Advertisement

Clinical evaluation of CT radiation dose in whole-body 18F-FDG PET/CT in relation to scout imaging direction and arm position

  • Yusuke Inoue
  • Kazunori Nagahara
  • Yuri Inoki
  • Toshimasa Hara
  • Hiroki Miyatake
Original Article
  • 19 Downloads

Abstract

Objective

Radiation exposure in CT is modulated by automatic exposure control (AEC) mainly based on scout images. We evaluated CT radiation dose in whole-body PET/CT in relation to scout imaging direction and arm position, and investigated the behavior of AEC.

Methods

Eighty adult patients who underwent whole-body 18F-FDG PET/CT were divided into groups A, B, C, and D. The posteroanterior scout image alone (PA scout) was used for AEC-based dose modulation in groups A and B, while the posteroanterior and lateral scout images (PA + Lat scout) were used in groups C and D. Patients in groups A and C were imaged with their arms beside the head, while those in groups B and D were imaged with their arms at the sides of the trunk. Dose-length product provided by the scanner was recorded. The tube current value, a determinant of radiation dose, for each slice was plotted against slice location to produce a tube current modulation curve. The scan range was divided into seven anatomical regions, and regional tube current was defined as average tube current for each region. Effective dose was calculated for each region and then summed together.

Results

Regional tube current was higher in the body trunk and proximal thigh using the PA scout than using the PA + Lat scout, resulting in higher dose-length product and effective dose using the PA scout. A marked dose increase was shown in the shoulder especially using the PA scout. Spike-like high current at the top of the head was often observed in tube current modulation curves using the PA scout but not using the PA + Lat scout. Raising the arms increased tube current in the head and neck and decreased it in the chest and abdomen. Although dose-length product did not differ significantly depending on arm position, raising the arms decreased effective dose significantly.

Conclusions

AEC-based CT dose modulation in whole-body PET/CT is affected by scout imaging direction and arm position, which should be considered to determine an optimal imaging protocol for whole-body PET/CT.

Keywords

PET/CT Radiation dose Scout imaging Arm position 

Notes

Compliance with ethical standards

Conflict of interest

There is no conflict of interest in relation to this study.

References

  1. 1.
    Martí-Climent JM, Prieto E, Morán V, Sancho L, Rodríguez-Fraile M, Arbizu J, et al. Effective dose estimation for oncological and neurological PET/CT procedures. EJNMMI Res. 2017;7:37.CrossRefGoogle Scholar
  2. 2.
    Jallow N, Christian P, Sunderland J, Graham M, Hoffman JM, Nye JA. Diagnostic reference levels of CT radiation dose in whole-body PET/CT. J Nucl Med. 2016;57:238–41.CrossRefGoogle Scholar
  3. 3.
    Inoue Y, Nagahara K, Tanaka Y, Miyatake H, Hata H, Hara T. Methods of CT dose estimation in whole-body 18F-FDG PET/CT. J Nucl Med. 2015;56:695–700.CrossRefGoogle Scholar
  4. 4.
    Etard C, Celier D, Roch P, Aubert B. National survey of patient doses from whole-body FDG PET-CT examinations in France in 2011. Radiat Prot Dosim. 2012;152:334–8.CrossRefGoogle Scholar
  5. 5.
    Khamwan K, Krisanachinda A, Pasawang P. The determination of patient dose from 18F-FDG PET/CT examination. Radiat Prot Dosim. 2010;141:50–5.CrossRefGoogle Scholar
  6. 6.
    Brix G, Lechel U, Glatting G, Ziegler SI, Münzing W, Müller SP, et al. Radiation exposure of patients undergoing whole-body dual-modality 18F-FDG PET/CT examinations. J Nucl Med. 2005;46:608–13.PubMedGoogle Scholar
  7. 7.
    Alenezi A, Soliman K. Trends in radiation protection of positron emission tomography/computed tomography imaging. Ann ICRP. 2015;44:259–75.CrossRefGoogle Scholar
  8. 8.
    Söderberg M, Gunnarsson M. Automatic exposure control in computed tomography–an evaluation of systems from different manufacturers. Acta Radiol. 2010;51:625–34.CrossRefGoogle Scholar
  9. 9.
    Lee CH, Goo JM, Ye HJ, Ye SJ, Park CM, Chun EJ, et al. Radiation dose modulation techniques in the multidetector CT era: from basics to practice. Radiographics. 2008;28:1451–9.CrossRefGoogle Scholar
  10. 10.
    Kalra MK, Maher MM, Toth TL, Schmidt B, Westerman BL, Morgan HT, et al. Techniques and applications of automatic tube current modulation for CT. Radiology. 2004;233:649–57.CrossRefGoogle Scholar
  11. 11.
    Boellaard R, Delgado-Bolton R, Oyen WJ, Giammarile F, Tatsch K, Eschner W, et al. FDG PET/CT: EANM procedure guidelines for tumour imaging: version 2.0. Eur J Nucl Med Mol Imaging. 2015;42:328–54.CrossRefGoogle Scholar
  12. 12.
    Delbeke D, Coleman RE, Guiberteau MJ, Brown ML, Royal HD, Siegel BA, et al. Procedure guideline for tumor imaging with 18F-FDG PET/CT 1.0. J Nucl Med. 2006;47:885–95.PubMedGoogle Scholar
  13. 13.
    Seong JH, Park SK, Kim JS, Jung WY, Kim HS, Dong KR, et al. A comparative study on the CT effective dose for various positions of the patient’s arm. J Korean Phys Soc. 2012;61:1137–42.CrossRefGoogle Scholar
  14. 14.
    Inoue Y, Nagahara K, Kudo H, Itoh H. CT dose modulation using automatic exposure control in whole-body PET/CT: effects of scout imaging direction and arm positioning. Am J Nucl Med Mol Imaging. 2018;8:143–52.PubMedPubMedCentralGoogle Scholar
  15. 15.
    Peng W, Li Z, Xia C, Guo Y, Zhang J, Zhang K, et al. 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.CrossRefGoogle Scholar
  16. 16.
    Franck C, Bacher K. Influence of localizer and scan direction on the dose-reducing effect of automatic tube current modulation in computed tomography. Radiat Prot Dosim. 2016;169:136–42.CrossRefGoogle Scholar
  17. 17.
    Söderberg M. Overview, practical tips and potential pitfalls of using automatic exposure control in CT: siemens CARE Dose 4D. Radiat Prot Dosim. 2016;169:84–91.CrossRefGoogle Scholar
  18. 18.
    Singh S, Petrovic D, Jamnik E, Aran S, Pourjabbar S, Kave ML, et al. Effect of localizer radiograph on radiation dose associated with automatic exposure control: human cadaver and patient study. J Comput Assist Tomogr. 2014;38:293–8.CrossRefGoogle Scholar
  19. 19.
    Papadakis AE, Perisinakis K, Damilakis J. Automatic exposure control in pediatric and adult multidetector CT examinations: a phantom study on dose reduction and image quality. Med Phys. 2008;35:4567–76.CrossRefGoogle Scholar
  20. 20.
    Suntharalingam S, Wetter A, Guberina N, Theysohn J, Ringelstein A, Schlosser T, et al. Impact of the scout view orientation on the radiation exposure and image quality in thoracic and abdominal CT. Eur Radiol. 2016;26:4072–9.CrossRefGoogle Scholar
  21. 21.
    Saltybaeva N, Alkadhi H. Vertical off-centering affects organ dose in chest CT: evidence from Monte Carlo simulations in anthropomorphic phantoms. Med Phys. 2017;44:5697–704.CrossRefGoogle Scholar
  22. 22.
    Lambert JW, Kumar S, Chen JS, Wang ZJ, Gould RG, Yeh BM. Investigating the CT localizer radiograph: acquisition parameters, patient centring and their combined influence on radiation dose. Br J Radiol. 2015;88:20140730.CrossRefGoogle Scholar
  23. 23.
    ICRP. The 2007 recommendations of the international commission on radiological protection. ICRP publication 103. Ann ICRP 2007;37.Google Scholar
  24. 24.
    ICRP. Managing patient dose in multi-detector computed tomography (MDCT). ICRP Publication 102. Ann ICRP 2007;37.Google Scholar
  25. 25.
    ICRP Statement on Tissue. Reactions/early and late effects of radiation in normal tissues and organs—threshold doses for tissue reactions in a radiation protection context. ICRP Publication Ann ICRP 2012; 118:41Google Scholar
  26. 26.
    Japan Network for Research and Information on Medical Exposures (J-RIME). Diagnostic reference levels based on latest surveys in Japan-Japan DRLs 2015. 2015. http://www.radher.jp/J-RIME/report/DRLhoukokusyoEng.pdf. Accessed 21 Oct 2018
  27. 27.
    Iball GR, Tout D. Computed tomography automatic exposure control techniques in 18F-FDG oncology PET-CT scanning. Nucl Med Commun. 2014;35:372–81.CrossRefGoogle Scholar

Copyright information

© The Japanese Society of Nuclear Medicine 2018

Authors and Affiliations

  • Yusuke Inoue
    • 1
  • Kazunori Nagahara
    • 2
  • Yuri Inoki
    • 3
  • Toshimasa Hara
    • 1
  • Hiroki Miyatake
    • 2
  1. 1.Department of Diagnostic RadiologyKitasato University School of MedicineSagamiharaJapan
  2. 2.Department of RadiologyKitasato University HospitalSagamiharaJapan
  3. 3.Kitasato University School of MedicineSagamiharaJapan

Personalised recommendations