A new study raises a provocative question: Is radiation dose from medical imaging exams too low? The authors propose in a paper in Nature’s Communications Medicine that lowering radiation dose too much negatively impacts patient care by making exams less diagnostic. But radiation dose experts are pushing back on the claim.
Efforts to minimize medical radiation dose are almost as old as radiology itself.
- The arrival of CT in the 1970s saw a sharp rise in radiation dose exposure, but a series of radiation overdose incidents in the 2000s spurred new efforts to monitor and reduce dose.
Today, CT radiation doses are remarkably low, with some ultra-low-dose protocols enabling exams at levels below 1 mSv – only slightly higher than a chest X-ray at 0.1 mSv.
- Driving the decline are technologies like iterative data reconstruction, photon-counting CT, and protocol optimization, while dose could be lowered even further thanks to AI-based reconstruction techniques.
What’s more, CMS this year is launching new dose reporting quality measures designed to reward radiology practices for tracking and reporting radiation dose.
- Imaging practices will be able to secure additional reimbursement by complying with an electronic clinical quality measure (eCQM), CMS1074v2, issued by CMS to reduce excessive CT dose exposure.
That brings us to the new paper. Researchers from Duke University developed a statistical model that they believe balances radiation risk from imaging exams with imaging’s clinical benefit.
- They created a “detectability index” to quantify the benefit of imaging’s precise characterization of disease – which could lead to misdiagnosis if pathology isn’t adequately visualized – and weigh it against the lifetime cancer risk from an exam.
They then tested the model in a simulated dataset of 1M liver cancer patients, finding …
- The clinical risk of lower dose outweighed the radiation risk by 400%.
- Radiation dose should be increased for over 90% of abdominal CT scans under their formula.
But pushing back against the paper are advocates for radiation dose reduction, including radiologist Rebecca Smith-Bindman, MD, of UCSF.
- She points out that the use of imaging continues to grow exponentially, with little evidence to justify its benefit for many uses, and therefore every effort should be taken to minimize harms like radiation risk.
The Takeaway
The new paper shows that even concepts thought to be self-evident – like the benefit of radiation dose reduction – can still be open to debate. Time will tell whether the new paper gains traction in the discussion over radiation dose management.
