According to an article published in the February issue of the Journal of the American College of Radiology, attention to radiation safety in the field of diagnostic radiology has recently increased, and yet, even at low levels, radiation can still present harm to the patient.
Shella Farooki, MD, radiologist and director of research for Columbus Radiology in Columbus, Ohio, wrote that epigenetics--which refers to changes in the appearance of gene expression caused by mechanisms other than alteration of the underlying DNA sequence--could potentially help researchers determine more conclusively if low-dose radiation can be associated with future risk.
In the article, Farooki wrote that according to the National Council on Radiation Protection and Measurements, radiation exposure has increased seven-fold since 1980. The ACR developed 33 recommendations for reducing radiation doses for diagnostic procedures and relative radiation levels have been added to the ACR Appropriateness Criteria. Despite these efforts, opposing views have been recently published regarding radiation dose and estimated potential risk.
“There remains a lack of consensus among the medical and scientific communities about the actual cancer risk from low-level radiation,” wrote Farooki. “One controversial study suggested that up to 2 percent of cancers in the U.S. may be due to CT radiation exposure. We must continue to practice amid this conundrum, showing due diligence through education, analyzing risk/benefit ratios, and adhering to the concept of keeping radiation doses as low as reasonably achievable.
Epigenetics involves DNA and chromatin modifications that continue from one cell division to the next despite a lack of change in the underlying DNA sequence and various factors that can cause the organism's genes to express themselves differently. The changes, or chromosomal instabilities, can span cell division and even multiple generations, noted Farooki.
The bystander effect, or effects of ionizing radiation in neighboring cells, have proven in past studies to span generations in mice, presenting in heritable birth defects, wrote Faroki. However, Farooki noted that epigenome functionality and radiation exposure need to be better understood before conclusions of risk vs. reward of radiation exposure can be reached.
“The effect of chromosomal instability is thought to be influenced by the genetic predisposition of the individual cell irradiated, the type of radiation exposure and the cell type,” explained Farooki, noting that the current focus of most radiologists does not account for the possibly of harm to future generations from radiation administered today.
“I believe that it is equally, if not more important, to consider potential harm to the patient's offspring and their offspring's offspring," she said.
Further studies are required to adequately determine if the investigation of epigenetics can play a role in the treatment of diseases, concluded Farooki, who wrote that the studies could potentially find “future trends in diseases linked to today's utilization of CT.”
"In the meantime,” she wrote, “we are faced with the continued struggle of radiation risk versus benefit."