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In the U.S., when we ask about radiation in medical imaging, we are usually just told not to worry about it. “It’s less radiation than you get flying across the Atlantic.” “The benefits of imaging outweigh the risks.”

All that is true, and yet, we can’t helping worrying a bit.

There are people in the world who take this question very seriously, none more than Dr. Madan Rehani, Director of Radiation Protection at the International Atomic Energy Agency in Vienna, Austria. Dr. Rehani and his colleagues have studied the use of radiation in medicine worldwide and are working to optimize its use.

In this interview, Joyce speaks with Dr. Rehani about radiation in medical imaging.

Medical imaging that uses ionizing radiation include Computed Tomography (CT), Mammography, and Fluoroscopy. The first question to ask is: is this the best type of imaging test to use to answer the medical question? Or might another modality that does not use ionizing radiation (such as MRI or Ultrasound) be used instead? Often MRI or Ultrasound will do the job just as well. But there are circumstances where CT is in fact needed:

  • CT gives the surgeon better pre-operative mapping information in certain areas
  • Ultrasound is highly dependent on the skill of the operator and the quality of the machine
  • Ultrasound is not sufficiently accurate to track the growth of small tumors
  • Ultrasound does not even see certain tissue types (such as the kidney tumors of HLRCC)

Dr Rehani talks about the recent advances in standardizing the terminology and calculations used by the various manufacturers of CT machines.

  • CT dose index (CTDI)
  • Dose Length Product (DLP)

giving us standard measures of the radiation delivered to the patient.

He also explains the use of Picture Archiving and Communications Systems (PACS) to enable hospitals to share images and their accompanying data over long distances. The vision is to enable all hospitals in the European Union to be able to share images electronically. PACS systems are in use in some hospital groups in the United States.

The dosage needed varies depending on the age and body mass index (BMI) of the person, and the organ being studied. Women need a slightly lower dose than men. Children are particularly sensitive. There is a concerted effort worldwide to take particular care in imaging children.

California is the first state in the U.S. to require recording into the patient’s record of the radiation dose administered. This is already standard practice throughout Europe.

In the U.S. it is not uncommon for a second round of imaging tests to be required for a second opinion. If images can be shared electronically with greater ease, this should rarely be medically necessary. The technology exists today to make this possible. It is already standard practice within many of the countries of Europe, and work is under way to enable it throughout the European Union. Electronic health records and consistent patient identifiers are keys to enabling this technology.

It is important to note that while we do want to be sure a CT is truly required (justifying the procedure) and that the right dose is chosen (optimizing the dose), we must keep this entire discussion in context. Any medical imaging procedure is certainly better than the old practice of “exploratory surgery” that was required before there was medical imaging. The radiation risks we are discussing are all much smaller than the risks of open surgery. We need and appreciate medical imaging! And we want to use it wisely.

Many thanks to Dr Rehani and his colleagues for the work they are spearheading worldwide.

Thank you.

mmxiv