Michigan collaborative slashes radiation for cardiac CTs in half
Researchers say model can be replicated in virtually any hospital
A collaborative of 15 hospitals in Michigan, which included cardiologists and radiologists working side by side, has succeeded in cutting the radiation dose for CT angiography on average by more than half for almost 5,000 patients with no effect on image quality. The study, supported by Blue Cross Blue Shield of Michigan and Blue Care Network, was published in the June 10 issue of the Journal of the American Medical Association.
Participating hospitals included Beaumont Hospitals; Borgess Medical Center; Henry Ford Hospital; Hillsdale Community Health Center; Lakeland Regional Health System; Marquette General Health System; Mercy Health Partners-Hackley Campus; Mercy Memorial; Oakwood Hospital; St. John Hospital and Medical Center; St. John Macomb; St. John Oakland; St. John Providence Hospital; Sparrow Health System; and the University of Michigan Health System.
Data for the radiation-reduction project were collected on 4,995 patients at hospitals in the Advanced Cardiovascular Imaging Consortium, which was organized in 2006. "Blue Cross and Blue Shield and Blue Care work together with the medical community to decide if a program merits support," explains Marc Keshishian, MD, vice president & medical director of clinical affairs for the Blue Care network. "Dr. [Gilbert L. Raff, MD, a Beaumont cardiologist] came to us, suggested we develop a collaborative, and we worked together to develop it."
Keshishian says that seven such collaboratives are currently under way in Michigan in breast cancer, general surgery, geriatric surgery, angioplasty, peripheral vascular disease, and open heart or cardiac surgery, with varying numbers of participants. "Each time, we invite hospitals or physician groups to participate and each one makes a decision as to whether they want to participate," he explains.
The "Blues," he continues, do not receive hospital-specific data. "We believe that by having the hospitals work together, they can understand and work to develop best practices in these areas," Keshishian states. "Information is reported to a central location; that location evaluates the data and each hospital receives their own and every other hospital's data, but all that data is blinded except their own. That way, they can see how they compare to others; it opens up a dialogue that leads to best practices." All of the collaborations, he adds, are designed "to improve care in the state of Michigan."
Heart CT angiography, or coronary computed tomography angiography, has a 90% success rate in diagnosing heart disease, according to Beaumont, and is especially useful in identifying whether low-risk patients with symptoms have the disease. The scan's high dose of ionizing radiation is a barrier to its widespread use, but the project participants were able to reduce the radiation dose by an average of 53.3%, to about the equivalent of three years' background radiation. (This refers to radiation one would get from such sources as sunlight and radioactivity from the earth.)
Care required with radiation
When considering heart CT angiography — or any procedure requiring radiation, for that matter — great care must be taken, says Duane Mezwa, MD, corporate chair of radiology at William Beaumont Hospital. "First of all, you want to make sure every exam has a medical necessity; you certainly want to do it if it is indicated," he says. "This involves proper patient selection."
If the testing is necessary, he continues, you want to perform the study with the minimal dose possible that will still give you the diagnostic information you require. "We always push the envelope to try to strike that balance between the amount necessary to make the diagnosis and anything that is wasteful," he says. "Technology is being used by manufacturers in creating safer machines, but those of us who are caretakers of radiation use as little as possible to get the results we want."
But heart cancers are very rare; why such concern with CT angiography? "Not only is the heart being radiated, but there is scatter radiation in the rest of the body — such as breasts and lung tissue," Mezwa explains. "One of our concerns, for example, is with young patients who come to the ED and have repetitive scans at the age of, say, 19. We're concerned about too many of them coming in for a cough receiving a CT scan for pulmonary embolism."
In the case of the current study, the drive to find this balance played out in three stages. "First, we let people scan in normal fashion," Mezwa shares. "Then we tried to do some education, did the intervention, then came back and looked at the results."
Risk-reduction protocols
How was the radiation dosage slashed so dramatically? The physicians introduced several different risk-reduction protocols. "For one thing, they minimized the scan range as much as possible," says Mezwa, noting that the radiation homed in more closely on the area of the heart. "In the past, it would have started higher and ended lower; we used more tight parameters," he says.
In addition, says Mezwa, the doctors tried to get the patients to be scanned when there were more optimal heart rates; lower rates yield better images. "They used an EKG to trigger when the radiation turned on or off. They wanted to do the scan at a certain part of the cycle — they wanted it instantaneous with the rest point," Mezwa explains. "This way, they were only doing it at a time when they were most likely to get diagnostic information."
The most important part of the protocol, says Mezwa, was a reduction in kilovoltage, or the amount of radiation energy used to try to get a diagnostic study. "It's analogous to a CT colonography; when compared with the radiology necessary for a regular abdominal CT scan, it is cut in half. Even though you are scanning the same basic area, you are looking for different things, so you do not need as much radiation," Mezwa explains. So, for example, the reduced amount of radiation in a CT colonography would still be diagnostic for the colon, but it wouldn't be adequate for the kidneys, liver, or pancreas.
"The same is true in the heart," Mezwa continues. "When you use a lower dosage and look at all the parts being irradiated, you can pick up additional findings that may have nothing to do with why you did the test — such as lung cancers. You will still see them with lower radiation, but you would have to bring the patient back for a diagnostic test at the proper dose."
This could happen in about 10% of the patients, says Mezwa, but he asserts that this is an acceptable tradeoff considering how many patients will be spared an unnecessarily high dose of radiation.
Reducing future cancers
Keshishian says he is very excited about these findings. "Any radiation exposure can lead to cancer down the road; the more you are exposed, the more likely you are to develop it," he notes. "This approach will reduce the number of cancers in the future for those who receive such scans."
In fact, adds Mezwa, technology will enable even greater safety for patients. "We just bought three new CTs that will bring down the radiation to about one fifth of what we were able to achieve in the study," he says. "The equipment is moving faster than we can get these papers out."
However, he adds, Beaumont is just one of two or three facilities to deploy these new machines, which cost about $2 million each. Some hospitals may never be able to afford such equipment. In that case, can they replicate what the Michigan doctors have accomplished?
"Absolutely," says Mezwa. "People could put these protocols into practice tomorrow. You just have to become diligent about examination doses, and find ways to employ lowers doses and still get diagnostic information. That ability is out there using the current equipment."
Reference
- Raff GL, Chinnaiyan KM, Share D, Goraya TY, et. Al. Radiation Does From Cardiac Computed Tomography Before and After Implementation of Radiation Dose – Reduction Techniques. JAMA 2009;301(22):2340-2348.
[For more information, contact:
Marc Keshishian, MD, Vice President & Medical Director of Clinical Affairs, Blue Care Network, Collaborative Quality Initiatives-Blue Cross Blue Shield of Michigan. Phone: (248) 799-6843. E-mail: [email protected].
Duane Mezwa, MD, Corporate Chair of Radiology, William Beaumont Hospital, 3601 W 13 Mile Road, Royal Oak, MI 48073, Phone: (248) 898-5000.]
A collaborative of 15 hospitals in Michigan, which included cardiologists and radiologists working side by side, has succeeded in cutting the radiation dose for CT angiography on average by more than half for almost 5,000 patients with no effect on image quality.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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