1
Are X-rays from C-arms harmful to humans?
Radiation is divided into electromagnetic radiation and ionizing radiation. Electromagnetic radiation (such as radiation from modern Home appliances) is very mild compared to ionizing radiation, while ionizing radiation is certain to cause harm to the human body, and the X-rays emitted by the C-arm are mainly ionizing radiation.
X-rays have three effects when they enter the body: 1. they pass through the body 2. they are absorbed by the body 3. they are scattered (the X-rays excite new rays).
Patients in the operating room are exposed to radiation directly from the x-ray machine. The radiation that doctors, nurses, and other operating room staff receive comes from radiation scattered by the patient’s body. The breast, gonads, eye crystals and thyroid are the organs that are more sensitive to radiation and should be given priority protection when exposed to radiation.
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C-arm diagram
2
What is the distribution of radiation emitted by the C-arm?
We need to know the radiation distribution of the C-arm machine. After the radiation from the bulb enters the body, 1% of the radiation passes through the body and enters the intensifier, while 80%-90% of the remaining radiation is absorbed by the patient and 10%-20% is scattered by the body. The radiation increases with distance by a factor of a and decays to 1/a2 of the original intensity.
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How can I reduce my own radiation exposure through personal protection?
- general surgeries can be controlled from a distance outside the operating room lead wall (>4m) without wearing protective clothing, as far away as possible without increasing the chance of surgical contamination.
- For special surgeries such as spinal surgery, which require multiple fluoroscopies, it is inconvenient to run around and it is easy to increase the chance of contamination, so keep in mind the “5 points at the bedside” ?
(1) Distance from the patient during fluoroscopy > 1.5m: Studies have shown that fluoroscopy at a distance of about 1.5m from the patient can reduce the radiation exposure of the operator by 48% to 63% compared to standing next to the C-arm machine, and does not increase the operation Time.
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(2) If the bulb tube and the intensifier are placed horizontally, then you should stand on the side of the intensifier, the farther away the better
(3) Use protective equipment (wear lead clothing, lead bib, lead glasses, lead gloves, etc.)
(4) Twist the eyes outward
(5) Avoid direct hand radiation: if you need to hold surgical instruments, you can also use forceps or other instruments
4
How to reduce the dose and scatter of C-arm radiation?
(1) Put the bulb under the bed in ortho position: If you are taking ortho pictures, the best way is to put the radiation source of the C-arm machine, i.e., the bulb, under the bed and then put a protective device such as a lead curtain between it and the operator, so that the scattered radiation is basically blocked.
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The closer the receiver is to the patient, the more X-rays it can effectively receive through the patient, and the farther the corresponding dome is from the patient, the less radiation the patient receives, so the C-arm receiver can be made as close to the site as possible to meet the sterility requirements, so that the quality of the film is high and the intensity of emission is not too great. Magnification mode should be avoided for image size, as reducing the field of view by half increases the dose rate up to 4 times.
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- The fluoroscopic part is aligned with the center of the intensifier: if it is not aligned with the center, it may lead to dark imaging or even a waste film, especially when taking images of the spine, it is easier to align when in the frontal position, but be careful when in the lateral position, anticipate the vertebral body position to ensure that the body covers at least 50% to 70% or so of the center.
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A machine’s orthogonal spine, lateral normal film, lateral off-center dark image, and lateral severely off-center resulting in a waste film. Note that the body model is used, and there are some differences with the real human X-ray film. 4.
The image quality does not have to be perfect, but can meet the needs of the procedure. Because a high quality image must mean a higher radiation dose. 5.
Different brands of machines may have their own individual settings, such as the adjustment of frequency for continuous fluoroscopy, the adjustment of voltage kV and current mA, and the selection of LowDose mode.
It is recommended that the staff operating the C-arm in the operating room learn more about the operation of the machine in order to meet the needs of the procedure with less radiation dose. Sometimes a 10-fold dose reduction can be achieved with proper operation!
After the first exposure is stabilized, subsequent exposures should be spot or single pulse fluoroscopy.
If continuous fluoroscopy is required, use 4pps or 8pps discharge and avoid continuous discharge as much as possible. A single pulse discharge (50ms pulse) can reduce the radiation dose by up to 5% compared to a continuous discharge, 4PPS discharge by up to 20%, and 8PPS discharge by up to 40%. 7.
Other ways to reduce scattered radiation: use of Collimator and removable filter grids and removable filters.
5
Can lead glasses be so cheap to protect against radiation?
What if the lead suit is too heavy?
Crystals and thyroid gland are the organs to be highly alert, so lead bib and lead glasses are also essential. 0.5 mm lead equivalent glasses can absorb 99% of rays, so try to choose lead glasses with side protection when purchasing.
Lead clothing is available in 0.25 mm, 0.35 mm and 0.5 mm lead equivalent. For 100kV fluoroscopy, 0.25 mm lead equivalent lead clothing can reduce radiation dose by 90%, and 0.5 mm lead equivalent clothing can reduce scattered radiation damage by 97%.
Lead vests are available in two-piece or one-piece versions. The two-piece type is better because it distributes some of the weight on the hips. If a one-piece suit is not belted, the entire weight is on the shoulders, so the belt should be tied to allow the hips to carry some of the weight.
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The lead suit can only be hung up after use, and cannot be put flat or folded, otherwise it will lead to local lead equivalent thinning and ray leakage.
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Is the radiation close to 0 at a distance of 2 meters from the machine?
If you do not take personal protective measures, the annual absorbed dose will definitely exceed the national safety standard. Even wearing a 0.5 mm lead equivalent lead suit can only reduce the dose by 99%, not to 0.
The International Atomic Energy Agency literature says that it is safe only if the following conditions are met: wearing personal protection, personal dose monitoring, and regular medical checkups.
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Is it safe to hide behind a lead screen when exposed to radiation?
The answer is not necessarily!
Rays hitting other equipment materials in the operating room can excite new scattered rays, which are relatively rare but do exist and can easily be overlooked in practical protection.
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How is personal dose monitoring done?
Personal dose monitoring is the monitoring of radiation dose received at work, commonly by wearing a dose pen.
The dose pen should be worn on the left front collar. If a lead suit is worn, it should be worn on the back of the lead suit. If the hands are frequently exposed to radiation emitted from the bulb tube during surgery, a finger-worn dose pen needs to be worn on the hands. After wearing it for a certain period of time, it needs to be sent to a special department to measure the accumulated dose. The maximum period of delivery should not exceed 3 months.
Whole body tissues
Annual cumulative dose limits (mSv)Occupational personnel
Public
Extremities
500
50
Skin
500
50
Thyroid
300
30
Crystal
50
5
Whole Body
50
5
Other tissues and organs
500
50
The International Commission on Radiation Protection recommends radiation dose limits for tissues and organs
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What about patient protection?
Patients are not exposed to radiation like doctors are in the operating room all year round, and thus their protection can be easily overlooked. However, it is important to understand that patients are in close proximity to the bulb tube and receive short, high doses of radiation that are more damaging than the long, low doses received by physicians.
Some patients exposed to C-arm machine X-rays are repeatedly exposed to X-rays for long periods of time due to the ease of the procedure, and the total amount of ionizing radiation received by some patients in a single procedure may be greater than the cumulative annual amount received by medical workers.
Therefore, we need to take protective measures for patients, especially pediatric patients. Always cover the patient’s thyroid, breast, eye, and gonadal areas with lead products before surgery.
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What are the effects of radiation on fertility?
Certain precautions should be taken when performing fluoroscopy on pregnant women in order to minimize the exposure of the unborn child to radiation.
Unborn babies are considered more sensitive to potentially harmful radiation effects than adults or children. In many examinations, such as X-rays of the head (including dental X-rays), chest and extremities, the dose to the unborn baby will be low because the patient’s pelvic region is not exposed to X-rays. However, in order to achieve a higher standard of protection, attention can be focused on protecting the pregnant woman’s pelvic region with protective products during the procedure.
For physicians, they should apply immediately after pregnancy for temporary leave from positions where they can be exposed to rays; fear of rays is not something to be ashamed of.
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Do you use the C-arm machine frequently in your department? How many times is the C-arm used for general spinal internal fixation or extremity surgery? Do you have all the protective equipment? Are there any other good ways to reduce radiation exposure? Feel free to leave a comment and let us know!
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