电离辐射安全防护根基知识.ppt

This slide demonstrates the various types of source assemblies in use. The first four are shielded source assemblies or rods and incorporate shielding slugs to reduce directional radiation for shutter or beam type device. The second three consist of teleflex wires of various lengths and connectors for use in different devices. The stop ball is in different locations to fit the lock assembly of different devices. The last four are aircraft cable and also show different connector styles. Aircraft cable is a stainless steel braided cable that is very flexible. For level detection, the beam is usually well confined to the volume of the detector to minimize scatter. One source with two collimators (one at an angle) or a vertical fan beam can achieve the same purpose. The means of attaching the source housings must be secure and able to withstand the environment. e.g. corrosion, heat, vibration, etc. Combined measurement gauge. The crushed moisture/density gauge was being used on a dam construction site. With the terrain contours, the gauge was not visible to the compactor operator until it was too late. The Cs 137 source rod was bent but the source intact, as was the Am 241 source in the body of the gauge. The operators were instructed to ensure that all workers were made aware of the use of gauges on site and to use flags on long poles to mark the measurement site. Discuss the main components of the equipment Discuss application of the different types of equipment presented in the slide (directional, panoramic and CP x-ray devices). The potential for serious injury when using x-ray equipment is very apparent when one considers the dose rate that x-ray equipment can produce. As an a Rigaku 250EGS2 250 kVp directional x-ray unit operating at 250 kVp and 5 mA produced a dose rate in air of approximately 1.2 Gy/min at 30 cm (with 2 mm Al filter). With only the 1mm Be window the dose rate was approximately 10.6 Gy/min at 30 cm. [Source: Radiation Health Branch, D