Radiation Exposure is Carefully Controlled at UCSF

A recent article in Consumer Reports raises some important issues for all patients to think about regarding exposure to radiation from medical imaging procedures and overuse of Computed Tomography (CT).

Why worry about radiation with CT? The overall dose to the population from medical imaging has grown over recent decades. And until recently, the impact of the increasing radiation dose has been based on speculative estimates derived from studies of survivors of blasts in Hiroshima and Nagasaki 70 years ago. More accurate estimates emerging from patient studies now suggest a direct relationship between CT scanning and the risk of developing cancer, especially in children.

In any discussion of radiation and medical imaging, it is important not to forget the degree to which CT scanning has revolutionized the diagnosis and treatment of many common and life-threatening medical problems. It remains an important tool for prompt and effective medical care. But as the Consumer Reports article suggests, it should be used judiciously and performed properly to maximize its benefits and minimize risk.

I am sometimes asked by patients what our department does to ensure the safe use of CT and other imaging techniques. We are committed to minimizing radiation exposure at a very fundamental level. Our researchers are at the forefront of understanding the risk of radiation to patients. Their research guides our radiologists and technologists and allows us to adjust the radiation dose according to the reason for the scan, the patient size, and the body part being imaged.  Our CT techniques are routinely reviewed to maximize diagnostic accuracy and minimize radiation exposure.  Very low-dose protocols are routinely used when pediatric CT is necessary.  Some of the other steps we take are also worth noting:

1.      Choosing the most appropriate imaging study

Minimizing the exposure to radiation begins with selecting appropriate imaging for the specific needs of the individual patient. Our radiologists are available 24 hours a day, seven days a week to consult with referring providers regarding the relative benefits of imaging tests that may or may not involve radiation exposure, and we encourage the use of alternative techniques that do not involve radiation (e.g., ultrasound or MRI) when they provide the same information as a CT scan or other test with radiation. For example, we often use MRI instead of CT to evaluate inflammatory bowel disease and apply ultrasound and MRI to diagnose appendicitis in pregnancy.

2.      Careful quality control

To further minimize the potential risks of radiation, quality control procedures are routinely performed to assure that all imaging devices are operating correctly and safely. All CT scanners within the UCSF Department of Radiology & Biomedical Imaging exceed all national standards for radiation safety.

Unlike most other institutions, we have a policy of monitoring and proactively evaluating radiation exposure for CT and Interventional Radiology procedures. Doses for procedures are compared to standard doses, and threshold levels are used to ensure that all imaging tests use the lowest possible radiation dose.

3.      Latest CT technology for automatic radiation dose reduction

All UCSF CT Scanners are equipped with automatic dose modulation software that reduces the dose to various body parts during a scan. This software tailors the amount of radiation depending on the body part being imaged and the size of the individual. For example, less radiation is needed to image parts of the thorax than the abdomen, and less is needed for a smaller person or smaller body part than a larger one. Dose in some areas of the body can be reduced by as much as 50 percent compared to CT scanners lacking this technology. UCSF has also installed on all its CT scanners image reconstruction software that further reduces dose by up to 30 percent while providing images with the same diagnostic information. We continually invest in dose reducing technology as it becomes available.

4.      Special attention to pediatric patients

At UCSF we are most concerned about radiation exposure to our pediatric population. Several of our radiologists specialize in pediatric imaging. Ultrasound and MRI, which require no radiation at all, are almost always used in this vulnerable group.

When it is necessary to image children, we use state-of-the-art radiographic equipment. We use collimation or coning, techniques that restrict the X-ray beam so only the region of interest is emphasized. The X-ray output is adjusted according to the child’s size. When a CT scan is necessary, we have special very low radiation dose protocols for children.

5.      Shielding

We employ shielding to reduce the dose to certain body organs when possible. In CT, bismuth shields are placed over female breasts, the thyroid, and eyes whenever possible. Especially in pediatric patients, these shields minimize exposure to these sensitive organs. In projection imaging, when testicles or ovaries are in the region being imaged, lead shields are placed over these organs, except for cases in which this would interfere with the diagnostic procedure.

6.      Beam collimation policy

For general X-ray procedures, the X-ray beam is carefully restricted to the area of clinical interest, a process called collimating.

7.      Radiation Oversight Committee

Cynthia Chin, MD, a neuroradiologist in our department, chairs UCSF’s Radiation Oversight Committee.  The committee oversees the proper use of radiation-intense protocols and educates patients and providers regarding imaging algorithms to minimize exposure to radiation when possible.

Another tip to patients: When getting a CT scan, ask the providers at the imaging center what they are doing to ensure the safe and effective use of this important imaging technique.

You can read more about patient safety in the UCSF Department of Radiology and Biomedical Imaging.