Risks of child CBCT revisited.
Last week’s blog post on the risks of chlld CBCT sparked many questions and controversy, particularly on social media, where I received considerable criticism for suggesting that we should not routinely use CBCT examinations on children. I wonder if my message was lost amid the substantial “white noise” surrounding this issue. Therefore, I have written a new post to outline what I believe are the main points regarding the routine use of CBCT for children.
I will start with the British Orthodontic Society Guidelines. Although they are getting rather old, their essential messages are still relevant.
British Orthodontic Society Guidelines
The general theme of the guidelines is set out in this statement.
“Before any radiographic examination, a clinical examination must be conducted to avoid unnecessary radiation exposure. To prevent radiographs from being taken simply because it is ‘routine’, the justification should conclude that the needed information is not available elsewhere and that radiography is the most suitable method for obtaining it.”
There is no safe dose for radiation exposure; radiation dose is accumulative. This is particularly important for child radiography.
What is the dose?
There is a surprising lack of knowledge about the dose from CBCT taken for orthodontic purposes. This is a rapidly evolving field, and I have taken this from the ADA recommendations on dental radiography.
| Type of examination | EFFECTIVE DOSE, AVERAGE OR RANGE,∗ μSv | AVERAGE BACKGROUND RADIATION EQUIVALENT, D† |
| Extra oral radiographs | ||
| Panoramic | 19.0-75.0 | 2-9 |
| Cephalometric | 2.0-10.0 | < 1-1.3 |
| Paediartic Cone-beam computed tomography | ||
| Small FOV | 7-521 | 1-61 |
| Medium or large FOV | 13-769 | 1.5-91 |
The most striking feature of this table is the wide range for CBCT doses. These were obtained from the paper by Ludlow in 2014.
To put a perspective on this information, people often quote the equivalence to natural background radiation.
- Natural background radiation: ~8–10 µSv/day.
- Depending on the settings, a CBCT scan can equal a few days to several months of background radiation.
- Panorex and cephalometric images roughly equal 1–3 days of background radiation.
One of the most frequent points raised by orthodontists justifying the routine use of CBCT is that the dose is the same as that for a cephalogram and panoramic examination. However, I cannot find any scientific publication that states this.
I have looked at the documentation for the Newtom, Morita Accuitomo 170 and Carestream CBCT machines but could not find any information on their effective doses for an “Orthodontic” CBCT. This was disappointing. There may be a lot of smoke and mirrors surrounding this critical issue. If I have missed something, can someone point me to the evidence supporting the claims about similar doses?
Is CBCT useful?
There is no doubt that we obtain great images with CBCT. However, limited research has been conducted into the utility of these images. The only papers that I have come across have suggested.
CBCT cannot be recommended for a valid and reliable comparison of airway dimensions for our patients.
CBCT images provided much additional information than conventional views, their use did not significantly impact the treatment decisions for impacted canines.
Therefore, there is a lack of evidence for the effect of CBCT on changing or reinforcing our clinical decisions. It still appears that we can get sufficient information for diagnosis from examining the patient and 2D radiographs.
ADA recommendations
The latest set of recommendations on dental CBCT are included in a recent set of guidelines produced by an expert panel from the ADA. These state:
- Exposure to any amount of ionizing radiation can increase the risk of adverse health effects.
- Dental imaging exposure levels are typically well below the threshold for harm. However, patients often undergo multiple radiographic examinations throughout their lives, and studies have shown that cumulative low-level radiation exposure may be associated with triggering oxidative stress or potentially inducing damage to cellular DNA or oral epithelium, thereby increasing the risk of carcinogenesis. In addition, the risk for children may be heightened due to longer cumulative exposure over their lifespans as well as their higher organ radiosensitivity.
- A CBCT examination should not be merely routine and should not be used for screening purposes.
- CBCT imaging should not be used routinely. CBCT examinations shall not be used as the primary or initial imaging modality when a lower-dose alternative is adequate for diagnosis and treatment planning.
Decisions
It is, of course, a personal decision for orthodontists to select the radiographs they deem most useful while ensuring the lowest level of radiation. However, we should not disregard guidelines merely because they do not align with our clinical experiences. If we do, we put our patients at risk. Furthermore, are we also risking ourselves? For instance, where would you stand if you performed a CBCT on an 8-year-old to assess the airway and, many years later, they developed cancer? What would your grounds for defence be?
Final comments
After reviewing much information and discussing child CBCT with maxillofacial radiologists, I would follow the ADA guidelines and not use CBCT routinely. I would stick with standard 2D views where indicated and only take CBCT views when I need them to investigate potential problems further.
Importantly, I don’t understand why some people reject the ADA guidelines and feel they know better than an expert panel. I, certainly, do not have the knowledge to disagree with these panels.
Let’s have a civilised chat about this.
Emeritus Professor of Orthodontics, University of Manchester, UK.
Congratulations! Even in adults, the guidelines should be the same. CBCT would not be a routine in orthodontic records.
the key word here is ROUTINE…I know of no one who takes routine CBCT on children…however only after doing a thorough and complete diagnosis can a decision be made and sometimes the decision is not to take a CBCT but on other occasions we decide to take a CBCT….and that makes in some cases all the difference…..after nearly 40 years I am seeing that 70-75% of my first consultations are retreatments…and almost always due to misdiagnosis…..diagnosis is the name of the game and sometimes CBCT helps
Kevin
well said – absolutely agree
Ross
Kevin,
I appreciate the post. A quick Google search revealed this handy PDF from Planmeca regarding the effective dose of their CBCT machines. Although it does not specifically call out “orthodontics,” the imaging profile used for an orthodontic exam is the “face” setting. https://www.planmeca.com/globalassets/planmeca/usaintranet/radiation/effective_doses_planmeca_xray_0413.pdf
Thanks this is useful. I have looked at this table and I cannot see a dose for a child. Unless, it is stated in the row “child skull”. This is 128 µSv. Unless I have missed something? Best wishes
I’m pleased to say that you are revisiting this issue and took the feedback you received seriously. I’m also pleased that you put in the ranges of effective dosage for CBCT imaging to prove the point that a full FOV CBCT image can be taken for LESS radiation than a panorex alone.
I’d also like to point out that your statement that “panorex and cephalometric images roughly equal 1–3 days of background radiation” has multiple flaws. Firstly, a panorex cannot equal 1 day of background radiation (8-10uSv), as the dosage at lowest end (per your numbers) = 19uSv. Additionally, the way you stated it makes it seem as if a pan and a ceph can be taken for 1 day of background. That is false.
Secondly, in the bullet point prior to that, you reference both the high and low ranges of the effective dose of CBCT when you state they can be “a few days to several months of background radiation.” Ironically, when referring to panorex and cephalometric images, you only cite the lowest end (1-3 days). To be fair and factual, you should state that the combined values of a pan/ceph can be as high as 10 days of background radiation.
For someone who is such a prolific writer and quite precise with their verbiage, I find such flagrant wordsmithing quite interesting. I sincerely hope the inaccuracy of your comments was merely an oversight and not intentionally meant to mislead the reader.
Lastly, I’ll repeat the question I asked you on social media but you neglected to answer. If we can take a full CBCT image on
a child (low-dose = 13uSv, per your numbers; 17uSv per Ludlow, AJODO 2013) for LESS radiation than a pan and ceph (total at lowest end = 21uSv, per your numbers), AND we know that we can get exponentially more diagnostic information from a 3D image (which is not disputable), what could possibly be the argument against the routine use of CBCT imaging for pediatric patients?
Thank you for your comments. The statements regarding dose equivalents were derived from multiple sources, including the International Atomic Energy Agency, which supports the accuracy of my remarks. Additionally, I believe you missed my point about the use of information from Cone Beam Computed Tomography (CBCT). There is limited research on this topic, and we should be cautious about assuming that high-quality images will automatically influence our treatment decisions.
Importantly, radiographic guidelines indicate that CBCT should not be used routinely. This fundamental information is crucial to consider, and it is the primary focus I aimed to convey in my blog post.
Not surprisingly, you continue to evade the question, which confirms that you cannot answer it. It also shows that you were likely trying ot decide the reader with the way you worded the bullet points. But nice job trying to deflect.
Also, are you really trying to make the argument that we need a study to say that a 2D pan/ceph allows you to see more diagnostic information than even a low-dose 3D image? I’d like to think you’re more intelligent than that.
Additionally, the “radiographic guidelines” you quote are irrelevant if they are not taking low-dose imaging into account.
Since you’re clearly either unwilling or unable to answer my previous question, let’s see if you can handle this one: Do you believe in ALARA principles?
I answered your question. Yes, I do believe in ALARA. I feel that you are getting too aggressive and rude. As I wrote in my blog post “let’s have a civil discussion. So this exchange stops now.
After reading both of your recent posts on CBCT, I appreciate how you flushed out your points here; they are well taken.