1, a head CT radiation
Traditional X-ray examination, also known as X-ray film, has now been basically replaced by CR or DR, is to penetrate the body's tissues, to obtain a two-dimensional photo of the organs in the body (such as the lungs, bones, etc.), the examination is painless. CT examination is like a large Dornai circle, the patient into The X-rays are directed around it to obtain a tomographic image of the body, which can also be reconstructed in three dimensions. This type of exam allows for more information about the organs in the body.
Both of these tests use imaging with X-rays, which are electromagnetic waves that are highly penetrating, so it has the potential to break through DNA strands in cells as it passes through the body, leading to abnormal DNA strand repair. It also has an ionizing effect, leading to the ionization of body components and causing damage to the body.
The good thing is that X-ray filming as well as CT only utilizes X-rays, and they are artificially created, and are only produced when they are energized, so there is usually no radiation in the radiology suite, and it is only the radiographer who emits rays in the moment they are being taken, and then the rays dissipate into thin air.
How much radiation does the human body receive during a radiological examination? Roughly converted to the time of exposure in daily life, if the radiation dose of 1 day in a normal environment as a benchmark, a chest X-ray and the benchmark is the same. Whereas a head CT is equivalent to 8 months of daily radiation, an abdominal CT is equivalent to 20 months.
These values may come as a shock, and in fact the specific results regarding the carcinogenicity of medical X-ray exposure are inconclusive. But what is undeniable is that large-scale population surveys have confirmed that X-rays can increase the probability of cancer in humans, especially children.
If radiation is dangerous, why do it? Through imaging, doctors can diagnose, localize, quantify and even characterize diseases, and can clarify the patient's lesion involvement, the degree of lesion regression, etc.
Thus, doctors often make the decision to perform radiologic exams based on the principle of choosing the lesser of examination or injury. Moreover, the pediatrician will choose the most beneficial and least harmful examination for the child among the available imaging examinations, such as the parenchymal organs
The organs and the urinary system can choose harmless ultrasonography, and the central nervous system can choose harmless magnetic **** vibratory imaging examination, and so on. Children are in the active period of growth and development, a variety of glands are very sensitive to X-ray, in the examination process, in addition to the need to expose the photographic
shooting site, the doctor will be on the child's thyroid, gonads well protected. Since eye crystals are also sensitive to X-rays, the crystals are also shielded.
2, normal performance
CT diagnosis is mainly based on the observation of tissue density differences. Cranium for the highest density white shadow, CT value up to +1000H. sinuses and mastoid air in the room containing air for the lowest black shadow, CT value of -1000H. cerebrospinal fluid-filled ventricles, cerebral pools for low density, CT value of 0-16H. cerebral cortex for the thin layer of white banded shadow, the medulla for the depth of varying shades of gray shadow, cortex and medulla often have a clear demarcation line between the caudate nucleus density is higher, the density of the blood vessels and cerebral parenchyma The density of blood vessels is similar to that of the brain parenchyma, and the pineal gland and choroid plexus are often calcified and appear as high-density shadows. The CT value depends on the calcium content, which is about 40-400 H.
Normal density of the brain parenchyma is symmetrical between the two sides and there should not be any high- or low-density areas on one side. The ventricles and cerebral pools are shown at different levels, (Figures 7-6-8). The lateral ventricles have clear boundaries. The contours are neat and symmetrical in shape and size; the septum pellucidum and the three ventricles are on the midline at a lower level. The subarachnoid space is a thin, low-density band located between the inner cranial plate and the cerebral cortex; the longitudinal hemispheric fissure is shown at a higher level as a low-density band located in the midline, and the lateral fissure pools are symmetrically located on both sides. The suprasellar pools are pentagon-shaped, and optic nerve crossings are visible in the anterior 1/3 of the suprasellar pools. The quadrate pool is posteriorly located and has an irregular shape, with the quadrate protruding into the anterior part of the pool. The annular pool is in the form of a narrow band around the periphery of the midbrain. The fourth ventricle is visible at the level of the posterior cranial fossa in the midline and is horseshoe shaped. The cerebellar pontine horn pool and the large occipital pool are visible. The large occipital pool is highly variable and is often mistaken for an abnormality.