Importance of Radiation Safety in Computed Tomography

Advances in computed tomography (CT) technology have continued to open new clinical applications, including several procedures for evaluating heart disease. The speed with which CT technology is changing is somewhat unparalleled in medical imaging. The equipment is becoming faster and faster. In the 1990s, a patient had to remain in a CT gantry for a period of approximately 10 minutes for a chest CT, whereas now it takes a few seconds to scan the entire chest.
This may give the impression that radiation dose in CT is small, which is not the case. To give an example, a typical chest CT can impart a radiation dose equivalent to hundreds of chest radiographs. The offshoot of higher speed is that shoulder to pelvic scans or even head to pelvic scans are becoming more common, and this is raising questions of justification. Repeat scans on the same patients are also not uncommon. It is becoming clear that many CT examinations (typically one third) are unjustified and can be avoided through appropriate clinical judgment.
There is no doubt that newer technology has increased the usefulness of CT examinations in areas where earlier there was little justification of CT. It has been documented that radiation dose to the patient can be reduced significantly through optimization actions. However, repeated examination on the same patient, or examination on a child or pregnant woman, requires a higher level of attention to radiation doses and consideration of risks.
Appropriate training of personal performing CT procedures and reporting the scans needs to be emphasized. Computed tomography (CT) is the method that extends the clinical capabilities of X-ray imaging because of its high contrast sensitivity for visualizing soft tissues and the production of tomographic (slice) and three-dimensional (3D) volumetric images.
Another distinction of CT compared to radiography is that CT is a both valuable and complex imaging method that can be used for a wide range of clinical applications. Much of the value of CT comes from the ability to optimize image acquisition for a wide range of anatomical sites and visualization of pathologic conditions. This is achieved by adjusting the relatively large number of exposure parameters in the examination protocol factors to produce the required visibility of the clinical condition that is being evaluated.
Many of the variables also have an effect on the radiation dose to the patient. Therefore, in CT imaging, an optimized protocol is one that produces the required image information with the lowest possible radiation exposure to the patient.
The absorbed dose in CT is significantly higher than in radiography. Therefore, specific exposure management actions are required. It is necessary to distinguish between the absorbed doses to a specific tissues or organs and the total radiation energy absorbed in the body. Both are related to the risk to the patient, but in different ways.