|Fig. 1: Pocket dosimeter. (Source: Wikimedia Commons)|
Exposure to radiation has been a longstanding health concern; however, the quantification of this exposure is relatively new in medicine. Although commonly used radiology equipment, such as x-rays, pose small risk to human health, medical studies have been performed to evaluate doctors' knowledge of the radiation doses received by patients. In a study of 130 doctors from two separate hospitals, where each doctor was asked to estimate the equivalent doses of radiation for various radiological investigations, 97% of the answers were underestimates of the actual dose. 
Through advancing technology, the amount of radiation energy can be calculated to determine absorbed radiation by an individual due to both internal and external exposure. For external exposure, personal dosimeters, such as pocket dosimeters (see Fig. 1), are used in order to provide a measure of exposure.  However, in order to measure internal exposure, personal computer software can be used to calculate the absorbed dose in various organ tissues.  The combination of these measures results in the effective dose on the entire body, which can then be assessed to ensure that an individual is not exposed to radiation over the recommended dose limits set by national and international agencies.
Dose limits vary from country to country, but the use of physical dosimetry is important in all professions where an individual may be exposed to radiation. However, there are limitations to current technology used in personal dosimetry. In order to gather readings from personal dosimeters, it is assumed that the device is always worn and is worn properly. Furthermore, with some passive forms of dosimetry, such as film badges and thermoluminescent badges, the results must be analyzed in a laboratory and are not immediate. Also, the device's proximity to the source of radiation may result in localized exposure, and the results would not be indicative of the entire body's exposure to radiation.  Lastly, personal dosimeter readings do not account for the biological differences in the damage caused to the cells, the DNA mutation, or the abnormal cell function due to radiation, which is strongly correlated to the risks of mortality and morbidity from cancer. 
As nuclear medicine progresses, it has become increasingly important to develop accurate dosimetry for both the healthcare workers' and patients' safety. In the United States alone, nearly 20 million nuclear medicine procedures using radiopharmaceuticals and imaging instruments are performed annually. Further advancements of nuclear medicine will hopefully allow doctors to diagnose diseases, such as cancer, as well as neurological disorders, and cardiovascular disease using nuclear medicine.  Along with these new clinical applications, advancements in dosimetry must be made in order to ensure that the individuals involved are not exposed to radiation levels above the recommended dose limits.
© Walter Goodwin. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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