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The relationship between CT scout landmarks and lung boundaries on chest CT: guidelines for minimizing excess z-axis scan length

  • Stuart L. CohenEmail author
  • Thomas J. Ward
  • Matthew D. Cham
Chest
  • 22 Downloads

Abstract

Objectives

As the relationship between CT scout landmarks and chest CT boundaries is not known, the selected scan length is often greater than necessary for the CT scan, resulting in increased radiation dose to the neck and upper abdomen. The purpose of this study is to establish the relationship between CT scout landmarks with the superior and inferior boundaries of the lungs on chest CT.

Methods

Retrospective comparison of the location of the top of the first rib on frontal scout and the most inferior costophrenic angle on lateral scout to the chest CT slice just above and below the lungs. The percent of scans that would exclude part of the lung based on CT initiated at several distances above or below these landmarks was calculated.

Results

There was 2.7 times greater variability between scout landmarks and lung boundaries inferiorly than superiorly on chest CT (p < 0.001). Initiating CT at the top of the first rib on scout did not exclude any lung on CT. Initiating CT 0, 1, 2, 3, and 4 cm inferior to the CPA on lateral scout excluded part of the lung in 45.7%, 12.9%, 4.3%, 1.9%, and 0.8% of CTs.

Conclusions

Chest CT to include the lungs should be performed from the top of the first rib to 3 or 4 cm below the costophrenic angle on lateral topogram.

Key Points

There is a greater motion at the inferior lung than at the superior lung.

Chest CT acquisition from the top of the first rib on scout would not exclude the lung.

Chest CT acquisition from CPA on lateral scout would exclude the lung 46% of time.

Keywords

Thorax Radiation dosage Tomography X-ray computed 

Abbreviations

CPA

Costophrenic angle

CT

Computed tomographic

PACS

Picture archiving and communication system

Notes

Funding

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

Compliance with ethical standards

Guarantor

The scientific guarantor of this publication is Stuart Cohen.

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

No complex statistical methods were necessary for this paper.

Informed consent

Written informed consent was waived by the Institutional Review Board.

Ethical approval

Institutional Review Board approval was obtained.

Methodology

• retrospective

• observational

• performed at one institution

References

  1. 1.
    Brenner DJ, Hall EJ (2007) Computed tomography--an increasing source of radiation exposure. N Engl J Med 357:2277–2284CrossRefGoogle Scholar
  2. 2.
    Smith-Bindman R, Miglioretti DL, Johnson E et al (2012) Use of diagnostic imaging studies and associated radiation exposure for patients enrolled in large integrated health care systems, 1996–2010. JAMA 307:2400–2409CrossRefGoogle Scholar
  3. 3.
    O’Connor GT, Hatabu H (2012) Lung cancer screening, radiation, risks, benefits, and uncertainty. JAMA 307:2434–2435Google Scholar
  4. 4.
    Brenner DJ, Doll R, Goodhead DT et al (2003) Cancer risks attributable to low doses of ionizing radiation: assessing what we really know. Proc Natl Acad Sci U S A 100:13761–13766CrossRefGoogle Scholar
  5. 5.
    Preston DL, Pierce DA, Shimizu Y et al (2004) Effect of recent changes in atomic bomb survivor dosimetry on cancer mortality risk estimates. Radiat Res 162:377–389CrossRefGoogle Scholar
  6. 6.
    Cardis E, Vrijheid M, Blettner M et al (2007) The 15-Country Collaborative Study of Cancer Risk among Radiation Workers in the Nuclear Industry: estimates of radiation-related cancer risks. Radiat Res 167:396–416CrossRefGoogle Scholar
  7. 7.
    Cardis E, Vrijheid M, Blettner M et al (2005) Risk of cancer after low doses of ionising radiation: retrospective cohort study in 15 countries. BMJ 331:77CrossRefGoogle Scholar
  8. 8.
    Bevelacqua JJ (2010) Practical and effective ALARA. Health Phys 98(Suppl 2):S39–S47CrossRefGoogle Scholar
  9. 9.
    (2002) The ALARA (as low as reasonably achievable) concept in pediatric CT intelligent dose reduction. Multidisciplinary conference organized by the Society of Pediatric Radiology. August 18-19, 2001. Pediatr Radiol 32:217–313Google Scholar
  10. 10.
    Strauss KJ, Kaste SC (2006) The ALARA (as low as reasonably achievable) concept in pediatric interventional and fluoroscopic imaging: striving to keep radiation doses as low as possible during fluoroscopy of pediatric patients—a white paper executive summary. Pediatr Radiol 36:110–112CrossRefGoogle Scholar
  11. 11.
    Callahan MJ (2011) CT dose reduction in practice. Pediatr Radiol 41(Suppl 2):488–492CrossRefGoogle Scholar
  12. 12.
    Kalra MK, Maher MM, Toth TL et al (2004) Strategies for CT radiation dose optimization. Radiology 230:619–628CrossRefGoogle Scholar
  13. 13.
    Kalra MK, Maher MM, Blake MA et al (2004) Detection and characterization of lesions on low-radiation-dose abdominal CT images postprocessed with noise reduction filters. Radiology 232:791–797CrossRefGoogle Scholar
  14. 14.
    Ziegler A, Kohler T, Proksa R (2007) Noise and resolution in images reconstructed with FBP and OSC algorithms for CT. Med Phys 34:585–598CrossRefGoogle Scholar
  15. 15.
    Brenner D, Elliston C, Hall E, Berdon W (2001) Estimated risks of radiation-induced fatal cancer from pediatric CT. AJR Am J Roentgenol 176:289–296CrossRefGoogle Scholar
  16. 16.
    Takahashi M, Maguire WM, Ashtari M et al (1998) Low-dose spiral computed tomography of the thorax: comparison with the standard-dose technique. Invest Radiol 33:68–73CrossRefGoogle Scholar
  17. 17.
    Goldman AR, Maldjian PD (2013) Reducing radiation dose in body CT: a practical approach to optimizing CT protocols. AJR Am J Roentgenol 200:748–754CrossRefGoogle Scholar
  18. 18.
    Campbell J, Kalra MK, Rizzo S, Maher MM, Shepard JA (2005) Scanning beyond anatomic limits of the thorax in chest CT: findings, radiation dose, and automatic tube current modulation. AJR Am J Roentgenol 185:1525–1530CrossRefGoogle Scholar
  19. 19.
    Zanca F, Demeter M, Oyen R, Bosmans H (2012) Excess radiation and organ dose in chest and abdominal CT due to CT acquisition beyond expected anatomical boundaries. Eur Radiol 22:779–788CrossRefGoogle Scholar
  20. 20.
    Cohen SL, Ward TJ, Jacobi AH, Cham M (2019) Institutional impact of a personalized technologist feedback program on scan length and radiation dose. J Am Coll Radiol.  https://doi.org/10.1016/j.jacr.2019.02.001
  21. 21.
    Schwartz F, Stieltjes B, Szucs-Farkas Z, Euler A (2018) Over-scanning in chest CT: comparison of practice among six hospitals and its impact on radiation dose. Eur J Radiol 102:49–54Google Scholar
  22. 22.
    Noh DK, Lee JJ, You JH (2014) Diaphragm breathing movement measurement using ultrasound and radiographic imaging: a concurrent validity. Biomed Mater Eng 24:947–952Google Scholar
  23. 23.
    Nason LK, Walker CM, McNeeley MF, Burivong W, Fligner CL, Godwin JD (2012) Imaging of the diaphragm: anatomy and function. Radiographics 32:E51–E70CrossRefGoogle Scholar
  24. 24.
    R Development Core Team (2010) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, AustriaGoogle Scholar
  25. 25.
    Frank EL, Bruce Smith, Barbara. (2013) Merrill’s atlas of radiographic positioning and procedures - E-Book: Volume 3. Elsevier Mosby, St. LouisGoogle Scholar
  26. 26.
    Aziz ZA, Padley SP, Hansell DM (2004) CT techniques for imaging the lung: recommendations for multislice and single slice computed tomography. Eur J Radiol 52:119–136CrossRefGoogle Scholar
  27. 27.
    Shepard JA (2019) Thoracic imaging the requisites (requisites in radiology), 3rd edn. Elsevier, PhiladelphiaGoogle Scholar
  28. 28.
    Gross BH, Brown RK, Kalemkerian GP (2011) Optimal anatomic coverage for CT in staging lung cancer: lessons from PET-CT correlation. Lung Cancer 73:59–62CrossRefGoogle Scholar
  29. 29.
    Kalra MK, Sodickson AD, Mayo-Smith WW (2015) CT radiation: key concepts for gentle and wise use. Radiographics 35:1706–1721Google Scholar
  30. 30.
    Kubo T, Ohno Y, Kauczor HU, Hatabu H (2014) Radiation dose reduction in chest CT--review of available options. Eur J Radiol 83:1953–1961CrossRefGoogle Scholar
  31. 31.
    Gross BH, Brown RK, Kalemkerian GP (2011) Optimal anatomic coverage for CT in staging lung cancer: lessons from PET-CT correlation. Lung Cancer 73:59–62CrossRefGoogle Scholar
  32. 32.
    Candemir S, Antani S (2019) A review on lung boundary detection in chest X-rays. Int J Comput Assist Radiol Surg 14:563–576CrossRefGoogle Scholar

Copyright information

© European Society of Radiology 2019

Authors and Affiliations

  1. 1.Imaging Clinical Effectiveness and Outcomes Research (ICEOR), Department of Radiology, Northwell HealthManhassetUSA
  2. 2.Center for Health Innovations and Outcomes Research (CHIOR)Feinstein Institute for Medical Research and Donald and Barbara Zucker School of Medicine at Hofstra/NorthwellManhassetUSA
  3. 3.Department of Radiology AdventHealthOrlandoUSA
  4. 4.Department of RadiologyUniversity of WashingtonSeattleUSA

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