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Optimized Camera-Based Patient Positioning in CT: Impact on Radiation Exposure. Invest Radiol 2023; 58:126-130. [PMID: 35926075 DOI: 10.1097/rli.0000000000000904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE The aim of this study was to evaluate whether a 3-dimensional (3D) camera can outperform highly trained technicians in precision of patient positioning and whether this transforms into a reduction in patient exposure. MATERIALS AND METHODS In a single-center study, 3118 patients underwent computer tomography (CT) scans of the chest and/or abdomen on a latest generation single-source CT scanner supported with an automated patient positioning system by 3D camera. One thousand five hundred fifty-seven patients were positioned laser-guided by a highly trained radiographer (camera off) and 1561 patients with 3D camera (camera on) guidance. Radiation parameters such as effective dose, organ doses, CT dose index, and dose length product were analyzed and compared. Isocenter accuracy and table height were evaluated between the 2 groups. RESULTS Isocenter positioning was significantly improved with the 3D camera ( P < 0.001) as compared with visual laser-guided positioning. Absolute table height differed significantly ( P < 0.001), being higher with camera positioning (165.6 ± 16.2 mm) as compared with laser-guided positioning (170.0 ± 20.4 mm). Radiation exposure decreased using the 3D camera as indicated by dose length product (321.1 ± 266.6 mGy·cm; camera off: 342.0 ± 280.7 mGy·cm; P = 0.033), effective dose (3.3 ± 2.7 mSv; camera off: 3.5 ± 2.9; P = 0.053), and CT dose index (6.4 ± 4.3 mGy; camera off: 6.8 ± 4.6 mGy; P = 0.011). Exposure of radiation-sensitive organs such as colon ( P = 0.015) and red bone marrow ( P = 0.049) were also lower using the camera. CONCLUSIONS The introduction of a 3D camera improves patient positioning in the isocenter of the scanner, which results in a lower and also better balanced dose reduction for the patients.
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Al-Hayek Y, Zheng X, Hayre C, Spuur K. The influence of patient positioning on radiation dose in CT imaging: A narrative review. J Med Imaging Radiat Sci 2022; 53:737-747. [PMID: 36280573 DOI: 10.1016/j.jmir.2022.09.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 09/21/2022] [Accepted: 09/29/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND PURPOSE Although it is fundamental for optimal scanner operation, it is generally accepted that accurate patient centring cannot always be achieved. This review aimed to examine the reported knowledge of the negative impact of patient positioning on radiation dose and image quality during CT imaging. Furthermore, the study evaluated the current optimisation tools and techniques used to improve patient positioning relative to the gantry iso-center. METHODOLOGY A comprehensive search through the databases PubMed, Ovid, and Google Scholar was performed. Keywords included patient off-centring, patient positioning, localiser radiograph orientation, radiation dose, and automatic patient positioning (including synonyms). The search was limited to full-text articles that were written in English. After initial title and abstract screening, a total of 52 articles were identified to address the aim of the review. No limitations were imposed on the year of publication. RESULTS Vertical off-centring was reported in up to 95% of patients undergoing chest and abdominal CT examinations, showing a significant influence on radiation dose. Depending on the scanner model and vendor, localiser orientation, bowtie filter used, and patient size, radiation dose varied from a decrease of 36% to an increase of 91%. A significant dose reduction was demonstrated when utilising an AP localiser, aligning with the trend for radiographers to off-center patients below the gantry iso-centre. Utilizing a 3D camera for body contour detection allowed for more accurate patient positioning and promoted further dose reduction. CONCLUSION Patient positioning has shown significant effects on radiation dose and image quality in CT. Developing a good understanding of the key factors influencing patient dose (off-centring direction, localiser orientation, patient size and bowtie filter selection) is critical in optimising CT scanning practices. Utilising a 3D camera for body contour detection is strongly recommended to improve patient positioning accuracy, image quality and to minimise patient dose.
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Affiliation(s)
- Yazan Al-Hayek
- School of Dentistry and Medical Sciences, Faculty of Science and Health, Charles Sturt University, Wagga Wagga, NSW, 2650, Australia; Department of Medical Imaging, Faculty of Applied Health Sciences, The Hashemite University, Zarqa, 13133, Jordan.
| | - Xiaoming Zheng
- School of Dentistry and Medical Sciences, Faculty of Science and Health, Charles Sturt University, Wagga Wagga, NSW, 2650, Australia.
| | - Christopher Hayre
- Department of Medical Imaging, College of Medicine and Health, University of Exeter, Devon, UK.
| | - Kelly Spuur
- School of Dentistry and Medical Sciences, Faculty of Science and Health, Charles Sturt University, Wagga Wagga, NSW, 2650, Australia.
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Mäkelä T, Kortesniemi M, Kaasalainen T. The impact of vertical off-centering on image noise and breast dose in chest CT with organ-based tube current modulation: A phantom study. Phys Med 2022; 100:153-163. [PMID: 35853275 DOI: 10.1016/j.ejmp.2022.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 06/11/2022] [Accepted: 06/28/2022] [Indexed: 10/17/2022] Open
Abstract
PURPOSE To determine the effects of patient vertical off-centering when using organ-based tube current modulation (OBTCM) in chest computed tomography (CT) with focus on breast dose. MATERIALS AND METHODS An anthropomorphic adult female phantom with two different breast attachment sizes was scanned on GE Revolution EVO and Siemens Definition Edge CT systems using clinical chest CT protocols and anterior-to-posterior scouts. Scans with and without OBTCM were performed at different table heights (GE: centered, ±6 cm, and ± 3 cm; Siemens: centered, -6 cm, and ± 3 cm). The dose effects were studied with metal-oxidesemiconductor field-effect transistor dosimeters with complementary Monte Carlo simulations to determine full dose maps. Changes in image noise were studied using standard deviations of subtraction images from repeated acquisitions without dosimeters. RESULTS Patient off-centering affected both the behavior of the normal tube current modulation as well as the extent of the OBTCM. Generally, both OBTCM techniques provided a substantial decrease in the breast doses (up to 30% local decrease). Lateral breast regions may, however, in some cases receive higher doses when OBTCM is enabled. This effect becomes more prominent when the patient is centered too low in the CT gantry. Changes in noise roughly followed the expected inverse of the change in dose. CONCLUSIONS Patient off-centering was shown to affect the outcome of OBTCM in chest CT examination, and on some occasions, resulting in higher exposure. The use of modern dose optimization tools such as OBTCM emphasizes the importance of proper centering when preparing patients to CT scans.
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Affiliation(s)
- Teemu Mäkelä
- HUS Diagnostic Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland; Department of Physics, University of Helsinki, Finland.
| | - Mika Kortesniemi
- HUS Diagnostic Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Touko Kaasalainen
- HUS Diagnostic Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
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Abstract
OBJECTIVE. Pediatric CT angiography (CTA) presents unique challenges compared with adult CTA. Because of the ionizing radiation exposure, CTA should be used judiciously in children. The pearls offered here are observations gleaned from the authors' experience in the use of pediatric CTA. We also present some potential follies to be avoided. CONCLUSION. Understanding the underlying principles and paying meticulous attention to detail can substantially optimize dose and improve the diagnostic quality of pediatric CTA.
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Shaffiq Said Rahmat SM, Abdul Karim MK, Che Isa IN, Abd Rahman MA, Noor NM, Hoong NK. Effect of miscentering and low-dose protocols on contrast resolution in computed tomography head examination. Comput Biol Med 2020; 123:103840. [PMID: 32658782 DOI: 10.1016/j.compbiomed.2020.103840] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/28/2020] [Accepted: 05/28/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Unoptimized protocols, including a miscentered position, might affect the outcome of diagnostic in CT examinations. In this study, we investigate the effects of miscentering position during CT head examination on the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). METHOD We simulate the CT head examination using a water phantom with a standard protocol (120 kVp/180 mAs) and a low dose protocol (100 kVp/142 mAs). The table height was adjusted to simulate miscentering by 5 cm from the isocenter, where the height was miscentered superiorly (MCS) at 109, 114, 119, and 124 cm, and miscentered inferiorly (MCI) at 99, 94, 89, and 84 cm. Seven circular regions of interest were used, with one drawn at the center, four at the peripheral area of the phantom, and two at the background area of the image. RESULTS For the standard protocol, the mean CNR decreased uniformly as table height increased and significantly differed (p < 0.05) at +20 cm for MCS (435.70 ± 9.39) and -20 cm for MCI (438.91 ± 10.94) from the isocenter. Similarly, significant reductions (p < 0.05) were also noted for SNR for MCS (at +20 cm) and MCI (at -20 cm). For the low dose protocol, both CNR and SNR were significantly reduced (p < 0.05) at table heights of +20 and -20 cm from the isocenter. CONCLUSION Miscentering is proven to significantly affect the image quality in both low and standard dose protocols for head CT procedure. This study implies that accurate patient centering is one of the approaches that can improve CT optimization practice.
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Affiliation(s)
- Said Mohd Shaffiq Said Rahmat
- Department of Radiology, National Cancer Institute, 4, Jalan P7, Presint 7, 62250, Putrajaya, Wilayah Persekutuan Putrajaya, Malaysia
| | | | - Iza Nurzawani Che Isa
- Diagnostic Imaging and Radiotherapy Programme, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, 50300, Kuala Lumpur, Wilayah Persekutuan Kuala Lumpur, Malaysia
| | - Mohd Amiruddin Abd Rahman
- Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - Noramaliza Mohd Noor
- Department of Radiology, Faculty of Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - Ng Kwan Hoong
- Department of Biomedical Imaging, Universiti of Malaya Medical Centre, 50603, Kuala Lumpur, Malaysia
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Eberhard M, Blüthgen C, Barth BK, Frauenfelder T, Saltybaeva N, Martini K. Vertical Off-Centering in Reduced Dose Chest-CT: Impact on Effective Dose and Image Noise Values. Acad Radiol 2020; 27:508-517. [PMID: 31358357 DOI: 10.1016/j.acra.2019.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 06/27/2019] [Accepted: 07/03/2019] [Indexed: 11/16/2022]
Abstract
OBJECTIVES To assess the effect of vertical off-centering in tube current modulation (TCM) on effective-dose and image-noise in reduced-dose (RD) chest-CT. METHODS One-hundred consecutive patients (36 female; mean age 56 years) were scanned on a 192-slice CT scanner with a standard-dose (ND) and a RD chest-CT protocol using tube current modulation. Image-noise was evaluated by placing circular regions of interest in the apical, middle, and lower lung regions. Two independent readers evaluated image quality. Study population was stratified according to patient position in the gantry: positioned in the gantry isocenter (i), higher than the gantry isocenter (ii), and lower than the gantry isocenter, (iii). Pearson correlation was used to determine the correlation between effective radiation dose and vertical off-centering. Student's t test was used to evaluate for differences in image-noise between groups (i-iii). RESULTS Mean vertical off-centering was of 10.6 mm below the gantry-isocenter (range -45.0-27.9 mm). Effective radiation dose varied in a linear trend, with the highest doses noted below gantry isocenter, and the lowest doses noted above gantry isocenter (ND: r = -0.296; p = 0.003 - RD: r = -0.258; p = 0.010). Lowest image-noise was observed where patients were positioned below the gantry isocenter, and highest in patients positioned above (ND: 79.35 HU vs. 94.86 HU - RD: 143.44 HU vs. 160.13 HU). Subjective image quality was not significantly affected by patient-position (p > 0.05). Overall, there was no over-proportional noise-increase from the ND to the RD protocol in patients which were positioned off-center. CONCLUSION Vertical off-centering influences effective radiation dose and image-noise on ND and RD protocols. ADVANCES IN KNOWLEDGE There is no over-proportional noise increase in RD compared to ND protocols when patients are positioned off-center.
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Affiliation(s)
- Matthias Eberhard
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland
| | - Christian Blüthgen
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland
| | - Borna K Barth
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland
| | - Thomas Frauenfelder
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland
| | - Natalia Saltybaeva
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland
| | - Katharina Martini
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland.
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Precise and Automatic Patient Positioning in Computed Tomography: Avatar Modeling of the Patient Surface Using a 3-Dimensional Camera. Invest Radiol 2019; 53:641-646. [PMID: 29762259 DOI: 10.1097/rli.0000000000000482] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The aim of this study was to evaluate the accuracy of a 3-dimensional (3D) camera algorithm for automatic and individualized patient positioning based on body surface detection and to compare the results of the 3D camera with manual positioning performed by technologists in routinely obtained chest and abdomen computed tomography (CT) examinations. MATERIALS AND METHODS This study included data of 120 patients undergoing clinically indicated chest (n = 68) and abdomen (n = 52) CT. Fifty-two of the patients were scanned with CT using a table height manually selected by technologists; 68 patients were automatically positioned with the 3D camera, which is based on patient-specific body surface and contour detection. The ground truth table height (TGT) was defined as the table height that aligns the axial center of the patient's body region in the CT scanner isocenter. Off-centering was defined as the difference between the ground truth table height (TGT) and the actual table position used in all CT examinations. The t test was performed to determine significant differences in the vertical offset between automatic and manual positioning. The χ test was used to check whether there was a relationship between patient size and the magnitude of off-centering. RESULTS We found a significant improvement in patient centering (offset 5 ± 3 mm) when using the automatic positioning algorithm with the 3D camera compared with manual positioning (offset 19 ± 10 mm) performed by technologists (P < 0.005). Automatic patient positioning based on the 3D camera reduced the average offset in vertical table position from 19 mm to 7 mm for chest and from 18 mm to 4 mm for abdomen CT. The absolute maximal offset was 39 mm and 43 mm for chest and abdomen CT, respectively, when patients were positioned manually, whereas with automatic positioning using the 3D camera the offset never exceeded 15 mm. In chest CT performed with manual patient positioning, we found a significant correlation between vertical offset greater than 20 mm and patient size (body mass index, >26 kg/m, P < 0.001). In contrast, no such relationship was found for abdomen CT (P = 0.38). CONCLUSIONS Automatic individualized patient positioning using a 3D camera allows for accurate patient centering as compared with manual positioning, which improves radiation dose utilization.
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Akin-Akintayo OO, Alexander LF, Neill R, Krupinksi EA, Tang X, Mittal PK, Small WC, Moreno CC. Prevalence and Severity of Off-Centering During Diagnostic CT: Observations From 57,621 CT scans of the Chest, Abdomen, and/or Pelvis. Curr Probl Diagn Radiol 2019; 48:229-234. [DOI: 10.1067/j.cpradiol.2018.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 02/20/2018] [Accepted: 02/21/2018] [Indexed: 11/22/2022]
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Paolicchi F, Bastiani L, Negri J, Caramella D. Effect of CT Localizer Radiographs on Radiation Dose Associated With Automatic Tube Current Modulation: A Multivendor Study. Curr Probl Diagn Radiol 2019; 49:34-41. [PMID: 30704769 DOI: 10.1067/j.cpradiol.2018.12.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/15/2018] [Accepted: 12/31/2018] [Indexed: 11/22/2022]
Abstract
OBJECTIVES To assess the influence of the CT localizer radiograph on the automatic tube current modulation system of 7 CT scanners produced by 4 different CT manufacturers. METHODS The influence of the localizer orientation, table height, tube current and tube potential values on the radiation dose of the related CT scan were evaluated. Images were acquired by using an anthropomorphic phantom positioned in the CT gantry isocenter as well as from -6 cm to +6 cm vertically to the isocenter. RESULTS Vertical movement of the CT table height affected the radiation dose in all scanners using anterior-posterior or a posterior-anterior localizer orientation albeit differently, depending on the manufacturer; only in 1/7 scanner no influence was observed. The latero-lateral localizer orientation proved to be more effective in limiting the influence of the vertical miscentering in all scanners. Changing localizer's tube voltage influenced the scan radiation dose in scanners produced by two manufacturers, while no significant effect was observed in scanners produced by the other two manufacturers. No significant dose variation was observed in 6/7 scanners when changing the localizer's tube current. CONCLUSION Localizer radiograph shows a significant influence on the radiation exposure but with different outcomes depending on the manufacturer of the CT scanner. Radiologists and radiographers should have a thorough understanding of these differences to assure patients the best examination in terms of radiation dose and image quality.
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Affiliation(s)
- Fabio Paolicchi
- Department of Diagnostic and Interventional Radiology, University of Pisa, Pisa, Italy.
| | - Luca Bastiani
- Institute of Clinical Physiology, National Research Council, Pisa, Italy
| | - Jacopo Negri
- Department of Radiology, Macerata General Hospital, Macerata, Italy
| | - Davide Caramella
- Department of Diagnostic and Interventional Radiology, University of Pisa, Pisa, Italy
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Isa INC, Rahmat SMS, Dom SM, Kayun Z, Karim MKA. The effects of mis-centering on radiation dose during CT head examination: A phantom study. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2019; 27:631-639. [PMID: 31205011 DOI: 10.3233/xst-190491] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
There are several factors that may contribute to the increase in radiation dose of CT including the use of unoptimized protocols and improper scanning technique. In this study, we aim to determine significant impact on radiation dose as a result of mis-centering during CT head examination. The scanning was performed by using Toshiba Aquilion 64 slices multi-detector CT (MDCT) scanner and dose were measured by using calibrated ionization chamber. Two scanning protocols of routine CT head; 120 kVp/ 180 mAs and 100 kVp/ 142 mAs were used represent standard and low dose, respectively. As reference measurement, the dose was first measured on standard cylindrical polymethyl methacrylate (PMMA) phantom that positioned at 104 cm from the floor (reference isocenter). The positions then were varied to simulate mis-centering by 5 cm from isocenter, superiorly and inferiorly at 109 cm, 114 cm, 119 cm, 124 cm and 99 cm, 94 cm, 89 cm, 84 cm, respectively. Scanning parameter and dose information from the console were recorded for the radiation effective dose (E) measurement. The highest mean CTDIvol value for MCS and MCI were 105.06 mGy (at +10 cm) and 105.51 mGy (at - 10 cm), respectively which differed significantly (p < 0.05) as compared to the isocenter. There were large significant different (p < 0.05) of mean Dose Length Product (DLP) recorded between isocenter to the MCS (85.8 mGy.cm) and MCI (93.1 mGy.cm). As the low dose protocol implemented, the volume CTDI (CTDIvol) were significantly increase (p < 0.05) for MCS (at +10 cm) and MCI (at - 10 cm) when compared to the isocenter. The phantom study revealed a noticeable different in radiation dose between isocenter and experimental groups due to degradation of the bowtie filter performance. It is anticipated that these noteworthy findings may emphasize the importance of accurate patient centering at the isocenter of CT gantry, so that CT optimization practice can be achieved.
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Affiliation(s)
- I N C Isa
- Diagnostic Imaging & Radiotherapy Program, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - S M S Rahmat
- Department of Radiology, National Cancer Institute, Putrajaya, Malaysia
- Faculty of Health Sciences, Universiti Teknologi MARA, Puncak Alam, Selangor, Malaysia
| | - S M Dom
- Faculty of Health Sciences, Universiti Teknologi MARA, Puncak Alam, Selangor, Malaysia
| | - Z Kayun
- Department of Physics, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - M K A Karim
- Department of Physics, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
- Center for Diagnostic Nuclear Imaging, Faculty of Medicine, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
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Kaasalainen T, Mäkelä T, Kortesniemi M. The effect of vertical centering and scout direction on automatic tube voltage selection in chest CT: a preliminary phantom study on two different CT equipments. Eur J Radiol Open 2018; 6:24-32. [PMID: 30619916 PMCID: PMC6298908 DOI: 10.1016/j.ejro.2018.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 12/11/2022] Open
Abstract
Purpose To determine the effect of patient's vertical off-centering and scout direction on the function of automatic tube voltage selection (ATVS) and tube current modulation (TCM) in chest computed tomography (CT). Methods Chest phantom was scanned with Siemens and GE CT systems using three clinical chest CT protocols exploiting ATVS and a fixed 120 kVp chest protocol. The scans were performed at five vertical positions of the phantom (-6 to +6 cm from the scanner isocenter). The effects of scout direction (posterior-to-anterior, anterior-to-posterior, and lateral) and vertical off-centering on the function of ATVS and TCM were studied by examining changes in selected voltage, radiation dose (volume CT dose index, CTDIvol), and image noise and contrast. Results Both scout direction and vertical off-centering affected ATVS. The effect differed between the vendors for the studied geometry, demonstrating differences in technical approaches. The greatest observed increase in CTDIvol due to off-centering was 91%. Anterior-to-posterior scout produced highest doses at the uppermost table position, whereas posterior-to-anterior scout produced highest doses at the lowermost table position. Dose varied least using lateral scouts. Vertical off-centering impacted image noise and contrast due to the combined effect of ATVS, TCM, structural noise, and bowtie filters. Conclusions Patient vertical off-centering and scout direction affected substantially the CTDIvol and image quality in chest CT examinations. Vertical off-centering caused variation also in the selected tube voltage. The function of ATVS and TCM methods differ significantly between the CT vendors, resulting in differences in CTDIvol and image noise characteristics.
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Affiliation(s)
- Touko Kaasalainen
- HUS Medical Imaging Center, Helsinki University Central Hospital, Finland.,Department of Physics, University of Helsinki, Finland
| | - Teemu Mäkelä
- HUS Medical Imaging Center, Helsinki University Central Hospital, Finland.,Department of Physics, University of Helsinki, Finland
| | - Mika Kortesniemi
- HUS Medical Imaging Center, Helsinki University Central Hospital, Finland.,Department of Physics, University of Helsinki, Finland
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Saltybaeva N, Alkadhi H. Vertical off-centering affects organ dose in chest CT: Evidence from Monte Carlo simulations in anthropomorphic phantoms. Med Phys 2017; 44:5697-5704. [DOI: 10.1002/mp.12519] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/13/2017] [Accepted: 07/29/2017] [Indexed: 11/08/2022] Open
Affiliation(s)
- Natalia Saltybaeva
- Institute of Diagnostic and Interventional Radiology; University of Zurich; Ramistrasse 100 8091 Zurich Switzerland
| | - Hatem Alkadhi
- Institute of Diagnostic and Interventional Radiology; University of Zurich; Ramistrasse 100 8091 Zurich Switzerland
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Peng W, Li Z, Xia C, Guo Y, Zhang J, Zhang K, Li L, Zhao F. A CONSORT-compliant prospective randomized controlled trial: radiation dose reducing in computed tomography using an additional lateral scout view combined with automatic tube current modulation: Phantom and patient study. Medicine (Baltimore) 2017; 96:e7324. [PMID: 28746180 PMCID: PMC5627806 DOI: 10.1097/md.0000000000007324] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 05/26/2017] [Accepted: 05/29/2017] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Radiation exposure has been a hot point in research field of computed tomography (CT). Recently, automated tube current modulation (ATCM) has emerged as an important technique to reduce radiation exposure. Many studies have shown that the difference in scout view would affect modulation. This prospective randomized controlled study is aimed to investigate the impact of an additional lateral scout view on radiation dose and image quality in CT using ACTM. METHODS Combined with ATCM (Care Dose 4D) on multidetector CT, 2 thoracic phantom CT image series were acquired in which planning was conducted with either an anteroposterior (AP) or an AP-lateral scout view. Also, 410 patients underwent thoracic CT examinations using Care Dose 4D modulation and were randomized to either a scan planned with an AP-lateral scout or a single AP scout. Effects of the different scout views on applied effective milliampere seconds (mAs), volume CT dose index (CTDIvol) and dose-length-product (DLP) were analyzed. The quality of patient CT images was also assessed. Data were analyzed using independent t tests and linear correlation analysis. RESULTS Compared with AP groups, the mean CTDIvol (phantom, 0.89 ± 0.08 vs 1.36 ± 0.26 mGy, P < .001; in patients, 1.12 [0.96, 1.34] vs 2.16 [1.66, 2.64] mGy, P < .001) and DLP (in phantom, 26 [23.25, 28] vs 40 [34.25, 48] mGy×cm, P < .001; in patients, 41 [33, 41] vs 77 [60.5, 99.5] mGy×cm, P < .001) were significantly reduced by approximately 50% in AP-lateral scout view group. With the AP-lateral topogram, the radiation dose on different off-center positions was essentially equal (CTDIvol: 0.76-0.99 mGy; DLP: 22-28 mGy×cm effective dose: 0.31-0. 39 mSv). For image quality, contrast-to-noise ratio and signal-to-noise ratio values in the AP group were similar to those of AP-lateral scout view group. CONCLUSION AP combined with an additional lateral scout view using ACTM can significantly reduce the radiation dose without compromising image quality in chest screening CT.
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Affiliation(s)
- Wanlin Peng
- Department of Radiology, West China Hospital of Sichuan University, Chengdu
| | - Zhenlin Li
- Department of Radiology, West China Hospital of Sichuan University, Chengdu
| | - Chunchao Xia
- Department of Radiology, West China Hospital of Sichuan University, Chengdu
| | - Yingkun Guo
- Department of Radiology, Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Chengdu, China
| | - Jinge Zhang
- Department of Radiology, West China Hospital of Sichuan University, Chengdu
| | - Kai Zhang
- Department of Radiology, West China Hospital of Sichuan University, Chengdu
| | - Lei Li
- Department of Radiology, West China Hospital of Sichuan University, Chengdu
| | - Fei Zhao
- Department of Radiology, West China Hospital of Sichuan University, Chengdu
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