Efficient Scanning – Reduced Radiation | Dr. Ben Wang

Nowadays, patients are becoming increasingly conscious of the harmful effects of radiation on their health. Many of my patients ask me about the safety of the x-ray system that I am using at my downtown Portland dental practice. At Centerport Dental, our aim is to provide excellent dental treatment to our patients in a safe and comfortable environment. Therefore, we are using a digital x-ray system which significantly minimizes the radiation exposure of the patients as well as my dental team. Before we indulge into the safety of the digital x-ray systems, let us compare the digital x-ray systems with the conventional ones.


Comparison of Conventional and Digital X-ray Systems & How they Work

In conventional dental radiography, a radiographic film is placed between the tooth that needs to be imaged, and the x-ray source. The x-ray machine generates a beam of photons that hits the radiographic film and generates an image of the intended structure. In contrast, a sensor is placed inside the oral cavity which electronically captures the image of the teeth and related structures. Since the digital imaging systems are precisely calibrated and controlled by a computer, their radiation exposure is quite less than that of the conventional radiographic system.

Comparison of the Digital Dental X-rays with Other Sources of Radiations

Dental x-rays are not the only form of radiation doses that we receive. According to the United States Nuclear Regulatory Commission1 Humans are exposed to two different forms of ionizing radiations:

1. Natural Sources of Radiation Exposure

These include radiations from the cosmic terrestrial radiation and internal sources. The highest radiation exposure to the Americans is through Radon gas, which is present in the air. Additionally, water sources also contain low level radiations, which can be ingested.
According to the United States Nuclear Regulatory Commission (USNRC), about 50%, or 0.31 rem of radiation exposure to humans occurs from natural radiation sources. For more details, please visit this page.


2. Medical Sources of Radiation

According to the USNRS, the remaining half of human radiation exposure occurs through medical sources. Among them, the highest exposure is from a Positron Emission Tomography – Computed Tomography (PET/CT) of about 2.5 rem, followed by 1.2 rem from Coronary Computed Tomography Angiography (CTA). Here is a comparison chart of various source of medical radiations, which is available at the website of American Dental Association:

Table 1. Effective Dose Exposures from Medical Examinations and Procedures2,3 . I mSV = 0.1 rem

Type  Average Effective Dose (Adults) in Millisieverts (mSv)  Equivalent Effective Dose (Adults) in Microsieverts (µSv) 
 Intraoral X-Ray  0.005 mSv 5.0 µSv
Dental panoramic radiography  0.01 mSv 10 µSv
Chest radiography  0.1 mSv 100 µSv
Dental computed tomography  0.2 mSv 200 µSv
Mammography  0.4 mSv 400 µSv
Upper G.I. tract radiography (including fluoroscopy)  6.0 mSv 6,000 µSv
Coronary computed tomography angiography 12 mSv 12,000 µSv

The Safety of Dental Digital X-rays

Now coming back to the dental x-rays. From the above chart, it is obvious that radiation exposure from digital intra-oral x-rays is the least among different types of medical radiations, about 0.0005 rem, which is 20 times less than a chest x-ray (0.01 rem). In contrast, according to the guidelines provided by the European Commission4 , radiation exposure from a single conventional radiograph is about 0.0017 rem, about 3 times more exposure than a digital radiograph.

Multiple X-ray Images are Required During Routine Dental Procedures; Are they Still Safe?

More than one x-ray may be required during your routine dental checkup. Let us suppose that we take an average of 4 intra-oral x-rays on each checkup for every patient. This would account for a total radiation exposure of about 0.002 rem. This is still 5 times less radiation than a single chest x-ray image! Here are the radiation exposures from other types of dental x-ray images.

Table 2. Effective Radiation Doses for Dental Radiographic Examinations5

 Type of Exposure  Effective Dose (Adults) in Millisieverts (mSv)   Effective Dose (Adults) in Microsieverts (µSv)
Full mouth series – 18 images    
–With PSP storage or F-speed film and rectangular collimation  0.035 mSv  34.9 µSv
–With PSP storage or F-speed film and round collimation  0.171 mSv  170.7 µSv
Bite wing (4 images) with PSP storage or F-speed film and rectangular collimation  0.005 mSv  5.0 µSv
Cone-Beam Computed Tomography    
–Dentoalveolar CBCT small and medium field view  0.011-0.674 mSv  11-674 µSv
–Maxillofacial CBCT with large field of view  0.030-1.073 mSv  30-1073 µSv

These radiations are well within the safe limit of 0.1 rem for the general public and individuals who do not have an occupational exposure to radiation .
It is estimated that the total yearly dose of radiation each person receives is about .62 rem, about .31 rem of this dosage is from medical sources. Therefore, the radiation exposure from a routine dental checkup (0.002) is 300 times less than the annual radiation exposure.

Other Safety Measures at Centerport Dental Against Unnecessary Radiation Exposure

That is not all! At Centerport dental, we follow the ALARA6 guideline provide by the American Dental Association. ALARA stands for “as low as reasonably achievable” dosage. Therefore, we only take x-rays when they are essential for your treatment and diagnosis. In addition, we also take great care to protect children and pregnant women from unnecessary radiation exposure. For this purpose, we use lead aprons and thyroid collars, which limit the radiation exposure to the fetus and the thyroid gland, respectively.

The Final Word

In conclusion, we can safely assume that radiation exposure from dental x-rays is very low and is very likely to cause any harmful effect on your body. Still, I take great care to limit the exposure of my patients as well as my dental staff to unnecessary radiation exposure.

[1] https://www.nrc.gov/about-nrc/radiation/around-us/sources.html
[2] http://www.ada.org/en/member-center/oral-health-topics/x-rays
[3] https://www.radiologyinfo.org/en/info.cfm?pg=safety-xray#safety-benefits-risks
[4] https://ec.europa.eu/energy/sites/ener/files/documents/136_0.pdf
[5] American Dental Association Council on Scientific Affairs. The use of cone-beam computed tomography in dentistry: an advisory statement from the American Dental Association Council on Scientific Affairs. J Am Dent Assoc 2012;143(8):899-902.
[6] American Dental Association Council on Scientific Affairs

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