TY - JOUR
AU - Wu, Jiabao
AB - Abstract The radiation doses absorbed by major organs of males and females were studied from three types of dental X-ray devices. The absorbed doses from cone-beam computed tomography (CBCT), panoramic and intraoral X-ray machines were in the range of 0.23–1314.85 μGy, and were observed to be high in organs and tissues located in or adjacent to the irradiated area, there were discrepancies in organ doses between male and female. Thyroid, salivary gland, eye lens and brain were the organs that received higher absorbed doses. The organ absorbed doses were considerably lower than the diagnostic reference level for dental radiography in China. The calculated effective radiation doses for males and females were 56.63, 8.15, 2.56 μSv and 55.18, 8.99, 2.39 μSv, respectively, when using CBCT, the panoramic X-ray machine and intraoral X-ray machine. The effective radiation dose caused by CBCT was much higher than those of panoramic and intraoral X-ray machines. INTRODUCTION Shortly after Roentgen published his discovery of X-rays in December 1895, Dr Otto Walkhoff captured the first ever dental radiograph(1). Since then, X-ray radiography has been used by dentists as an effective diagnosis tool for precise treatment. Currently, dental radiological examination is essential in the clinical diagnosis and treatment of various diseases, such as tooth and periodontal tissue lesions, maxillofacial bone inflammation and jaw cysts or tumors(2–4). Common dental radiography techniques include traditional 2D intraoral and panoramic radiography and the newly developed 3D technique of cone-beam computed tomography (CBCT). The use of CBCT has become increasingly popular in dentistry because it provides high-resolution 3D images with no overlapping and distortion(5–6). Among the artificial source of ionizing radiation, medical radiation contributes the most to the global annual collective effective dose(7). Although the radiation doses received by patients from dental X-ray machines are significantly lower than those from multidetector-row computed tomography (MDCT), the effects of radiation on organs, especially the thyroid and brain, are of widespread concern due to the exposure area in dental radiological examination(8–9). Furthermore, a controversy exists regarding whether pregnant patients can undergo dental radiological examination. Pregnant women are generally advised to avoid radiography(10). However, Tsapaki(11) recommended abandoning the practice of inquiring the pregnancy status of female patients in dental radiology due to the extremely low fetus dose. Numerous studies have investigated the radiation doses of dental X-ray devices. These studies have mostly focused on the exposure of head and neck organs(12–15). However, studies on the radiation exposure of various organs throughout the body in dental X-ray examination are still limited(16–17), and such studies may help us understand the whole-body radiation dose of dental X-ray devices. According to the 2008 United Nations Scientific Committee on the Effects of Atomic Radiation report, 480 million dental radiological examinations are conducted worldwide every year. Dental radiological examinations account for 13% of all medical diagnostic radiological examinations, and their number has increased considerably in recent years(17). The exposure of major organs to radiation during dental radiological examination should be investigated to establish principles for the safe application of X-ray radiation. The purpose of this study was to determine the radiation doses absorbed by the major organs of patients when using dental X-ray devices of various types, to study the discrepancies in organ doses between male and female, and to evaluate the radiation dose to embryo and fetus of pregnant women. The absorbed dose was determined using an anthropomorphic adult phantom equipped with thermoluminescent dosimeters (TLDs). The radiation doses absorbed by 22 organs and tissues were evaluated for male and female patients under common scanning protocols to determine the effective doses of CBCT, a panoramic X-ray machine and an intraoral X-ray machine. MATERIALS AND METHODS Dose measurement This study was conducted in the Department of Stomatology of Shenzhen University General Hospital in China. It investigated the radiation doses of CBCT (KaVo 3D eXami, Imagine Sciences International LLC, USA), a digital panoramic X-ray machine (PP1, SoredexPalodex Group Oy, Finland) and an intraoral X-ray machine (Focus, Instrumentarium Dental Palodex Group Oy, Finland). In this study, common scanning protocols were adopted for each device. The technical parameters recommended by the manufacturers are presented in Table 1. When performing CBCT and the panoramic X-ray machine, the maxillofacial mode was used with a field of view (FOV) of 14.5 × 8.5 cm. The projection in the intraoral X-ray machine was maxillary premolar (left) with a FOV of 4.5 × 3.5 cm. Table 1 Technical parameters for the standard scanning protocols. Devices . Tube voltage (kV) . Tube current (mA) . Exposure time (s) . CBCT 120 5 23 Digital panoramic X-ray machine 73 10 11 Intraoral X-ray machine 70 7 0.125 Devices . Tube voltage (kV) . Tube current (mA) . Exposure time (s) . CBCT 120 5 23 Digital panoramic X-ray machine 73 10 11 Intraoral X-ray machine 70 7 0.125 Open in new tab Table 1 Technical parameters for the standard scanning protocols. Devices . Tube voltage (kV) . Tube current (mA) . Exposure time (s) . CBCT 120 5 23 Digital panoramic X-ray machine 73 10 11 Intraoral X-ray machine 70 7 0.125 Devices . Tube voltage (kV) . Tube current (mA) . Exposure time (s) . CBCT 120 5 23 Digital panoramic X-ray machine 73 10 11 Intraoral X-ray machine 70 7 0.125 Open in new tab A standard anthropomorphic adult phantom (CDP-R1, Chengdu Fangtuo Simulation Technology Company Limited, China) was used for dose measurement. This phantom represents a standardized male with a height of 1.7 m and weight of 65 kg. The phantom was converted to a female with a height of 1.6 m and weight of 58 kg by adding breast attachments and replacing the pelvis part. The phantom simulates human skin, human muscles, human fat, and the human skeleton as well as more than 20 human internal organs. It has the same effective atomic number, mass density, electron density and spatial distribution as the human body. The phantom was composed of 20 contiguous sections, each of which contained a matrix of holes for holding TLDs (Figure 1). Figure 1 Open in new tabDownload slide Anthropomorphic phantom under CBCT (a), panoramic X-ray machine (b), and intraoral X-ray machine (c). In our study, TLD chips with dimensions of 4.5 × 4.5 × 0.80 mm3 (TLD-100H, Harshaw Chemical Company, USA) that were made of LiF (Mg, Cu and P) were placed into the phantom. The TLD chips were calibrated using a Discovery 750HD CT Scanner (GE Healthcare, USA). The absolute dose outputs were measured with a Farmer ionization chamber (TN30013, PTW, Germany), which has an air-kerma calibration that is traceable to Chinese national standards through a therapy-level secondary standard. The variation of the TLD response to uniform radiation was measured to be ±2%. Each time before being inserted into the phantom, all the TLD chips were annealed using a thermoluminescent infrared precision annealing furnace (LM2, China Institute of Radiation Protection). In this study, 88 and 94 TLD chips were equipped in the organs of the phantom for male and female (Table 2), respectively. At least two TLD chips were used per organ to lower the uncertainty. The phantom implanted with the TLD chips was arranged in a standing position on a horizontal plane. All the orientations specified correspond to the orientation of a patient on the machine during dental X-ray examination. The TLD chips were processed using a TLD dose reader (LM3, China Institute of Radiation Protection, China) 24 h after being exposed to the dental X-ray machines. For each device, the measurement was repeated three times with the same settings, and the averages were calculated. About 10 TLD chips were used to measure the background radiation, and the radiation doses to different organs were obtained by subtracting the average background dose. Table 2 Distribution of the TLDs. Organs/Tissues . Male . Female . Breast 6 8 Bone marrow 5 6 Colon 8 6 Lung 14 14 Stomach 6 6 Gonads 2 4 Bladder 4 4 Liver 7 7 Esophagus 4 4 Thyroid 2 2 Skin 4 4 Bone surface 2 4 Brain 12 12 Salivary gland 2 2 Remainder Prostate/Uterus 3 4 Muscle 2 2 Lens 2 2 Kidney 2 2 Pancreas 2 2 Spleen 2 2 Heart 5 5 Adrenal gland 2 2 Background 10 10 Total 98 104 Organs/Tissues . Male . Female . Breast 6 8 Bone marrow 5 6 Colon 8 6 Lung 14 14 Stomach 6 6 Gonads 2 4 Bladder 4 4 Liver 7 7 Esophagus 4 4 Thyroid 2 2 Skin 4 4 Bone surface 2 4 Brain 12 12 Salivary gland 2 2 Remainder Prostate/Uterus 3 4 Muscle 2 2 Lens 2 2 Kidney 2 2 Pancreas 2 2 Spleen 2 2 Heart 5 5 Adrenal gland 2 2 Background 10 10 Total 98 104 Open in new tab Table 2 Distribution of the TLDs. Organs/Tissues . Male . Female . Breast 6 8 Bone marrow 5 6 Colon 8 6 Lung 14 14 Stomach 6 6 Gonads 2 4 Bladder 4 4 Liver 7 7 Esophagus 4 4 Thyroid 2 2 Skin 4 4 Bone surface 2 4 Brain 12 12 Salivary gland 2 2 Remainder Prostate/Uterus 3 4 Muscle 2 2 Lens 2 2 Kidney 2 2 Pancreas 2 2 Spleen 2 2 Heart 5 5 Adrenal gland 2 2 Background 10 10 Total 98 104 Organs/Tissues . Male . Female . Breast 6 8 Bone marrow 5 6 Colon 8 6 Lung 14 14 Stomach 6 6 Gonads 2 4 Bladder 4 4 Liver 7 7 Esophagus 4 4 Thyroid 2 2 Skin 4 4 Bone surface 2 4 Brain 12 12 Salivary gland 2 2 Remainder Prostate/Uterus 3 4 Muscle 2 2 Lens 2 2 Kidney 2 2 Pancreas 2 2 Spleen 2 2 Heart 5 5 Adrenal gland 2 2 Background 10 10 Total 98 104 Open in new tab Effective dose evaluation The TLD readings of specific organs were averaged and converted to organ-absorbed doses by multiplying them with the factor obtained from the TLD calibration. According to the International Commission on Radiation Protection (ICRP), the effective dose is the summation of all multiplicative products of organ-absorbed doses with two weighting factors, as presented in equation (1). $$\begin{equation} E=\sum WR\cdotp WT\cdotp DT \end{equation}$$(1) where E is the effective dose, DT is the organ-absorbed dose, WR is the radiation weighting factor that is 1 for X-rays and WT is the tissue-weighting factor recommended in ICRP Publication 103(18) for an organ or tissue. RESULTS Tables 3 and 4 present the measurement results of the organ-absorbed doses and effective doses for the three devices. The effective doses of males from CBCT, the digital panoramic X-ray machine and the intraoral X-ray machine were 56.63, 8.15 and 2.56 μSv, respectively, and were 55.18, 8.99 and 2.39 μSv, respectively, for females. The effective dose of CBCT was considerably higher than those of the panoramic and intraoral X-ray machines. There were discrepancies in organ doses between the males and females, whereas little differences were observed in the effective doses between the males and females. Table 3 Organ absorbed doses and effective doses of the three devices for males. Organ absorbed dose (μGy) . Tissue weighting factor . CBCT . Panoramic . Intraoral . Male . Male . Male . Breast 0.12 40.79 ± 0.11 8.90 ± 0.08 2.33 ± 0.04 Bone marrow 0.12 15.22 ± 1.17 8.08 ± 0.16 0.55 ± 0.01 Colon 0.12 1.71 ± 0.32 0.63 ± 0.01 0.40 ± 0.01 Lung 0.12 29.30 ± 0.30 8.67 ± 0.07 0.85 ± 0.01 Stomach 0.12 6.58 ± 0.07 2.00 ± 0.02 0.30 ± 0.01 Gonads 0.08 1.27 ± 0.01 0.38 ± 0.01 0.74 ± 0.01 Bladder 0.04 1.27 ± 0.01 0.53 ± 0.01 0.68 ± 0.01 Liver 0.04 8.28 ± 0.08 2.01 ± 0.03 0.48 ± 0.01 Esophagus 0.04 25.86 ± 0.48 6.65 ± 0.13 0.77 ± 0.01 Thyroid 0.04 476.04 ± 6.36 54.31 ± 0.89 24.47 ± 0.37 Skin 0.01 56.08 ± 0.59 4.21 ± 0.04 3.00 ± 0.06 Bone surface 0.01 13.52 ± 0.17 5.04 ± 0.10 0.23 ± 0.01 Brain 0.01 427.82 ± 6.85 33.10 ± 0.36 6.12 ± 0.12 Salivary gland 0.01 1177.24 ± 22.63 113.30 ± 2.26 45.25 ± 0.63 Remainder Prostate/Uterus 0.015 1.66 ± 0.02 1.21 ± 0.02 3.01 ± 0.05 Muscle 0.015 38.39 ± 0.63 6.40 ± 0.09 1.86 ± 0.03 Lens 0.015 454.57 ± 9.04 21.26 ± 0.27 16.55 ± 0.27 Kidney 0.015 4.30 ± 0.05 1.78 ± 0.04 0.46 ± 0.01 Pancreas 0.015 3.76 ± 0.08 0.95 ± 0.02 0.85 ± 0.02 Spleen 0.015 4.67 ± 0.08 1.42 ± 0.02 0.27 ± 0.01 Heart 0.015 24.80 ± 0.34 5.65 ± 0.10 0.72 ± 0.01 Adrenal gland 0.015 7.36 ± 0.13 3.31 ± 0.05 0.88 ± 0.02 Effective dose (μSv) 56.63 ± 1.01 8.15 ± 0.08 2.56 ± 0.04 Organ absorbed dose (μGy) . Tissue weighting factor . CBCT . Panoramic . Intraoral . Male . Male . Male . Breast 0.12 40.79 ± 0.11 8.90 ± 0.08 2.33 ± 0.04 Bone marrow 0.12 15.22 ± 1.17 8.08 ± 0.16 0.55 ± 0.01 Colon 0.12 1.71 ± 0.32 0.63 ± 0.01 0.40 ± 0.01 Lung 0.12 29.30 ± 0.30 8.67 ± 0.07 0.85 ± 0.01 Stomach 0.12 6.58 ± 0.07 2.00 ± 0.02 0.30 ± 0.01 Gonads 0.08 1.27 ± 0.01 0.38 ± 0.01 0.74 ± 0.01 Bladder 0.04 1.27 ± 0.01 0.53 ± 0.01 0.68 ± 0.01 Liver 0.04 8.28 ± 0.08 2.01 ± 0.03 0.48 ± 0.01 Esophagus 0.04 25.86 ± 0.48 6.65 ± 0.13 0.77 ± 0.01 Thyroid 0.04 476.04 ± 6.36 54.31 ± 0.89 24.47 ± 0.37 Skin 0.01 56.08 ± 0.59 4.21 ± 0.04 3.00 ± 0.06 Bone surface 0.01 13.52 ± 0.17 5.04 ± 0.10 0.23 ± 0.01 Brain 0.01 427.82 ± 6.85 33.10 ± 0.36 6.12 ± 0.12 Salivary gland 0.01 1177.24 ± 22.63 113.30 ± 2.26 45.25 ± 0.63 Remainder Prostate/Uterus 0.015 1.66 ± 0.02 1.21 ± 0.02 3.01 ± 0.05 Muscle 0.015 38.39 ± 0.63 6.40 ± 0.09 1.86 ± 0.03 Lens 0.015 454.57 ± 9.04 21.26 ± 0.27 16.55 ± 0.27 Kidney 0.015 4.30 ± 0.05 1.78 ± 0.04 0.46 ± 0.01 Pancreas 0.015 3.76 ± 0.08 0.95 ± 0.02 0.85 ± 0.02 Spleen 0.015 4.67 ± 0.08 1.42 ± 0.02 0.27 ± 0.01 Heart 0.015 24.80 ± 0.34 5.65 ± 0.10 0.72 ± 0.01 Adrenal gland 0.015 7.36 ± 0.13 3.31 ± 0.05 0.88 ± 0.02 Effective dose (μSv) 56.63 ± 1.01 8.15 ± 0.08 2.56 ± 0.04 Open in new tab Table 3 Organ absorbed doses and effective doses of the three devices for males. Organ absorbed dose (μGy) . Tissue weighting factor . CBCT . Panoramic . Intraoral . Male . Male . Male . Breast 0.12 40.79 ± 0.11 8.90 ± 0.08 2.33 ± 0.04 Bone marrow 0.12 15.22 ± 1.17 8.08 ± 0.16 0.55 ± 0.01 Colon 0.12 1.71 ± 0.32 0.63 ± 0.01 0.40 ± 0.01 Lung 0.12 29.30 ± 0.30 8.67 ± 0.07 0.85 ± 0.01 Stomach 0.12 6.58 ± 0.07 2.00 ± 0.02 0.30 ± 0.01 Gonads 0.08 1.27 ± 0.01 0.38 ± 0.01 0.74 ± 0.01 Bladder 0.04 1.27 ± 0.01 0.53 ± 0.01 0.68 ± 0.01 Liver 0.04 8.28 ± 0.08 2.01 ± 0.03 0.48 ± 0.01 Esophagus 0.04 25.86 ± 0.48 6.65 ± 0.13 0.77 ± 0.01 Thyroid 0.04 476.04 ± 6.36 54.31 ± 0.89 24.47 ± 0.37 Skin 0.01 56.08 ± 0.59 4.21 ± 0.04 3.00 ± 0.06 Bone surface 0.01 13.52 ± 0.17 5.04 ± 0.10 0.23 ± 0.01 Brain 0.01 427.82 ± 6.85 33.10 ± 0.36 6.12 ± 0.12 Salivary gland 0.01 1177.24 ± 22.63 113.30 ± 2.26 45.25 ± 0.63 Remainder Prostate/Uterus 0.015 1.66 ± 0.02 1.21 ± 0.02 3.01 ± 0.05 Muscle 0.015 38.39 ± 0.63 6.40 ± 0.09 1.86 ± 0.03 Lens 0.015 454.57 ± 9.04 21.26 ± 0.27 16.55 ± 0.27 Kidney 0.015 4.30 ± 0.05 1.78 ± 0.04 0.46 ± 0.01 Pancreas 0.015 3.76 ± 0.08 0.95 ± 0.02 0.85 ± 0.02 Spleen 0.015 4.67 ± 0.08 1.42 ± 0.02 0.27 ± 0.01 Heart 0.015 24.80 ± 0.34 5.65 ± 0.10 0.72 ± 0.01 Adrenal gland 0.015 7.36 ± 0.13 3.31 ± 0.05 0.88 ± 0.02 Effective dose (μSv) 56.63 ± 1.01 8.15 ± 0.08 2.56 ± 0.04 Organ absorbed dose (μGy) . Tissue weighting factor . CBCT . Panoramic . Intraoral . Male . Male . Male . Breast 0.12 40.79 ± 0.11 8.90 ± 0.08 2.33 ± 0.04 Bone marrow 0.12 15.22 ± 1.17 8.08 ± 0.16 0.55 ± 0.01 Colon 0.12 1.71 ± 0.32 0.63 ± 0.01 0.40 ± 0.01 Lung 0.12 29.30 ± 0.30 8.67 ± 0.07 0.85 ± 0.01 Stomach 0.12 6.58 ± 0.07 2.00 ± 0.02 0.30 ± 0.01 Gonads 0.08 1.27 ± 0.01 0.38 ± 0.01 0.74 ± 0.01 Bladder 0.04 1.27 ± 0.01 0.53 ± 0.01 0.68 ± 0.01 Liver 0.04 8.28 ± 0.08 2.01 ± 0.03 0.48 ± 0.01 Esophagus 0.04 25.86 ± 0.48 6.65 ± 0.13 0.77 ± 0.01 Thyroid 0.04 476.04 ± 6.36 54.31 ± 0.89 24.47 ± 0.37 Skin 0.01 56.08 ± 0.59 4.21 ± 0.04 3.00 ± 0.06 Bone surface 0.01 13.52 ± 0.17 5.04 ± 0.10 0.23 ± 0.01 Brain 0.01 427.82 ± 6.85 33.10 ± 0.36 6.12 ± 0.12 Salivary gland 0.01 1177.24 ± 22.63 113.30 ± 2.26 45.25 ± 0.63 Remainder Prostate/Uterus 0.015 1.66 ± 0.02 1.21 ± 0.02 3.01 ± 0.05 Muscle 0.015 38.39 ± 0.63 6.40 ± 0.09 1.86 ± 0.03 Lens 0.015 454.57 ± 9.04 21.26 ± 0.27 16.55 ± 0.27 Kidney 0.015 4.30 ± 0.05 1.78 ± 0.04 0.46 ± 0.01 Pancreas 0.015 3.76 ± 0.08 0.95 ± 0.02 0.85 ± 0.02 Spleen 0.015 4.67 ± 0.08 1.42 ± 0.02 0.27 ± 0.01 Heart 0.015 24.80 ± 0.34 5.65 ± 0.10 0.72 ± 0.01 Adrenal gland 0.015 7.36 ± 0.13 3.31 ± 0.05 0.88 ± 0.02 Effective dose (μSv) 56.63 ± 1.01 8.15 ± 0.08 2.56 ± 0.04 Open in new tab As presented in Tables 3 and 4, the organs and tissues located in or adjacent to the irradiated area received relatively higher radiation doses. For CBCT, the radiation doses absorbed by thyroid, salivary gland, eye lens and brain were 476.04, 1314.85, 454.57 and 494.50 μGy, respectively. For panoramic X-ray machine, they were 63.90, 148.55, 26.28 and 33.10 μGy, respectively. And for intraoral X-ray machine, they were 24.47, 45.25, 16.55 and 7.76 μGy, respectively. For those indirectly irradiated organs or tissues received high radiation doses, the organs were breast (24.93 μGy) and skin (56.68 μGy) when performing CBCT. For panoramic X-ray machine, the organs were breast, bone marrow, lung, esophagus and muscles (doses ranging from 6.04 to 8.90 μGy). And for intraoral X-ray machine, the organs were breast, skin and muscles (doses ranging from 1.71 to 4.38 μGy). DISCUSSION Intraoral X-ray machine, digital panoramic X-ray machine and CBCT are widely used X-ray devices in dental radiology. Among the three devices, CBCT caused the highest effective dose, both for the male and female. Our results were in consistent with other studies which concluded that patient doses from CBCT were much higher than those from conventional dental radiography techniques(16,19–20), and this was mainly due to the higher working voltage and longer irradiation time of CBCT(8). As seen in Tables 3 and 4, the effective radiation doses from CBCT, the digital panoramic X-ray machine and the intraoral X-ray machine were approximately 56, 9 and 2.5 μSv, respectively. The effective dose of CBCT was nearly 6 times that of the panoramic X-ray machine and 22 times that of the intraoral X-ray machine. Studies have indicated that the effective dose from CBCT was largely influenced by the selected FOV, resolution and X-ray parameters(21–22). A lower mAs setting, a lower resolution as well as a smaller FOV would result in a lower effective dose. Soares et al.(23) observed that the effective doses in CBCT protocols with a single FOV were in the range of 43.1–111.5 μSv, and they were 44.5–236.2 μSv for a complete dental arcade with stitched FOV. In another study by Schilling and Geibel(21), the effective doses ranged from 32.8 to 169.8 μSv for the KaVo 3D eXam CBCT unit, and was from 40.2 to 183.7 μSv for the KaVo Pan eXam Plus 3D CBCT unit. In this study, common scanning protocols were adopted, and the corresponding parameters were recommended by the manufacturers. The effective doses obtained for CBCT in this study were similar to those obtained from CBCT with small FOV(21,23), but were lower than those obtained from CBCT with large FOV(16). Table 4 Organ absorbed doses and effective doses of the three devices for females. Organ absorbed . Tissue weighting factor . CBCT . Panoramic . Intraoral . dose (μGy) . Female . Female . Female . Breast 0.12 24.93 ± 0.13 6.04 ± 0.11 1.71 ± 0.01 Bone marrow 0.12 11.63 ± 0.05 8.34 ± 0.15 1.19 ± 0.02 Colon 0.12 1.49 ± 0.02 1.11 ± 0.02 0.52 ± 0.01 Lung 0.12 28.83 ± 0.53 8.83 ± 0.18 1.29 ± 0.03 Stomach 0.12 6.89 ± 0.07 2.36 ± 0.04 0.78 ± 0.02 Gonads 0.08 1.25 ± 0.01 0.84 ± 0.02 0.62 ± 0.01 Bladder 0.04 0.93 ± 0.01 1.18 ± 0.01 0.51 ± 0.01 Liver 0.04 8.36 ± 0.14 2.73 ± 0.05 0.99 ± 0.01 Esophagus 0.04 26.69 ± 0.28 8.17 ± 0.12 1.16 ± 0.02 Thyroid 0.04 452.68 ± 6.02 63.90 ± 1.25 18.38 ± 0.35 Skin 0.01 56.68 ± 0.08 6.33 ± 0.06 4.38 ± 0.07 Bone surface 0.01 6.60 ± 0.09 3.43 ± 0.07 0.66 ± 0.01 Brain 0.01 494.50 ± 7.89 29.59 ± 0.48 7.76 ± 0.13 Salivary gland 0.01 1314.85 ± 17.82 148.55 ± 1.39 33.88 ± 0.38 Remainder Prostate/Uterus 0.015 1.07 ± 0.28 1.26 ± 0.02 0.77 ± 0.01 Muscle 0.015 37.97 ± 0.47 8.80 ± 0.17 2.15 ± 0.04 Lens 0.015 444.74 ± 4.49 26.28 ± 0.37 16.46 ± 0.17 Kidney 0.015 4.51 ± 0.05 2.23 ± 0.02 0.71 ± 0.01 Pancreas 0.015 4.15 ± 0.08 1.77 ± 0.03 1.18 ± 0.01 Spleen 0.015 5.16 ± 0.02 2.89 ± 0.03 0.92 ± 0.02 Heart 0.015 24.74 ± 0.41 6.67 ± 0.09 1.22 ± 0.02 Adrenal gland 0.015 7.84 ± 0.14 3.96 ± 0.06 1.15 ± 0.02 Effective dose (μSv) 55.18 ± 0.71 8.99 ± 0.14 2.39 ± 0.05 Organ absorbed . Tissue weighting factor . CBCT . Panoramic . Intraoral . dose (μGy) . Female . Female . Female . Breast 0.12 24.93 ± 0.13 6.04 ± 0.11 1.71 ± 0.01 Bone marrow 0.12 11.63 ± 0.05 8.34 ± 0.15 1.19 ± 0.02 Colon 0.12 1.49 ± 0.02 1.11 ± 0.02 0.52 ± 0.01 Lung 0.12 28.83 ± 0.53 8.83 ± 0.18 1.29 ± 0.03 Stomach 0.12 6.89 ± 0.07 2.36 ± 0.04 0.78 ± 0.02 Gonads 0.08 1.25 ± 0.01 0.84 ± 0.02 0.62 ± 0.01 Bladder 0.04 0.93 ± 0.01 1.18 ± 0.01 0.51 ± 0.01 Liver 0.04 8.36 ± 0.14 2.73 ± 0.05 0.99 ± 0.01 Esophagus 0.04 26.69 ± 0.28 8.17 ± 0.12 1.16 ± 0.02 Thyroid 0.04 452.68 ± 6.02 63.90 ± 1.25 18.38 ± 0.35 Skin 0.01 56.68 ± 0.08 6.33 ± 0.06 4.38 ± 0.07 Bone surface 0.01 6.60 ± 0.09 3.43 ± 0.07 0.66 ± 0.01 Brain 0.01 494.50 ± 7.89 29.59 ± 0.48 7.76 ± 0.13 Salivary gland 0.01 1314.85 ± 17.82 148.55 ± 1.39 33.88 ± 0.38 Remainder Prostate/Uterus 0.015 1.07 ± 0.28 1.26 ± 0.02 0.77 ± 0.01 Muscle 0.015 37.97 ± 0.47 8.80 ± 0.17 2.15 ± 0.04 Lens 0.015 444.74 ± 4.49 26.28 ± 0.37 16.46 ± 0.17 Kidney 0.015 4.51 ± 0.05 2.23 ± 0.02 0.71 ± 0.01 Pancreas 0.015 4.15 ± 0.08 1.77 ± 0.03 1.18 ± 0.01 Spleen 0.015 5.16 ± 0.02 2.89 ± 0.03 0.92 ± 0.02 Heart 0.015 24.74 ± 0.41 6.67 ± 0.09 1.22 ± 0.02 Adrenal gland 0.015 7.84 ± 0.14 3.96 ± 0.06 1.15 ± 0.02 Effective dose (μSv) 55.18 ± 0.71 8.99 ± 0.14 2.39 ± 0.05 Open in new tab Table 4 Organ absorbed doses and effective doses of the three devices for females. Organ absorbed . Tissue weighting factor . CBCT . Panoramic . Intraoral . dose (μGy) . Female . Female . Female . Breast 0.12 24.93 ± 0.13 6.04 ± 0.11 1.71 ± 0.01 Bone marrow 0.12 11.63 ± 0.05 8.34 ± 0.15 1.19 ± 0.02 Colon 0.12 1.49 ± 0.02 1.11 ± 0.02 0.52 ± 0.01 Lung 0.12 28.83 ± 0.53 8.83 ± 0.18 1.29 ± 0.03 Stomach 0.12 6.89 ± 0.07 2.36 ± 0.04 0.78 ± 0.02 Gonads 0.08 1.25 ± 0.01 0.84 ± 0.02 0.62 ± 0.01 Bladder 0.04 0.93 ± 0.01 1.18 ± 0.01 0.51 ± 0.01 Liver 0.04 8.36 ± 0.14 2.73 ± 0.05 0.99 ± 0.01 Esophagus 0.04 26.69 ± 0.28 8.17 ± 0.12 1.16 ± 0.02 Thyroid 0.04 452.68 ± 6.02 63.90 ± 1.25 18.38 ± 0.35 Skin 0.01 56.68 ± 0.08 6.33 ± 0.06 4.38 ± 0.07 Bone surface 0.01 6.60 ± 0.09 3.43 ± 0.07 0.66 ± 0.01 Brain 0.01 494.50 ± 7.89 29.59 ± 0.48 7.76 ± 0.13 Salivary gland 0.01 1314.85 ± 17.82 148.55 ± 1.39 33.88 ± 0.38 Remainder Prostate/Uterus 0.015 1.07 ± 0.28 1.26 ± 0.02 0.77 ± 0.01 Muscle 0.015 37.97 ± 0.47 8.80 ± 0.17 2.15 ± 0.04 Lens 0.015 444.74 ± 4.49 26.28 ± 0.37 16.46 ± 0.17 Kidney 0.015 4.51 ± 0.05 2.23 ± 0.02 0.71 ± 0.01 Pancreas 0.015 4.15 ± 0.08 1.77 ± 0.03 1.18 ± 0.01 Spleen 0.015 5.16 ± 0.02 2.89 ± 0.03 0.92 ± 0.02 Heart 0.015 24.74 ± 0.41 6.67 ± 0.09 1.22 ± 0.02 Adrenal gland 0.015 7.84 ± 0.14 3.96 ± 0.06 1.15 ± 0.02 Effective dose (μSv) 55.18 ± 0.71 8.99 ± 0.14 2.39 ± 0.05 Organ absorbed . Tissue weighting factor . CBCT . Panoramic . Intraoral . dose (μGy) . Female . Female . Female . Breast 0.12 24.93 ± 0.13 6.04 ± 0.11 1.71 ± 0.01 Bone marrow 0.12 11.63 ± 0.05 8.34 ± 0.15 1.19 ± 0.02 Colon 0.12 1.49 ± 0.02 1.11 ± 0.02 0.52 ± 0.01 Lung 0.12 28.83 ± 0.53 8.83 ± 0.18 1.29 ± 0.03 Stomach 0.12 6.89 ± 0.07 2.36 ± 0.04 0.78 ± 0.02 Gonads 0.08 1.25 ± 0.01 0.84 ± 0.02 0.62 ± 0.01 Bladder 0.04 0.93 ± 0.01 1.18 ± 0.01 0.51 ± 0.01 Liver 0.04 8.36 ± 0.14 2.73 ± 0.05 0.99 ± 0.01 Esophagus 0.04 26.69 ± 0.28 8.17 ± 0.12 1.16 ± 0.02 Thyroid 0.04 452.68 ± 6.02 63.90 ± 1.25 18.38 ± 0.35 Skin 0.01 56.68 ± 0.08 6.33 ± 0.06 4.38 ± 0.07 Bone surface 0.01 6.60 ± 0.09 3.43 ± 0.07 0.66 ± 0.01 Brain 0.01 494.50 ± 7.89 29.59 ± 0.48 7.76 ± 0.13 Salivary gland 0.01 1314.85 ± 17.82 148.55 ± 1.39 33.88 ± 0.38 Remainder Prostate/Uterus 0.015 1.07 ± 0.28 1.26 ± 0.02 0.77 ± 0.01 Muscle 0.015 37.97 ± 0.47 8.80 ± 0.17 2.15 ± 0.04 Lens 0.015 444.74 ± 4.49 26.28 ± 0.37 16.46 ± 0.17 Kidney 0.015 4.51 ± 0.05 2.23 ± 0.02 0.71 ± 0.01 Pancreas 0.015 4.15 ± 0.08 1.77 ± 0.03 1.18 ± 0.01 Spleen 0.015 5.16 ± 0.02 2.89 ± 0.03 0.92 ± 0.02 Heart 0.015 24.74 ± 0.41 6.67 ± 0.09 1.22 ± 0.02 Adrenal gland 0.015 7.84 ± 0.14 3.96 ± 0.06 1.15 ± 0.02 Effective dose (μSv) 55.18 ± 0.71 8.99 ± 0.14 2.39 ± 0.05 Open in new tab The patient effective dose from dental CBCT has been well documented, and CBCT was considered to be a low-dose radiological method(24–25). As children are more sensitive to ionization, and children organs are at closest distance than for adult, they had a higher median effective dose and cumulative dose when exposed to CBCT(26–27). In fact, CBCT can reach a radiation dose similar or comparable to those of MDCT, which uses a large FOV and high-resolution protocols. In the study of Ludlow and Ivanovic(28), the effective dose was noted as 860 μSv for MDCT, and it was 69–560 μSv for eight dental CBCT units with similar FOVs. Although the radiation dose of CBCT remains in the lower level of medical exposure, it is still important to evaluate the patient dose under various scanning protocols and in different CBCT units. In the current study, the highest effective dose for CBCT was 56.63 μSv, and the radiation dose for CBCT was equivalent with 8.6 days of natural background radiation, which is 2.4 mSv per year on global average(7). Previous studies(16,21) have indicated that the radiation doses absorbed by organs or tissues are related to irradiation position. In dental X-ray examinations, the thyroid, salivary gland, eye lens and brain—which are located in or adjacent to the exposure area—are expected to receive relatively high radiation doses. As presented in Tables 3 and 4, the salivary gland received the highest radiation doses of 1314.85, 148.55 and 45.25 μGy in the CBCT, panoramic X-ray and intraoral X-ray examinations, respectively. Zenóbio and Silva(29) observed that the radiation doses absorbed by the salivary glands (parotid and submandibular) were higher than those absorbed by other organs because the salivary glands were in the path of the primary beam and the other organs only received scattered X-ray radiation. For CBCT, the highest radiation doses absorbed by the thyroid, eye lens and brain were 476.04, 454.57 and 494.50 μGy, respectively, in our study. For the panoramic machine, the highest radiation doses absorbed by the thyroid, eye lens and brain were 63.90, 26.28 and 33.10 μGy, respectively. And for intraoral X-ray machine, the highest radiation doses absorbed by the thyroid, eye lens and brain were 24.47, 16.55 and 7.76 μGy, respectively. For those indirectly irradiated organs or tissues, the radiation doses were in the range of 1.07–56.68, 0.38–8.90 and 0.23–4.38 μGy, respectively, in the CBCT, panoramic X-ray and intraoral X-ray examinations. When compared to the diagnostic reference levels (DRLs) in China(30), for both of the directly and indirectly irradiated organs or issue, their absorbed doses were far below the DRLs in dental X-rays examination. As far as adult phantom is concerned, there are sex specific organs and differences between males and females in masses and positions (physical characteristics), and this may cause discrepancies in organ doses between males and females. In this study, the sex specific organs were mainly breast attachments and pelvis part. As shown in Tables 3 and 4, the absorbed doses in the breast of males were 64%, 48% and 36% higher than those of females from CBCT, panoramic X-ray and intraoral X-ray examinations, respectively. It is interesting to note that, for the females, the absorbed doses of gonads, bladder and prostate/uterus were higher than those of the males from panoramic machine, whereas were lower from CBCT and intraoral machine. To our knowledge, few studies have been conducted on the sex specific organs doses. The results of this study were similar to those reported in Kentaro et al.(31), which indicated tens of percents of discrepancies in organ doses between males and females. Pregnant women are advised to avoid the exposure of medical X-rays to avoid harming the developing fetus. The study of Hujoel et al.(32) showed that women who had dental X-rays during pregnancy were three times as likely to have a low-birth-weight. However, it still remains unclear what caused the association. By contrast, Tsapaki(11) recommended abandoning the practice of inquiring the pregnancy status of female patients in dental radiology due to the extremely low fetus dose. In medical radiation dosimetry, the dose absorbed by the uterus is often used as a substitute for the dose absorbed by the embryo and fetus(33). In this study, the abdominopelvic region was situated far from the main irradiation area, and the fetus received similar doses in the CBCT (1.07 μGy), panoramic X-ray (1.26 μGy) and intraoral X-ray (0.77 μGy) examinations. The natural background gamma dose rate in Shenzhen, China, was noted to be 0.082 ± 0.033 μGy/h(34). The dose absorbed by the fetus in dental radiological examination was equivalent to 11 h of background gamma radiation. According to ICRP Publication 103, after the declaration of pregnancy, the additional radiation dose to the embryo or fetus should not exceed approximately 1 mGy during the remainder of the pregnancy(18). In this study, the radiation doses to the fetus were considerably lower than the radiation level associated with any practical radiation detriment to the fetus. It is suggested that pregnant patient is safe to take a dental radiological examination due to its extremely low radiation dose to the fetus. CONCLUSION The radiation doses absorbed by the major organs of males and females were studied from three types of dental X-ray devices. There were discrepancies in organ doses between males and females. Thyroid, salivary gland, eye lens and brain received much higher absorbed doses than those indirectly irradiated organs or tissues. The maximum effective doses from CBCT, panoramic X-ray and intraoral X-ray examinations were 56.63, 8.99 and 2.56 μSv, respectively. 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TI - ESTIMATING RADIATION DOSE TO MAJOR ORGANS IN DENTAL X-RAY EXAMINATIONS: A PHANTOM STUDY
JF - Radiation Protection Dosimetry
DO - 10.1093/rpd/ncaa196
DA - 2020-12-30
UR - https://www.deepdyve.com/lp/oxford-university-press/estimating-radiation-dose-to-major-organs-in-dental-x-ray-examinations-poiTsDo0Yq
SP - 328
EP - 334
VL - 192
IS - 3
DP - DeepDyve
ER -