Dr. Moritz, why are X-rays risky particularly for children?
Dr. Jörg Moritz: Maybe you can best imagine it like this: cells are damaged most during the cell division phase. A child’s organism is still growing. That’s why there is a higher rate of cell division that might easier lead to damages. The following damages might occur:
X-radiation can induce cancer for example. The latency period is approximately 20 years. Due to the higher life expectancy of children, the probability of radiation-induced cancer to clinically manifest is much higher compared to older adults.
If X-ray radiation causes damage to DNA in the ovaries or testes, it may lead to hereditary diseases. Since children may be parents someday, these inherited defects can manifest.
Another set of problems comes from child body proportions. A child’s organism is far smaller than that of an adult. That’s why the organs lie much closer together. When X-rays pass through the body, it generally also produces scattered radiation, that being radiation that travels in arbitrary directions and cannot be completely shielded. For example, if X-rays are taken of a little girl’s thorax, the ovaries are hit with relatively more scattered radiation than would occur with the ovaries of an adult woman.
That is why X-rays for children need to be taken very carefully with strict indications. The risk of damages caused by X-rays is subject to the laws of probability. There is no threshold. Having said that, the risk of radiation damage from a single X-ray image is negligible.
What is the difference between an ultrasound and X-ray imaging procedure?
Moritz: They are essentially two entirely different procedures. Corresponding to their density, X-rays are attenuated at varying degrees by the different types of tissues as they pass through the body. X-rays are only slightly attenuated by air. In the case of pneumonia, the air in the lungs is pushed aside by inflammatory secretions and X-rays are correspondingly more strongly attenuated. That is why pneumonia appears as a densification on an X-ray image.