PAC2 is honored to publish the following article prepared for the PAC2 community by Marilyn J. Goske, MD, on behalf of the Alliance of Radiation Safety in Pediatric Imaging. In it she outlines the need for "child-sizing" medical imaging doses to minimize the risk of secondary cancers. Image Gently is a wonderful initiative which can help us reduce the long-term effects our children face from the 'cure'. Thank you Dr. Goske!
Image Gently: A letter to parents and caregivers of children with cancer about medical imaging tests
Medical imaging and in particular CT scans have been one of the most amazing discoveries in the past thirty-five years in medicine. Within seconds, radiologists (physicians who specialize in performing and interpreting imaging studies) are able to see inside the body with little pain to the child undergoing the test. Scientific studies have shown that the use of CT has decreased the number of surgeries, decreased the amount of time for a child to be in the hospital or emergency room, and have helped us understand some childhood illness. Particularly in children with cancer, this test can help determine if the cancer is shrinking, if it has spread, if treatment can be stopped or needs to be continued or if the child’s fever can be caused by an infection. This is very important information for your doctor to know. However, since the late 1980s pediatric radiologists (radiologists with additional training and expertise in childhood illnesses), medical physicists, and government agencies have noted the increased use of CT scans in children and have advised using these tests when “justified” or needed because of the child’s illness. Since 2002, the Society for Pediatric Radiology sponsored a series of conferences focusing on CT and other imaging tests that use radiation. In spite of these efforts, it became clear that often children were being scanned using adult doses. How did this happen?
Ten to twenty years ago, if a chest x-ray was taken on a small child using adult settings, the x-ray would turn out “black”. The radiologic technologist, the medical professional who took the chest x-ray would know immediately that the film was taken at higher settings than needed. In CT scanning, the opposite is true. Up to a certain point, the more x-ray that is used, the better the image looks and the pictures appear sharp and the body is well seen. However, over time and with advances in the equipment, it became clear to many researchers that it would be possible to lower doses for children while still obtaining pictures that could make a diagnosis. If you think about it, you can lower radiation dose so much that you cannot even create a picture! (This would be like taking a picture in the dark without a flash.) That would not help your child or their doctor figure out what is wrong. The point of these tests is to use just the right amount of x-rays to get a picture that helps the radiologist and your child’s doctor diagnose a problem to help the child.
There are many groups throughout the country that are working on this very issue and I have high hopes that within the next five to ten years much of “child sizing” will be automated and built into computers on CT scanners. In the meantime, we have developed a campaign called “Image Gently” that works toward educating medical professionals, doctors who order these tests, government agencies, manufacturers of CT equipment, and the public about radiation safety. We formed an alliance called the Alliance for Radiation Safety in Pediatric Imaging in 2007. We now have over 58 member organizations including the American Academy of Pediatrics (AAP) and international member societies such as the International Atomic Energy Agency (IAEA). By forming an alliance, we work together to create awareness, free educational materials and educational conferences where all the professionals involved with imaging are present. We really need to and are working together to lower the radiation dose, but still make sure the tests are of good quality.
So, do CT scans cause cancer? Simply put, we do not know whether medical radiation causes cancer. A friend of mine said… “do you realize you may have developed a whole campaign for no reason?” That would be fine…as long as we are using the lowest radiation dose and getting the best information for your child as possible…that is what is most important. Therefore, it is important for us as medical professionals and those involved with medical imaging to act as cautiously as possible and use medical imaging when it is needed for a particular child. This means that we recognize the fact that many times CT scanning is the only way to get the information. For example, in certain kidney tumors which may travel to the lungs (metastases) CT scanning is the only method for identifying tiny amounts of tumor in the lung, some as small as 2 – 3 mm. These tiny tumors can simply not be seen with a regular chest x-ray. This test may be very necessary to inform your child’s doctor (pediatric oncologist) as it will often change the child’s treatment. Therefore, it does not mean that CT scans are not performed but rather requires that thought go into the performance of each scan, that it be “child-sized” and the benefit for your child’s particular situation be taken into account.
One question that is asked is, “How much radiation does a CT scan give to a child?”
The Image Gently website parent pamphlets give some relative radiation doses. For example, because a chest x-ray travels through the lungs which contain air, only a very small amount of radiation is needed. A head CT is thought to be like approximately 8 months of background radiation (the amount of radiation we get from living on earth and from the sun, soil and rocks). We are in the middle of gathering data from six children’s hospitals across the United States and attempting to determine what are the best CT settings to be used for different size children.
Radiation is a complex issue to discuss. We can’t see it, and we do not know what effect it will have on an individual child. We really do not know. We can only look at data from other scientific studies that look at large groups of patients (population studies) and try to estimate what may happen. Risk also involves a person’s genes that they inherited or their family history. Environment also plays a role. Currently, to my knowledge, there is no way to determine that a specific CT scan can cause cancer in a patient 20 – 30 years later. We are left then with attempting to do the right thing and act as if it may so that we use this amazing tool as thoughtfully as possible. It does not mean that we should be afraid of a CT scan…. But rather be thoughtful about its use and use the test to care for the child.
We urge you to visit the www.imagegently.org website. This can give you as parents more information as to an estimate as to how much radiation your child may receive from different tests.
As a parent or family member you may want to ask your doctor or the radiologist if the imaging for your child is being done at the lowest possible dose that is needed to care for your child. There are also ways for equipment to be accredited and demonstrated as using radiation doses that are “child-sized”.
I hope this brief letter has provided you with a little bit more information about this complex topic. Radiation safety is not the only thing to think about when your doctor requests a CT scan for your child’s condition. It is but one of many things to think about when trying to make treatment decisions for a life threatening illness such as cancer. This note is to let you know that there are many medical professionals and researchers as well at the equipment manufacturing companies who are working on this problem together.
Thank you for the opportunity for our group to speak with you all about this.
Marilyn J. Goske, MD
On behalf of the Alliance of Radiation Safety in Pediatric Imaging
Professor of Radiology
Corning Benton Endowed Chair for Radiology Education
Cincinnati Children’s Hospital Medical Center
Thank you for posting this, it has been such a topic with our Onco.