the Growing Concern Over Radiation Exposure

computed tomography (CT) scans are a vital diagnostic tool,but growing evidence suggests their use is associated with an increased risk of cancer. A recent study published in JAMA Internal Medicine reveals that the risk may be higher than previously estimated [3].

dr.david johnson, professor of medicine and chief of gastroenterology at eastern virginia medical school and old dominion university, emphasized the importance of understanding these risks. the projected lifetime cancer risks from CT scans are increasing.

understanding the Risks: Stochastic vs. Deterministic Effects

radiation exposure has two primary types of effects:

• deterministic effects: these are immediate and observable, such as skin necrosis, often seen in radiation oncology.
• stochastic effects: these occur over time and are insidious, potentially manifesting as cancer years or decades later. dr. johnson notes, stochastic effects occur over time and are insidiousness in that they are not overtly clear, but perhaps become evident over years and decades.

the stochastic effects are especially concerning in younger patients.

quantifying the Risk: New Study Highlights Increased Estimates

a 2006 national academy of science report estimated that a single abdominal CT scan (approximately 10 mSv of radiation) carries a 1 in 1,000 lifetime risk of developing solid cancer or leukemia.

a 2007 review in the new england journal of medicine indicated that younger patients face a three times greater likelihood of cancer-related death from radiation exposure.

the latest data suggests the risk is even more notable. previously, it was estimated that approximately 1% of new cancers were due too radiogenic exposure. however, with the dramatic increase in CT scan usage—from 3 million in 1980 to 93 million in 2023—the estimated risk has risen.

a new Risk Model’s Striking Projections

a recent study in jama internal medicine developed a new risk model using data from 143 u.s. hospitals and outpatient facilities. researchers analyzed approximately 120,000 ct scans from both pediatric and adult populations at the university of california, san francisco.

the study excluded examinations in the last year of life, pet scans, and ct scans associated with interventions or biopsies that increase radiation exposure.

the findings revealed:

• age-adjusted estimates of radiation-induced cancer risks were higher in children, although they represented only about 5% of ct scans in 2023.
• the most frequent projected cancers in children were thyroid, lung, and breast cancer.
• ct scans among adults accounted for 95% of examinations.
• across all age groups, ct scans were associated with projected increases of over 22,000 new cases of lung cancer, 8,700 new cases of colon cancer, nearly 8,000 new cases of leukemia, and 7,100 new cases of bladder cancer.
• in female patients, breast cancer was the second most common, accounting for 5,700 new cases.
• abdominal and pelvic ct scans in adults contributed to the largest number of projected cancers (approximately 37% and 32% respectively), followed by chest ct scans (21%). [2]

this analysis suggests that ct scans might potentially be responsible for 5% of incident cancers annually,up from the previous estimate of 1%.

challenges and Interpretations

interpreting this data presents challenges. the study used average life expectancies, which may not accurately reflect the life expectancies of patients undergoing ct scans due to underlying illnesses.

however, the new analysis is more specific, considering a higher combination of ct categories by body region and clinical indication (18 in adults, 13 in children).

moving Forward: Informed Decisions and Alternatives

dr. johnson urges caution: ct scans are a wonderful technology. there’s there’s no doubt whatsoever of that. though, we may want to consider potential alternatives.

he suggests considering whether ct scans are the best tools available and whether they will ultimately change patient management.

dr. johnson also advocates for informed consent: ct scans or any radiation exposures should be subject to the informed consent process that requires us to talk to patients about the risks, benefits, and alternatives. this would be similar to our discussions with patients for othre procedures or surgeries.

he concludes with a call to action: thus, my plea is to hit the pause button on ordering ct scans just as you think it’s easy and convenient. ask whether it’s really in the best interest of the patient. [1]

faq: Ct Scans and Cancer Risk

are ct scans dangerous?

ct scans expose patients to ionizing radiation, which can increase the risk of cancer over time.

how much radiation is too much?

there is no safe level of radiation exposure. any exposure carries some risk, but the benefits of a necessary ct scan may outweigh the risks.

what can i do to minimize my risk?

discuss the necessity of the ct scan with your doctor, explore alternative imaging methods, and keep a record of your radiation exposure.

are children more vulnerable?

yes, children are more sensitive to radiation, and the projected cancer risks per ct scan are higher in children than adults.