How much damage can a CT do to your body? Can it cause cancer?

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I. What exactly is a CT?

First of all, it is important to understand what CT is, which is a computerized secondary imaging of the body through the layers of X-rays, equivalent to slicing bread into slices.

CT is an important tool for the detection of acute cerebral hemorrhage, aortic coarctation.

CT can be divided into plain scan, which requires lying on top of the CT machine for a few seconds, and enhanced scan, which is based on plain scan with intravenous iodine contrast that is circulated throughout the body to observe the diseased tissue and compare it with the surrounding tissue.

Why do doctors sometimes want patients to have an enhanced CT after they have had a CT exam?

Enhanced CT exams can enhance the contrast between the lesion and the surrounding tissue, clearly show lesions that cannot be detected in plain CT, and clarify the extent and nature of the lesion, which is important for qualitative diagnosis of the lesion. However, before having an enhanced CT examination, the patient should be clear about any iodine contrast allergy and needs to be evaluated before the examination can be performed.

II. Is CT harmful to the body? How many times will it cause cancer?

A 2013 study involving 680,000 children who received CT scans and 10 million children of the same age who did not receive CT scans estimated that a radiation dose of 1 mSv increased the risk of cancer by 0.0017 to 0.002%.

The most important questions about CT exams are whether the radiation produced during the exam will affect health and whether multiple exams will cause cancer.

It is undeniable that ionizing radiation from X-rays used during CT exams can damage some of the macromolecular structures in the body, which in turn can damage cells and the human body, posing a certain risk of cancer.

However, the radiation dose from a single CT session ranges from 2mSv-10mSv, which is a negligible amount of radiation, so there is no need to be overly alarmed. In fact, there is radiation in many common occasions in life, for example:

According to China's radiation protection standards, the annual dose limit for radiation workers is 50 mSv, and the average annual radiation limit for five years is 20 mSv. Based on the maximum dose of 10 mSv from one CT examination, the maximum radiation received from two CT examinations a year is 20 mSv. </p

As long as you don't have too many CT exams in a short period of time, you can keep the total radiation dose within safe limits.

3. CT exam or MRI, how do I choose?

Even so, many people are afraid of the radiation in CT exams and want to give preference to MRI, which is radiation-free.

In fact, both CT and MRI have their own advantages and disadvantages; CT has the advantage of speed and good density resolution, but the disadvantage of radiation. The advantages of MRI are that it does not require contrast injection and there is no radiation. It has high resolution for soft tissues and shows better results than CT in the cranial, neurological, and spinal cord areas. However, MRI has the disadvantage of being noisy and taking a long time to acquire data, and it is also not suitable for patients with metal or pacemakers in their bodies.

In comparison, MRI's have no radiation and are safer for humans, so why do doctors very rarely prescribe MRI in the clinic? There are 4 main reasons:

CT exams are important for diagnosing a wide range of diseases, and it is important not to be overly resistant when your doctor recommends them, and the appropriate frequency of exams does not pose excessive health risks.