Medical Physicists Key to “Image Gently™” Success Campaign aimed at prudent pediatric imaging continues strong national push
Since the Jan. 22 inauguration of the Image Gently™ campaign, the message from the four charter members of the Alliance for Safety in Pediatric Imaging — the Society for Pediatric Radiology, the ACR, the American Society of Radiologic Technologists and the American Association of Physicists in Medicine — has been directed at the nation’s radiologists and radiologic technologists.
But medical physicists, as the go-to experts on the technical aspects of imaging, also have key roles in ensuring the campaign’s success.
That’s the word from medical physicists E. Russel Ritenour, Ph.D., past chairman of the board of the American Association of Physicists in Medicine, and James M. Hevezi, Ph.D., chair of the ACR Commission on Medical Physics.
Throughout its anticipated run, the Image Gently campaign will underscore one key point: Children may be more sensitive to radiation received from medical imaging scans than adults, and cumulative radiation exposure to their smaller bodies could, over time, have adverse effects. Therefore, radiologists who perform imaging exams on children are urged to:
* Significantly reduce, or “child-size,” the amount of radiation used
* Scan only the indicated area
* Scan once: Multi phase scanning (pre- and post-contrast, delayed exams) is rarely helpful
* Involve your medical physicist to review your adult and pediatric CT protocols.
* Work with technologists to implement changes
“Radiation sensitivity is a relatively new finding,” Ritenour said, “but recent scientific presentations and refresher courses have made it more familiar to medical physicists.” As the Image Gently campaign continues its national push, he said, “A lot of medical physicists are now getting contacted by physicians for consultation. We are heartened to see this important, updated information reach the nation’s imaging teams.”
The Image Gently campaign emphasizes the judicious use of pediatric imaging. “First, children have higher sensitivity to radiation,” Hevezi said. “Second, the software in scanners automatically compensates for higher than necessary technique,” leaving the radiologist with an excellent image, but no corresponding feedback. “Third, this higher than necessary technique may produce no immediate, measurable, biological indication of any kind. The effects might not be seen for decades.”
The issue of radiation safety is indeed important, but Ritenour and Hevezi urge perspective. “CT has tremendous medical uses that have opened new doors and replaced many dangerous, invasive techniques,” Ritenour said. “Ultimately, we are trying to use CT in the best way possible by minimizing the risk and maximizing the benefit.”
“If there is good reason for doing the examination to extract the diagnostic information to help the patient, then certainly, the risk associated with not doing the examination is greater than the small risk of doing the examination,” Ritenour said,
The answer is teamwork. The Image Gently campaign encourages radiologists to involve medical physicists in reassessing pediatric CT techniques. “Medical physicists are uniquely qualified to aid the radiologist and technologist in adjusting or developing protocols to image the pediatric patient,” Hevezi said. “Using objective measurement tools, medical physicists can establish techniques that produce the best image quality at the lowest radiation dose."
Ritenour identifies several “straightforward things we can do right away” to help lower pediatric dose levels without compromising image quality. “We can reduce milliamperage. We can decide if fewer slices than standard protocol are acceptable. When provided the right information by a medical physicist, a radiologist can assess if a modification in techniques will impact the image quality. In many cases, it may not change it,” he said.
Marilyn Goske, M.D., chair of the Alliance for Safety in Pediatric Imaging and chair of the Board of Directors of the Society for Pediatric Radiology, noted that imaging centers and hospitals can now access scientifically validated protocols to compute appropriate mAs for age groups, independent of the age of the CT scanner or manufacturer. These CT protocols — pioneered by Keith Strauss, MSc of the American Association of Physicists in Medicine, in conjunction with Richard L. Morin, Ph.D., and Priscilla Butler, M.S. ACR Senior Director of Breast Imaging Accreditation Programs — are designed to result in a radiation dose that is approximately equal to or less than an adult CT dose for the same procedure. They are available on the www.imagegently.org Web site.
“The new CT protocols provide a simple method to allow any hospital with any CT scanner to impact the radiation protection of children by ensuring that the dose they deliver to children is ‘child-sized,’ said Strauss. Medical physicists should prepare to measure standard CTDI doses on their institution’s CT scanners. These baseline doses allow the calculation of the proper ‘child-sized’ techniques from correction factors provided in the CT protocols. Even further dose reduction is encouraged as long as the resulting image quality satisfies diagnostic needs.”
Technical background and additional guidance is provided in the new AAPM Task Group 23 report, “The Measurement, Reporting, and Management of Radiation Dose in CT, ” chaired by Cynthia McCollough, Ph.D. The appendix includes manufacturer-specific tables with age- or size-based techniques; the report is available at www.aapm.org/pubs/reports/RPT_96.pdf.
As the Image Gently campaign increases awareness, Ritenour said medical physicists who do not routinely work with CT may be asked to assist radiologists and other physicians. These medical physicists, he said, can find ample information about radiation doses on scanner screens and in manuals. Utilizing these data — along with tissue weighting factors — medical physicists can help radiologists understand effective dose levels.
Imaging stakeholders can visit the Image Gently Alliance Web site (www.imagegently.org) for the latest research and educational materials, including information on optimizing CT protocols in pediatric patients. The campaign is partly funded by an unrestricted educational grant from GE Healthcare.