CT scans, the life-saving imaging technology, can silently increase your cancer risk. An alarming new research published in JAMA Internal Medicine, has warned that the medical scans can potentially trigger tens of thousands of new cancer cases due to repeated radiation exposure.
More people are now going for computed tomography (CT) scans than ever before, which can help diagnose tumours, muscles, and bone conditions. However, the low doses of ionizing radiation may increase your odds of cancer.
A research team in the US and the UK has estimated that CT scans could theoretically account for 5 percent of all new cancer diagnoses in the US. CT scans done in 2023 could be responsible for an estimated 103,000 future cases of cancer, say the experts.
When it comes to individual risk, it isn't much, and this shouldn't dissuade patients from undergoing CT scans if required. However, the number of people at cancer risk due to CT scans may be increasing as CT examinations performed each year in the US has increased by more than 30 percent since 2007.
"CT is frequently lifesaving, yet its potential harms are often overlooked, and even very small cancer risks will lead to a significant number of future cancers given the tremendous volume of CT use in the United States," write the international team of analysts, led by epidemiologist Rebecca Smith-Bindman from the University of California, San Francisco.
While the risk associated with high doses of radiation to cancer is known, there is not enough evidence to link low-level radiation to cancer.
The potential link comes largely from long-term studies of atomic bomb survivors and individuals exposed to nuclear power plant disasters. For example, among 25,000 Hiroshima survivors who were exposed to radiation levels comparable to three or more CT scans, researchers observed a small but statistically significant increase in lifetime cancer risk.
How the study was conducted
Anonymous data from 143 hospitals and outpatient centers across the US, collected through the UCSF International CT Dose Registry, paints a concerning picture. Analyzing trends from 2016 to 2022, researchers estimate that a staggering 93 million CT scans were performed in 2023 on about 62 million Americans. Alarming projections suggest these scans could be linked to as many as 103,000 future cancer cases.
"To empirically quantify lifetime risk would require decades-long follow-up studies of very large populations," the authors wrote.
The risk is however not the same for all populations. It is estimated that radiation-induced cancer risks were higher in children and adolescents. Children receiving CT scans at under one year of age, perhaps had higher potential lifetime risk for thyroid cancers, especially in females.
What to expect during a CT scan
A CT scan is a quick, painless procedure that provides detailed images of your body's internal structures. Here's what you can expect before, during, and after the scan.
Preparing for the scan
Depending on the area being examined, you may be asked to change into a hospital gown and remove metal items like jewelry, belts, glasses, or dentures, as these can interfere with the imaging. You might also be advised not to eat or drink for a few hours beforehand.
If your infant or toddler is getting a CT scan, a sedative may be recommended to help them stay calm and still. Since movement can blur the images, keeping your child still is essential for accurate results. Speak to your healthcare provider for guidance on how to prepare your child.
What does CT scanner look like
The CT scanner looks like a large, upright doughnut. You'll lie on a narrow motorized table that slides through the center of the scanner. Straps or pillows may be used to help you stay in position, and for head scans, a special cradle may be used to hold your head still.
What you will experience
As the scan begins, an X-ray tube will rotate around you, capturing cross-sectional images (or "slices") of your body. You’ll hear whirring and buzzing sounds as the machine works. A technologist will monitor the scan from another room and communicate with you through an intercom. They may ask you to hold your breath briefly to reduce movement and ensure clear images.
How long the process lasts
Although the actual scanning takes just a few minutes, the entire process typically lasts about 30 minutes from start to finish. After the scan, you can usually return to your normal activities unless otherwise directed by your doctor.
More people are now going for computed tomography (CT) scans than ever before, which can help diagnose tumours, muscles, and bone conditions. However, the low doses of ionizing radiation may increase your odds of cancer.
A research team in the US and the UK has estimated that CT scans could theoretically account for 5 percent of all new cancer diagnoses in the US. CT scans done in 2023 could be responsible for an estimated 103,000 future cases of cancer, say the experts.
When it comes to individual risk, it isn't much, and this shouldn't dissuade patients from undergoing CT scans if required. However, the number of people at cancer risk due to CT scans may be increasing as CT examinations performed each year in the US has increased by more than 30 percent since 2007.
"CT is frequently lifesaving, yet its potential harms are often overlooked, and even very small cancer risks will lead to a significant number of future cancers given the tremendous volume of CT use in the United States," write the international team of analysts, led by epidemiologist Rebecca Smith-Bindman from the University of California, San Francisco.
While the risk associated with high doses of radiation to cancer is known, there is not enough evidence to link low-level radiation to cancer.
The potential link comes largely from long-term studies of atomic bomb survivors and individuals exposed to nuclear power plant disasters. For example, among 25,000 Hiroshima survivors who were exposed to radiation levels comparable to three or more CT scans, researchers observed a small but statistically significant increase in lifetime cancer risk.
How the study was conducted
Anonymous data from 143 hospitals and outpatient centers across the US, collected through the UCSF International CT Dose Registry, paints a concerning picture. Analyzing trends from 2016 to 2022, researchers estimate that a staggering 93 million CT scans were performed in 2023 on about 62 million Americans. Alarming projections suggest these scans could be linked to as many as 103,000 future cancer cases.
"To empirically quantify lifetime risk would require decades-long follow-up studies of very large populations," the authors wrote.
The risk is however not the same for all populations. It is estimated that radiation-induced cancer risks were higher in children and adolescents. Children receiving CT scans at under one year of age, perhaps had higher potential lifetime risk for thyroid cancers, especially in females.
What to expect during a CT scan
A CT scan is a quick, painless procedure that provides detailed images of your body's internal structures. Here's what you can expect before, during, and after the scan.
Preparing for the scan
Depending on the area being examined, you may be asked to change into a hospital gown and remove metal items like jewelry, belts, glasses, or dentures, as these can interfere with the imaging. You might also be advised not to eat or drink for a few hours beforehand.
If your infant or toddler is getting a CT scan, a sedative may be recommended to help them stay calm and still. Since movement can blur the images, keeping your child still is essential for accurate results. Speak to your healthcare provider for guidance on how to prepare your child.
What does CT scanner look like
The CT scanner looks like a large, upright doughnut. You'll lie on a narrow motorized table that slides through the center of the scanner. Straps or pillows may be used to help you stay in position, and for head scans, a special cradle may be used to hold your head still.
What you will experience
As the scan begins, an X-ray tube will rotate around you, capturing cross-sectional images (or "slices") of your body. You’ll hear whirring and buzzing sounds as the machine works. A technologist will monitor the scan from another room and communicate with you through an intercom. They may ask you to hold your breath briefly to reduce movement and ensure clear images.
How long the process lasts
Although the actual scanning takes just a few minutes, the entire process typically lasts about 30 minutes from start to finish. After the scan, you can usually return to your normal activities unless otherwise directed by your doctor.
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