Slashing CT Radiation Dose

Cutting CT radiation dose should be the goal of every medical imaging facility. A new paper in European Radiology offers a promising technique that slashed CT dose to one-tenth of conventional CT – and just twice that of a standard chest X-ray.

CT’s wide availability, excellent image quality, and relatively low cost make it an invaluable modality for many clinical applications.

  • CT proved particularly useful during the COVID-19 pandemic for diagnosing lung pathology caused by the virus, and it continues to be used to track cases of long COVID.

But patient monitoring can involve multiple CT scans, leading to cumulative radiation exposure that can be concerning, especially for younger people.

  • Researchers in Austria wanted to see if they could use commercially available tools to produce ultra-low-dose CT scans, and then assess how they compared to conventional CT for tracking patients with long COVID.

Using Siemens Healthineers’ Somatom Drive third-generation dual-source CT scanner, they adjusted the parameters on the system’s CAREDose automated exposure control and ADMIRE iterative reconstruction to drive down dose as much as possible.

  • Other ultra-low-dose CT settings versus conventional CT included fixed tube voltage (100 kVp vs. 110 kVp), tin filtration (enabled vs. disabled), and CAREDose tube current modulation (enabled – weak vs. enabled – normal). 

They then tested the settings in a group of 153 patients with long COVID seen from 2020 to 2021; both ultra-low-dose and conventional CT scans were compared by radiologists, finding … 

  • Mean entrance-dose radiation levels with ultra-low-dose CT were less than one-tenth those of conventional CT in (0.21 mSv vs. 2.24 mSv); a two-view chest X-ray is 0.1 mSv
  • Image quality was rated 40% lower on a five-point scale (3.0 vs. 5.0)
  • But all ultra-low-dose scans were rated as diagnostic quality
  • Intra-reader agreement between the two techniques was “excellent,” at 93%

The findings led the researchers to conclude that ultra-low-dose CT could be a good option for tracking long COVID, such as in younger patients. 

The Takeaway

The study demonstrates that CT radiation dose can be driven down dramatically through existing commercially available tools. While this study covers just one niche clinical application, such tools could be applied to a wider range of uses, ensuring that the benefits of CT will continue to be made available at lower radiation doses than ever.

RTs and Radiation Dose

There’s good news and bad news from a new study in Journal of Vascular and Interventional Radiology that tracks 40 years of occupational radiation dose to radiologic technologists who assist with fluoroscopically guided interventional procedures. The good news is that radiation dose is low and trending lower over time; the bad news is that dose to RTs can vary based on work setting. 

As we discussed last month, interventional radiology has delivered major benefits in patient care, replacing invasive surgery for many clinical applications. 

  • But the downside of interventional procedures is that they are performed for extended periods under fluoroscopy guidance, and more complex procedures are requiring longer times with the fluoro beam on – potentially leading to more radiation exposure. 

Researchers from the NIH wanted to investigate how changes in interventional use over the past 40 years affected occupational radiation dose exposure to RTs, while also looking at the impact of radiation exposure control methods. 

  • They reviewed records from 1980 to 2020, starting with RTs participating in the US Radiologic Technologists (USRT) research study who they then linked to data submitted to radiation dosimeter badge maker Landauer. 

In all, 19.7k RTs who reported assisting with fluoroscopically guided interventional procedures over the study period were included, with researchers finding … 

  • Median annual radiation dose of 0.65 mSv, well below the occupational limit of 20 mSv
  • Median doses were highest in the 1980s and decreased over time, reflecting greater awareness of patient radiation dose and better radiation protection gear
  • A second peak in radiation dose happened from 1999-2011, most likely due to more sensitive dosimeters
  • RTs who worked closer to patients (<3 feet) had higher median annual dose, at 1.20 mSv
  • RTs who reported assisting with ≥ 20 procedures per month had higher dose, at 0.75 mSv

The researchers concluded that their findings show that radiation dose control measures are working, and better radiation dosimetry technology offers a far more accurate picture of how much dose RTs are actually exposed to. 

The Takeaway

The study’s findings should give technologists who assist with interventional procedures peace of mind that their radiation dose exposure is well within established limits. But as always with radiation exposure, vigilance is warranted. 

MSK Problems Weigh Down Interventional Radiologists

Musculoskeletal problems are common among interventional radiologists, caused by many hours wearing heavy radiation protection gear. That’s according to a new study in European Journal of Radiology which found that almost half of interventionalists suffered from multiple orthopedic problems, issues that forced a significant portion to either reduce or stop their interventional practice. 

Interventional radiology has been responsible for major improvements in patient care through image-guided procedures that are noninvasive and can eliminate the need for open surgery, reducing patient recovery times to hours rather than days.

  • But these advances can come at the cost of higher radiation doses to the personnel who perform and assist with interventional radiology procedures, which has led to issues such as higher breast cancer rates among women who work with image-guided procedures and even DNA damage in cases of long-term exposure.

Radiation protection gear is worn by interventionalists to mitigate that radiation risk, but this gear is heavy and can carry risks of its own, which were investigated by researchers from the University Hospital Marburg in Germany. They conducted a 17-question survey of orthopedic problems among interventional radiologists, receiving 221 responses indicating that …

  • Some 48% of responders experienced more than five orthopedic problems during their interventional career
  • Problems of the lumbar spine were reported by 82% of respondents, followed by cervical spine (33%), shoulder (29%), and knee (25%)
  • Orthopedic problems caused 16% of respondents to reduce their interventional activities, and 2.7% to stop their practice altogether
  • Just 16% of respondents said they had never experienced an orthopedic problem in their career

The new findings track with previous research highlighting the toll that radiation protection gear takes on interventional personnel. The researchers said that one positive finding of their study was that all interventional radiologists reported wearing radiation protection, although fewer respondents reported using radiation glasses (49%) or visors (11%) despite radiation’s known risk of cataracts.

The Takeaway

This study indicates that interventional radiologists are caught between a rock (radiation dose) and a hard place (orthopedic problems). Relief could come from companies that are developing radiation protection solutions such as free-hanging radiation protection gear; for interventional personnel, these options can’t come soon enough.

Radiation and Cancer Risk

New research on the cancer risk of low-dose ionizing radiation could have disturbing implications for those who are exposed to radiation on the job – including medical professionals. In a new study in BMJ, researchers found that nuclear workers exposed to occupational levels of radiation had a cancer mortality risk that was higher than previously estimated.

The link between low-dose radiation and cancer has long been controversial. Most studies on the radiation-cancer connection are based on Japanese atomic bomb survivors, many of whom were exposed to far higher levels of radiation than most people receive over their lifetimes – even those who work with ionizing radiation. 

The question is whether that data can be extrapolated to people exposed to much lower levels of radiation, such as nuclear workers, medical professionals, or even patients. To that end, researchers in the International Nuclear Workers Study (INWORKS) have been tracking low-dose radiation exposure and its connection to mortality in nearly 310k people in France, the UK, and the US who worked in the nuclear industry from 1944 to 2016.

INWORKS researchers previously published studies showing low-dose radiation exposure to be carcinogenic, but the new findings in BMJ offer an even stronger link. For the study, researchers tracked radiation exposure based on dosimetry badges worn by the workers and then rates of cancer mortality, and calculated rates of death from solid cancer based on their exposure levels, finding: 

  • Mortality risk was higher for solid cancers, at 52% per 1 Gy of exposure
  • Individuals who received the occupational radiation limit of 20 mSv per year would have a 5.2% increased solid cancer mortality rate over five years
  • There was a linear association between low-dose radiation exposure and cancer mortality, meaning that cancer mortality risk was also found at lower levels of exposure 
  • The dose-response association seen the study was even higher than in studies of atomic bomb survivors (52% vs. 32%)

The Takeaway

Even though the INWORKS study was conducted on nuclear workers rather than medical professionals, the findings could have implications for those who might be exposed to medical radiation, such as interventional radiologists and radiologic technologists. The study will undoubtedly be examined by radiation protection organizations and government regulators; the question is whether it leads to any changes in rules on occupational radiation exposure.

Get every issue of The Imaging Wire, delivered right to your inbox.

You might also like..

Select All

You're signed up!

It's great to have you as a reader. Check your inbox for a welcome email.

-- The Imaging Wire team

You're all set!