10 Things for RTs to Consider in Repeat X-Ray Imaging
Things to consider when doing repeat imaging in an X-ray
A list of common causes of repeat imaging and how technologists can avoid unnecessary repeats or, if a repeat X-ray really is necessary, how to fix their mistakes
Before we get started, there’s one critical thing to keep in mind: repeat imaging happens!
The radiographer’s main job is to acquire images of excellent diagnostic quality while adhering to the ALARA principle. Sometimes that means repeating an image, and sometimes it doesn’t. It is your responsibility as an RT to ensure that the benefits of repeating an exam outweigh the harm. What counts most here is your ability to analyze your images to determine if a repeat is even necessary and to know just what to do to correct imaging flaws on the next go around. In fact, one study showed that a significant amount of medical imaging exams are needlessly repeated within hospital departments due to poor technical judgment, the radiologist being unavailable to help, patient movement or motion, equipment misuse, disorganized practice, or inadequate student supervision [1]. In this article, we’re going to cover 10 key things to do or check when considering whether to repeat an X-ray imaging exam.
- Check the area of interest carefully before doing repeat imaging in an X-ray
- To repeat or not to repeat—is a question you should ask a radiologist
- Choice of exposure factors in X-ray repeat imaging
- Check for poor positioning in X-ray repeat imaging
- Student radiographer contributions
- Patient motion
- Check the equipment
- Check for over-collimation
- Pathology
- Correcting with post-processing
Check the area of interest carefully before doing repeat imaging in an X-ray
Before scanning patients again and inflicting an unnecessary radiation dose on them, it is important to check the usability of the acquired image. In fact, even if you’ve gotten a sub-par X-ray, you don’t actually need to repeat every faulty X-ray image. If the anatomy and/or the disease of interest is not clearly visible, only then should a repeat be performed.
Repeat imaging has a serious impact on both imaging services and patients. Imaging services are impacted by the extra costs of wasted resources and longer patient waiting time, additional workload for radiographers, and reduced X-ray tube life. Patients are affected by the additional radiation doses and discomfort. Patients having their medical examinations repeated are exposed to double the harmful radiation that has detrimental biological effects especially on sensitive organs such as the gonads (if included in the imaged area, of course).
The gist: First check if the area of interest or the disease is clearly visible. Even if other parts of the image have faults, if the area of interest is clear, you shouldn’t repeat the exam.
To repeat or not to repeat—is a question you should ask a radiologist
Radiographers frequently choose to repeat an image just because they think they can acquire a better one, even though the radiologist would be glad to accept that film or image as is. As an example, a radiographer may deem a slightly overexposed or underexposed image as unsuitable, whereas the radiologist would be satisfied. Similarly, this can occur when the body part in question is rotated or some of it is cut-off. In this situation, the information provided by the film could be considered sufficient for diagnostic purposes by the radiologist.
Whenever in doubt, you should find an available radiologist for consultation and advice. Simply double-checking can greatly reduce the number of rejected good films. With digital imaging, these cases can be reduced even further by digitally adjusting the images to an acceptable window and level.
The gist: Radiology departments should ensure the involvement of radiologists in the supervision and training of radiographers, who in turn should take great care to confer with the radiologist before repeating a scan.
Choice of exposure factors in X-ray repeat imaging
Most repeat imaging has been found to be caused by exposure errors. Weirdly enough, it has been shown that the majority of these repeats were performed by senior radiographers who rarely consult exposure charts and almost never assess the patient’s size [1]. Indeed, the methods used by these radiographers were quite peculiar: Some carried pocket-sized notes of their courses and exposures values from their training days, despite having access to modern procedures and techniques; others used the controversial “skull equals pelvis equals half a knee and so on” concept. Although some radiographers believe this strategy works, it unfortunately is not always the case! Not all patients have the same pelvis or abdomen size, and the proportionality between body parts varies between patients.
To avoid having to repeat an X-ray, refer to your department’s exposure chart before performing the exam. (and if they don’t have one established, you can stand out in your department by leading the push to develop one!). You should then should choose the relevant parameters associated with the body part in question to produce an acceptable image quality that meets the diagnostic standards.
The gist: Most repeat imaging is caused by exposure errors that could be avoided by establishing and referring to a departmental exposure chart.
Check for poor positioning in X-ray repeat imaging
A large proportion of repeat examinations is also attributed to inadequate positioning techniques. Automatic exposure controls were developed to achieve more consistent exposures, reduce repeat imaging, and, ultimately, reduce radiation exposure to patients. However, when positioning technique is wrongfully applied, a misalignment of the body part in question with the photo-timer will result leading to a repeat. This has been shown to be mostly due to a lack of knowledge about the bucky stand’s architecture.
Contrary to the exposure errors, studies have shown that positioning errors are mostly associated with less experienced, junior radiographers. This suggests that the problem may be due to a lack of expertise, training, or supervision. The mistakes were mostly due to the rotation of the body part in question that can also have poor alignment with the cassette. Educational references, such as Merrill’s Atlas of Radiographic Positions [2] can be extremely helpful here (and can we suggest Medical Professionals’ positioning guides, as well?).
The gist: Poor positioning accounts for a significant portion of repeat X-ray exams. Always have ready access to educational reference guides so you can check if poor positioning is the cause of an unusable image so you can correct this for your repeat scan.
Student radiographer contributions
The amount of repeated scans are also influenced by student technologists. This a problem primarily faced by teaching hospitals and may not apply to your healthcare institution. If your institution doesn’t take on student technologists, feel free to skip ahead.
In policy and depending on the rules and regulations for student supervision of any each site, student technologists are supposed to always under the complete authority and supervision of the senior radiographer during a case. In practice, however, senior radiographers may often start a case with the students and leave them unsupervised to finalize the exam. In certain cases, senior students were even found to be coaching junior students, a practice that should be avoided at all costs.
The gist: Technologists supervising students should always lead by example and keep a keen eye on the students they supervise to avoid imaging mistakes commonly made technologists-in-training that lead to the need for repeat imaging.
Patient motion
Some repeated scans are due to patient movement during the acquisition. The patient might be having a hard time holding their breath, or the severity of their illness could be a major contributing factor. It is therefore very important to keep constant communication with the patient and clearly explain the procedure to avoid any issues. Remember, patients don’t typically know how imaging works and may not understand intuitively what you want from them, when, or why.
Motion is the biggest issue when it comes to an image sharpness of detail. It is recommended to always use shorter exposure times. However, this does not always ensure that motion will not occur. But because some kinds of movement are beyond the radiographer’s control, it is usually thought that the shorter the exposure time, the sharper the images are likely to be.
The gist: Check your image for patient motion. If you have to repeat the X-ray, be sure to communicate clearly with the patient, and use shorter exposure times to reduce the chance of motion.
Check the equipment
- The tube is centered to the image receptor
- The tube and the body part are properly aligned
- The body part is centered to the image receptor
- The body part is properly positioned
Skipping any of these can lead to off-centered images, elongation, or foreshortening distortion that would require you to repeat the X-ray.
The gist: If you see off-centered images, elongation, or foreshortening, check the alignment of the equipment and body part before performing a repeat. Make it a habit to perform this check before each scan.
Check for over-collimation
Many repeated scans are the due to the overzealous use of collimation. Though it seems obvious, you should always check to make sure you have included the anatomy of interest inside the X-ray field. Excessive collimation can result in clipping critical parts from view, requiring you to repeat the X-ray—which entirely defeats the fundamental aim of collimation in saving patient exposure.
With practice, radiographers learn that the X-ray beam’s borders are not always completely aligned with the edges of the projected light field. In fact, each border of the light field is only required to be within one-half inch of the actual X-ray field’s margins. With this in mind, it is prudent to allow at least 1 cm of light beyond each border of the anatomy of interest, as long as it does not reach beyond the edge of the cassette plate.
The gist: Allow at least 1 cm of light beyond each border of the anatomy of interest (provided is doesn’t extend past the edge of the cassette plate) in order to avoid clipping important body parts from view.
Pathology
The patient’s condition often makes obtaining a high-quality image challenging. You should also be aware of any aberrant changes caused by disease, trauma, or medical intervention, in addition to the patient’s overall state. The reason each procedure is ordered should be justified, since this information frequently reflects directly on method selection and can prevent repeat imaging. It can always be beneficial to review the patient’s chart when available or ask the patient for a brief history.
Correcting with post-processing
The major advantage of all digital imaging is its ability to modify and adjust the image’s contrast, brightness, and other features without having to repeat the initial X-ray exposure. Digital imaging has saved millions of dollars by minimizing repeat imaging and has also significantly decreased the overall radiation exposure to the patients. This is the very purpose of medical radiography: to increase diagnostic information while reducing radiation exposure.
Be sure you check to see if an X-ray can be digitally corrected before you repeat the scan. It is important to note that an image that is mottled due to gross under-exposure may only be corrected by repeating the exam.
The gist: Remember, even if the image turns out to be too light, too dark, or to have poor contrast, it can probably be digitally corrected and a repeat exposure avoided.
It is important to keep in mind that each patient is different from the other in terms of size and shape and will require different exposures. Always refer to your department’s exposure charts. Do not rely on notes you took a long time ago. Choose your exposure ranges wisely and consider what is best for the patient, the part size, and/or the disease. But mostly, do not rush! Take your time positioning the patient accurately and choosing the correct exposure factors for an optimal quality of a diagnostic image. Be sure to check the X-ray carefully yourself, and even with a radiologist, to see if there really is a need to repeat the exam. And remember: repeat imaging will happen—it just doesn’t have to happen nearly as often as it does.
We hope this information has been helpful! for more reference guides, please visit this Link
References
- Nol, J., Isouard, G. & Mirecki, J. (2005). Uncovering the causes of unnecessary repeated medical imaging examinations, or part of, in two hospital departments. Radiographer, 52(3), 26-31. [Link]
- Nol, J., Isouard, G., & Mirecki, J. (2006). Digital repeat analysis; setup and operation. Journal of Digital Imaging, 19(2), 159–166. Revised September 1, 2014. [Link]
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