When it comes to CT tests, you're no stranger to them.
And many people still have this question in their minds:
How much radiation does chest x-ray or CT have?
Will you get cancer if you do too much?
How many times a year is a reasonable check?
Can I breastfeed after breastfeeding?
Today, let's walk into it together.
In 1895, the German physicist Röntgen first discovered X-rays and took the first X-ray photograph of humans.
(Röntgen x-rayed her wife's hand bone))
X-rays are then applied to medicine, which has a strong penetrating force, if the X-ray is emitted to the human body, part of it passes through the human body and part of it is absorbed into the human body.
The denser the tissue, the stronger the absorption capacity of the X-ray, so that by recording the X-ray dose through the human body, you can understand the absorption of the situation, understand the state of the internal organs of the body, such as whether there are no nodules with high density in the lungs, which is the simplest principle of chest x-ray.
CT is an equipment upgrade based on the X-ray principle, showing the distribution of fault tissue, so it is also called tomographic CT, just like nori rolls, CT machines are responsible for cutting sushi into slices to reflect the situation of cross-sectional organs.
Finer contrast resolution, no overlapping anatomical comparison, is an advantage of CT over X-ray, which will make the doctor more intuitive to see the lesion.
With the rise of new technologies, CT is widely used in more fields:
CT angiography, CT perfusion imaging, multi-layer spiral CT with higher pattern quality, petCT for rapid full-body examination, etc., have greatly expanded the application of CT.
CT and X-rays have set off a revolution in disease diagnosis, doctors can obtain information about lesions in patients without trauma, and surgeons can get a definitive diagnosis before surgery.
Malignant tumors, skin ulceration, tooth loss, hair loss...
The scientists who originally studied X-rays were unprotected, and these symptoms may occur after frequent, high-dose systemic exposure to radiation.
Despite the continuous improvement of modern imaging technology, radiation problems are still inevitable.
Until now, radiology has also been regarded as one of the "high-risk occupations".
X-rays produce ionizing radiation that releases free radicals that damage DNA, potentially causing cell cancer[1].
But putting aside the dose to talk about toxicity is a hooligan!
Millisievert (mSv), which is a unit of organs absorbing an effective dose of radiation.
Let's look at the radiation effective dose values that tissues in different parts of the body can withstand [2-4]:
So, how much radiation dose can cause cancer?
A 2013 study: Scientists compared 680,000 children who received CT scans with 10 million children of the same age who did not receive CT scans and estimated that every 1 mSv radiation dose increased the probability of cancer by 0.0017 to 0.002 percent [5].
A chest x-ray is 0.1mSv, and roughly calculated, the cancer rate will increase by 0.00017% to 0.0002%.
Clinical practice has concluded that a single dose of 50 mSv or a lifetime dose of 100 mSv does not pose a health risk, which is the upper dose limit for diagnostic imaging tests [6].
Therefore, there is no need to worry too much about the side effects of CT examination, according to the condition to listen to the doctor, it is necessary to check.
CT radiation does not remain in the body, much less into the milk.
However, there are several tests that can affect a child through milk.
Iodine-131/I131 or iodine-123/I123 (thyroid), iron-59 (liver), gallium-67 (spleen), and strontium-90 and yttrium-90 (bone) remain in radionuclides in these nuclear medicine imaging agents.
The American Academy of Pediatrics' Committee on Drugs recommends that breastfeeding should be discontinued for at least three weeks after maternal receipt of I131, I125, N22, and Ga67 [7]. Women should stop breastfeeding for at least 4 weeks after a system scan using I131.
In contrast, the iodized contrast agent of CT angiography (CTA) is rapidly removed from the mother.
The American Radiological Society considers it safe for women to breastfeed after receiving CT angiography.
If the previous X-ray was the doctor's "clairvoyant eye", the development to the present, CT is the doctor's "heavenly eye":
Car accident trauma, cerebral infarction hemiparesis, pulmonary embolism and dyspnea, from inflammation to tumors, from the skull to the thoracic and abdominal flap.
It is also possible to inject contrast media or contrast media to help doctors determine the diagnostic analysis:
Where are the lesions? How big is it? Is the density high or low?
Prejudge the tumor, whether the lymph nodes and blood vessels have been violated, and whether there is metastasis in other parts.
All of this provides accurate information for follow-up treatment.
Doctors, like you and me, are flesh-and-blood people with feelings, and there is no presence of God to give them insight, and they need examinations to compare the difference between the diagnosis results and the effects after treatment.
One of the biggest characteristics of medicine is uncertainty and individual differences.
There will always be people who worry that the doctor prescribes "unnecessary examinations" and blames the doctor.
Brother Dian would like to say: Choose trust, in order to better fight our common enemy - disease.
The vast majority of diagnostic imaging tests have more advantages than disadvantages, and the consequences of refusing to test may be missed/misdiagnosed/mistreated, missing the best period for disease treatment, and causing tragedy.
Special Author: Yuan Shuai
Doctoral student in Neurosurgery, Peking Union Medical College
Review expert: Xu Gang
Deputy Chief Physician, Department of Radiotherapy, Peking University Cancer Hospital
bibliography
[1] ICRP. The 2007 recommendations of the International Commission on Radiological Protection. ICRP publication 103[J]. Annals of the ICRP, 2007, 2007(37).
[2] Mettler, FA, Huda, W, Yoshizumi, TT, Mahesh, M. Effective
doses in radiology and diagnostic nuclear medicine: a catalog.
Radiology 2008; 248:254.
[3] Smith-Bindman, R, Lipson, J, Marcus, R, et al. Radiation dose
associated with common computed tomography examinations
and the associated lifetime attributable risk of cancer. Arch
Internal Med 2009: 169:2078.
[4] Shrimpton, PC, Hillier, MC, Lewis, MA, Dunn, M. National survey
of doses from CT in the UK: 2003. Br J Radiol 2006; 79:968.
[5] Drozdovitch V . Radiation Exposure to the Thyroid After the Chernobyl Accident[J]. Frontiers in Endocrinology, 2021, 11.
[6] Gujral D . Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians[J]. BMJ (online), 2013.
[7] American Association of Physicists in Medicine. AAPM Position Statement on Radiation Risks from Medical Imaging Procedures 2011. http://www.aapm.org/org/policies/details.asp?id=318&type=PP (Accessed on November 13, 2017).
Editors: Guo Qian, Zhang Xiaoyi, Zhang Liang
Proofreading: Wu Yihe | Typesetting: Li Yongmin
Operation: Han Ningning | Coordinator: Wu Wei