Short answer: A small dental X-ray sits at a few microsieverts, a panoramic at roughly 10 to 20, a CBCT at roughly 20 to 200 depending on the volume. A flight to New York carries something like 30 to 70 microsieverts of cosmic radiation per leg, purely from the altitude. In Germany, every person receives around 2,100 microsieverts a year from natural sources anyway. Dental X-rays therefore move within everyday orders of magnitude — which does not make it any less necessary to justify each image.
“Do we really need the X-ray?” is one of the most common questions in our practice, and it is a fair one. It is just badly answered with reassurance. Better answered with numbers — and with a unit you can put in context.
What is measured is the effective dose, in microsieverts (µSv). It weights how sensitive the irradiated tissue is, and that makes very different situations comparable: a small image at a tooth, and a long-haul flight.
The orders of magnitude, side by side
Bitewing or single-tooth image, digital
The small image used to detect decay, with a rectangular collimator
1–5 µSv
Natural background radiation in Germany, one day
Cosmic radiation, soil, building materials, food — without you doing anything
approx. 6 µSv
Panoramic image (OPG), digital
Both jaws in one image, including sinuses and jaw joints
10–20 µSv
Frankfurt–New York flight, one way
Cosmic radiation at 10 to 12 km altitude, roughly 5 to 6 µSv per hour
30–70 µSv
CBCT — 3D scan, depending on volume and resolution
A small volume in low-dose mode at the lower end, a large high-resolution volume at the upper
20–200 µSv
CT scan of the head, in hospital
For comparison, because CBCT and CT are often confused — they are different procedures
1,000–3,000 µSv
Natural background radiation in Germany, one year
The reference figure everything else can be measured against
approx. 2,100 µSv
All values are ranges, not measurements of your image. They vary with the unit, the settings, the scan volume and body build; published figures partly disagree. Based on figures from the German Federal Office for Radiation Protection, ICRP 103 and the European guidelines on radiation protection in dentistry.
In orders of magnitude: a bitewing is roughly equivalent to one day of living in Germany. A panoramic is roughly two to three days. A single flight to New York is somewhere between a panoramic and a small CBCT — except it reaches the whole body.
Why the flight comparison is imperfect — and still useful
It is useful because it translates a number into an experience: almost nobody cancels a holiday flight over cosmic radiation, and the order of magnitude is the same. It is imperfect because the distribution differs. On a flight the whole body is irradiated evenly, including the trunk and the blood-forming bone marrow. With a dental image a small field sits at the jaw, and that is precisely why the effective dose is so low.
Flight figures also vary considerably: with route, altitude, duration and solar activity. For Frankfurt–New York, published figures range from roughly 30 to 70 microsieverts per leg, and in some sources considerably higher. Anyone presenting such numbers as exact quantities is overstating their data.
What we do about it in our practice
Radiation protection is not an attitude but a series of concrete decisions — about the equipment, the settings, and whether to image at all.
Osstem T2 — CBCT and panoramic in one unit
Digital sensors, selectable scan volume and a low-dose mode. We limit the volume to the clinical question rather than routinely capturing the whole jaw: a smaller field means less dose.
A small, rectangular collimator
For single images the collimator limits the beam to the area of the sensor. A rectangular field instead of a round one substantially reduces the irradiated volume at the same image quality. The most effective simple measure a practice can take.
A justified indication, every time
Under German radiation protection law, imaging is only permitted where the expected information will actually influence treatment. No image “just to be safe”, no routine scan without a question to answer.
That includes the unspectacular part: where a previous dentist has images, we request them rather than repeat them. You can have your own images digitally on request — including for a second opinion. And every image is recorded in your radiation passport, so that you and any future practitioner keep track.
Children, pregnancy, and fear of radiation
With children the same principle applies more strictly: smaller fields, shorter exposure, and no image where there is doubt. For decay in baby teeth, the decision is often made by looking rather than imaging. In pregnancy we postpone everything that can wait; where treatment is acutely needed, an image at the head with shielding is defensible, because the beam is far from the abdomen. Please always tell us about a pregnancy beforehand, including a suspected one.
And the most important sentence last: the greater danger is almost always the diagnosis not made, not the image taken. An undetected infection under a crown does more damage over years than 15 microsieverts. If you are unsure, ask us before the image why we think it is necessary — the answer should be specific, not “we always do this”.
Frequently asked questions
Are dental X-rays dangerous?
The dose of a dental image sits in a range you receive anyway in daily life: a small dental X-ray is roughly equivalent to one day of natural background radiation in Germany. At this level a risk cannot be measured, only modelled mathematically. What matters is therefore not fear of the individual image, but that every image has a reason.
How much radiation does a CBCT have compared with a panoramic?
A panoramic image sits at roughly 10 to 20 microsieverts depending on the unit and settings. A CBCT sits at roughly 20 to 200 microsieverts depending on the volume and resolution. A small, tightly limited CBCT in low-dose mode can therefore come close to a panoramic, while a large high-resolution volume is considerably above it. We limit the volume to the clinical question.
Is an X-ray really equivalent to a flight?
The comparison helps put things in context but it is not a like-for-like match. On a flight the whole body is exposed evenly to cosmic radiation; with a dental image a small, clearly limited field is exposed. Figures for a Frankfurt–New York flight vary with route, altitude and solar activity; values around 30 to 70 microsieverts per leg are commonly cited.
Why do you use a small rectangular collimator?
The collimator limits the beam to the area actually being imaged. A rectangular field instead of a round one substantially reduces the irradiated volume without reducing image quality. It is the simplest and most effective dose reduction available in a dental practice.
Can X-rays be taken during pregnancy?
Anything that can wait, we postpone. Where there is an acute need, such as an infection requiring treatment, a dental image with shielding is possible: the beam is at the head, not the abdomen, and scattered radiation in the region of the uterus is vanishingly small. Please always tell us about a pregnancy beforehand, including a suspected one.
How often can you be X-rayed?
There is no legal annual limit on the number of images, because no such number would be meaningful: the measure is not a quota but a justified indication for each individual image. Where images already exist, we request them rather than repeat them.