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Factors influencing the effective dose associated with CBCT: a systematic review

  • Wilana da Silva Moura
  • Kelly Chiqueto
  • Gustavo Menezes Pithon
  • Leniana Santos Neves
  • Renata Castro
  • José Fernando Castanha Henriques
Original Article
  • 823 Downloads

Abstract

Introduction

Due to potential impact of the effects of ionizing radiation used in medical and dental examinations on public health in recent years, many studies are being conducted to quantify the radiation dose values, evaluate scanners, and indicate factors that could influence or reduce radiation doses.

Objectives

This study aimed to evaluate, by a systematic review, the factors that influence the effective radiation dose associated with cone beam computed tomography and respective effects, and compared the effective dose of different cone beam computed tomography (CBCT) scanners with similar exposure parameters.

Materials and methods

A search was conducted on five databases from 2007 to 2015.

Results

The search identified 741 abstracts, among which 44 eligible articles were retrieved in full text. Twenty-three studies met the inclusion criteria and were included. Additional copper filter was evaluated in one study, patient size in 2 studies, region of interest in 1 study, use of a thyroid shield in 2 studies, scan angle in 3 studies, exposure time in 10 studies, FOV diameter in 17 studies, FOV height in 17 studies, kV in 16 studies, mA in 18 studies, mAs in 13 studies, voxel in 8 studies, and resolution in 3 studies. When similar exposure parameters were evaluated, it was observed that CBCT scanner with lower effective dose was Kodak® 9000C 3D (mean 21.2 μSv) in selected studies.

Conclusions

Thirteen factors were related to changes in the effective dose emitted by different scanners. More studies are needed to identify the image quality requirements in addition to measure the radiation.

Clinical relevance

Studies that give more information for professionals who request and interpret the exams and for technicians who perform 3D images about effective radiation dose associated with CBCT are necessary.

Keywords

Tomography Radiation exposure measurement Radiation dosage 

Introduction

For many years, two-dimensional (2D) dental radiographic techniques have been used to assess patients in dentistry. However, three-dimensional (3D) imaging offers numerous advantages for dental diagnosis. Initially, these images were obtained by conventional CT (computed tomography) scanners, yet currently, cone beam tomography has been more used [1].

Cone beam computed tomography (CBCT) was introduced in dentistry in 1998 by Mozzo et al. [1] to obtain volumetric images. It offers the advantage of highly accurate images with lower radiation dose compared to conventional computed tomography (CT). Currently, there is a range of CBCT devices, and the application of CT images is increasing in dentistry, especially in oral implantology, oral surgery, and orthodontics [2, 3, 4].

To select the appropriate technique, health professionals should consider their responsibility to work with ionizing radiation and request exams that have minimal radiation exposure in favor of better diagnosis. The risk generated by exposure to ionizing radiation constitutes a public health problem [2].

With the increasing use of 3D scans, which use higher radiation doses than 2D scans, there has been increased discussion about the carcinogenic potential of such examinations, especially in children, who are more susceptible to radiation [5]. Due to the potential impact of the effects of ionizing radiation used in medical exams on public health, in recent years [6], many studies [7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30] are being conducted to quantify the radiation dose values, evaluating various scanners, to indicate the factors that could affect or reduce the radiation doses.

Objectives

This study evaluated, by a systematic review, the factors that influence the effective radiation dose associated with cone beam computed tomography and their respective effects, and compared the effective dose of different CBCT scanners with similar exposure parameters.

Material and methods

Protocol and registration

The protocol for a systematic review was registered on the National Institute of Health Research Database (www.crd.york.ac.uk/prospero, Protocol: CRD42015027969). This systematic review was based on the PRISMA guidelines [31].

Eligibility criteria

(1) Measurement of radiation dose values for CBCT using physical phantoms and thermoluminescent dosimeters; (2) Evaluation of the oral and maxillofacial region; (3) Quantification of the effective radiation dose (μSv unit or mSv); (4) Use of the weighting factor recommended by the ICRP 103 published in 2007 for calculation of the effective dose. Review articles, theses, dissertations, editorials, or articles involving the treatment of tumors or radiotherapy were not included.

Information sources, search strategy, and study selection

The MeSH terms shown in Fig. 1 were used for the research. Five electronic databases (MEDLINE, EMBASE, PubMed, Web of Science, and SCOPUS) were systematically searched between January 1, 2007 and December 31, 2015. The references list of the selected studies and relevant reviews were manually searched. Grey literature was also assessed by proper registers and databases. When considered necessary, authors were contacted for complementary data or clarifications.
Fig. 1

MeSH terms used in the databases search

The search was restricted to articles published since 2007 because the latest recommendations of the International Commission on Radiological Protection (ICRP 103) were published in that year, presenting the most current weighting factors to calculate the effective dose emitted by ionizing radiation with inclusion of remainder tissues.

An initial analysis was performed independently by two researchers (W.S.M and G.M.P.). Article titles and abstracts were screened according to the selection criteria. After examining the abstracts, potential articles were obtained in full-text and checked for the inclusion criteria. In case of disagreement, a third reviewer was subsequently consulted for decision.

Data items and collection

A customized data extraction method was developed. Data from the selected articles were divided into 25 groups according to the type of scanner used for the study.

Risk of bias/quality assessment in individual studies

The quality of each article was scored using an adapted version of two methods previously used by Grec et al. [32] and Chen et al. [33]. The following characteristics were considered: sample, valid measurement methods, error analysis, statistical analysis, and confounding factors. Seven variables were evaluated in the study: adequate sample size, 1 point; 2 items characterized in sample (age, gender), 2 points; only 1 item characterized in sample, 1 point; selection description, 1 point; valid measurement methods, 1 point; citation of error analysis, 1 point; adequate statistics provided, 2 points; partially adequate statistics, 1 point; and confounders included in analysis, 1 point. The quality of each study was categorized as low (0–3 points), medium (4–6 points), or high (7–8 points).

Summary measures and approach to synthesis

The included studies were sufficiently homogenous; therefore, a quantitative synthesis was used.

Results

A total of 741 citations were identified by the electronic search. After examining the abstracts, 44 abstracts of potential articles were considered eligible for inclusion, and full-text articles were obtained. After careful examination of the remaining full texts, 23 studies satisfied the inclusion criteria and were included in the review. The PRISMA flow diagram is shown in Fig. 2.
Fig. 2

PRISMA flow diagram

Twenty-one articles were excluded for the following reasons: 9 used dose measurement methods other than phantoms with thermoluminescent dosimeters [34, 35, 36, 37, 38, 39, 40, 41, 42]; 1 calculated the effective dose based on ICRP 60, published in 1990 [43]; 2 only used medical tomography [44, 45]; 4 did not measure the effective dose [42, 46, 47, 48]; and 5 did not consider the remainder tissues to calculate the effective dose [7, 8, 10, 11, 21]. Among the 23 selected studies, 21 compared different exposure parameters for 25 studied scans and their alternative versions (Table 1).
Table 1

Selected studies: objectives, CBCT scanner used, and main finding of the article

Study

Objective

CBCT scanner

Main finding of the article

Ali et al. (2015)

2 CBCT with different protocols

3D Accuitomo 80®, Scanora 3D®

Scanora 3D, with less radiation time, showed less dosing values compared to 3D Accuitomo 80 (mean 0.33 mSv, SD ± 0.16 vs. 0.18 mSv, SD ± 0.1)

Davies et al. (2012)

1 CBCT with different protocols

i-CAT Next Generation®

New generation i-CAT scanner effective dose is lower than the original machine.

Grunheid et al. (2012)

1 CBCT × 1 pan with different protocols

i-CAT®

i-CAT scanner effective dose was higher than conventional digital radiography.

Jadu et al. (2010)

1 CBCT × plain radiographs (1 pan, 2 pa, and 4 cef) with different protocols

CB MercuRay®

Effective doses from CBCT with 15 cm FOV, 80 kVp, and 10 mA were similar to those calculated for plain radiograph sialography.

Loubele et al. (2009)

3 CBCT × 3 CT with different protocols

NewTom 3G®, i-CAT®, 3D Accuitomo®

CBCT dose levels were the lowest for the Accuitomo 3D, and highest for the i-CAT.

Ludlow and Ivanovic (2008)

8 CBCT × 1 CT with different protocols

NewTom 3G®, CB MercuRay®, i-CAT Next Generation®, Ilumina, i-CAT Classic, Galileos®, CB MercuRay®, Promax 3D®, Prexion 3D®

Large FOV CBCT ranged from 68 to 1073 μSv. Medium FOV CBCT ranged from 69 to 560 μSv, whereas a similar FOV MDCT produced 860 μSv.

Ludlow (2011)

1 CBCT with different protocols (KV) and additional copper filter

Kodak 9500®

An average exposure reduction of 43% was found with additional filtration and default adult settings.

Ludlow and Walker (2013)

1 CBCT with different protocols

i-CAT FLX®

Child phantom doses were on average 36% greater than adult phantom doses. Use of higher Voxel and smaller FOVs result in significant patient dose reductions.

Lukat et al. (2013)

2 CBCT with different protocols

CB MercuRay®, Kodak 9000 3D®

Kodak 9000 3D CBCT produced more than tenfold reduction in the effective dose compared with the larger single field acquisition with the Hitachi CB MercuRay.

Kadesjö et al. (2015)

1 CBCT × 1 CT with changes in mA

Promax® 3D

The tube currents between 4 and 12 mA, with an interval of 2 mA, were used. The study indicates a potential dose reduction of up to 50% for TMJ imaging using Promax 3D, compared with the manufacturer’s recommended exposure parameters.

Okano et al. (2009)

2 CBCT × 1 CT with different protocols

CB MercuRay®, 3D Accuitomo FP®, 3D Accuitomo tipo II®

The dose in the 3D Accuitomo is lower than the CB MercuRay and much less than MDCT.

Pauwels et al. (2012)

14 CBCT with different protocols

Promax 3D®, Galileos Comfort®, i-CAT Next Generation®, Iluma Elite®, Kodak 9000 3D®, Kodak 9500®, NewTom VG®, NewTom VGi®, Pax-Uni3D®, Picasso Trio®, Promax 3D®, Scanora 3D®, SkyView®, Veraviewepocs 3D®, 3D Accuitomo 170®

Effective dose ranged from 19 to 368 μSv. The dose received is strongly related to field size.

Pauwels et al. (2014)

1 CBCT with different protocols

3D Accuitomo 170®

Significant dose reduction can be achieved by reducing the FOV size, particularly the FOV height, of CBCT examinations to the actual region of interest. The use of a 180° rotation resulted in an average dose reduction of 45% compared with a 360°rotation.

Qu et al. (2010)

1 CBCT with different protocols

Promax 3D®

ProMax 3D can provide a wide range of radiation dose levels. Reduction in radiation dose can be achieved when using lower settings of exposure parameters.

Qu et al. (2012)

1 CBCT with different protocols and thyroid collar

DCT PRO®, NewTom 9000®

Regarding same maxillofacial regions, the dose levels for NewTom 9000 and DCT Pro CBCT images were lower than those for Bright speed edge select 8 slice MSCT images. Dose level reduction could be obtained when smaller regions were scanned.

Qu et al. (2012)

1 CBCT with different protocols and thyroid collar

NewTom 9000®

Thyroid collars can effectively reduce the radiation effective dose.

Roberts et al. (2009)

1 CBCT with different protocols

i-CAT®

i-CAT CBCT scanner effective dose reduced with decreasing the FOV.

Rottke et al. (2013)

10 CBCT with different protocols

KaVo 3D eXam®, Kodak 9000 3D®, Kodak 9500®, Promax 3D®, Galileos Comfort®, Orthophos XG 3D®, Scanora 3D®, Master3Ds®, PaX-Duos3D®, 3D Accuitomo®

The effective dose calculation resulted in values between 17.2 and 396 μSv for the ten devices.

Schilling and Geibel (2013)

2 CBCT with different protocols

KaVo 3D eXam®, KaVo Pan eXam Plus 3D®

Effective doses from the 3D eXam were less than the Pan eXam Plus.

Sezgin et al. (2012)

2 CBCT × pan × with different protocols

Kodak 9500®, Kodak 9500®, NewTom FP®, Veraviewepocs 3D®

Effective doses were higher for MSCT than for CBCT.

Soares et al. (2015)

4 CBCT with different protocols

ProMax 3D®, GXCB 500®, i-CAT Classical®, Orthophos XG 3D®, CS 9000®

The effective dose values by field of view (FOV) size are within the following ranges: 9.3–51.2 mSv, 17.6–52.0 mSv, and 43.1–111.5 mSv for small/located, medium, and large FOV respectively. Protocols with same purpose, carried out with different models of equipment, presented significant differences in the values of the equivalent and effective doses.

Suomalainen et al. (2009)

4 CBCT × 2 CT with different protocols

Accuitomo 3D® CCD, Accuitomo 3D® FP, ProMax 3D®, Scanora 3D®

Low-dose CT protocols provided effective dose comparable with those from CBCT scanners. The effective doses varied between 27 and 674 μSv with the CBCT scanners.

Theodorakou et al. (2012)

5 CBCT with different protocols to pediatric dose

Accuitomo 3D® 170, New Tom® VG, i-CAT® Next Generation, ProMax 3D®, Kodak® 9000C 3D

The lowest effective doses were calculated for units that offered small FOV and pediatric settings.

pan panoramic, fmx full mouth series of intraoral radiographs, cef cephalometric radiographs, pa posterior-anterior skull radiograph

Table 2 shows that an additional copper filter was the factor least evaluated in studies, and milliamperage was the most investigated factor. Analysis of the selected studies revealed 13 factors related to changes in the effective dose emitted by different scanners. Two factors were related to patients, one factor was related to protection measures, and 10 factors were inherent to CBCT scanners.
Table 2

Factors related to changes in the effective dose emitted by scanners and frequency with which were measured in studies (N = 23)

Factor

Number of studies that measured the factor

Percentage of studies that measured the factor (%)

Scan angle (rotation protocols)

3

13.0

Size patient

2

8.7

Region of interest

11

47.8

Use of a thyroid shield

2

8.7

Additional copper filter

1

4.3

Exposure time

10

43.5

FOV (field of view) diameter

17

73.9

FOV (field of view) height

17

73.9

KV (peak kilovoltage)

16

69.6

mA (milliampere)

18

78.3

mAs (milliampere-second)

13

56.5

Voxel

8

34.8

Resolution

3

13.0

Patient-related factors were patient size and region of interest. Only 2 studies [26, 27, 28, 29, 30] evaluated the effect of patient size on the effective dose and observed that the smaller the patient, especially children, the higher the effective radiation dose for similar exposure parameters. The region of interest was assessed in 11 studies [12, 14, 16, 17, 19, 26, 27, 29, 30], and revealed that scans in the upper (maxillary) region subjected the patient to a lower amount of radiation than the lower (mandible) region. Scans in the anterior region subjected the patient to a lower amount of radiation than the posterior (molars) region (Tables 2 and 3).
Table 3

Effect of the factors in relation radiation effective dose (de)

Factor

Reduction (de)

Increased (de)

Size of the patient

Adults

Children

Region of interest

Upper (maxillary) region

Lower (mandible) region

 

Anterior region

Posterior (molars) region

Thyroid collar

Use thyroid collar

Without use thyroid collar

Copper filter

With additional filter

Without additional filter

Scan angle

Reduction scan angle

Increased scan angle

Exposure time

Reduction exposure time

Increased exposure time

FOV (field of view) diameter

Reduction FOV diameter

Increased FOV diameter

FOV (field of view) height

Reduction FOV height

Increased FOV height

KV (Peak kilovoltage)

Reduction KV

Increased KV

mA (milliampere)

Reduction mA

Increased mA

mAs (milliampere-second)

Reduction mAs

Increased mAs

Resolution

Reduction resolution

Increased resolution

Voxel

Increased voxel

Reduction voxel

The use of a thyroid collar on the patient during scanning was the only protective measure assessed. Two studies [23, 24] evaluated this factor, and the authors observed a reduction in the radiation dose when the thyroid collar was used (Tables 2 and 3).

Regarding factors related to the scanners, only one study [18] evaluated the effect of an additional copper filter on the radiation dose and found that the effective dose was reduced when these filters were added (Tables 2 and 3).

Other examined factors related to the scanners were the effect of scan angle, exposure time, FOV diameter, FOV height, kV, mA, mAs, voxel, and resolution evaluated in 3 [49, 50, 51], 10 [9, 15, 17, 19, 20, 25, 27, 28, 29, 30], 17 [9, 12, 13, 15, 16, 17, 22, 23, 25, 26, 27, 28, 29, 30, 50, 51, 52], 17 [9, 12, 13, 14, 15, 17, 19, 20, 23, 25, 26, 28, 29, 30, 50, 51, 52], 16 [9, 12, 13, 14, 15, 16, 17, 22, 25, 26, 27, 28, 29, 30, 51, 52], 18 [9, 13, 15, 16, 17, 19, 20, 22, 25, 26, 27, 28, 29, 30, 50, 51, 52, 53], 13 [9, 12, 13, 15, 16, 17, 22, 25, 26, 27, 28, 29, 30], 8 [12, 15, 19, 20, 26, 28, 29, 30], and 3 [9, 17, 22] studies, respectively. Higher values of these parameters increased the effective dose value for the CBCT scanners studied, except for the voxel, in which changes to lower values increased the effective dose (Tables 2 and 3).

A quality analysis of the 23 studies, summarized in Table 4, shows that research quality and methodologic soundness was high in one study and medium in the others. Only two studies [26, 30] described two items in the sample identifying gender and age of the phantom, and the others described just one item. The measurement methods were valid in all articles that calculated the effective dose as a product of the radiation weighted average organ doses, and the relevant ICRP 103 tissue weighting factors summed over all tissues/organs exposed. The error analysis was also present in all articles considering that the standard deviation of readings from TLD is less than ± 5%. Regarding statistical analysis, most studies used appropriate descriptive analyses. However, the studies of Ludlow and Walker [30] and Theodorakou et al. [26] described that two items in the sample needed comparative analysis, but only the study of Ludlow and Walker [30] performed analysis of variance [40] and Tukey HSD test for comparison of results. No study considered the risk of confounding factors, such as total dose, cell type, and type of radiation.
Table 4

Quality evaluation of 23 studies

Study

Sample size

Sample characterization

Selection description

Valid Measurement methods

Error analysis

Statistical analysis

Confounding factors

Quality Score 0–8

Judged quality standard

Ali et al. (2015)

1

1

1

1

1

2

0

7

Medium

Davies et al. (2012)

1

1

1

1

1

2

0

7

Medium

Grunheid et al. (2012)

1

1

1

1

1

2

0

7

Medium

Jadu et al. (2010)

1

1

1

1

1

2

0

7

Medium

Kadesjö et al. (2015)

1

1

1

1

1

2

0

7

Medium

Loubele et al. (2009)

1

1

1

1

1

2

0

7

Medium

Ludlow and Ivanovic (2008)

1

1

1

1

1

2

0

7

Medium

Ludlow (2011)

1

1

1

1

1

2

0

7

Medium

Ludlow and Walker (2013)

1

2

1

1

1

2

0

8

High

Lukat et al. (2013)

1

1

1

1

1

2

0

7

Medium

Okano et al. (2009)

1

1

1

1

1

2

0

7

Medium

Pauwels et al. (2012)

1

1

1

1

1

2

0

7

Medium

Pauwels et al. (2014)

1

1

1

1

1

2

0

7

Medium

Qu et al. (2010)

1

1

1

1

1

2

0

7

Medium

Qu et al. (2012)

1

1

1

1

1

2

0

7

Medium

Qu et al. (2012)

1

1

1

1

1

2

0

7

Medium

Roberts et al. (2009)

1

1

1

1

1

2

0

7

Medium

Rottke et al. (2013)

1

1

1

1

1

2

0

7

Medium

Schilling and Geibel (2013)

1

1

1

1

1

2

0

7

Medium

Sezgin et al. (2012)

1

1

1

1

1

2

0

7

Medium

Soares et al. (2015)

1

1

1

1

1

2

0

7

Medium

Suomalainen et al. (2009)

1

1

1

1

1

2

0

7

Medium

Theodorakou et al. (2012)

1

2

1

1

1

2

0

8

High

Table 5 shows the comparison between different CBCT scanners with similar exposed parameters. It was observed that the devices with the lowest effective dose were Kodak® 9000C 3D (mean of 21.2 μSv), Galileos® (mean of 77 μSv) and i-CAT® Next Generation® (mean of 74.62 μSv), for small, medium, and large FOVs, respectively. The FOV was classified according to Lorenzoni et al. [5]: small FOV was considered for diameter or height ≤ 10 cm, which captures most of one or both arches, but not the entire maxillary anatomy; medium FOV was considered for diameter or height between 10 and 15 cm, which captures the entire dentition and temporomandibular joints, but generally does not include the complete soft profile of the chin and nose, which is necessary for orthodontic care; and large FOV was considered for diameter or height > 15 cm, which captures the maxillofacial complex, chin, and nose.
Table 5

Effective dose comparison between different scanners with similar exposure parameters

Study

CBCT scanner

t (s)

FOV Ø-cm

FOV h-cm

FOV

Region

KV

mA

mAs

Voxel (mm)

de (μS)

Suomalainen et al. 2009

Accuitomo 3D® CCD

17, 5

4

3

Small

 

80

4

70

 

27

Theodorakou et al. 2012

Accuitomo 3D® 170

 

4

4

Small

Molars

90

 

87.5

 

32

Mean

          

29.5

Theodorakou 2012

i-CAT® Next Generation dental CBCT

 

16

6

Small

md

120

 

18.5

0.4

45

Davies et al. 2012

i-CAT® Next Generation dental CBCT

8, 9

 

6

Small

md

120

2.1

18.69

0.4

58

Mean

          

51.5

Lukat et al. 2013

Kodak® 9000 3D

10, 8

5

3.7

Small

atm

70

10

108

 

20.5

Pauwels et al. 2012

Kodak® 9000 3D

 

5

3.7

Small

 

70

 

107

 

19

Theodorakou et al.2012

Kodak® 9000C 3D

 

5

3.7

Small

Molars

70

 

106.8

0.076

24

Mean

          

21.17

Theodorakou et al. 2012

Accuitomo 3D® 170

 

14

5

Medium

mx

90

 

87.5

 

70

Pauwels et al. 2012

Accuitomo 3D® 170

 

14

5

Medium

 

90

 

87.5

 

54

Mean

          

62

Ludlow and Ivanovic (2008)

CB MercuRay®

10

15

15

Medium

 

120

15

150

 

560

Palomo et al. 2008

CB MercuRay®

9, 6

15.2

 

Medium

 

120

15

144

 

603

Mean

          

581.5

Ludlow and Ivanovic (2008)

Galileos®

 

15

15

Medium

 

85

5

21

0.15–0.3

70

Pauwels et al. 2012

Galileos® Comfort

 

15

15

Medium

 

85

 

28

 

84

Mean

          

77

Davies et al. 2012

i-CAT® Next Generation dental CBCT

8, 9

 

13

Large

 

120

2.1

18.69

0.4

77

Ludlow and Ivanovic (2008)

i-CAT® Next Generation dental CBCT

 

16

13

Large

 

120

 

19

0.25–0.4

69

Pauwels et al. 2012

i-CAT® Next Generation dental CBCT

 

16

13

Large

 

120

 

18.5

0.4

83

Theodorakou et al. 2012

i-CAT® Next Generation dental CBCT

 

16

13

Large

Maxillofacial

120

 

18.5

 

82

Davies et al. 2012

i-CAT® Next Generation dental CBCT

8, 9

 

17

Large

Maxillofacial

120

2.1

18.69

0.4

78

Grunheid et al. 2012

i-CAT® Next Generation dental CBCT

8, 9

 

17

Large

 

120

 

18.54

0.3

69.2

Grunheid et al. 2012

i-CAT® Next Generation dental CBCT

8, 9

 

17

Large

 

120

 

18.54

0.4

64.7

Ludlow and Ivanovic (2008)

i-CAT® Next Generation dental CBCT

8, 9

23.2

17

Large

 

120

 

19

0.4

74

Mean

          

74.62

Lukat et al. 2013

CB MercuRay®

9, 6

22.9

 

Large

Maxillofacial

100

10

96

 

223.6

Palomo et al. 2008

CB MercuRay®

9, 6

22.9

 

Large

 

100

10

96

 

266

Mean

          

244.8

t exposure time (seconds), Ø diameter, h height, mx maxillary, md mandible, de radiation effective dose; FOV large > 15 cm, FOV medium, between 10 and 15 cm , and FOV small ≤ 10 cm

Discussion

The risk generated by exposure to ionizing radiation is well documented in the literature and constitutes a public health problem, especially because of the carcinogenic effects of such exposure. According to the National Council on Radiation Protection and Measurements (NCRP) in the USA, medical radiation is the main source of artificial exposure to ionizing radiation. It is estimated that this exposure for the achievement of medical images had an increase of 600% between 1980 and 2006 [54, 55, 56, 57, 58, 59]. Therefore, the evaluation of factors that can reduce such exposure should be considered, which was the objective of this systematic review.

To perform this study, inclusion criteria were established to obtain studies with similar methodologies. The selected studies used phantoms and thermoluminescent dosimeters to measure the radiation dose, which is the method of choice in most studies. However, phantoms cannot be adapted to each patient, which is a limitation of such studies [27]. Furthermore, the simplified and punctual location of dosimeters in sites cannot reflect the real doses, and the correct position of sites can be difficult due to the limited space available in the head and neck phantom [27, 28, 29]. Nevertheless, the use of phantoms and thermoluminescent dosimeters was more powerful to evaluate the effective dose than other forms as pencil ionization chambers and exposure computational model. Pencil ionization chambers do not allow determination of the dose profile, and exposure computational model has been introduced just recently and there are few studies using this method [34, 35, 36, 37, 38, 39, 40, 41].

The effective dose was the dosimetric quantity, which was chosen because it is recommended by the International Commission on Radiological Protection (ICRP) and because the type, quantity, sensitivity, and carcinogenic potential of irradiated tissue can be evaluated, and the values found can be compared [54].

The effective dose was calculated by the weighting factor proposed by the recommendations of the ICRP standard 103, published in 2007 [57]. These recommendations are the most current, and changes in the weighting factor lead to changes in the effective dose values, thus avoiding comparisons for the same level of radiation exposure. The weighting factors revised in 2007 include tissues located in the head and neck, such as salivary glands, lymph nodes, muscles, and oral mucosa. The inclusion of these tissues led to changes in the weighting factors that resulted in substantial increases in effective doses (ranging from 32 to 422%) for the same radiographic procedures. The remainder tissues, which include oral mucosa, extrathoracic airway, muscle, and lymph nodes, contribute 27–42% to the effective dose [49, 50, 51, 52, 53, 54, 55, 56, 57, 58].

After reviewing published articles on the effective radiation dose, only 23 met the inclusion criteria. This systematic review included studies that used phantoms and thermoluminescent dosimeters to measure the radiation dose. When the methodological quality assessment was performed, most articles obtained medium-quality scores, but only one had high-quality scores (Table 4). Consequently, the present findings should be interpreted with caution.

Limitations related to studies using phantoms have been previously reported. However, there are other associated problems, such as number of repetitions due to the lack of patient complaint, motion artifacts, and especially lack of training and understanding about this technology by professionals requesting and interpreting it, and by technicians who performed the exams. Hence, further studies like this are necessary to offer more information about this issue [58, 59, 60, 61].

The patient size was evaluated in only two articles [26, 27, 28, 29, 30]. This factor is very important, because children are more sensitive to radiation than adults, and most published studies on dental CBCT dosimetry have focused on effective doses to adult patients. Further research about this factor is necessary [26]. Analysis of the effect of patient size in relation to the effective dose revealed that the smaller the patient, especially children, the higher the radiation exposure when similar parameters are used. These data are consistent with the literature, in which authors have reported their concern, especially with regard to children, due to high radiation exposure levels [5]. The effective dose in children varied from 16 to 282 μS for dental CBCT [26], regarding the region of interest and scanner settings. According to Theodorakou et al. [26], the effective dose for children at 10 years old was 30% higher than the dose for adolescents, except for Kodak® 9000C 3D, in which the protocol with reduction in milliamperes allowed a decrease in the effective dose, as well as for Accuitomo® 170 3D, whose reduced FOV for children also enabled a reduction in the dose. A similar result was shown by Ludlow and Walker [30] who found that the mean effective dose in children was 36% higher than in adults.

The region of interest to be scanned is another factor that affects the reduction of the effective radiation dose. This variation is due to the presence of tissues and/or organs that are more radiosensitive than others. Therefore, scans in the anterior region reach less radiosensitive organs and tissues than scans in the posterior region, which reach organs such as the thyroid, and provide a lower effective radiation dose. Similarly, scans in the upper region generate lower effective radiation doses than scans performed in the lower region [12, 17, 19, 22, 26, 29, 30, 59]. Although the use of a protective thyroid collar is not common in tomography scans, two studies by Qu et al. [23, 24] showed a reduction of 32% in the effective radiation dose when the thyroid collar is used. The collar reduces radiation in the thyroid, which is a very radiosensitive organ, thereby reducing the effective dose, which predicts the risk of consequences caused by ionizing radiation. The difference in radiation dose was not significant between the use of one or two collars. Regarding factors related to CBCT scanners, the effect of additional copper filters in reducing the radiation dose was evaluated by one study [18]. This author observed mean exposure reduction of 43% [18] when the copper filters were added, due to the reduced intensity of radiation to which organs and tissues were exposed.

Other factors related to CBCT scanners that affect radiation exposure are exposure time, FOV diameter, FOV height, kV, mA, mAs, voxel, and resolution. Higher values of these parameters increased the effective dose for the CBCT scanners studied, except for the voxel, in which lower values increased the effective dose [7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30]. Some of these factors have already been reported in the literature [3, 5, 57]. The change in the effective radiation dose caused by each of these factors may be explained as follows: increases in the scan angle and exposure time subject the patient to a longer exposure; increase in FOV diameter often increases the height of the irradiated area, thereby irradiating more organs and tissues; increased kV, mA, mAs, and resolution increase the intensity of radiation, as does decreasing the voxel.

In this review, one study evaluated rotation protocols and observed that the effective dose increases when the scan angle increases from 180° to 360°. According to Pauwels et al. [50], the use of 180° rotation resulted in mean dose reduction of 45% compared with 360° rotation. Loubelle et al. [12] increased time exposure from 20 to 40 s and observed a mean increase of 170% in the effective dose.

Using the CB MercuRay® scanner, Palomo et al. [10] found a reduction of approximately 38% in the effective dose when kV was decreased from 120 to 100; and Jadu et al. [16] also found a reduction of 30 and 60% in dose when kV was changed from 120 to 100 and 80 kV, respectively. A reduction in dose from 5 to 10% was obtained when FOV was reduced [10]. In another study, when FOV was decreased from 30 to 15 cm, a 40% reduction was observed in the effective dose [16]. If the FOV is restricted to the maxilla or mandible, effective doses are reduced by 44 and 57%, respectively; and if the FOV diameter is limited to anterior or posterior, there is a reduction of 42 and 66% [17]. Pauwels et al. [22] suggested that the radiation dose is strongly related to the FOV size, and dose optimization should be done by appropriate selection of FOV and other exposure parameters, depending on the diagnostic needs. Jadu et al. [16] showed that a reduction in mA from 15 to 10 resulted in 37% reduction of the effective dose. High-resolution protocols increased the effective dose in approximately 600% compared to low-resolution protocols [28], and reduction in voxel values increased the effective dose in nearly 100% [26].

According to the inclusion criteria used in this study, among the 23 selected studies, 21 compared different exposure parameters for 25 scans and their alternative versions. When scans with similar exposure parameters were evaluated, only five scans were analyzed, revealing a variation in effective dose of 19–58 μSv for small FOV, 54–603 μSv for medium FOV, and 64.7–266 μSv for large FOV (Table 5). Different exposure parameters can change the radiation effective dose. In 2014, Bornstein et al. [60] found a variation in effective dose of 11–252 μSv for small FOV, 28–652 μSv for medium FOV, and 52–1.073 μSv for large FOV. These results are different from our study due to different inclusion criteria, period of study selection, and method of data analysis, namely scans with similar exposure parameters in our study.

Table 5 groups the results of studies that used similar exposure parameters. However, it should be noted that differences between the exposure parameters of each scanner should be evaluated. Scanners without a small FOV will probably subject the patient to increased radiation exposure than scanners that have this adjustment. Also, some parameters cannot be changed separately in some scanners that have predefined protocols. It is also important to call attention to select the appropriate examination for the patient.

Changes in factors related to CBCT scanners, such as the changes mentioned above, may be a good alternative for reducing the effective radiation dose and hence the damage that ionizing radiation can cause to humans. However, changes in these factors can reduce image quality, making this procedure unfeasible [18]. This study evaluated the factors that influence the effective radiation dose associated with cone beam computed tomography and their effect over it, but this information was not correlated with changes in image quality. Other studies should be conducted to establish this correlation to obtain effective clinical protocols with minimal radiation exposure.

This study identified which factors influence the reduction in radiation dose, yet it could not identify the efficacy of dose reduction methods. More studies should be conducted to evaluate the efficacy of dose reduction methods varying only the factor of interest and fixing the other, then achieving the percentage of radiation reduction according to each factor to allow comparison. Due to the several factors and the availability of more studies evaluating several factors simultaneously, comparisons could not be performed [7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]. There is a need for research to identify the image quality requirements in addition to measuring the radiation dose, because the objective in radiology is to use a dose as low as diagnostically acceptable according to the ALARA principle (As Low As Reasonably Achievable).

In the 2014 NCRP Annual Meeting, Dr. Jerrold Bushberg proposed the term ALADA (As Low As Diagnostically Acceptable) as a variation of ALARA to highlight the importance of improvement in medical imaging. The new concept was formed due to the advent of low-dose protocols that have the advantage of selecting specific exposures to each patient [60]. Studies [60, 61] indicated the importance of the low-dose protocols, because these protocols change the method through which the CBCT scans are achieved and consequently the way through which diagnoses is achieved by 3D images. Reduced radiation dose was observed by some authors when low-dose protocols are used [62, 63].

In 2015, Hidalgo Rivas et al. [62] performed a study to develop a low-dose protocol for CBCT 3D Accuitomo F170® (J. Morita, Kyoto, Japan) when the device is used for examination of an impacted maxillary canine in children. To conduct this study, the authors used a combination of dosimetry with objective and subjective image quality assessment. A low-dose protocol of 80 kV and 3 mA for implementation into clinical practice, corresponding to a dose-area-product (DAP) value of 146 mGy cm2, was chosen. The present protocol allowed a 50% reduction compared with manufacturer’s recommendations in radiation dose.

Feragalli et al. [63] evaluated image quality and radiation doses of cone beam computed tomography (CBCT) for dental and maxillofacial imaging testing five different acquisition protocols for CBCT Pax Zenith 3D CBCT® (Vatech, Korea). The authors observed that a low-dose protocol with large FOV, normal resolution quality images, 80 kVp, 5 mA, and acquisition time of 15 s resulted in an effective dose of 35 μSv, and that this protocol allows examination of the maxillofacial region with high-quality images and a very low radiation dose.

It is important to emphasize the concept of diagnostic reference levels (DRLs), because DRL is a significant tool for identifying high patient doses from radiologic examinations. The International Commission on Radiological Protection introduced the concept of DRL in 1991; since then, DRL is considered a grade for optimization of radiologic procedures and radiation protection of patients [54]. DRLs determine the dose reference values (DRVs), which can be used to evaluate patient doses. In general, DRLs are defined for CT in internationally accepted terms of reproducible dose metrics as the volume CT dose index (CTDIvol), the dose-length product (DLP), the dose-area-product (DAP), and are calculated as the third quartile of dose distribution obtained of dose levels used for a patient of average body size [64, 65].

The UK’s Health Protection Agency recommended that manufacturers of dental CBCT equipment should give a dose metrics after each exposure. According to the UK’s Health Protection Agency, DRL for CBCT imaging appropriate for placement of an upper first molar implant in a standard adult patient is 250 mGy cm2. These levels are not absolute limits, but they should not be exceeded for a good practice [66].

Conclusion

Thirteen factors were related to changes in the effective dose emitted by different scanners. The scan angle was the least evaluated factor in studies and mAs was the most investigated factor. The choice of parameters and the scanner should be based on minimal radiation exposure for the patient. Further research should evaluate the influence of phantom size and scan angle to optimize CBCT and to identify the image quality requirements in addition to measuring the radiation dose, with respect to ALADA.

Notes

Funding

The work was supported by the researchers themselves.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.

Informed consent

For this type of study, formal consent is not required.

References

  1. 1.
    Mozzo P, Procacci C, Tacconi A, Martini PT, Andreis IA (1998) A new volumetric CT machine for dental imaging based on the cone-beam technique: preliminary results. Eur Radiol 8:1558–1564CrossRefPubMedGoogle Scholar
  2. 2.
    Garib DG, Raymundo R Jr, Raymundo MV, Raymundo DV, Ferreira SN (2007) Cone beam computed tomography (CBCT): understandind this new imaging diagnostic method with promissing application in orthodontics. Rev Dent Press Ortodon Ortop Facial 12:139–156CrossRefGoogle Scholar
  3. 3.
    De Vos W, Casselman J, Swennen G (2009) Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: a systematic review of the literature. Int J Oral Maxillofac Surg 38:609–625CrossRefPubMedGoogle Scholar
  4. 4.
    Swennen GR, Mollemans W, De Clercq C, Abeloos J, Lamoral P, Lippens F et al (2009) A cone-beam computed tomography triple scan procedure to obtain a three-dimensional augmented virtual skull model appropriate for orthognathic surgery planning. J Craniofac Surg 20:297–307CrossRefPubMedGoogle Scholar
  5. 5.
    Lorenzoni DC, Bolognese AM, Garib DG, Guedes FR, Sant’Anna EF (2012) Cone-beam computed tomography and radiographs in dentistry: aspects related to radiation dose. Int J Dent 2012:813768.  https://doi.org/10.1155/2012/813768 CrossRefPubMedPubMedCentralGoogle Scholar
  6. 6.
    Pearce MS, Salotti JA, Little MP, McHugh K, Lee C, Kim KP, Howe NL, Ronckers CM, Rajaraman P, Craft AW, Parker L, Berrington de González A (2012) Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet 380:499–505CrossRefPubMedPubMedCentralGoogle Scholar
  7. 7.
    Garcia Silva MA, Wolf U, Heinicke F, Grundler K, Visser H, Hirsch E (2008) Effective dosages for recording Veraviewepocs dental panoramic images: analog film, digital, and panoramic scout for CBCT. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 106:571–577CrossRefPubMedGoogle Scholar
  8. 8.
    Hirsch E, Wolf U, Heinicke F, Silva MA (2008) Dosimetry of the cone beam computed tomography Veraviewepocs 3D compared with the 3D Accuitomo in different fields of view. Dentomaxillofac Radiol 37:268–273CrossRefPubMedGoogle Scholar
  9. 9.
    Ludlow JB, Ivanovic M (2008) Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 106:106–114CrossRefPubMedGoogle Scholar
  10. 10.
    Palomo JM, Rao PS, Hans MG (2008) Influence of CBCT exposure conditions on radiation dose. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 105:773–782CrossRefPubMedGoogle Scholar
  11. 11.
    Silva MA, Wolf U, Heinicke F, Bumann A, Visser H, Hirsch E (2008) Cone-beam computed tomography for routine orthodontic treatment planning: a radiation dose evaluation. Am J Orthod Dentofac Orthop 133:640 e641–640 e645CrossRefGoogle Scholar
  12. 12.
    Loubele M, Bogaerts R, Van Dijck E, Pauwels R, Vanheusden S, Suetens P et al (2009) Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications. Eur J Radiol 71:461–468CrossRefPubMedGoogle Scholar
  13. 13.
    Okano T, Harata Y, Sugihara Y, Sakaino R, Tsuchida R, Iwai K, Seki K, Araki K (2009) Absorbed and effective doses from cone beam volumetric imaging for implant planning. Dentomaxillofac Radiol 38:79–85CrossRefPubMedGoogle Scholar
  14. 14.
    Roberts JA, Drage NA, Davies J, Thomas DW (2009) Effective dose from cone beam CT examinations in dentistry. Br J Radiol 82:35–40CrossRefPubMedGoogle Scholar
  15. 15.
    Suomalainen A, Kiljunen T, Kaser Y, Peltola J, Kortesniemi M (2009) Dosimetry and image quality of four dental cone beam computed tomography scanners compared with multislice computed tomography scanners. Dentomaxillofac Radiol 38:367–378CrossRefPubMedGoogle Scholar
  16. 16.
    Jadu F, Yaffe MJ, Lam EW (2010) A comparative study of the effective radiation doses from cone beam computed tomography and plain radiography for sialography. Dentomaxillofac Radiol 39:257–263CrossRefPubMedPubMedCentralGoogle Scholar
  17. 17.
    Qu XM, Li G, Ludlow JB, Zhang ZY, Ma XC (2010) Effective radiation dose of ProMax 3D cone-beam computerized tomography scanner with different dental protocols. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 110:770–776CrossRefPubMedGoogle Scholar
  18. 18.
    Ludlow JB (2011) A manufacturer’s role in reducing the dose of cone beam computed tomography examinations: effect of beam filtration. Dentomaxillofac Radiol 40:115–122CrossRefPubMedPubMedCentralGoogle Scholar
  19. 19.
    Davies J, Johnson B, Drage N (2012) Effective doses from cone beam CT investigation of the jaws. Dentomaxillofac Radiol 41:30–36CrossRefPubMedPubMedCentralGoogle Scholar
  20. 20.
    Grunheid T, Kolbeck Schieck JR, Pliska BT, Ahmad M, Larson BE (2012) Dosimetry of a cone-beam computed tomography machine compared with a digital x-ray machine in orthodontic imaging. Am J Orthod Dentofac Orthop 141:436–443CrossRefGoogle Scholar
  21. 21.
    Jeong DK, Lee SC, Huh KH, Yi WJ, Heo MS, Lee SS, Choi SC (2012) Comparison of effective dose for imaging of mandible between multi-detector CT and cone-beam CT. Imaging Sci Dent 42:65–70CrossRefPubMedPubMedCentralGoogle Scholar
  22. 22.
    Pauwels R, Beinsberger J, Collaert B, Theodorakou C, Rogers J, Walker A, Cockmartin L, Bosmans H, Jacobs R, Bogaerts R, Horner K, SEDENTEXCT Project Consortium (2012) Effective dose range for dental cone beam computed tomography scanners. Eur J Radiol 81:267–271CrossRefPubMedGoogle Scholar
  23. 23.
    Qu X, Li G, Zhang Z, Ma X (2012) Thyroid shields for radiation dose reduction during cone beam computed tomography scanning for different oral and maxillofacial regions. Eur J Radiol 81:e376–e380CrossRefPubMedGoogle Scholar
  24. 24.
    Qu XM, Li G, Sanderink GC, Zhang ZY, Ma XC (2012) Dose reduction of cone beam CT scanning for the entire oral and maxillofacial regions with thyroid collars. Dentomaxillofac Radiol 41:373–378CrossRefPubMedPubMedCentralGoogle Scholar
  25. 25.
    Sezgin Ö, Kayipmaz S, Yasar D, Yilmaz A, Ozturk M (2012) Comparative dosimetry of dental cone beam computed tomography, panoramic radiography, and multislice computed tomography. Oral Radiol 28:32–37CrossRefGoogle Scholar
  26. 26.
    Theodorakou C, Walker A, Horner K, Pauwels R, Bogaerts R, Jacobs R (2012) Estimation of paediatric organ and effective doses from dental cone beam CT using anthropomorphic phantoms. Br J Radiol 85:153–160CrossRefPubMedPubMedCentralGoogle Scholar
  27. 27.
    Lukat TD, Wong JC, Lam EW (2013) Small field of view cone beam CT temporomandibular joint imaging dosimetry. Dentomaxillofac Radiol 42:20130082CrossRefPubMedPubMedCentralGoogle Scholar
  28. 28.
    Rottke D, Patzelt S, Poxleitner P, Schulze D (2013) Effective dose span of ten different cone beam CT devices. Dentomaxillofac Radiol 42:20120417CrossRefPubMedPubMedCentralGoogle Scholar
  29. 29.
    Schilling R, Geibel MA (2013) Assessment of the effective doses from two dental cone beam CT devices. Dentomaxillofac Radiol 42:20120273CrossRefPubMedPubMedCentralGoogle Scholar
  30. 30.
    Ludlow JB, Walker C (2013) Assessment of phantom dosimetry and image quality of i-CAT FLX cone-beam computed tomography. Am J Orthod Dentofac Orthop 144:802–817CrossRefGoogle Scholar
  31. 31.
    PRISMA. Reporting guideline for systematic reviews and metaanalyses; 2009. Available at: http://www.prisma-statement.org/statement.htm. Accessed on June 24, 2015.
  32. 32.
    Grec RH, Janson G, Branco NC, Moura-Grec PG, Patel MP, Castanha Henriques JF (2013) Intraoral distalizer effects with conventional and skeletal anchorage: a meta-analysis. Am J Orthod Dentofac Orthop 143:602–615CrossRefGoogle Scholar
  33. 33.
    Chen Y, Kyung HM, Zhao WT, Yu WJ (2009) Critical factors for the success of orthodontic mini-implants: a systematic review. Am J Orthod Dentofac Orthop 135:284–291CrossRefGoogle Scholar
  34. 34.
    Batista EL Jr, Moreira CC, Batista FC, de Oliveira RR, Pereira KK (2012) Altered passive eruption diagnosis and treatment: a cone beam computed tomography-based reappraisal of the condition. J Clin Periodontol 39:1089–1096CrossRefPubMedGoogle Scholar
  35. 35.
    Koivisto J, Kiljunen T, Tapiovaara M, Wolff J, Kortesniemi M (2012) Assessment of radiation exposure in dental cone-beam computerized tomography with the use of metal-oxide semiconductor field-effect transistor (MOSFET) dosimeters and Monte Carlo simulations. Oral Surg Oral Med Oral Pathol Oral Radiol 114:393–400CrossRefPubMedGoogle Scholar
  36. 36.
    Al-Okshi A, Nilsson M, Petersson A, Wiese M, Lindh C (2013) Using GafChromic film to estimate the effective dose from dental cone beam CT and panoramic radiography. Dentomaxillofac Radiol 42:20120343CrossRefPubMedPubMedCentralGoogle Scholar
  37. 37.
    Lofthag-Hansen S, Thilander-Klang A, Ekestubbe A, Helmrot E, Grondahl K (2008) Calculating effective dose on a cone beam computed tomography device: 3D Accuitomo and 3D Accuitomo FPD. Dentomaxillofac Radiol 37:72–79CrossRefPubMedGoogle Scholar
  38. 38.
    Moze G, Seehra J, Fanshawe T, Davies J, McDonald F, Bister D (2013) In vitro comparison of contemporary radiographic imaging techniques for measurement of tooth length: reliability and radiation dose. J Orthod 40:225–233CrossRefPubMedGoogle Scholar
  39. 39.
    Vassileva J, Stoyanov D (2010) Quality control and patient dosimetry in dental cone beam CT. Radiat Prot Dosim 139:310–312CrossRefGoogle Scholar
  40. 40.
    Morant J, Salvadó M, Hernández-Girón I, Casanovas R, Ortega R, Calzado A (2013) Dosimetry of a cone beam CT device for oral and maxillofacial radiology using Monte Carlo techniques and ICRP adult reference computational phantoms. Dentomaxillofac Radiol 42:92555893CrossRefPubMedPubMedCentralGoogle Scholar
  41. 41.
    Zhang G, Marshall N, Bogaerts R, Jacobs R, Bosmans H (2013) Monte Carlo modeling for dose assessment in cone beam CT for oral and maxillofacial applications. Med Phys 40:072103CrossRefPubMedGoogle Scholar
  42. 42.
    Chambers D, Bohay R, Kaci L, Barnett R, Battista J (2015) The effective dose of different scanning protocols using the Sirona GALILEOS® comfort CBCT scanner. Dentomaxillofac Radiol 44:20140287CrossRefPubMedGoogle Scholar
  43. 43.
    Carrafiello G, Dizonno M, Colli V, Strocchi S, Pozzi Taubert S, Leonardi A, Giorgianni A, Barresi M, Macchi A, Bracchi E, Conte L, Fugazzola C (2010) Comparative study of jaws with multislice computed tomography and cone-beam computed tomography. Radiol Med 115:600–611CrossRefPubMedGoogle Scholar
  44. 44.
    Gervaise A, Osemont B, Lecocq S, Noel A, Micard E, Felblinger J, Blum A (2012) CT image quality improvement using adaptive iterative dose reduction with wide-volume acquisition on 320-detector CT. Eur Radiol 22:295–301CrossRefPubMedGoogle Scholar
  45. 45.
    Ohman A, Kull L, Andersson J, Flygare L (2008) Radiation doses in examination of lower third molars with computed tomography and conventional radiography. Dentomaxillofac Radiol 37:445–452CrossRefPubMedGoogle Scholar
  46. 46.
    Thongvigitmanee SS, Pongnapang N, Aootaphao S, Yampri P, Srivongsa T, Sirisalee P et al (2013) Radiation dose and accuracy analysis of newly developed cone-beam CT for dental and maxillofacial imaging. Conf Proc IEEE Eng Med Biol Soc 2013:2356–2359PubMedGoogle Scholar
  47. 47.
    Okano T, Matsuo A, Gotoh K, Yokoi M, Hirukawa A, Okumura S, Koyama S (2012) Comparison of absorbed and effective dose from two dental cone beam computed tomography scanners. Nihon Hoshasen Gijutsu Gakkai Zasshi 68:216–225CrossRefPubMedGoogle Scholar
  48. 48.
    Qu XM, Li G, Zhang ZY, Ma XC (2011) Comparative dosimetry of dental cone-beam computed tomography and multi-slice computed tomography for oral and maxillofacial radiology. Zhonghua Kou Qiang Yi Xue Za Zhi 46:595–599PubMedGoogle Scholar
  49. 49.
    Ludlow JB, Timothy R, Walker C, Hunter R, Benavides E, Samuelson DB, Scheske MJ (2015) Effective dose of dental CBCT—a meta analysis of published data and additional data for nine CBCT units. Dentomaxillofac Radiol 44:20140197CrossRefPubMedGoogle Scholar
  50. 50.
    Pauwels R, Zhang G, Theodorakou C, Walker A, Bosmans H, Jacobs R, Bogaerts R, Horner K, The SEDENTEXCT Project Consortium (2014) Effective radiation dose and eye lens dose in dental cone beam CT: effect of field of view and angle of rotation. Br J Radiol 87:20130654CrossRefPubMedPubMedCentralGoogle Scholar
  51. 51.
    Soares MR, Batista WO, Antonio Pde L, Caldas LV, Maia AF (2015) Study of effective dose of various protocols in equipment cone beam CT. Appl Radiat Isot 100:21–26CrossRefPubMedGoogle Scholar
  52. 52.
    Ali AS, Fteita D, Kulmala J (2015) Comparison of physical quality assurance between Scanora 3D and 3D Accuitomo 80 dental CT scanners. Libyan J Med 10:28038CrossRefGoogle Scholar
  53. 53.
    Kadesjo N, Benchimol D, Falahat B, Nasstrom K, Shi XQ (2015) Evaluation of the effective dose of cone beam CT and multislice CT for temporomandibular joint examinations at optimized exposure levels. Dentomaxillofac Radiol 44:20150041CrossRefPubMedPubMedCentralGoogle Scholar
  54. 54.
    National Council on Radiation Protection & Measurements (2009) Radiation Protection in Dentistry (Report No. 160). NRCP Publications, BethesdaGoogle Scholar
  55. 55.
    American Academy of Oral and Maxillofacial Radiology (2013) Clinical recommendations regarding use of cone beam computed tomography in orthodontics. Position statement by the American Academy of Oral and Maxillofacial Radiology. Oral Surg Oral Med Oral Pathol Oral Radiol 116:238–257CrossRefGoogle Scholar
  56. 56.
    Claus EB, Calvocoressi L, Bondy ML, Schildkraut JM, Wiemels JL, Wrensch M (2012) Dental x-rays and risk of meningioma. Cancer 118:4530–4537CrossRefPubMedPubMedCentralGoogle Scholar
  57. 57.
    2007 Recommendations of the International Commission on Radiological Protection. Available at: htpp://www.icrp.org. Accessed April 5, 2015.
  58. 58.
    Thilander-Klang A, Helmrot E (2010) Methods of determining the effective dose in dental radiology. Radiat Prot Dosim 139:306–309CrossRefGoogle Scholar
  59. 59.
    Roberts SK, Weltman MD, Crawford DH, McCaughan GW, Sievert W, Cheng WS et al (2009) Impact of high-dose peginterferon alfa-2A on virological response rates in patients with hepatitis C genotype 1: a randomized controlled trial. Hepatology 50:1045–1055CrossRefPubMedGoogle Scholar
  60. 60.
    Bornstein MM, Scarfe WC, Vaughn VM, Jacobs R (2014) Cone beam computed tomography in implant dentistry: a systematic review focusing on guidelines, indications, and radiation dose risks. Int J Oral Maxillofac Implants 29 Suppl:55–77.  https://doi.org/10.11607/jomi.2014suppl.g1.4 CrossRefPubMedGoogle Scholar
  61. 61.
    Bornstein MM, Horner K, Jacobs R (2017) Use of cone beam computed tomography in implant dentistry: current concepts, indications and limitations for clinical practice and research. Periodontol 2000 73(1):51–72.  https://doi.org/10.1111/prd.12161 CrossRefPubMedGoogle Scholar
  62. 62.
    Hidalgo Rivas JA, Horner K, Thiruvenkatachari B, Davies J, Theodorakou C (2015) Development of a low-dose protocol for cone beam CT examinations of the anterior maxilla in children. Br J Radiol 88(1054):20150559CrossRefPubMedPubMedCentralGoogle Scholar
  63. 63.
    Feragalli B, Rampado O, Abate C, Macrì M, Festa F, Stromei F, Caputi S, Guglielmi G (2017) Cone beam computed tomography for dental and maxillofacial imaging: technique improvement and low-dose protocols. Radiol Med 122(8):581–588CrossRefPubMedGoogle Scholar
  64. 64.
    McCollough C, Branham T, Herlihy V, Bhargavan M, Robbins L, Bush K, McNitt-Gray M, Payne JT, Ruckdeschel T, Pfeiffer D, Cody D (2011) Diagnostic reference levels from the ACR CT accreditation program. J Am Coll Radiol 8(11):795–803CrossRefPubMedGoogle Scholar
  65. 65.
    Tonkopi E, Duffy S, Abdolell M, Manos D (2017 May) Diagnostic reference levels and monitoring practice can help reduce patient dose from CT examinations. Am J Roentgenol 208(5):1073–1081CrossRefGoogle Scholar
  66. 66.
    Radiation Protection. Cone Beam CT for dental and maxillofacial radiology. Evidence based guidelines. The SEDENTEXCT project (2008–2011). In May 2012. Available at: http://wwwsedentexcteu/content/guidelines-cbct-dental-and-maxillofacial-radiology

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© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Wilana da Silva Moura
    • 1
    • 2
  • Kelly Chiqueto
    • 3
    • 4
  • Gustavo Menezes Pithon
    • 3
    • 5
  • Leniana Santos Neves
    • 3
    • 6
  • Renata Castro
    • 3
  • José Fernando Castanha Henriques
    • 1
  1. 1.Department of OrthodonticsBauru Dental SchoolBauruBrazil
  2. 2.TeresinaBrazil
  3. 3.Department of OrthodonticsSão Leopoldo Mandic Institute and Research CenterCampinasBrazil
  4. 4.Porto AlegreBrazil
  5. 5.SalvadorBrazil
  6. 6.Belo HorizonteBrazil

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