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National Survey of Radiation Dose and Image Quality in Adult CT Head Scans in Taiwan.

Lin CJ, Mok GS, Tsai MF, Tsai WT, Yang BH, Tu CY, Wu TH - PLoS ONE (2015)

Bottom Line: SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C.MDCT with higher slice numbers used more tube potential resulting in higher effective doses.Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices.

View Article: PubMed Central - PubMed

Affiliation: School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan.

ABSTRACT

Introduction: The purpose of the present study was to evaluate the influence of different variables on radiation dose and image quality based on a national database.

Materials and methods: Taiwan's Ministry of Health and Welfare requested all radiology departments to complete a questionnaire for each of their CT scanners. Information gathered included all scanning parameters for CT head scans. For the present analysis, CT machines were divided into three subgroups: single slice CT (Group A); multi-detector CT (MDCT) with 2-64 slices (Group B); and MDCT with more than 64 slices (Group C). Correlations between computed tomography dose index (CTDI) and signal-to-noise ratio (SNR) with cumulated tube rotation number (CTW(n)) and cumulated tube rotation time (CTW(s)), and sub group analyses of CTDI and SNR across the three groups were performed.

Results: CTDI values demonstrated a weak correlation (r = 0.33) with CTW(n) in Group A. SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C. MDCT with higher slice numbers used more tube potential resulting in higher effective doses. There were both significantly lower CTDI and SNR values in helical mode than in axial mode in Group B, but not Group C.

Conclusion: CTW(n) and CTW(s) did not influence radiation output. Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices.

No MeSH data available.


Related in: MedlinePlus

The ROI chosen for calculating the SNR.
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pone.0131243.g001: The ROI chosen for calculating the SNR.

Mentions: Effective dose was calculated using DLP-to-effective dose conversion factor, 0.0021 mSv/mGy-cm for adult head scan, which was derived based on the definition of effective dose defined in ICRP Publication 103 [21]. The CTDI was retrieved from the dose information page of the console. For single slice CT without a dose information page, the CTDI was calculated using ImPACT (Version 1.0.4, Imaging Performance Assessment of CT Scanners, London UK) based on the acquisition parameters. The image quality for each CT scan was assessed based on a manually drawn region-of-interest (ROI) of 100 mm2 located in the right periventricular was assessed based on a manually drawn ROI of 100 mm2 located in the right periventricular brain parenchyma, immediately next to the right ventricular wall (Fig 1). If there were old infarcts or other insults, we moved the ROI anteriorly-posteriorly along the right ventricular wall to locate a normal brain region. The SNR was defined as ROI mean/ROI standard deviation. We collected the questionnaires from the technicians for data anonymization and further analysis.


National Survey of Radiation Dose and Image Quality in Adult CT Head Scans in Taiwan.

Lin CJ, Mok GS, Tsai MF, Tsai WT, Yang BH, Tu CY, Wu TH - PLoS ONE (2015)

The ROI chosen for calculating the SNR.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4488422&req=5

pone.0131243.g001: The ROI chosen for calculating the SNR.
Mentions: Effective dose was calculated using DLP-to-effective dose conversion factor, 0.0021 mSv/mGy-cm for adult head scan, which was derived based on the definition of effective dose defined in ICRP Publication 103 [21]. The CTDI was retrieved from the dose information page of the console. For single slice CT without a dose information page, the CTDI was calculated using ImPACT (Version 1.0.4, Imaging Performance Assessment of CT Scanners, London UK) based on the acquisition parameters. The image quality for each CT scan was assessed based on a manually drawn region-of-interest (ROI) of 100 mm2 located in the right periventricular was assessed based on a manually drawn ROI of 100 mm2 located in the right periventricular brain parenchyma, immediately next to the right ventricular wall (Fig 1). If there were old infarcts or other insults, we moved the ROI anteriorly-posteriorly along the right ventricular wall to locate a normal brain region. The SNR was defined as ROI mean/ROI standard deviation. We collected the questionnaires from the technicians for data anonymization and further analysis.

Bottom Line: SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C.MDCT with higher slice numbers used more tube potential resulting in higher effective doses.Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices.

View Article: PubMed Central - PubMed

Affiliation: School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan.

ABSTRACT

Introduction: The purpose of the present study was to evaluate the influence of different variables on radiation dose and image quality based on a national database.

Materials and methods: Taiwan's Ministry of Health and Welfare requested all radiology departments to complete a questionnaire for each of their CT scanners. Information gathered included all scanning parameters for CT head scans. For the present analysis, CT machines were divided into three subgroups: single slice CT (Group A); multi-detector CT (MDCT) with 2-64 slices (Group B); and MDCT with more than 64 slices (Group C). Correlations between computed tomography dose index (CTDI) and signal-to-noise ratio (SNR) with cumulated tube rotation number (CTW(n)) and cumulated tube rotation time (CTW(s)), and sub group analyses of CTDI and SNR across the three groups were performed.

Results: CTDI values demonstrated a weak correlation (r = 0.33) with CTW(n) in Group A. SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C. MDCT with higher slice numbers used more tube potential resulting in higher effective doses. There were both significantly lower CTDI and SNR values in helical mode than in axial mode in Group B, but not Group C.

Conclusion: CTW(n) and CTW(s) did not influence radiation output. Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices.

No MeSH data available.


Related in: MedlinePlus