Low-dose method of performing CT heart scans developed at Porter Adventist Hospital

Jul 17 2010

As warnings and concern increase over the health risks of commonly used scanning tests involving high doses of radiation, radiologists and scientists are seeking ways to improve the safety of the tools they use in diagnosing disease.

At Porter Adventist Hospital, for example, physicians and technicians have developed a relatively low-dose method of doing computed tomography (CT) scans of the heart, as well as ways to decrease radiation exposure in other routine procedures. CT heart scans are commonly used in detecting early heart disease.

"As the technology became more advanced and highly useful in diagnosing people with disease at an earlier stage, we grew concerned over the amount of radiation exposure patients may face over their lifetimes," said Dr. Simeon Abramson, lead heart CT radiologist at Porter. "We learned that it was possible to use software within our system that allowed us to reduce the radiation exposure in CT heart scans for most of our patients. The quality of the image has not been affected and we know that we are protecting our patients from potential harmful doses."

While CT scans are an important tool providing great medical benefits, they also involve much higher doses of radiation than routine X-rays. In fact - the radiation from a chest CT scan can be more than the radiation dose from 100 regular chest X-rays. The number of CT scans performed jumped from 3 million per year in the early 1980s to 70 million in 2007.

"The CT scan is a powerful clinical and diagnostic tool, and a non-invasive method to positively impact patient care, which is why we have seen such an increase in its use," Dr. Abramson added.

In two recent articles published in the Archives of Internal Medicine, researchers suggested that the increased use of diagnostic CT has led to an increase in certain cancers and cancer deaths in the United States. The American Association of Physicists in Medicine (AAPM) has offered guidance to its members recommending using the minimum amount of radiation needed to provide the diagnostic information requested in such tests.

A CT scan is a series of regular X-rays mounted on a circle and connected to a computer. The computer takes the shadows from the series of images done and reconstructs the images to show much greater detail than a plain film. Since it takes multiple X-ray beams to construct the image, the radiation dose is higher. So, CT scans are useful in seeing the organs inside of the body and finding tumors, infections and other problems. In fact, radiologists can now see the plaques in coronary arteries that used to require a cardiac catheterization to see.

Dr. Abramson and his colleagues have succeeded in reducing the dose of radiation for CT heart scans from the equivalent of 100 to 140 chest X-rays to the equivalent of 10 to 30 X-rays - making it less than the dose of radiation from the traditional cardiac catheterization - for patients meeting the size and heart rate criteria. This is done in part by turning off the X-ray during parts of the rotation that target sensitive areas, such as organs. This low-dose radiation scan provides the same quality image with no impact on cost or time for the test.

Additionally, Porter's radiology department has created a system to report the radiation dose from tests done at the facility to the patient's radiologist, as well as a system that encourages physicians to order the best and lowest radiation dose diagnostics for their patients.

"Our focus is on getting the physician the best quality information possible from these tests, but we are also focused on the safety and health of our patients," Dr. Abramson added.