The Current Use and Effectiveness of Bismuth Shielding in Computed Tomography: A Systematic Review.
The use of computed tomography has increased exponentially since its introduction into the clinical setting in 1971. This growth comes as a consequence of numerous technological advances, namely multi-detector capabilities,
which have seen CT move to the forefront of medical imaging. Consequently, the expansion of CT has raised concerns regarding radiation exposure and patient-induced health risks.
CT contributes to a large portion of the population’s radiation exposure, subjecting patients on average to higher
doses than its medical imaging counterparts. It is these considerably higher doses that are fuelling concerns regarding the
lifetime attributable chance of fatal malignancy, estimated to range from 25 to 33 cases per 100,000 for pelvic, abdominal and chest CT procedures.
Additionally, concerns exist regarding the dose received by radiosensitive organs, specifically the thyroid, breast, gonads and lens of the eye. These organs are made up of radiosensitive cells and are regarded to have a greater stochastic risk of future malignancy with repeated exposure to ionising radiation. It is therefore important that all CT examinations are justified and implement practical and reliable dose reduction techniques.
In the past, lead shielding was the leading dose reduction strategy used in CT examinations. However, its use was replaced by bismuth shielding, which provided improved opportunities to reduce dose to superficial organs within the field of view.
While various studies have proven that lead and bismuth provide equivalent dose reductions; bismuth shields are designed for specific superficial organs and have the added benefit of being lightweight and easy to manoeuvre.
Radiol Open J. 2017; 2(1): 7-16. doi: 10.17140/ROJ-2-113
