Tag: medical radiation

CT Use Linked to Higher Radiation Exposure

Posted on by Brian Casey

A new study revisits the debate over CT radiation risk, finding a link between greater use of CT scanning in a country and the percentage of patients getting higher cumulative doses of radiation over time.

Managing medical radiation has been a priority for decades, but the issue gained new prominence in April with the publication of a controversial paper linking CT use to future cancers. 

  • Critics accused study authors of sensationalizing the radiation dose issue, but researchers pointed out that they used existing models for radiation dose and cancer risk.

Enter the new study, in which a team led by international radiation safety expert Madan Rehani, PhD, calculated the number of patients getting over 100 mSv of cumulative radiation dose over five years across 27 countries, mostly in Europe. 

  • Radiation at such levels is concerning due to the established dose-response nature of current radiation theory – that is, higher doses are believed to lead to higher cancer risk.

Radiation dose exposure rates for CT, fluoroscopy-guided interventions, and PET were analyzed for 2022 for 513M people from Austria to the U.K., with a particular focus on patients getting over 100 mSv in a five-year period. 

  • For point of reference, a chest X-ray PA view is typically 0.02 mSv, a CT scan 1-10 mSv, and the average for a year of background radiation is about 3 mSv.

Researchers found … 

  • In all, 0.27% of the population received cumulative radiation exposure over 100 mSv.
  • The countries with the highest rates of patients per 1k getting over 100 mSv included Belgium (4.52), Portugal (4.48), Luxembourg (4.19), and France (4.15).
  • These same countries also tended to have the highest use rates of CT exams per 1k population, led by Portugal (285), Luxembourg (249), Belgium (226), and France (224).
  • Countries with the lowest exposure rates over 100 mSv included Finland (1.09), Romania (1.1), Norway (1.64), and Bulgaria (1.76), and all had CT use rates below 100 exams per 1k population.

While the U.S. was not included in the study, other research shows it might fall at the upper end of the scale – if not at the top. 

The Takeaway

The new study offers a sobering take on the radiation dose issue. While reasonable people can debate the exact link between low-level radiation exposure and cancer risk, it’s harder to justify such wide variation in CT use and cumulative radiation exposure between countries, especially those at similar levels of economic development.

Is Radiation Dose Too Low?

Posted on by Brian Casey

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. 

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 some 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.

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