Radiation exposure to foetus and breasts from dental X-ray examinations: effect of lead shields

Abstract

Objectives: Dental radiography may involve situations where the patient is known to be pregnant or the pregnancy is noticed after the X-ray procedure. In such cases, the radiation dose to the foetus, though low, needs to be estimated. Uniform and widely used guidance on dental X-ray procedures during pregnancy are presently lacking, the usefulness of lead shields is unclear and practices vary. Methods: Upper estimates of radiation doses to the foetus and breasts of the pregnant patient were estimated with an anthropomorphic female phantom in intraoral, panoramic, cephalometric and CBCT dental modalities with and without lead shields. Results: The upper estimates of foetal doses varied from 0.009 to 6.9 mGy, and doses at the breast level varied from 0.602 to 75.4 mGy. With lead shields, the foetal doses varied from 0.005 to 2.1 mGy, and breast doses varied from 0.002 to 10.4 mGy. Conclusions: The foetal dose levels without lead shielding were ,1% of the annual dose limit of 1 mSv for a member of the public. Albeit the relative shielding effect, the exposure-induced increase in the risk of breast cancer death for the pregnant patient (based on the breast dose only) and the exposure-induced increase in the risk of childhood cancer death for the unborn child are minimal, and therefore, need for foetal and breast lead shielding was considered irrelevant. Most important is that pregnancy is never a reason to avoid or to postpone a clinically justified dental radiographic examination.

Skin entrance dose with and without lead apron in digital panoramic radiography for selected sensitive body regions

“…Of course, the absolute values are small, and their impact on the patient can be questioned. This general conclusion is in line with the recent findings of Kelaranta and coworkers [8]. The authors report on average 3.57 μGy (without lead apron) versus 0.61 μGy (with lead apron) for the female breast in panoramic radiography.…”

“…While some reports [3][4][5] suggest shielding with aprons is not necessary since the dose to the body of the patient is negligible, others [6] recommend application of lead aprons. Interestingly, not many papers have been published investigating this issue [7,8]. For the thyroid, thyroid collars have been found effective for digital panoramic units yet interestingly not for storage phosphor-based systems [9].…”

“…This would allow highly sensitive direct measurements for a few specific regions of interest. We are aware of only one very recent publication [8] that has investigated doses with and without lead apron by means of a high-sensitivity solidstate-dosimeter. As the concept of ALARA in combination with the generally adopted linear-non-threshold theory (LNT, [14]) suggests that all avoidable radiation should be avoided, further research seems advisable.…”

Are Bismuth Shields Useful in Dentomaxillofacial Radiology Practice for the Protection of Eyes and Thyroid Glands from Ionizing Radiation?

“…Although lead thyroid collars and lead glasses are proved to be effective in dose reduction, large lead glasses decrease image quality of the area between the maxillary sinus floor and the orbit, and thyroid shielding impairs the image quality in OPTG and CBCT scanning (7,14,20). Therefore, bismuth shielding may be considered as an alternative in shielding these areas.…”

“…Recently, the American Thyroid Association (ATA) (13) issued new guidelines on how to minimize any unnecessary exposure to radiation during the execution of medical and dental imaging procedures, such as the use of thyroid collars for dental X-rays. Thyroid collars are used in intraoral and cephalometric examinations; however, they are not used in OPTG due to the fact that they may prevent the primary beam, and their use in CBCT requires further inquiry (14).…”