CT Scans and Radiation Exposure

Why had the National Cancer Institute of the US suggested to physicians to decrease unnecessary CT Scans in children?

Dr. Greene’s Answer:

A typical x-ray delivers 0.01 mSv (millisievert) of radiation. CT scans give us much more information, but they can also deliver as much radiation as getting 300 regular x-rays — or 600, if the CT scanner has not been adjusted for children! Even though CT scans are a small minority of the total number of x-rays done, in the US they are responsible for about 65 percent of all medical radiation exposure.

In order to understand how this relates to day-to-day radiation exposure, I looked to information from the American College of Radiology. They have found that the average person living in the United States is exposed to about 3 mSv annually from “naturally occurring radioactive materials and cosmic radiation from outer space.”

Read More From This Series:
CT Scan Defined
CT Scan, Ultrasound or MRI?
CT Scan Safety
CT Scans and Radiation Exposure
CT Scan Risks
Higher Risks in Children
Who Should Receive a CT Scan?
X-Ray or a CT Scan?
Alternatives to a CT Scan
When Should a CT Scan be Performed?
Important Tip to Reduce to Radiation
Questions to Ask before Every CT Scan
Other Radiation Exposures
Measures That Radiologists Should Adhere to When Administering a CT Scan
CT Scans and Cancer
When are MRIs not Practical?
What is Ionizing Radiation?
Who are Radiologists?

Dr. Alan Greene

Dr. Greene is a practicing physician, author, national and international TEDx speaker, and global health advocate. He is a graduate of Princeton University and University of California San Francisco.

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  1. Hans de Rycke

    According to a study in the Archives of Internal Medicine in 2009, CT scan radiation alone will cause nearly 30,000 unnecessary cancer cases. This will lead to about 14,500 deaths, and a 2007 New England Journal of Medicine study even gives a much higher estimate of up to 3 million cancer cases due to the overuse of CT scans.

    Full body scans are notoriously unreliable and worry the patient needlessly, creating the desire for follow-up tests and/or even more unnecessary medical interventions.

    The risk of misdiagnosis is particularly rampant in mammograms – as high as 89 percent today! This is why many women are unnecessarily and harmfully treated by being given a mastectomy, more radiation, or chemotherapy.

    Many of these machines are owned by doctors. From 2001 to 2006, Medicare private-office CT scan volume in facilities owned by radiologists increased by 85%.

    Nonradiologist physicians are acquiring or leasing CT scanners in increasing numbers, and the growth trend is much more rapid among them than it is among radiologists (85% among radiologists from 2001 to 2006, compared with 263% among nonradiologists).

    As a result, nonradiologists’ market share has increased considerably. At a time when both cost containment and reduction in radiation exposure are urgent priorities, the self-referral opportunities resulting from this trend should be of concern to payers and policymakers.
    CT scan volume in facilities owned or leased by nonradiologist physicians as a group increased by 263%.
    The nonradiologic specialties with the largest volumes in 2006 were primary care (192,255 scans), internal medicine subspecialties other than cardiology and medical oncology (184,991 scans), urology (125,850 scans), cardiology (104,739 scans), and medical oncology (61,976 scans).

    Excluding CT scans performed in independent diagnostic testing facilities (for which physician ownership cannot be determined), nonradiologists’ private-office CT market share rose from 16% in 2001 to 28% in 2006.


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