How much radiation is involved when seeing a doctor or getting a checkup? What about children and pregnant women?

We live in a world where radiation is everywhere. Sunlight shines for 8 hours a day, and a mobile phone is radiated every 3 hours when it is charged. Patients are happy to undergo X-ray and CT scans in hospitals. However, when they hear about nuclear medicine examinations, they are more resistant, believing that nuclear medicine examinations will cause radiation damage, cancer, and malformations to the human body. They also avoid patients who have undergone nuclear medicine examinations, fearing that they will be exposed to harmful radiation. Is this really the case? Today I will give you some popular science.

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1. X-ray examination

X-ray examination is the most widely used radiation examination method. It directly irradiates the human body surface and produces ionization through skin, bones, internal organs and other tissues to diagnose diseases. For example, chest X-ray examination will contact lung tissue, while abdominal X-ray examination may contact liver and other organ tissues, of course, this also depends on the irradiated part.

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In fact, X-ray radiation is ionizing radiation, which has strong penetrating power. When the human organs and tissues absorb a certain amount of it, it will cause biological effects and even lead to death. At present, the impact of ordinary X-ray examinations on the human body is minimal.

Therefore, when a routine X-ray examination is performed in a hospital, radiation damage is generally not caused. However, if it involves some special parts of important organs (such as the heart) or important tissue structures (such as the head, internal organs, etc.), enhanced scanning or angiography is required.

2. CT examination

CT scan is also the most common examination in hospitals. It mainly uses X-rays to scan the human body to understand the internal conditions of the body. But we must know that both X-rays and CT have certain radiation. Although the radiation is very small, the damage to the human body is also obvious.

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CT examination has the advantages of accurate positioning, clear imaging, and high resolution, so doctors generally recommend patients to undergo CT examination. However, during the examination, doctors will use different scanning methods and scanning parameters according to the patient's condition. For example, plain scanning + enhancement + contrast agent perfusion is used for more lesions, or plain scanning + enhancement + contrast agent perfusion is used for less lesions. These different scanning methods will also produce different radiation doses. For some tumor patients, the radiation dose is even as high as ten times, so different scanning methods need to be selected according to the actual condition.

3. Nuclear Magnetic Resonance

Magnetic resonance imaging uses the magnetic resonance phenomenon to image human tissues. During the entire scanning process, there is no radiation to the human body. Magnetic resonance imaging uses the resonance phenomenon of hydrogen atoms in a magnetic field to create images, so the magnetic field radiation is almost zero. For healthy people, the radiation from MRI is only one-tenth to one-fifth of that from X-rays. For some special populations, such as children, the elderly, pregnant women, or some patients with complex organ structures, MRI imaging has certain advantages. But after all, MRI also has radiation, so in order to ensure the safety of patients and doctors, it is recommended that these people try not to undergo MRI examinations.

Special reminder: This examination is not recommended for people with metal implants such as pacemakers, artificial heart valves, cochlear implants, and other patients who are not suitable for MRI examinations.

4. Nuclear Medicine

Nuclear medicine examinations are generally divided into radionuclide imaging agent examinations and positron emission tomography (PET). Both types of nuclear medicine examinations will cause certain radiation to the human body.

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Radionuclide imaging agent examination mainly involves taking a certain dose of radioactive nuclides to cause a certain radioactive reaction in the human body, thereby forming a radioactive substance in the human body, namely, the imaging agent, which is called imaging material in medicine, which is also the so-called nuclear medicine examination. It is mostly used in the diagnosis of tumors, cardiovascular, nervous system, respiratory system and other diseases in clinical practice. Among them, PET uses some radioactive nuclides contained in the human body and uses imaging technology to image these nuclides to find the location of diseased tissues or cells, thereby diagnosing diseases. Taking 99m Tc, the most commonly used nuclide in nuclear medicine, as an example, its half-life is 6 hours. After being injected into the patient's body, it will decay rapidly over time. At the same time, combined with the metabolism and excretion of the drug from the body, the effective half-life in the patient's body is generally at most 2 to 3 hours.

5. Radiation Intensity of Nuclear Medicine Examinations

The radiation generated by various examinations conducted in hospitals is very small and within the national standard range. Therefore, you don’t have to worry about radiation causing harm to yourself. In fact, nuclear medicine examinations are non-invasive and low-radiation examinations. For some examinations, the radiation received by patients is only half or less than that of ordinary X-ray examinations. For example, the effective radiation dose received by a nuclear medicine kidney examination is only 1.6 mSv, while the effective radiation dose received by a chest CT scan is 6.9 mSv.

6. Children and pregnant women

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Generally speaking, for children, it depends on their conditions. Depending on the child's condition, some nuclear medicine examinations can be performed. Since children have many diseases, such as neonatal jaundice, in order to distinguish whether it is physiological jaundice or bile duct obstruction, or to locate the bleeding in the children's digestive tract, or abnormalities in the children's renal function and urinary system, nuclear medicine examinations cannot be replaced by other testing methods.

For pregnant women, in order to avoid unnecessary radiation damage to the fetus and the pregnant woman herself, low-dose radiation examinations can be selected under the doctor's advice. Generally, nuclear medicine examinations and treatments are not recommended during pregnancy and breastfeeding, especially treatments. However, if it is really necessary, some examinations can be performed, and radionuclide therapy is generally not performed.

Since radionuclide tracing technology is very sensitive, the examinee only needs to inject a small amount of radioactive drugs intravenously. The chemical components in these drugs are extremely trace and almost negligible. In addition, the injected drug is an isotope with an ultra-short half-life. The radioactivity of this isotope is extremely low and decays quickly. It completely disappears from the human body within a dozen minutes to a few hours, causing little radiation damage to the examinee. Even newborn babies are safe to undergo nuclear medicine imaging examinations. Radiation in medical examinations is considered to be justified in practice and the dose is strictly controlled. As long as it is used correctly under the guidance of a doctor, the positive significance of nuclear medicine examinations far outweighs the impact of radiation on the body.

In summary, in fact, after the patient's examination, the radioactivity level in the body is already at a very low level, and generally will not affect the people around who are in close contact with the patient. Because the dosage of nuclear medicine imaging radioactive drugs is strictly controlled within an absolutely safe range. In daily life, our radiation range is generally within the safe range. Believe in science, there is no need to scare yourself, do the necessary examinations, and don't delay the health of yourself and your children.