Dose indices in dental cone beam CT and correlation with dose–area product

Background During transarterial chemoembolization (TACE), cone-beam computed tomography (CBCT) can be used for tumor and feeding vessel detection as well as postembolization CT imaging. However, there will be additional radiation exposure from CBCT. Purpose To evaluate the additional dose raised through CBCT-assisted guidance in comparison to TACE procedures guided with pulsed digital subtraction angiography (DSA) alone. Material and Methods In 70 of 140 consecutive patients undergoing TACE for liver cancer, CBCT was used to facilitate the TACE. Cumulative dose area product (DAP), cumulative kerma(air), DAP values of DSA, total and cine specific fluoroscopy times (FT) of 1375 DSA runs, and DAP of 91 CBCTs were recorded and analyzed using Spearman's correlation, Mann–Whitney U-test, and Kruskal–Wallis test. P values < 0.05 were considered significant. Results Additional CBCT increased DAP by 2% ( P = 0.737), kerma(air) by 24.6% ( P = 0.206), and FT by 0.02% ( P = 0.453). Subgroup analysis revealed that postembolization CBCT for detection of ethiodized oil deposits added more DAP to the procedure. Performing CBCT-assisted TACE, DSA until first CBCT contributed about 38% to the total DAP. Guidance CBCT acquisitions conduced to 6% of the procedure's DAP. Additional DSA for guidance after CBCT acquisition required approximately 46% of the mean DAP. The last DSA run for documentation purposes contributed about 10% of the DAP. Conclusion CBCT adds radiation exposure in TACE. However, the capability of CBCT to detect vessels and overlay in real-time during fluoroscopy facilitates TACE with resultant reduction of DAPs up to 46%.

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A review of dental cone-beam CT dose conversion coefficients

Dentomaxillofacial Radiology ◽

10.1259/dmfr.20200225 ◽

2020 ◽

pp. 20200225

Author(s):

Eugene Mah ◽

E Russell Ritenour ◽

Hai Yao

Keyword(s):

Effective Dose ◽

Cone Beam Ct ◽

Field Of View ◽

Cone Beam ◽

Tube Voltage ◽

Conversion Factors ◽

Dose Area Product ◽

Ct Dose ◽

Conversion Coefficients ◽

Area Product

Objective: The purpose of this study was to review the literature to examine the usage and magnitude of effective dose conversion factors (DCE) for dental cone beam CT (CBCT) scanners. Methods: A PubMed literature search for publications relating to radiation dosimetry in dental radiography was performed. Papers were included if they reported DCE, or reported ICRP 103 effective dose and dose-area product. 71 papers relating to dental CBCT dosimetry were found, of which eight reported effective dose conversion factors or provided enough information to calculate dose conversion factors. Scanner model, effective dose, dose-area product, tube voltage, field of view size and DCE were extracted from the papers for analysis. Results: DCE values ranged from 0.035 to 0.31 µSv/mGy-cm2 with a mean of 0.129 µSv/mGy-cm2 (SD = 0.056). When categorized into small (<100 cm2), medium (100–225 cm2) and large (>225 cm2) fields of view (FOV), linear fits to the effective dose and dose-area product yielded slopes of 0.129, 0.111 and 0.074 µSv/mGy-cm2 for small, medium and large FOVs respectively. Conclusion: The range of reported DCE values and spread with respect to field of view category suggests that DCE values that depend on FOV would provide more accurate effective dose estimates. Tube voltage was found to be a smaller factor in determining DCE. Reasonable values for DCE taking into account FOV size were obtained. There is considerable room for more work to be done to examine the behaviour of DCE with changes to patient age and dental CBCT imaging parameters.

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Estimation of the radiation dose for dental spectral cone-beam CT

Dentomaxillofacial Radiology ◽

10.1259/dmfr.20200372 ◽

2020 ◽

pp. 20200372

Author(s):

Kaan Orhan ◽

Ruben Pauwels ◽

Yi Chen ◽

Dandan Song ◽

Reinhilde Jacobs

Keyword(s):

Radiation Dose ◽

Effective Dose ◽

Cone Beam Ct ◽

Cone Beam ◽

Dose Area Product ◽

Ion Chamber ◽

Effective Doses ◽

Artefact Reduction ◽

Area Product ◽

Dose Measurements

Objectives: The purpose of this study was to estimate the radiation dose for a dental spectral cone-beam CT (SCBCT) unit at different scanning parameters. Methods: Radiation dose measurements were performed for a commercially available dental SCBCT. Scans were obtained at different exposure times and fields of view (FOV), both for non-spectral (25 × 18 cm, 14 × 18 cm, 14 × 12 cm, 9 × 9 cm, 6 × 6 cm) and spectral modes (14 × 18 cm, 14 × 12 cm, 9 × 9 cm, 6 × 6 cm) with the tube voltage alternating between 80 and 110 kV for spectral mode, and fixed at 110 kV for non-spectral mode. An ion chamber was used for air kerma and dose area product (DAP) measurements. The effective dose was estimated based on the mAs using previously published logarithmic curves for CBCT units with a similar X-ray spectrum. Results: The adult effective dose, in non-spectral mode, was 44-269µSv for small FOVs, 131-336µSv for the medium FOV, and 163-476µSv for the large FOV. In spectral mode, the estimated adult effective doses were 96-206µSv for small, 299µSv for medium and 372µSv for large FOV protocols. Pediatric effective doses were estimated to be 75% higher than corresponding adult doses. Conclusion: SCBCT showed comparable doses with other CBCT devices, but DAP values were generally above currently published DRLs. Spectral imaging might allow for artefact reduction at comparable dose levels, which should be assessed in further image quality studies at both a technical and diagnostic level.

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Quality Control in Dental Cone-Beam Computed Tomography

Applied Sciences ◽

10.3390/app11178162 ◽

2021 ◽

Vol 11 (17) ◽

pp. 8162

Author(s):

Jin-Feng Huang ◽

Xiao-Zhao Chen ◽

Hong Wang

Keyword(s):

Computed Tomography ◽

Cone Beam Computed Tomography ◽

Detection Method ◽

Subjective Evaluation ◽

Safety Information ◽

Evaluation Methods ◽

Cone Beam ◽

Dose Area Product ◽

Effective Manner ◽

Area Product

Poor medical equipment may lead to misdiagnosis and missed diagnosis by doctors, leading to medical accidents. Given the differences in imaging methods, the performance determination method for conventional computed tomography (CT) does not apply to dental cone-beam computed tomography (CBCT). Therefore, a detection method that is more suitable for the characteristics of dental CBCT and more convenient for on-site operation in hospitals needs to be urgently developed. Hence, this study aimed to design a robust and convenient detection method to control the quality of dental CBCT, grasp the safety information of the equipment in a timely and effective manner, discover and evaluate equipment risks, and take reasonable and necessary countermeasures, thereby, reducing the risk of medical malpractice. This study adopted dose-area product to measure dose parameters and used objective quantitative evaluation methods instead of subjective evaluation methods for spatial resolution, contrast-to-noise ratio index, and uniformity. The dental CBCT of 10 dental hospitals and clinics were tested, and the findings revealed that the testing methods used had good accuracy and applicability.

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Dose-length-product determination on cone beam computed tomography through experimental measurements and dose-area-product conversion

Medical Imaging 2021: Physics of Medical Imaging ◽

10.1117/12.2575906 ◽

2021 ◽

Author(s):

Veronica Fransson ◽

Anders Tingberg

Keyword(s):

Computed Tomography ◽

Cone Beam Computed Tomography ◽

Cone Beam ◽

Experimental Measurements ◽

Dose Length Product ◽

Dose Area Product ◽

Area Product

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CONE BEAM CT IN DENTAL IMPLANT PLANNING: HOW CLOSE ARE PATIENT DOSIMETRY RESULTS WITH DATA FROM PHANTOM STUDIES FOUND IN LITERATURE?

Radiation Protection Dosimetry ◽

10.1093/rpd/ncz169 ◽

2019 ◽

Author(s):

S Kottou ◽

A Zapros ◽

N Stefanopoulou ◽

N Krompas ◽

V Tsapaki

Keyword(s):

Radiation Exposure ◽

Low Cost ◽

Cone Beam Ct ◽

Cone Beam ◽

Study Patient ◽

Tube Voltage ◽

Voxel Size ◽

Phantom Studies ◽

Area Product ◽

Patient Radiation Exposure

Abstract Advantages of Cone Beam Computed Tomography (CBCT) include high-quality 3D imaging and reduced radiation exposure with relatively low cost. In this study, patient radiation exposure in CBCT implant planning dentistry was measured in terms of Kerma Area Product (KAP). Data were obtained from 217 CBCT scans on 168 individuals using a CS9300 Carestream system. Scans were made using 80–90 kVp, 4–5 mA, 8 and 13.3 s exposure time (depending on voxel size) and a fixed field of view (FOV) of 10 × 10 cm2 (medium). Mean KAP was estimated using two voxel sizes 180 × 180 × 180 μm3 and 200 × 200 × 200 μm3 and found to be 399 and 314 mGycm2, respectively. Corresponding KAP values found in literature ranged between 210 and 2140 mGycm2. Mean E was estimated using conversion coefficient factors found in literature, according to FOV size and tube voltage value and found to range between 24 and 161 μSv.

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Analysis of Patients’ X-ray Exposure in 146 Percutaneous Radiologic Gastrostomies

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren ◽

10.1055/s-0043-109690 ◽

2017 ◽

Vol 189 (09) ◽

pp. 820-827 ◽

Cited By ~ 1

Author(s):

Tim-Ole Petersen ◽

Martin Reinhardt ◽

Jochen Fuchs ◽

Dieter Gosch ◽

Alexey Surov ◽

...

Keyword(s):

Cone Beam Ct ◽

Image Intensifier ◽

Flat Panel ◽

Flat Detector ◽

Dose Length Product ◽

X Ray ◽

Dose Area Product ◽

Flat Panel Detector ◽

Significant Prolongation ◽

Area Product

Purpose Analysis of patient´s X-ray exposure during percutaneous radiologic gastrostomies (PRG) in a larger population. Materials and Methods Data of primary successful PRG-procedures, performed between 2004 and 2015 in 146 patients, were analyzed regarding the exposition to X-ray. Dose-area-product (DAP), dose-length-product (DLP) respectively, and fluoroscopy time (FT) were correlated with the used x-ray systems (Flatpanel Detector (FD) vs. Image Itensifier (BV)) and the necessity for periprocedural placement of a nasogastric tube. Additionally, the effective X-ray dose for PRG placement using fluoroscopy (DL), computed tomography (CT), and cone beam CT (CBCT) was estimated using a conversion factor. Results The median DFP of PRG-placements under fluoroscopy was 163 cGy*cm2 (flat panel detector systems: 155 cGy*cm2; X-ray image intensifier: 175 cGy*cm2). The median DLZ was 2.2 min. Intraprocedural placement of a naso- or orogastric probe (n = 68) resulted in a significant prolongation of the median DLZ to 2.5 min versus 2 min in patients with an already existing probe. In addition, dose values were analyzed in smaller samples of patients in which the PRG was placed under CBCT (n = 7, median DFP = 2635 cGy*cm2), or using CT (n = 4, median DLP = 657 mGy*cm). Estimates of the median DFP and DLP showed effective doses of 0.3 mSv for DL-assisted placements (flat panel detector 0.3 mSv, X-ray image converter 0.4 mSv), 7.9 mSv using a CBCT – flat detector, and 9.9 mSv using CT. This corresponds to a factor 26 of DL versus CBCT, or a factor 33 of DL versus CT. Conclusion In order to minimize X-ray exposure during PRG-procedures for patients and staff, fluoroscopically-guided interventions should employ flat detector systems with short transmittance sequences in low dose mode and with slow image frequency. Series recordings can be dispensed with. The intraprocedural placement of a naso- or orogastric probe significantly extends FT, but has little effect on the overall dose of the intervention. Due to the significantly higher X-ray exposure, the use of a CBCT as well as PRG-placements using CT should be limited to clinically absolutely necessary exceptions with strict indication. Key Points Citation Format

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