Exposure time should be based on the exposure curve of the machine to determine the exposure curve and the actual operation of the exposure curve has a little error, if you want to calculate the time, you must know the machine's ray intensity, and then according to the exposure factor calculation.
Because the X-ray exposure time affects more factors, generally can not be calculated directly through the formula, each machine radiation source is different, because in addition to the detection of factors affecting the object, but also includes the ray machine itself, such as: the model of the machine, the manufacturer's brand, the ability to heat dissipation, the ray machine continues to run for a period of time and the stability of the machine, and so on.
So X-ray to determine the exposure time, the need to do a comparison test, which is often referred to as the exposure curve, different ray machine, for different materials, exposure mode, to produce a complete set of exposure curves, so as to be used as a reference in the subsequent operation.
Of course, experienced RT inspectors can roughly estimate the exposure time based on their experience, but it is not 100% accurate, and sometimes it is necessary to determine the exact time by estimating the test piece, so the reliable method is still to produce an exposure curve to know the exposure time.
Expanded Information
Protection
1. Without compromising the effectiveness of the diagnosis and treatment, the amount of radiation to which the staff and the patient are exposed is kept to the lowest possible amount, which can be achieved by shortening the duration of the exposure, increasing the distance and utilizing radiation shielding? [13]?
2. Dose limitation: irradiated staff must be dosimetered. Dosimeters provide an accurate indication of the amount of radiation to which a staff member has been exposed, and the recorded values of the dosimeters are checked monthly, with particular attention being paid to the fact that there is no absolutely safe dose of exposure.
3. The United States, Japan and most other developed countries have eliminated the chest X-ray examination, in the few countries that use it, the United Kingdom's frequency of use is only 0.2%, while our country is as high as 61.8%! It is more than 300 times that of developed countries. Ionizing radiation should not be used in clinical practice. As far as possible to use other harmless means of diagnosis.
4. China's Ministry of Health on January 3, 2002 issued the "national radiation work health protection management measures" clearly stipulates: (with radiation rays) for diagnosis, treatment, should be in accordance with operating procedures, strict control of the dose of illumination, the proximity of sensitive organs and tissues of the field of illumination should be shielded protection.
Medical irradiation of pregnant women and children should be informed of the health effects. For procedures requiring intraoperative C-arm examination and bedside irradiation, staff should wear lead clothing, lead leather gloves, goggles and lead-containing bibs.
5. Minimize the exposure time of X-rays. The longer the exposure time to the beam, the higher the dose of radiation received. Require skilled X-ray staff to avoid repetitive exposures and minimize exposure time.
6. Place a shielding material that can effectively absorb radiation between the radiation source and the staff, thus weakening or eliminating the hazards of radiation on the human body. Shielding protection has a certain protective effect, but for high-energy rays to protect the shielding effect is less, such as lead apron can only be used in diagnostic radiology, the role of high-energy protection is weak.
With people's understanding of the biological effects of X-rays continue to improve, in the new X-ray equipment, the use of a large number of new materials, new technologies, new techniques, so that the radiation protection of these equipment is increasingly perfect.
Today's rapid development of clinical radiology shows that its merits outweigh its demerits. As long as we use it wisely, X-ray will always be a friend of human health. Hope that in the near future, hospitals and patients on both sides can comply with national regulations, the use of X-ray caution, safety protection. Can not for medical personnel and patients buried invisible bomb of future diseases.
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