Accessible Requires Authentication Published by Oldenbourg Wissenschaftsverlag March 10, 2018

Influence of conventional and extended CT scale range on quantification of Hounsfield units of medical implants and metallic objects

Einfluss des konventionellen und erweiterten CT-Skalenbereiches auf die Quantifizierung von Hounsfield-Werten von medizinischen Implantaten und metallischen Objekten
Zehra Ese, Marcel Kressmann, Jakob Kreutner, Gregor Schaefers, Daniel Erni and Waldemar Zylka
From the journal tm - Technisches Messen

Abstract

We report on the suitability of two different ranges of Hounsfield units (HU) in computed tomography (CT) for the quantification of metallic components of active implantable medical devices (AIMD). The conventional Hounsfield units (CHU) range, which is traditionally used in radiology, is well suited for tissue but suspected inappropriate for metallic materials. Precise HU values are notably beneficial in radiotherapy (RT) for accurate dose calculations, thus for the safety of patient carrying implants. Some of today’s CT machines offers an extended Hounsfield units (EHU) range. This study presents CT acquisitions of a water phantom containing various metallic discs and an implantable-cardioverter defibrillator (IPG). We show that the comparison of HU values at EHU and CHU ranges clearly reveals the superiority and accuracy of EHU. Some geometrical discrepancies perpendicular to slices are observed. At EHU metal artifact reduction algorithms (MAR) underestimates HU values rendering MAR potentially inappropriate for RT.

Zusammenfassung

Wir berichten über den Einfluss von zwei verschiedenen Skalenbereichen für Hounsfiled-Werte (HU) auf die Quantifizierung von metallischen Komponenten von aktiven medizinisch implantierbaren Medizinprodukten (AIMD) in der Computertompgraphie (CT). Der konventionelle Hounsfield-Wertebereich (CHU), welcher seine Anwendung in der traditionellen Radiologie findet, ist geeignet für Gewebe jedoch ungeeignet für metallische Materialien. Präzise HU-Werte sind besonders wichtig für eine akurate Dosis-Berechnung in der Strahlentherapie, insbesondere bei Patienten mit medizinischen Implantaten. Einige der heutigen CT-Systeme bieten einen erweiterten HU-Bereich (EHU). In dieser Arbeit werden CT-Aufnahmen von diversen metallischen Platten und einem Kardioverter-Defibrillator (ICD) im Wasserphantom präsentiert. Der Vergleich von HU-Werten bei EHU- und CHU-Bereichen zeigt eine deutlich höhere Genauigkeit im EHU-Bereich. Es werden einige geometrische Diskrepanzen senkrecht zu Schichtaufnahme beobachtet. Festgestellt wird, dass bei EHU-Metall-Artefakt-Reduktionsalgorithmen (MAR) HU-Werte unterschätzt werden, wodurch MAR für RT möglicherweise unangemessen ist.

Funding source: Bundesministerium für Wirtschaft und Energie

Award Identifier / Grant number: ZF4205702AW6

Funding statement: This study is supported by the Federal Ministry for Economic Affairs and Energy on the basis of a decision by the German Bundestag, grant no. ZF4205702AW6.

Acknowledgment

We would like to thank L. Lüdemann, University Hospital Essen, Germany, for supporting this study.

References

1. Robert Koch Institute. Beitraege zur gesundheutsberichterstattung des bundes. krebs in deutschland, 2016. URL http://www.rki.de/Krebs/DE/Content/Publikationen. last visited on 2017-09-26. Search in Google Scholar

2. Krebsgesellschaft. Strahlentherapie, 2017. URL https://www.krebsgesellschaft.de/onko-internetportal/basis-informationen-krebs/therapieformen/strahlentherapie-bei-krebs.html. last visited on 2017-09-26. Search in Google Scholar

3. B. Gauter-Fleckenstein, C.W. Israel, M. Dorenkamp, J. Dunst, M. Roser, R. Schimpf, V. Steil, J. Schäfer, U. Höller, and F. Wenz. Degro/dgk guideline for radiotherapy in patients with cardiac implantable electronic devices. Strahlentherapie Onkologie, 191: 393–404, March 2015.10.1007/s00066-015-0817-3 Search in Google Scholar

4. T. Zaremba. Radiotherapy in Patients with Pacemakers and Implantable Cardioverter-Defibrillators. PhD thesis, Aalborg University, 2015. Search in Google Scholar

5. J.I. Prisciandaro, A. Makkar, C.J. Fox, J.A. Hayman, F. Horwood, L. Pelosi, and J.M. Moran. Dosimetric review of cardiac implantable electronic device patients receiving radiotherapy. Journal of Applied Clinical Medical Physics, 16: 1–8, October 2014. Search in Google Scholar

6. C.W. Hurkmans, E. Scheepers, B.G.F. Springorum, and H. Uiterwaal. Influence of radiotherapy on the latest generation of implantable cardioverter-defibrillator. Int. J. Radiation Oncology Biol. Phys., 63 (1): 282–289, April 2005. Search in Google Scholar

7. C.W. Hurkmans, E. Scheepers, B.G.F. Springorum, and H. Uiterwaal. Influence of radiotherapy on the latest generation of pacemakers. Radiotherapy and Oncology, 76 (1): 93–98, April 2005. Search in Google Scholar

8. J.R. Marbach, M.R. Sontag, J. Van Dyk, and A.B. Wolbarst. Management of radiation oncology patients with implanted cardiac pacemakers: Report of aapm task group no. 34. Medical Physics, 21 (1): 85–90, January 1994.10.1118/1.597259 Search in Google Scholar

9. C.W. Hurkmans, J.L. Knegjens, B.S. Oei, Ad.J.J Maas, G.J. Uiterwaal, A.J. Van der Borden, M.J. Ploegmakers, and L. Van Erven. Management of radiation oncology patents with a pacemaker or icd: a new comprehensive practical guideline in the netherlands. dutch society of radiotherapy and oncology (nvro). Radiation Oncology, 7 (198): 1–10, November 2012. Search in Google Scholar

10. A. Bourgouin, N. Varfalvy, and L. Archambault. Estimating and reducing dose received by cardiac devices for patients undergoing radiotherapy. Journal of Applied Clinical Medical Physics, 16 (6): 411–420, August 2015.10.1120/jacmp.v16i6.5317 Search in Google Scholar

11. J.Y. Huang, D.S. Followill, X.A. Wang, and S.f. Kry. Accuracy and sources of error out-of-field dose calculations by commercial treatment planning system for intensity-modulated radiation therapy treatments. Journal of Applied Clinical Medical Physics, 14 (2): 4139, 2015. Search in Google Scholar

12. R.M. Howell, S.B. Scarboto, S.F. Kry, and D.Z. Yaldo. Accuracy of out-of-field dose calculations by a commercial treatment planning system. Physics in Medicine and Biology, 55 (23): 6999–7008, 2010.10.1088/0031-9155/55/23/S03 Search in Google Scholar

13. T. Kairn, S.B. Crowe, J. Kenny, J. Mitchell, D. Burke, M. Schlect, and J.V. Trapp. Dosimetric effects of a high-density spinal implant. Journal of Physics: Conference Series, 7th International Conference on 3D Radiation Dosimetry, 444: 1–4, January 2008. Search in Google Scholar

14. J.P. Mullins, M.P. Grams, M.G. Herman, D.H. Brinkmann, and J.A. Antolak. Treatment planning for metals using an extended ct number scale. Journal of Applied Clinical Medical Physics, 17 (6): 179–188, August 2016.10.1120/jacmp.v17i6.6153 Search in Google Scholar

15. M.S. Gossman, A.R. Graves-Calhoun, and J.D. Wilkinson. Establishing radiation therapy treatment planning effects involving implantable pacemakers and implantable cardioverter-defibrillator. Journal of Applied Clinical Medical Physics, 11 (1): 33–45, August 2009. Search in Google Scholar

16. C. Coolens and P.J. Childs. Calibration of ct Hounsfield units for radiotherapy treatment planning of patients with metallic hip prostheses: the use of the extended ct-scale. Physics in Medicine and Biology, 48: 1591–1603, May 2003.10.1088/0031-9155/48/11/308 Search in Google Scholar

17. G. Hilgers, T. Nuver, and A. Minken. The ct number accuracy of a novel commercial metal artifact reduction algorithm for large orthopedic implants. Journal of Applied Clinical Medical Physics, 15 (1): 274–278, September 2014.10.1120/jacmp.v15i1.4597 Search in Google Scholar

18. K.M. Andersson, A. Ahnesjö, and C.V. Dahlgren. Evaluation of a metal artifact reduction algorithm in ct studies used for proton radiotherapy treatment planning. Journal of Applied Clinical Medical Physics, 15 (5): 112–119, May 2014.10.1120/jacmp.v15i5.4857 Search in Google Scholar

19. J. Schindelin, I. Arganda-Carreras, and E. Frise. Fiji: an open-source platform for biological-image analysis. Nature methods, 9 (7): 676–682, 2012.10.1038/nmeth.2019 Search in Google Scholar

20. M.S. Gossman. Clinical Concerns and Strategies in Radiation Oncology, Aspects of Pacemakers-Functions and Interactions in Cardiac and Non-cardiac Indications. InTech, 2016. Search in Google Scholar

Received: 2017-10-9
Revised: 2017-12-12
Accepted: 2018-2-21
Published Online: 2018-3-10
Published in Print: 2018-5-25

© 2018 Walter de Gruyter GmbH, Berlin/Boston