A preliminary study to determine the diagnostic reference level using dose–area product for limited-area cone beam CT

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

Dentomaxillofacial Radiology ◽

10.1259/dmfr.20120362 ◽

2013 ◽

Vol 42 (5) ◽

pp. 20120362 ◽

Cited By ~ 6

Author(s):

K Araki ◽

S Patil ◽

A Endo ◽

T Okano

Keyword(s):

Cone Beam Ct ◽

Cone Beam ◽

Dose Area Product ◽

Area Product

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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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