Radiation and contrast considerations


The entire trauma team should be mindful of the risks of radiation for both the patient and the team members. The number of x rays taken in the resuscitation area should be kept to a minimum and the installation of permanent lead barriers in the resuscitation room should also be considered. Staff should position themselves at a maximum distance from x-ray equipment wherever possible. Exposure should be minimised and staff should wear protective lead gowns and thyroid shields which will protect against ionizing radiation within recommended occupational limits.
Background radiation is the ionizing radiation present in the environment, it originates from a variety of sources, both natural and artificial. Sources include cosmic radiation, naturally occurring radioactive materials such as radon, fallout from nuclear weapons testing and nuclear accidents. The average human exposure to artificial radiation is 0.6mSv/a with a typical chest x-ray delivering 0.02 mSv.
 
Taken from Lin, E. (2010). Radiation risk from medical imaging.
Mayo Clinic Proceedings, 1141-1146.
 

  
Ionising radiation in X-ray and CT examinations may directly or indirectly damage DNA which may not be corrected by cellular repair mechanisms. This damage to DNA has been associated with an increased risk of developing cancer. The radiation dose from various diagnostic exams may be calculated as an “effective dose” for the purposes of comparison and quantification of risk. Effective dose, calculated in milliseverts (mSv), refers to the radiation dose from an examination averaged over the entire body and accounts for the different tissues exposed.
The typical CT scan gives tissue doses in the range of 10-30mSv. Tissue doses in the range of 50 -200 mSv have been shown to cause an increase in cancer among atomic bomb survivors and the risk is higher for lower age at exposure.
Radiation dose values should be considered as an estimate only. Doses vary depending on the size of the patient, the type of procedure and equipment and the operational technique used. This is particularly relevant for CT, where estimates of effective dose can vary widely.

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