CT Dose Summit to establish freely available guidelines for performing CT scans

Medical physicists, radiologists, technologists and equipment manufacturers gather in Atlanta, Ga., to establish freely available guidelines for routine procedures

A national "CT Dose Summit" in Atlanta, GA this week will bring together some of the world's leading experts on medical imaging to lay the foundation for assembling optimized guidelines for performing CT scans -- a common medical imaging procedure that uses X-rays to show cross-sectional images of the body.

The summit, which takes place April 29-30, will be hosted by the American Association of Physicists in Medicine (AAPM), a professional organization whose members are board-certified health professionals and research scientists specializing in the use of radiation in medicine. The summit itself is a working meeting that is closed to the press, but reporters who are interested in speaking to any of its organizers or invited speakers can arrange for interviews by contacting Jason Bardi at 858-775-4080 or [email protected]

The goal of the summit is to lay the foundation for establishing a set of consensus protocols, which will help to ensure that life-saving CT exams can always be done as safely and effectively as possible. These protocols -- or scan instructions -- vary considerably according to the particular procedure, the age and body type of the patient, and the make and model of the CT scanner.

Up to now, hospitals and imaging centers have developed their own protocols, typically based on the ones that come from their system's manufacturer.

Starting with protocols developed at some of the nation's largest and most prestigious hospitals, the AAPM plans to work with technical experts from throughout the imaging community, including leading radiologists and manufacturers, to develop consensus protocols that will be freely available via the Internet.

"These protocols determine the quality of the CT exam. With the increased capabilities and complexities of modern CT systems, it doesn't make sense to reinvent protocols at every institution," says Cynthia McCollough, Ph.D., an AAPM member and co-organizer of the summit. "Users are asking for optimized protocols, and we're responding to that need."

Medical imaging techniques such as CT scans have become more and more sophisticated in the last few years and have revolutionized medicine. CT scans are safe, life-saving procedures that help doctors treat millions of people each year in the United States. By providing clear pictures from deep inside a person's body, they have nearly eliminated exploratory surgery and have replaced many more risky or less accurate alternatives.

CT scans are critical for guiding the treatment of people who are in car accidents, people diagnosed with cancer, people who have blood clots in their lungs, and people suffering from a vast number of other symptoms and conditions.

Since CT scanners employ X-rays, which in high doses have the potential to damage cells and cause cancer, hospitals and clinics follow the general practice of always seeking to minimize CT dose -- a measure of the X-ray exposure a person receives while undergoing a scan.

The standard in modern medicine is to maximize the benefit while minimizing the risk by keeping the doses as low as reasonably achievable (a principle so commonly discussed in professional circles that it is often referred to by the acronym ALARA).

Modern CT systems have the capability to achieve these objectives, but they must be used wisely and with the guidance of established protocols. These protocols identify the equipment settings and define starting points for a given procedure. No one set of equipment parameters is perfect for every situation, so even after choosing a protocol, doctors will sometimes adjust and adapt according to the needs of their patients. Nevertheless, the protocols serve as valuable starting points for the exact equipment parameters needed for a procedure.

The AAPM has long led efforts to support the use of standards for measuring and minimizing radiation dose in medical applications, including CT procedures. Hospitals and clinics employ AAPM members to help establish and review CT protocols, check the proper functioning of scanners, and adapt protocols as the technology changes.

In the last several months, many medical physicists have witnessed first-hand how some patients have grown concerned about stories in the media questioning the risks and challenging the safety of CT scans.

"We all hear it every day" says Dianna Cody, Ph.D., co-organizer of the Atlanta summit. "Patients ask: do I really need to have this procedure?"

Cody states in no uncertain terms that patients should not be afraid of getting medically appropriate CT exams. When medically justified, she says, the benefits of CT scans always far outweigh the risks.

Even though the risk to patients is very small, or even negligible, their fear can be very real, and the Atlanta CT Dose Summit arose partly as a response to these fears. Planning for the summit began at a meeting in Chicago late last year where physicists were discussing what more their field could do to ensure patient safety and to reassure patients coming for CT.

The summit will begin by reviewing the fundamental principles of protocol design and will then examine protocols for the most common types of CT examinations, from routine imaging of the head and body, to newer applications such as cardiac CT and CT perfusion imaging. As the highest dose CT procedure, the AAPM has started their protocol optimization with CT perfusion. Their consensus guidelines will soon be publicly available resource to help practices nationwide be sure they are performing this examination correctly.

"This will move us a long way forward," says William Hendee, Ph.D., the third co-organizer of the summit.