Metal appears as a bright area on an X-ray, blocking visibility of underlying structures. The reason you're asked to remove metal is to give the radiologist an unobstructed view of the area of interest. Basically, you remove metal because it blocks anatomy. If you have a metal implant, obviously you can't remove it for an X-ray. If the technician is aware of it, he may position you differently to get the best imaging results or take X-rays from multiple angles. The reason metal appears bright on the X-ray image is that it is extremely dense, so X-radiation does not penetrate it as well as it does soft tissues. This is also why bones appear bright on an X-ray. Bones are denser than blood, cartilage, or soft organs. Unless the metal item is directly in the path between the X-ray collimator and the image receptor, there's no issue with having metal objects in the same room as an X-ray machine. On the other hand, metal objects are not permitted in a room housing MRI equipment because the objects will be drawn toward the powerful magnets when the machine is turned on. Then, the problem isn't with the image; it's with the items, which could become hazardous projectiles, possibly injuring people or damaging equipment.
Sir, panoramic radiography (PR) is used worldwide for the screening of oral and maxillofacial diseases. One of the main considerations, before PR, is the removal of the patient's personal objects (piercings, glasses etc). To our knowledge, there are no studies that focus on this aspect, especially in private dental surgeries, and so we evaluated the presence of radiopaque objects in PR made by dentists. All PR performed by dentists at the Dental Clinic of Brescia from 2005 to 2015 were evaluated to detect foreign objects. A total of 1,584 PR were reviewed by two calibrated clinicians, and in 43 cases (2.7 %) radiopaque objects were detected: piercings (22 cases), earrings (14), glasses (7). These numbers are almost embarrassing. When metal jewellery is present during radiographic examination, it may prevent visualisation of normal anatomy and/or pathologic findings (Fig. 1). Dentists should be strongly advised to remove any objects in the head area and oral cavity from patients before X-ray exposure. Non-diagnostic images may lead to retakes, with an increase of the patient's ionising radiation exposure. Figure 1: Personal objects in panoramic radiographs a) glasses b) earrings c) earrings d) lingual piercing
Category: Medical and Dental Equipment/Shielding — Shielding The following question was answered by an expert in the appropriate field: Q In an x-ray room, what should I do about metal objects like lighting and doorknobs? Are these things okay to have if they are not in the way of the x-ray beam? A Your question is not totally clear regarding your concern. I will assume that you are asking whether or not the presence of metal objects in a typical x-ray room may cause issues with scatter radiation or image quality issues if those objects are not in the x-ray beam. As long as these items are not in the path from the x-ray collimator to the image receptor, they will not cause any problems with the x-ray beam or the image. If metal objects are in the primary x-ray beam (such as patient jewelry, coins, a pocket knife, etc.), then there is concern mainly because they may obstruct the anatomy that is being diagnosed with the x ray. Also, for installations with magnetic resonance imaging (MRI), it is critical that certain metal objects not be inside the room because they can become drawn to the magnet bore as dangerous projectiles. Kennith “Duke” Lovins, CHP Health Physicist Answer posted on 9 November 2011. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society. |