What is the difference between a chest X-ray and a CT scan?

From a clinical perspective, a chest X-ray is a routine static examination, while CT is a comprehensive, dynamic, multi-layer spiral scan. In addition, the radiation from a chest X-ray is very small and can be metabolized in a week, while the radiation from CT is relatively large and generally takes nearly a month to completely disappear. Finally, the clarity of a chest X-ray is not as high as that of a CT, and there is also a certain difference in the accuracy of positioning.

1. What is the difference between a chest X-ray and a CT scan?

The biggest difference between perspective and filming is that one is dynamic and the other is static! Filming is to emit rays all at once and then project them onto film! But perspective is to generate rays all the time.

CT is simply a multi-layer spiral scan. Multi-layer refers to, for example, a lung CT scan, which starts from the apex of your lung, and then scans the entire lung layer by layer until the entire lung is divided into several layers to complete the scan. The advantage of CT scanning is that you can observe the location you scan in three dimensions, and you can rotate at different angles to accurately determine the specific location of the lesion. Then, based on clinical qualitative analysis, you can determine what disease the lesion may be. The film is a plane view, which looks very intuitive, but it cannot achieve the three-dimensional effect of CT and the accurate location of the lesion.

2. Chest X-ray is simple and useful

A chest X-ray, commonly known as a "chest radiograph," is also listed as one of the examination items in a routine physical examination. The advantages of X-ray photography, such as speed, simplicity and economy, are becoming increasingly prominent, making it the preferred choice for chest examinations.

Characteristics of chest X-rays: Chest X-rays can clearly record gross lesions of the lungs, such as lung inflammation, masses, tuberculosis, etc. X-rays use the different densities of human tissue to observe lesions in areas with smaller differences in thickness and density. Compared with chest fluoroscopy, chest X-rays have clearer images and can detect subtle lesions; the objective record of imaging data is conducive to the review and comparison of disease diagnosis and treatment; and the radiation dose received by patients during fluoroscopy is also relatively larger.

Although the examination is good, it is an indisputable fact that excessive radiation is harmful to the human body, and X-rays are a double-edged sword for human health. According to the standards set by the International Commission on Radiological Protection, the total radiation risk is 0.0165/Sievert, while a chest X-ray takes less than half a second and the exposure rate is about 0.045 millisievert/second (1 sievert = 1000 millisievert), which poses a very limited health risk to the public. However, the gonads, eye lenses, breasts and thyroid glands in the human body are particularly sensitive to radiation, and too frequent examinations are not beneficial.

Note: ① Special groups, including infants, young children, and pregnant women (especially within the first three months of pregnancy), should undergo X-ray examinations with caution and take necessary protective measures. ②Except the inspector, other personnel should not stay in the inspection room for a long time. ③ Do not put coins or mobile phones in the chest pocket of the examiner; remove necklaces, mascots and other accessories from the neck; female patients should take off bras with metal supports and dresses with snap buttons. ④ Bring the most recent imaging data with you to the follow-up visit so that the doctor can diagnose and treat you based on your condition.