{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"omics_type":["Unknown"],"volume":["6"],"submitter":["Kaasalainen T"],"funding":["Radiological Society of Finland","State Subsidy for University Hospitals in Finland"],"pubmed_abstract":["<h4>Purpose</h4>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).<h4>Methods</h4>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, CTDI<sub>vol</sub>), and image noise and contrast.<h4>Results</h4>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 CTDI<sub>vol</sub> 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.<h4>Conclusions</h4>Patient vertical off-centering and scout direction affected substantially the CTDI<sub>vol</sub> 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 CTDI<sub>vol</sub> and image noise characteristics."],"journal":["European journal of radiology open"],"pagination":["24-32"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC6298908"],"repository":["biostudies-literature"],"pubmed_title":["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."],"pmcid":["PMC6298908"],"pubmed_authors":["Kortesniemi M","Makela T","Kaasalainen T"],"additional_accession":[]},"is_claimable":false,"name":"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.","description":"<h4>Purpose</h4>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).<h4>Methods</h4>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, CTDI<sub>vol</sub>), and image noise and contrast.<h4>Results</h4>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 CTDI<sub>vol</sub> 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.<h4>Conclusions</h4>Patient vertical off-centering and scout direction affected substantially the CTDI<sub>vol</sub> 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 CTDI<sub>vol</sub> and image noise characteristics.","dates":{"release":"2019-01-01T00:00:00Z","publication":"2019","modification":"2025-04-19T16:36:31.466Z","creation":"2019-03-26T22:34:33Z"},"accession":"S-EPMC6298908","cross_references":{"pubmed":["30619916"],"doi":["10.1016/j.ejro.2018.12.001"]}}