Issue
Radioprotection
Volume 57, Number 1, January-March 2022
Page(s) 55 - 59
DOI https://doi.org/10.1051/radiopro/2021033
Published online 12 January 2022

© SFRP, 2022

1 Introduction

Intraoral and panoramic dental X-ray play an important role in the treatment of patients requiring dental care for acute problems. The 2008 report of the United Nations Scientific Committee on the Effects of Atomic Radiation classified dental radiography as one of the most frequently performed radiological procedures (UNSCEAR, 2000). In childhood and adolescence, children may undergo many of these procedures and this may be attributed to the fact that these early examinations help prevent cavities and tooth decay, which can lead to pain, trouble concentrating and other medical issues. According to the dose-response model (ICRP, 2007), which is used in radiation protection to estimate stochastic health effects, the radiation risk from low-dose diagnostic radiological examinations is expected to be small. However, they are stochastic in nature, as demonstrated by the increased probability of carcinogenic radiation with absorbed doses. Therefore, accurate evaluation of the radiation dose is necessary to enhance the protection of the patient receiving dental radiation.

It is well known that there are no dose limits for patients undergoing radiological diagnostic examinations but the principles of justification and optimization of practice must always be under consideration (ICRP, 1996). International Commission of Radiological Protection (ICRP) recommend that the typical radiation doses for patients undergoing common examinations are measured at approved intervals and compared with the reference levels (ICRP, 2007; Gulson et al., 2007; IAEA, 2014). The comparison results are used to determine whether the measures used in facilities to ensure patient protection and safety are optimized and appropriate. In some cases, corrective action may be required if typical doses are exceeded or significantly below the relevant reference values.

Several publications have reported different dose measurement methods for estimating intraoral and panoramic diagnostic reference levels (DRLs) c, such as measuring of dose area product (DAP), entrance surface dose (ESD), dose width product (DWP) or entrance surface air kerma (ESAK) (ICRP, 1996). However, the most commonly used is the dose area product (DAP). The DRLs are based on the third quartile values for the distributions of doses found in the national or regional surveys. In literature, the dose values for the adult maxillary molar were reported in the range of 5–7 mGy (Napier, 1999; Williams and Montgomery, 2000; Vaño et al., 2001; Isoardi and Ropolo, 2003). Other dose values for incisor and premolar teeth were also reported in the literature (Hodolli et al., 2019). The Internal Atomic Energy Agency (IAEA) reported the panoramic diagnostic reference doses for adults in the range of 84–120 mGy.cm2, in terms of kerma-area product, and in the range between 0.65 to 3.7 mGy, in terms of entrance surface air kerma, for intraoral dental radiography (IAEA, 2020).

The dental radiation dose reported by previous studies has shown wide variations values measured at different facilities (Napier, 1999; Williams and Montgomery, 2000; Isoardi and Ropolo, 2003; Gulson et al., 2007; Hodolli et al., 2019). The diagnostic reference doses for intraoral were in the range between 60 to 120 mGy.cm2 for both paediatric and adult patients. Many factors influence the dose such as the tube voltage, exposure time, film speed, beam filtration, and film processing, and detector type (in the case of digital systems) (EC, 2004). The present paper describes the efforts of the Radiological Sciences Department of Najran University Hospital in establishing the first local DRLs for children and adults undergoing intraoral and panoramic dental examinations at the radiology units of the public hospitals in southern Saudi Arabia.

2 Materials and methods

This study was carried out in southern Saudi Arabia to assess the radiation dose received by patients undergoing intraoral and dental panoramic examinations. In November 2019 the study was ethically cleared by the Scientific Research Ethics Committee at Najran University (Registration number: 443-37-23038-DS). A DAP meter (GAMMEX RMI 841-RD) was used to measure DAP for intraoral and panoramic X-ray units. The meter was placed at the collimator surface at the end of the cone of the dental X-ray unit’s (Fig. 1a). For purpose of comparison between the two dosimeters, an additional calibrated Unfors Xi dosimeter (Unfors Inc., Billdal, Sweden) was used and placed at a focus to skin distance (FSD) of 100 cm (Fig. 1b). As regards panoramic units, the DAP meter was placed in front of the collimator (Fig. 2a). Further, the DAP was calculated indirectly by obtaining the dose width product (DWP) using the Unfors Xi CT dosimeter pencil ionization chamber (Fig. 2b).

Data were collected between 2019–2020 using 31 intraoral and 17 panoramic dental radiology units (Tab. 1). The patient exposure used was based on the settings performed by the Department of Radiology, Najran University, and surrounding clinics in Najran City. The clinical tube voltage (kVp) setup ranged between 60–70, whereas tube current (mA) ranged between 5–11 for all intraoral and panoramic measurements. Room temperature and pressure corrections were not involved in this study. All beam cones of intraoral units have a round shape with 60 mm diameter at the beam exit point and have a total filtration range between 2–2.5 mm Al equivalent at 70 kV. The Focus to Surface Distance (FSD) was 100 cm. As DAP cannot be measured directly using Unfors dosimeters, it was calculated for intraoral and panoramic examinations using equations (1) and (2), respectively. (1) where A is the beam area. (2)where DWP (dose width product) is the absorbed dose in the air that can be obtained from the beam characteristics at the receiving slit, and H is the beam height.

Statistical parameters such as the mean, standard deviation and 3rd quartile, include both digital and analogue panoramic units, have been calculated using SPSS version 14 (SPSS Inc, Chicago, IL) according to the recommendations of the European Commission (EC, 1999).

thumbnail Fig. 1

Measurement setup of the (a) dose area product (DAP) and (b) entrance surface air kerma (ESAK) for intraoral radiography using DAP meter and Unfors Xi dosimeter.

thumbnail Fig. 2

Measurement setup of the (a) dose area product (DAP) and (b) dose width product (DWP) for panoramic radiography using DAP meter and Unfors Xi CT dosimeter.

Table 1

Characteristics of the intraoral and panoramic dental units.

3 Results

Mean values of exposure parameters, measured and calculated DAP for the intraoral units are shown in Table 2 using DAP and Unfors Xi dosimeter meters. Measured and calculated DAP values for the panoramic units for paediatrics and adults are shown in Table 3, together with the mean of different exposure times, and tube voltages values. Children ages were ranged between 3 and less than 17 years old. The mean beam height value was 13.3 cm, whereas the mean beam area value was 13.5 cm2. Furthermore, the 3rd quartile for intraoral and dental panoramic units are also presented in Tables 2 and 3, respectively.

Table 2 show the mean ESAK values of the 31 intraoral dental radiology units. The 3rd quartile values indicated in Table 2 include both paediatric and adult program. The overall mean DAP was 28.7, 30.1, 40.2 and 39.4 mGy.cm2 for incisive, premolar and canine, molar upper and lower jaws, respectively. As expected, the calculated mean DAP and the 3rd quartile DAP for the digital units were found lower than that of the analogue units.

Table 3 shows the mean DWP values of the 17 panoramic dental radiology units. The mean DWP and 3rd quartile were calculated for each of paediatric and adult program. The overall mean DWP was 4.68 and 6.78 mGy, whereas the measured mean DAP was 61.5 and 89.8 mGy.cm2 for paediatric and adult, respectively. It is evident, in Table 3, that the calculated and measured mean DAP values are comparable. However, the 3rd quartile DAP for the digital units was found lower than that of the analogue unit.

Table 2

Intraoral mean values using DAP and Unfors Xi meters.

Table 3

Panoramic mean values using DAP and Unfors Xi meters.

4 Discussion

In this study, we noticed that some private dental clinics for intraoral radiography systems are still using systems that are more than 30 years old, and some of them are equipped with mechanical exposure timers or had pointed cones. As the beam diameter at the top of cones in these old units is about 11 cm and a target-to-skin distance (TSD) is less than 15 cm, we recommend that these units be taken out of service. The National Council for Radiation Protection and Measurements (NCRP) reported that distances between 20 cm and 40 cm for intraoral radiography systems are appropriate (NCRP, 2019). In addition, Goren et al. reported that using a distance of 40 cm, rather than 20 cm, decreases radiation exposure by up to 25% (AAOMR, 2000). To continue to reduce dental radiation dose to patients in Saudi Arabia, a distance between 20 cm and 40 cm are appropriate to be used as possible in all intraoral units. However, longer distances are also ideal without compromising image quality.

Regarding the current status of radiation protection, none of the dental clinics involved in this study was covered by a regular quality assurance program. Furthermore, some dental clinics depend on a panoramic screening in order to detect diseases before the patient receives a clinical evaluation. It is well known that ionizing radiation exposure can be limited by the golden roles. To decrease radiation exposure hazards, the dental radiographic exposure must be justified to be medically indicated and useful and the examination must be optimized. In 2012, the American Dental Association recommended avoiding such radiographic screening prior to the clinical examination (ADA, 2012). As a result, new regulations should be introduced in Saudi Arabia to organizes and limit the use of panoramic screening prior to receiving a clinical examination.

The DAP results showed that the deviation between the measured and calculated values ranged between 1–4% (Tabs. 2 and 3). This confirms that measurements performed by the DAP dosimeter give results consistent with those calculated from ESAK or DWP meter. Further, the results showed that the DAP ranged from 6 to 70 mGy.cm2. As previously mentioned in the Introduction section, setting DRLs can be performed by different methods, however, the most commonly used is the DAP method. This trend could probably be attributed to the simplicity of using the DAP meter. In this study, the tube voltage ranged from 60 to 72 kV, and the tube current ranged from 6.5 to 12 mA. Accordingly, hospital dose variations were large. Variation in patients’ doses is a clear indication that dose reduction is possible without losing the image quality.

The DRLs values reported for intraoral examinations in the Europe and UK were 4.0 and 2.3 mGy, respectively (Hart et al., 2009). In literature, the average standard of DAP for adult panoramic examination was reported 0.113 Gy cm2 (Williams and Montgomery, 2000). This study shows comparable values with the doses reported in similar studies (Jose et al., 2019; Holroyd et al., 2020). The small number of X-ray devices used can be considered as one of the limitations of this study. This may lead to the development of a nationwide dose survey to include several dental X-ray facilities and inevitably will be a major reason for updating the DRLs reported in this study.

5 Conclusions

This study provides insight into the recommended DRLs value for intraoral and panoramic dental radiology in Saudi Arabia. The DAP meter is a useful tool for determining dental patient doses. Therefore, it is recommended to use the measured DAP values to determine the DRLs in dental radiology.

For dental intra-oral radiography, the recommended DRLs value for incisive, molars and both premolar and canine are 27.6, 39.7, and 28.8 mGy.cm2, respectively. Further, the DRLs value for panoramic radiography for paediatric and adult are 61.5 and 89.8 mGy.cm2, respectively. Panoramic screening before clinical investigations should be prohibited to use due to the high dose produced by ionizing radiations. Finally, more data will be needed to establish additional diagnostic reference levels in Saudi Arabia, such as dental cone-beam computed tomography systems.

Conflicts of interest

The authors have no potential conflicts of interest to disclose.

Funding

Deanship of Scientific Research, Najran University, Kingdom of Saudi Arabia for their financial and technical support (Project no. NU/-/MRC/10/304).

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This study received ethical approval from the Ethics committee of Najran University under the protocol number 443-37-23038-DS.

Informed consent

This article does not contain any studies involving human subjects.

Authors contributions

Mohammed K. Saeed: conceptualization, methodology; Khalaf Alshamrani: simulation and analysis; Abdullah A.M. Asiri: supervision; Qaed S. Alhamami: writing-reviewing and editing.

Acknowledgement

The authors are grateful to all hospitals in Saudi Arabia which participated in this work and especially the radiographers at the Radiological Departments for their time and cooperation during the data collection. The authors would like to express their gratitude to the Ministry of Education and the Deanship of Scientific Research, Najran University, Kingdom of Saudi Arabia for their financial and technical support (Project no. NU/-/MRC/10/304).

References

Cite this article as: Saeed MK, Asiri AAM, Alhamami QS, Alshamrani K. 2022. Intraoral and dental panoramic imaging: A diagnostic reference level study comparing radiation dose using two dosimeters in Saudi Arabia. Radioprotection 57(1): 55–59

All Tables

Table 1

Characteristics of the intraoral and panoramic dental units.

Table 2

Intraoral mean values using DAP and Unfors Xi meters.

Table 3

Panoramic mean values using DAP and Unfors Xi meters.

All Figures

thumbnail Fig. 1

Measurement setup of the (a) dose area product (DAP) and (b) entrance surface air kerma (ESAK) for intraoral radiography using DAP meter and Unfors Xi dosimeter.

In the text
thumbnail Fig. 2

Measurement setup of the (a) dose area product (DAP) and (b) dose width product (DWP) for panoramic radiography using DAP meter and Unfors Xi CT dosimeter.

In the text

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