Dual-Energy CT Applications in Radiation Therapy

Transcription

1 THE UNIVERSITY OF WISCONSIN MADISON Dual-Energy CT Applications in Radiation Therapy - Jessica Miller 1

2 Disclosures Funding provided by Siemens Medical 2

3 Learning objectives General principles of dual energy CT Technical approaches to dual energy CT Potential applications and challenges of dualenergy CT in radiation oncology 3

4 What is dual energy CT? 80 kvp Low Energy Image 140 kvp High Energy Image 4

5 Basis pair decomposition Above k edge energy, a linear attenuation can be approximated by the sum of PE and CS (basis pairs) + Where and Alternatively, the linear attenuation coefficient for an arbitrary material can be represented as a weighted sum of two independent material s attenuation coefficients + 5

6 Basis pair decomposition Szczykutowicz, T. in press. Dual Energy and Spectral Imaging. Comprehensive Biomedical Physics 6

7 Basis pair decomposition Szczykutowicz, T. in press. Dual Energy and Spectral Imaging. Comprehensive Biomedical Physics 7

8 Dual source DECT technology Two x ray tubes separated by 90 degrees Dual Energy CT FOV of 33 cm Filters can be optimized for spectral separation Image courtesy of SIEMENS 8

9 Sequential scans Image courtesy of SIEMENS Sequential CT scans: 140 kv 80 kv Creates a low and high energy spectra, sequentially 140 kv return to starting position 80 kv 9

10 Fast kvp switching 0.5 ms switching between 80 and 140 kvp to acquire interleaved projection data Requires fast generator response and detector response Image courtesy of GE Healthcare 10

11 Dual layer detector Sandwich scintillation detectors: Low energy data collected from the top/proximal layer High energy data acquired from the bottom/distal layer Cynthia H. McCollough; Shuai Leng; Lifeng Yu; Joel G. Fletcher; Radiology 2015, 276,

12 Single source DECT TwinBeam system A removable split filter composed of gold (Au) and tin (Sn) which filters a 120 kv x ray beam Creates a low and high energy spectra simultaneously Images courtesy of SIEMENS 12

13 Potential radiation therapy applications for DECT Mixed 120 kvp equivalent 13

14 Potential radiation therapy applications for DECT True Contrast Image Virtual Non contrast Iodine Map Rho/Z Map 14

15 Potential radiation therapy applications for DECT 40 kev 55 kev 77 kev 190 kev 15

16 Virtual monoenergetic reconstructions (VMI) Roele, E.D., Timmer, V.C.M.L., Vaassen, L.A.A. et al. Curr Radiol Rep (2017) 5: 19.

17 Metal Artifact Reduction at Higher VMI Energies Shima Aran, Laleh Daftari Besheli, Musturay Karcaaltincaba, Rajiv Gupta, Efren J. Flores and Hani H. Abujudeh American Journal of Roentgenology :4, W314 W324 17

18 Radiation therapy applications: Improved dose calculation 18

19 Improved dose calculations Brachytherapy Protons External Beam Photon Therapy Wouter van Elmpt et al. Radiotherapy and Oncology 2016, 3119, N. Hudobivnik et al. Med. Phys. 2016, 43,

20 Dose calculations virtual non contrast (VNC) images True Contrast Image Virtual Non contrast 20

21 Dose calculations virtual non contrast (VNC) images HU difference map (Mixed VNC) Images courtesy of Dr. Huang Vredevoogd, University of Wisconsin 21

22 Dose calculations virtual non contrast (VNC) images Ideal plan No override plan Ideal plan VNC plan Images courtesy of Dr. Huang Vredevoogd, University of Wisconsin 22

23 Radiation therapy applications: Tumor identification, characterization and delineation 23

24 Cyst or Carcinoma? Mukta D. Agrawal; Daniella F. Pinho; Naveen M. Kulkarni; Peter F. Hahn; Alexander R. Guimaraes; Dushyant V. Sahani; RadioGraphics 2014, 34, Hyperattenuating cyst Renal call carcinoma 24

25 Calcium or hemorrhage? Ranliang Hu; Laleh Daftari Besheli; Joseph Young; Markus Wu; Stuart Pomerantz; Michael H. Lev; Rajiv Gupta; Radiology 2016, 280,

26 Material decomposition iodine map Roele, E.D., Timmer, V.C.M.L., Vaassen, L.A.A. et al. Curr Radiol Rep (2017) 5: 19.

27 Material decomposition iodine map Mukta D. Agrawal; Daniella F. Pinho; Naveen M. Kulkarni; Peter F. Hahn; Alexander R. Guimaraes; Dushyant V. Sahani; RadioGraphics 2014, 34,

28 Tumor delineation Mukta D. Agrawal; Daniella F. Pinho; Naveen M. Kulkarni; Peter F. Hahn; Alexander R. Guimaraes; Dushyant V. Sahani; RadioGraphics 2014, 34,

29 Tumor delineation for pancreatic cancer 29

30 Tumor delineation for pancreatic cancer 30

31 Tumor delineation 31

32 Radiation therapy applications: Treatment response assessment 32

33 Treatment response with DECT Xu Dai et al. European Journal of Radiology (2013) 82: Apfaltrer et al. Invest Radiol. (2012) 42:(1):

34 Radiation therapy applications: Normal tissue segmentation 34

35 Normal tissue delineation Supratentorial white matter/basal ganglia 50 kev to 70 kev Postma et al. Dual Energy CT: What the Neuroradiologist Should Know. Current Radiology Reports. 2015;3(5):16. Posterior fossa Higher energies 35

36 Radiation therapy applications: Functional normal tissue segmentation and toxicity 36

37 Material decomposition xenon map & iodine map Ventilation Xenon inhalation Zhang, L.J., Zhou, C.S., Schoepf, U.J. et al. Eur Radiol (2013) 23: 2666 Perfusion Iodine injection 37

38 Dose calculation accounting for functional lung Houda Bahig et al., International Journal of Rad. Onc., Biology, Physics. V99,Issue 1, Paes (Oct 2017). 38

39 Bone Marrow Fornaro et al. Dual and multi energy CT: approach to functional imaging. Insights into Imaging. 2011;2(2): Taiki Magome et al., Int J Radiation Oncol Biol Phys, Vol. 96, No. 3, pp ,

40 Bone Marrow Sarah McGuire et al., Radiotherapy and Oncology, Vol. 99, No. 1, pp ,

41 Conclusions Improving dose calculation Tumor identification and delineation Treatment response Normal tissue segmentation Functional normal tissue toxicities Challenges in commissioning and quality assurance of DECT systems for radiation therapy applications 41

42 Thank you 42

43 Which of the following is NOT a current application of Dual energy CT? A. Visualization of bone marrow edema via virtual calcium removal B. Enhancement of CNR between tumor and healthy tissue via iodine uptake C. Visualization of tissue metabolic activity via glucose uptake D. Improvement of dose calculation accuracy with effective atomic number information van Elmpt W, Landry G, Das M, Verhaegen F. Dual energy CT in radiotherapy: Current applications and future outlook. Radiother Oncol Apr;119(1): McCollough CH, Leng S, Yu L, Fletcher JG. Dual and multi energy CT: principles, technical approaches, and clinical applications. Radiology 2015; 276:

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45 Houda Bahig et al., International Journal of Rad. Onc., Biology, Physics. V99,Issue 1, Paes (Oct 2017). 45