Every now and then when your doctor asks you to stay still and poise for an x ray, do you realize that you are at the receiving end of ionizing radiations. These are invisible rays that traverse through your entire thickness, sweeping along every cell in your body before finally reaching the x ray plate where an image of your insides is formed. The x rays are an indispensable aid for proper diagnosis and treatment but it comes at a price.
Excessive and repeated exposure to ionizing radiation harms the DNA of cells and intercedes with the division of body cells, thereby increasing the risk of cancer. Especially vulnerable are children and pregnant women. Exposing the thyroid at a young age to radiation is a recognized risk factor for the development of thyroid cancer. The human fetus is particularly sensitive to ionizing radiation, and even low radiation doses should be avoided. The fetus is at a risk of growth retardation, malformations and impaired brain function when bombarded with x rays.
Nevertheless, we do not live in a radiation free zone. The ionizing radiation from the natural sources (eg. sun, soil, rock) ranges from 1-10 mSv with 2 mSv (milliSievert) being an average.( A Sievert (Sv) is the unit which measures the effective dose in terms of overall risk due to the radiation). So we are persistently, day after day living among radiations. Medical imaging too, exposes you to radiation but they vary among various kinds of imaging modalities.
But why do dental surgeons keep taking an awful lot of x rays of your teeth? The reason is that a major portion of the tooth along with the bone, soft tissue, nerves and blood vessels are embedded in the gums and they are visible only with the help of radiographs. It is usually impossible to properly diagnose by looking at the portion of the tooth above the gums. Digital imaging and electronic sensors used in most dental offices nowadays provide an excellent picture while requiring much less x-ray radiation.
Enlisted below are the radiation exposures from commonly advised dental imaging methods:
|Imaging||Exposure in mSv|
|X ray tooth (dental film)||~0.004|
|Panoramic X ray (OPG or full mouth)||~0.014|
|CBCT (small area) [3D imaging]||0.005 – 0.0383|
|CBCT (full mouth) [3D imaging]||0.068 – 0.599|
|MRI and Ultrasound||No Radiation|
Dental X rays are relatively safe and are targeted to a very small and focused area of the body with the exposure being minimal compared to other conventional X rays. Referring to the table above, the radiation from one dental x ray equals 0.004 mSv which is much less than the natural radiation we receive in a day or from a 1-2 hour flight. The radiation doses from dental CBCT exams are also generally lower than other CT scans (eg CT chest, CT abdomen, CT head).
But since x rays are mandatory for the clinician, can patient exposure be reduced without reducing diagnostic quality? The answer is yes. Every doctor should aim to keep exposures as low as reasonably achievable (ALARA principle) and minimize doses received by their patients to even lower levels.
Few methods to attain this are:
i) Use of lead impregnated aprons to protect the reproductive organs .These should be worn by all patients undergoing a dental x ray examination. They also protect against scattered radiation.
ii) Lead impregnated thyroid shields protect the thyroid gland from the ill effects of radiations.
iii) Protective barriers to minimize radiation beyond the examination area.
Now that you are more radiation wise, the next time your doctor asks you to pose in front of the x ray clicking machine, spare a thought and make sure you are armed against radiation. Limit radiations, Be healthy, Be wise!
Photo Credit : Shutterstock
By Dr. Anveeta Agarwal, BDS, MDS
Consultant Oral Pathologist, Associate Dental Surgeon
Specialist at Dantah