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Excessive z-axis scan coverage in body CT: frequency and causes

  • Computed Tomography
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Abstract

Objectives

The aim of this study was to determine the frequency and causing factors of excessive z-axis coverage in body CT examinations.

Methods

A total of 2032 body CT examinations performed between 1 March and 1 April 2018 in 1531 patients were included in this study. The over-scanned length values in the z-axis for each CT examination on each patient were determined by calculating the difference between the actual scanned length and optimal scan length in the z-axis. Over-scanning and over-scanning ratios were interrogated in terms of potential underlying factors that can be affected by patient demography, time, the throughput of CT, and the experience of technologists.

Results

Over-scanned CTs in z-axis were 66% of all CTs performed. CT scans were over-scanned in the cranial side in 18.4% and caudal side in 48.5% of patients. Over-scanning was found to be more frequent in 55–64-year-old age group (74%), thorax CTs (89.2%), patients with consciousness change (88.9%), patients with misleading findings related to lung apex or diaphragm on the scout images (76.6%), CTs performed in day shift (66.8 %), in CT with low daily scan (72.4%), and CT scans performed by less-experienced technologists (75.9%).

Conclusions

Over-scanning in z-axis in body CT examinations is not infrequently encountered in routine practice. Awareness of causes of over-scanning in z-axis can be helpful to prevent over-scanning in CT and unnecessary ionizing radiation exposure in patients.

Key Points

• Over-scanning in z-axis frequently occurs in body CT.

• The frequency of over-scanning in caudal side is higher than cranial side.

• Chest CT and any CT performed in following situation were more prone to over-scanning: older patients, patients with consciousness change, presence of misleading findings on the scout images related to lung apex or diaphragm, day shift, CT with low daily scan, less-experienced technologist.

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Abbreviations

AEC:

Automatic exposure control

BMI:

Body mass index

CE:

Contrast-enhanced

CT:

Computed tomography

DLP:

Dose length product

PACS:

Picture archiving and communication systems

SPSS:

Statistical Package for Social Sciences

T10:

Tenth thoracic vertebra

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Funding

The authors state that this work has not received any funding.

Author information

Authors and Affiliations

  1. Department of Radiology, Artvin Public Hospital, 08000, Artvin, Turkey

    Ozan Yar

  2. Hacettepe University Faculty of Medicine, Department of Radiology, Hacettepe Universitesi Tıp Fakultesi Hastanesi Sıhhiye, 06100, Ankara, Turkey

    Mehmet Ruhi Onur

  3. Faculty of Medicine, Department of Radiology, Hacettepe University, Ankara, Turkey

    İlkay Sedakat İdilman, Erhan Akpınar & Deniz Akata

Authors
  1. Ozan Yar
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  2. Mehmet Ruhi Onur
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  3. İlkay Sedakat İdilman
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  4. Erhan Akpınar
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  5. Deniz Akata
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Corresponding author

Correspondence to Mehmet Ruhi Onur.

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Guarantor

The scientific guarantors of this publication are Mehmet Ruhi Onur, M.D., and Deniz Akata, M.D.

Conflict of interest

The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.

Statistics and biometry

One of the authors (İlkay Sedakat Idilman) has significant statistical expertise.

Informed consent

Written informed consent was not required for this study because study being of retrospective

Ethical approval

Institutional Review Board approval was obtained (Decision no: GO 18/557-23).

Study subjects or cohorts overlap

Some study subjects or cohorts have not been previously reported in an article before. This study was presented in ECR 2019 as an oral presentation (B – 1594) in scientific session (SS 1813).

Methodology

• Retrospective

• Cross sectional study

• Performed at one institution

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Yar, O., Onur, M.R., İdilman, İ.S. et al. Excessive z-axis scan coverage in body CT: frequency and causes. Eur Radiol 31, 4358–4366 (2021). https://doi.org/10.1007/s00330-020-07510-4

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  • DOI: https://doi.org/10.1007/s00330-020-07510-4

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