Perspectives on radiation dose in abdominal imaging
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ª Springer Science+Business Media New York 2013 Published online: 27 August 2013
Abdom Imaging (2013) 38:1190–1196 DOI: 10.1007/s00261-013-0028-2
Perspectives on radiation dose in abdominal imaging Tessa S. Cook, Susan Hilton, Nicholas Papanicolaou Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce Street, 1 Silverstein, Philadelphia, PA 19104, USA
Abstract Reported instances of patients’ overexposure to imagingrelated radiation have spurred the radiology and medical physics communities to identify and develop methods for decreasing the amount of radiation used to achieve diagnostic-quality images. These initiatives include examining and optimizing conventional CT scanning parameters, introducing innovative scan protocols, and incorporating novel dose reduction technologies. The greatest challenge to effective dose reduction in the abdomen and pelvis remains patient size. Here, we review the state of the art in abdominopelvic CT in both adult and pediatric patients and describe some of our own efforts in dose reduction for these types of examinations.
There have been well-publicized instances of patients’ overexposure to ionizing radiation from computed tomography (CT) brain perfusion examinations. In response to these events, the radiology and medical physics communities have ramped up efforts to educate physicians and non-physicians alike as to the benefits and risks of exposure to imaging-related radiation from CT, nuclear medicine, and fluoroscopy throughout the body. In addition, methods for dose reduction using both existing technologies and newer dose-lowering techniques have been developed and publicized. The challenge in effective dose reduction for abdominopelvic CT primarily relates to patient size and the number of phases of imaging that may be needed to make a diagnosis. Body habitus is a significant variable that can make it difficult to achieve diagnostic-quality images without using a substantial amount of radiation. In pregnant patients, depending on the gestational age of the fetus, many of the same issues are faced, with the additional challenge of minimizing exposure to the fetus Correspondence to: Tessa S. Cook; email: [email protected]
from either direct irradiation or scatter. Pediatric abdominopelvic CT is challenging for a different reason: smaller patients can be imaged using less radiation; however, this also affects diagnostic image quality because of the paucity of intra-abdominal fat to provide inherent contrast.
Relevant CT physics for dose reduction There are a number of CT parameters that ultimately affect the radiation dose received by the patient [1]. Reducing the kVp (X-ray tube voltage peak, measured in kilovolts) will decrease the energy of the photons used to create the CT image and ultimately exponentially decrease the dose to the patient. Decreasing the mA (X-ray tube current, measured in milliamperes) or the gantry rotation time (seconds), together represented as the mAs (X-ray tube current-time product), will result in a linear decrease
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