposure in routine radiography close to negligible.
Greg