The second paper I’ll be discussing at the Penn Trauma reunion tomorrow deals with radiation exposure in trauma. Specifically, I’ll be talking about the amount of radiation the patient is exposed to during their initial evaluation. A lot of work is being published on this topic, but the paper I selected took a different and more accurate approach.
The trauma group at Sunnybrook in Toronto measured surface radiation exposure in a group of 172 major trauma patients. Dosimiters were placed on the neck, chest and groin, and were ideally kept there during the entire hospital stay. A software algorithm was used to calculate organ dose based on the surface measurements. This differs from the more commonly used method of counting studies and calculating dose based on published averages of radiation delivery.
The study was weakened by the number of patients that were excluded or who decided to remove their dosimeter at some point. But a number of interesting facts were revealed:
- Patients received an average of 5 CT scans and 14 plain xrays during their stay
- The average total effective dose was 23mSv, about 10 times the normal background exposure for an entire year
- A surprisingly high dose was delivered to the thyroid, which is more sensitive to radiation exposure
- A total of 190 extra cancer mortalities would be expected per 100,000 patients, given these exposure numbers
- Radiation was underestimated using non-dosimeter techniques
Bottom line: We know radiation exposure occurs in our patients, and we know that it’s increasing. It won’t be that long until we start to see the after-effects of these imaging studies, especially in younger patients. What you can’t see does hurt your patients! We need to quickly strike a balance between avoiding missed injuries and irradiating the patient. Specific guidelines to direct ordering of radiographic studies must be developed, and our radiology colleagues need to continue to strive for techniques that adhere to the ALARA (as low as reasonably achievable) philosophy.
Reference: Radiation exposure from diagnostic imaging in severely injured trauma patients. J Trauma 62(1):151-156, 2007.