What a dental image actually costs in dose: 5 microsieverts for four bitewings, 388 for a D-speed full-mouth series, and a cone beam that ranges to 1,073

What it says#

Effective dose is the quantity that lets you compare a bitewing set with a chest film or a week of living. It weights the dose to each organ by that organ's radiosensitivity and adds them up, which is why the numbers moved when the International Commission on Radiological Protection revised the weights in 2007 and gave the salivary glands and the oral mucosa more weight than they had before.

The measurements the ADA's own topic page rests on come from a tissue-equivalent head phantom. Ludlow, Davies-Ludlow and White published them in JADA in September 2008, calculated under both the 1990 and the 2007 schemes, and reported that the 2007 values run 32 to 422 percent higher than the older ones. Under the 2007 recommendations, in microsieverts: a full-mouth series with photostimulable phosphor storage plates or F-speed film and rectangular collimation, 34.9. Four-image posterior bitewings with the same receptor and rectangular collimation, 5.0. A full-mouth series using PSP or F-speed film with round collimation, 170.7. A full-mouth series with D-speed film and round collimation, 388. A panoramic Orthophos XG with a charge-coupled device, 14.2, and a panoramic ProMax with a CCD, 24.3. A posteroanterior cephalogram on PSP, 5.1, and a lateral cephalogram on PSP, 5.6.

Read the intraoral numbers as a sequence rather than a list. The same fourteen or eighteen films, taken on the same patient, cost 34.9 microsieverts with a rectangular collimator and a modern receptor, about five times that with a round cone, and about eleven times that if the office is still running D-speed film through a round cone. The authors' own clinical implication is that clinicians can reduce patients' dose substantively by using digital receptors or F-speed film instead of D-speed film, rectangular collimation instead of round collimation, and radiographic selection criteria. Two of those three are purchases that cost less than a single crown.

Cone beam does not collapse to a number. Ludlow and colleagues reviewed the English-language literature on CBCT effective dose in Dentomaxillofacial Radiology in 2015, reducing 519 PubMed and 743 EMBASE hits to 20 publications, and added data for nine more units. Reported adult effective doses for any protocol ranged from 46 to 1,073 microsieverts for large fields of view, 9 to 560 for medium and 5 to 652 for small. Child doses ran 13 to 769 for large or medium fields and 7 to 521 for small. Where a standard or default exposure protocol was used, they had 167 adult and 52 child exposures to work from, and the mean adult effective doses by field of view were 212 microsieverts for large, 177 for medium and 84 for small; the child means were 175 for large and medium combined and 103 for small. Their own conclusion is that large exposure ranges make CBCT doses difficult to generalize, and that large differences were seen between different units. A published correction the following April withdrew a criticism the authors had made of one cited study and changed no dose figure.

The yardstick comes from the National Council on Radiation Protection and Measurements. The ADA quotes NCRP's estimate that the mean effective dose from all sources in the United States is 6.2 millisieverts a year, about 3.1 of it from natural sources such as soil and radon and about 3.1 from man-made sources, about half of that man-made half being CT. EPA repeats the 6.2 millisievert figure from NCRP Report 160 and puts 48 percent of it down to medical procedures. Three point one millisieverts a year of natural background works out to roughly 60 microsieverts a week, or about 8.5 a day; that division is arithmetic on the NCRP figure, not a number either body publishes. The ADA also states that dental imaging accounts for less than 1 percent of the estimated collective annual effective dose received from medical imaging.

Who it applies to#

Anyone who has to answer the question at the chair or on the phone, which in most offices means the assistant, the hygienist and the front desk more often than the dentist. The numbers cover the intraoral, panoramic and cephalometric images a general practice takes, and the cone beam scans an implant or endodontic case triggers.

They do not cover the operator. Occupational dose is a separate measurement against separate limits, and it is the subject of the companion entry on occupational radiation dose limits and personal monitoring. They also do not describe your equipment. These are measurements of named units at named settings; a practice that wants its own figures has to have a medical physicist measure them, which is what a state radiation control program inspection may require anyway.

One limitation is worth naming because it gets misquoted. The 2008 study's intraoral groups are defined by receptor speed and collimator shape, with photostimulable phosphor plates and F-speed film grouped together. It does not publish a separate full-mouth figure for a solid-state intraoral sensor, so anyone quoting "digital sensors versus PSP" as a dose comparison is not quoting this study. The honest statement is the one the authors make: digital receptors or F-speed film instead of D-speed film, and rectangular instead of round collimation.

What changed#

Twice over. First the arithmetic: the 2007 ICRP weighting raised calculated effective doses for dental imaging by 32 to 422 percent without any change in what the machines emit, which is why an older textbook figure for a full-mouth series can be a quarter of the current one. Second the equipment: D-speed film and round cones, which produce the 388 microsievert full-mouth series, have largely given way to digital receptors, and rectangular collimation is now the ADA's central patient-protection recommendation, replacing the lead apron that was the prior generation's answer. That is the subject of the 2024 recommendations, slug ada-radiation-safety-recommendations-2024.

The other change is cone beam itself, which the ADA's topic page describes as the major single contributor of diagnostic radiation in dentistry and which did not exist in United States practice before the late 1990s. The ADA's position, quoted from the 2024 panel, is that clinicians should only perform radiographic imaging, including CBCT, after reaching the professional judgment that there is a clear clinical benefit and that the benefit outweighs the risks.

Where the source is#

The ADA's X-rays and radiographs topic page, last updated March 26, 2026, is the link under the title; it carries the NCRP background figures, the occupational limits, the pregnancy section and the reference list from which both dosimetry studies come. The 2008 JADA paper and the 2015 Dentomaxillofacial Radiology meta-analysis are both behind publisher access, but their abstracts carry the dose values quoted here and are linked above on PubMed. The 2012 ADA and FDA patient-selection document is a free 29-page PDF from the ADA and is still the fullest free statement of the technique factors. EPA's Radiation Sources and Doses page carries the NCRP Report 160 average and a set of everyday comparisons. The FDA's dental cone-beam computed tomography page, content current as of September 28, 2020, carries the agency's justification and optimization recommendations but publishes no dose figures; it blocks automated retrieval, so it is described here rather than linked as a download.