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Padole A, Deedar Ali Khawaja R, Otrakji A, Zhang D, Liu B, Xu XG, Kalra MK. Comparison of Measured and Estimated CT Organ Doses for Modulated and Fixed Tube Current:: A Human Cadaver Study. Acad Radiol 2016; 23:634-42. [PMID: 26852248 DOI: 10.1016/j.acra.2015.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 11/27/2015] [Accepted: 12/08/2015] [Indexed: 10/22/2022]
Abstract
RATIONALE AND OBJECTIVES The aim of this study was to compare the directly measured and the estimated computed tomography (CT) organ doses obtained from commercial radiation dose-tracking (RDT) software for CT performed with modulated tube current or automatic exposure control (AEC) technique and fixed tube current (mAs). MATERIALS AND METHODS With the institutional review board (IRB) approval, the ionization chambers were surgically implanted in a human cadaver (88 years old, male, 68 kg) in six locations such as liver, stomach, colon, left kidney, small intestine, and urinary bladder. The cadaver was scanned with routine abdomen pelvis protocol on a 128-slice, dual-source multidetector computed tomography (MDCT) scanner using both AEC and fixed mAs. The effective and quality reference mAs of 100, 200, and 300 were used for AEC and fixed mAs, respectively. Scanning was repeated three times for each setting, and measured and estimated organ doses (from RDT software) were recorded (N = 3*3*2 = 18). RESULTS Mean CTDIvol for AEC and fixed mAs were 4, 8, 13 mGy and 7, 14, 21 mGy, respectively. The most estimated organ doses were significantly greater (P < 0.01) than the measured organ doses for both AEC and fixed mAs. At AEC, the mean estimated organ doses (for six organs) were 14.7 mGy compared to mean measured organ doses of 12.3 mGy. Similarly, at fixed mAs, the mean estimated organ doses (for six organs) were 24 mGy compared to measured organ doses of 22.3 mGy. The differences among the measured and estimated organ doses were higher for AEC technique compared to the fixed mAs for most organs (P < 0.01). CONCLUSIONS The most CT organ doses estimated from RDT software are greater compared to directly measured organ doses, particularly when AEC technique is used for CT scanning.
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Zenóbio EG, Zenóbio MAF, Nogueira MS, Silva TA, Shibli JA. Absorbed Radiation Doses During Tomographic Examinations in Dental Implant Planning: A Study in Humans. Clin Implant Dent Relat Res 2010; 14:366-72. [DOI: 10.1111/j.1708-8208.2010.00277.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Chau ACM, Fung K. Comparison of radiation dose for implant imaging using conventional spiral tomography, computed tomography, and cone-beam computed tomography. ACTA ACUST UNITED AC 2009; 107:559-65. [PMID: 19168378 DOI: 10.1016/j.tripleo.2008.11.009] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 10/09/2008] [Accepted: 11/12/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE The objective of this study was to compare typical patient radiation dose delivered in implant imaging with spiral computed tomography (CT), conventional spiral tomography, and cone-beam CT (CBCT). STUDY DESIGN The Scanora (Orion Corporation Soredex, Helsinki, Finland), Spiral HiSpeed/Fxi (General Electric, Milwaukee, WI), and Classic iCAT (Imaging Sciences International, Hatfield, PA) units were selected to represent conventional spiral tomography, spiral CT, and CBCT, respectively. Thermoluminescent dosimeters were used in a Rando phantom to measure radiation-absorbed doses to the lenses, parotid glands, submandibular glands, sublingual gland, and the thyroid for maxillary and mandibular implant imaging techniques. RESULTS Spiral CT delivered the highest absorbed dose, whereas CBCT delivered the lowest in both maxillary and mandibular implant scans. The salivary glands received the highest absorbed doses. Scanora delivered lower radiation doses than CBCT when the anterior region of the maxilla or mandible was irradiated. CONCLUSION In implant imaging, CT delivers the highest radiation dose to the salivary glands, whereas the CBCT system studied delivers the lowest dose. Irrespective of imaging modality, during implant imaging as conducted for this study, salivary glands receive most radiation.
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Affiliation(s)
- Anson C M Chau
- Oral Radiology, Faculty of Dentistry, The University of Hong Kong, Hong Kong.
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Comparison between effective radiation dose of CBCT and MSCT scanners for dentomaxillofacial applications. Eur J Radiol 2008; 71:461-8. [PMID: 18639404 DOI: 10.1016/j.ejrad.2008.06.002] [Citation(s) in RCA: 332] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Revised: 04/30/2008] [Accepted: 06/03/2008] [Indexed: 11/22/2022]
Abstract
OBJECTIVES To compare the effective dose levels of cone beam computed tomography (CBCT) for maxillofacial applications with those of multi-slice computed tomography (MSCT). STUDY DESIGN The effective doses of 3 CBCT scanners were estimated (Accuitomo 3D, i-CAT, and NewTom 3G) and compared to the dose levels for corresponding image acquisition protocols for 3 MSCT scanners (Somatom VolumeZoom 4, Somatom Sensation 16 and Mx8000 IDT). The effective dose was calculated using thermoluminescent dosimeters (TLDs), placed in a Rando Alderson phantom, and expressed according to the ICRP 103 (2007) guidelines (including a separate tissue weighting factor for the salivary glands, as opposed to former ICRP guidelines). RESULTS Effective dose values ranged from 13 to 82 microSv for CBCT and from 474 to 1160 microSv for MSCT. CBCT dose levels were the lowest for the Accuitomo 3D, and highest for the i-CAT. CONCLUSIONS Dose levels for CBCT imaging remained far below those of clinical MSCT protocols, even when a mandibular protocol was applied for the latter, resulting in a smaller field of view compared to various CBCT protocols. Considering this wide dose span, it is of outmost importance to justify the selection of each of the aforementioned techniques, and to optimise the radiation dose while achieving a sufficient image quality. When comparing these results to previous dosimetric studies, a conversion needs to be made using the latest ICRP recommendations.
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Zenóbio MAF, da Silva TA. Absorbed doses on patients undergoing tomographic exams for pre-surgery planning of dental implants. Appl Radiat Isot 2007; 65:708-11. [PMID: 17398103 DOI: 10.1016/j.apradiso.2007.01.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2006] [Revised: 01/03/2007] [Accepted: 01/11/2007] [Indexed: 11/23/2022]
Abstract
The thermoluminescent (TL) dosimetry was used to measure entrance skin absorbed doses at anatomical points close to critical organs of patients undergoing tomographic techniques as part of a pre-surgery planning for dental implants. The dosimetric procedure was applied in 19 patients, and absorbed doses could be measured with a combined uncertainty down to 14%. Results showed that patient doses may be increased by a factor of 20 in the helical computed tomography compared to panoramic and spiral conventional tomographic exams.
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Affiliation(s)
- M A F Zenóbio
- Centro de Desenvolvimento da Tecnologia Nuclear, Comissão Nacional de Energia Nuclear, Caixa Postal 941, CEP 30123-970 Belo Horizonte, MG, Brazil
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Liang X, Jacobs R, Lambrichts I. An assessment on spiral CT scan of the superior and inferior genial spinal foramina and canals. Surg Radiol Anat 2005; 28:98-104. [PMID: 16341824 DOI: 10.1007/s00276-005-0055-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Accepted: 09/05/2005] [Indexed: 10/25/2022]
Abstract
To characterise the superior as well as the inferior genial spinal foramen and their bony canal using a large CT data sample. The study included 555 mandibular spirals CT scans, taken from patients for pre-operative implant planning. Basic observation by three observers included the number of canals, their respective anatomical location and morphological variations. Furthermore, linear measurements were performed to describe the foramina and canal characteristics. On spiral CT scans, the superior and inferior genial spinal foramina were detected in 448 CT scans (81%). In 29% of the mandibular CTs, two or more midline canals were noted. 47% of the foramina were located in a position inferior to the genial spines; the others were located in a superior position. The mean (SD) lingual and buccal diameters of the canal structures were 0.73 (0.27) and 0.54 (0.29) mm, respectively with an average length of 3.94 (1.29) mm. The canal was located on average 7.40 (5.31) mm from the mandibular base at the lingual entrance and 7.96 (3.47) mm at the buccal canal end point. The average canal extended towards the buccal bone for an average 37% of the bone width. The results demonstrated the presence of both superior and inferior genial spinal foramina, with 29% of the individuals having double foramina. About 53% of the foramina was located superior to the genial spines. Considering its neurovascular content, these foramina should be carefully evaluated during pre-operative planning.
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Affiliation(s)
- X Liang
- Oral Imaging Centre and Department of Periodontology, Faculty of Medicine, Katholieke Universiteit Leuven, Leuven, Belgium
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Tsiklakis K, Donta C, Gavala S, Karayianni K, Kamenopoulou V, Hourdakis CJ. Dose reduction in maxillofacial imaging using low dose Cone Beam CT. Eur J Radiol 2005; 56:413-7. [PMID: 15978765 DOI: 10.1016/j.ejrad.2005.05.011] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2005] [Revised: 05/13/2005] [Accepted: 05/18/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVES (a) To measure the absorbed dose at certain anatomical sites of a RANDO phantom and to estimate the effective dose in radiographic imaging of the jaws using low dose Cone Beam computed tomography (CBCT) and (b) to compare the absorbed and the effective doses between thyroid and cervical spine shielding and non-shielding techniques. STUDY DESIGN Thermoluminescent dosimeters (TLD-100) were placed at 14 sites in a RANDO phantom, using a Cone Beam CT device (Newtom, Model QR-DVT 9000, Verona, Italy). Dosimetry was carried out applying two techniques: in the first, there was no shielding device used while in the second one, a shielding device (EUREKA!, TRIX) was applied for protection of the thyroid gland and the cervical spine. Effective dose was estimated according to ICRP(60) report (E(ICRP)). An additional estimation of the effective dose was accomplished including the doses of the salivary glands (E(SAL)). A Wilcoxon Signed Ranks Test was used for statistical analysis. RESULTS In the non-shielding technique the absorbed doses ranged from 0.16 to 1.67 mGy, while 0.32 and 1.28 mGy were the doses to the thyroid and the cervical spine, respectively. The effective dose, E(ICRP), was 0.035 mSv and the E(SAL) was 0.064 mSv. In the shielding technique, the absorbed doses ranged from 0.09 to 1.64 mGy, while 0.18 and 0.95 mGy were the respective values for the thyroid and the cervical spine. The effective dose, E(ICRP), was 0.023 mSv and E(SAL) was 0.052 mSv. CONCLUSIONS The use of CBCT for maxillofacial imaging results in a reduced absorbed and effective dose. The use of lead shielding leads to a further reduction of the absorbed doses of thyroid and cervical spine, as well as the effective dose.
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Affiliation(s)
- Kostas Tsiklakis
- Department of Oral Diagnosis and Oral Radiology, School of Dentistry, University of Athens, Greece.
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Frei C, Buser D, Dula K. Study on the necessity for cross-section imaging of the posterior mandible for treatment planning of standard cases in implant dentistry. Clin Oral Implants Res 2004; 15:490-7. [PMID: 15248885 DOI: 10.1111/j.1600-0501.2004.01032.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To investigate whether cross-section imaging influences the planning and therapy of standard implant cases in the posterior mandible. MATERIAL AND METHODS In a prospective study conducted over 16 months, the planned treatment (standard implant therapy without bone augmentation procedures in the premolar and molar regions of the mandible) was compared with the postoperative result in 50 randomly selected patients. Clinical examinations and panoramic radiographs were performed pre- and postoperatively, whereas cross-sectional tomography was performed only preoperatively. RESULTS The vertical magnification factor in the panoramic radiographs was very constant pre- and postoperatively with 1 : 1.27 and in the spiral tomograms with 1 : 1.52. In 11 of 77 implant sites, the mandibular canal could not be evaluated in the spiral tomograms. The additional information from cross-sectional spiral tomography did not influence the original planning in 74 of 77 (96.1%) implant sites. Based on the postoperative panoramic radiograph, the average distance from the tip of the implants to the mandibular canal was 3.04+/-2.06 mm. In two cases (2.6%), transient postoperative altered tactile sensation of the mental nerve was found. CONCLUSION The information from preoperative cross-sectional spiral tomography has minor impact on treatment planning in standard implant cases in mandibular premolar and molar regions. The clinical examination provides sufficient information for selecting implant diameter and the panoramic radiograph provides sufficient information for implant length selection.
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Affiliation(s)
- Christian Frei
- Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Berne, Berne, Switzerland
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Affiliation(s)
- Reinhilde Jacobs
- Department of Periodontology and Oral Imaging Center, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Catholic University Leuven, Belgium
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BouSerhal C, Jacobs R, Quirynen M, van Steenberghe D. Imaging technique selection for the preoperative planning of oral implants: a review of the literature. Clin Implant Dent Relat Res 2003; 4:156-72. [PMID: 12516649 DOI: 10.1111/j.1708-8208.2002.tb00167.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND As the use of oral implants for the treatment of partially as well as fully edentulous patients has increased the past two decades, more specialized radiographic techniques have become available for the preoperative planning of oral implant placement. PURPOSE The goal of this article was to enable clinicians to select the appropriate imaging techniques when planning for oral implants. MATERIALS AND METHODS This artide reviews the available literature about various imaging techniques and their indication for the preoperative planning of oral implants. The advantages and drawbacks of each technique are described. A dosimetric overview is given relative to different radiologic techniques used in various clinical situations. RESULTS For preoperative planning of implant placement, advantages and drawbacks of the available imaging techniques have been considered, which allows guidelines for image technique selection to be formulated based on the clinical situation provided, considering the diagnostic yield of each technique and the radiation doses involved. CONCLUSIONS From the available literature, it can be stated that many clinical situations demand the use of cross-sectional imaging techniques for optimal preoperative planning of implant placement. Nevertheless, such techniques are not required in cases in which the clinical examination reveals sufficient bone width and where standard radiographic examinations, such as intraoral and panoramic radiography, reveal adequate bone height and space for implant placement.
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Affiliation(s)
- Charbel BouSerhal
- Department of Periodontology, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Katholieke Universiteit Leuven, Leuven, Belgium
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Bou Serhal C, Jacobs R, Gijbels F, Bosmans H, Hermans R, Quirynen M, van Steenberghe D. Absorbed doses from spiral CT and conventional spiral tomography: a phantom vs. cadaver study. Clin Oral Implants Res 2001; 12:473-8. [PMID: 11564107 DOI: 10.1034/j.1600-0501.2001.120507.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
For several radiological examinations, a clinician can select between conventional and spiral computed tomography. Using both techniques, this study aimed at evaluating the difference in absorbed doses when examining a single lateral jaw segment in a human cadaver head and Rando phantom. The present study involved the placement of thermoluminescent dosimeter (TLD) chips (GR-200) in the thyroid gland, and bilaterally, in the parotid and submandibular glands and the lenses of the eyes in both a human cadaver and a Rando phantom at corresponding locations. Consecutive conventional spiral tomographic examinations were carried out in both the left upper and lower premolar area, using a Cranex TOME multifunctional unit. Each examination consisted of 4 slices with a 2 mm slice thickness and exposure parameters of 57 kV, 56 seconds and 1.6-2.0 mA. Regarding spiral computed tomography (CT), a Somatom Plus S scanner (Siemens, Erlangen, Germany), with a slice thickness of 1 mm with settings at 120 kV and 165 mA, was used on both phantoms and separately in the upper and lower jaw. With conventional tomography, the findings of the present study showed that the parotid and submandibular glands on the side near the X-ray tube received the highest dose, both for the cadaver head (doses ranging from 0.5 to 1.3 mGy) and the phantom (doses ranging from 0.6 to 2.6 mGy). For CT of the upper jaw, the highest doses were delivered to the parotid glands with an average absorbed dose of 9.2 and 10.6 mGy for the cadaver head and phantom, respectively. The submandibular glands received the highest doses during CT examination of the lower jaw with an average of 7.8 and 12.9 mGy for the cadaver head and phantom, respectively. It appears from the present investigation that if small edentulous regions are examined, radiation doses during conventional tomography remain much lower than during CT imaging. However, when multiple tomographic cuts are required, a spiral CT examination can replace a series of conventional examinations, especially in cases such as the rehabilitation of an edentulous upper jaw or a more complex surgery.
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Affiliation(s)
- C Bou Serhal
- Department of Periodontology, Oral Imaging Cluster, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Catholic University Leuven, Kapucijnenvoer 7, 3000 Leuven, Belgium
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Bou Serhal C, van Steenberghe D, Quirynen M, Jacobs R. Localisation of the mandibular canal using conventional spiral tomography: a human cadaver study. Clin Oral Implants Res 2001; 12:230-6. [PMID: 11359480 DOI: 10.1034/j.1600-0501.2001.012003230.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
For certain surgical procedures (e.g. placement of implants), an accurate localisation of the mandibular canal is of utmost importance to avoid injuries to the neurovascular bundle. The aim of the present study was to evaluate, on human fresh cadavers (n = 6), the accuracy of conventional spiral tomography for the localisation of the mandibular canal. By means of the Cranex TOME multifunctional unit (Orion Corporation Soredex, Helsinki, Finland), tomographic slices were taken at 3 different locations in the left posterior mandible (distal to the mental foramen). The mandibles were then sectioned at these 3 sites with a microtome. With a digital sliding caliper, the following 3 measurements were performed both on the tomograms and the bone sections at the three sites: 1) distance from the crest to mandibular canal, 2) overall bone height and 3) bone width. Overestimations of the distance to the mandibular canal (8/18) ranged from 1.05 to 0.10 mm and underestimations from 0.30 to 1.36 mm. The same number of over- and underestimations occurred for the bone height (1.14 to 0.14 mm and 0.15 to 1.40 mm, respectively). The bone width scored more overestimations (10/18), ranging from 1.40 to 0.12 mm, while underestimations ranged from 0.25 to 1.35 mm. From the present results, it is concluded that spiral tomography using the Cranex TOME multifunctional X-ray unit provides accurate information and sufficient detail for preoperative planning of implant placement in the posterior mandible.
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Affiliation(s)
- C Bou Serhal
- Department of Periodontology, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Catholic University of Leuven, Leuven, Belgium
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