A new tool for embolism visualisation: The 3D X-ray microtomography

Transcription

1 A new tool for embolism visualisation: The 3D X-ray microtomography Eric BADEL Hervé COCHARD UMR PIAF, INRA-UBP 5 chemin de Beaulieu, Clermont Ferrand

2 Röntgen D X-ray radiography I 0 X-ray source e, µ I I 0 I ln( ) I µ : X-ray absorption is a function of : - atomic components - matter density - incident x-ray energy 0 = µ e I thin sample 2D detector integrative information throught the thickness spatial resolution is a function of sample thickness and tomographic components (X-ray spot size, detector )

3 0 0 Medical scanner (low resolution) 2-D X-ray tomography 2D tomography (high resolution) High resolution detector Microfocus X-ray source - ln ( I / I 0 ) θ = 0 Supreme Council of Antiquities

4 The 3D µtomography 1000 to 2000 projections for 360 rotation

5 Few X-ray tools Small lab device Lab device Synchrotrons lights X-ray polychromatic polychromatic monochromatic Beam divergent divergent parallel Spatial resolution 5-10 microns 1 micron 0.3 micron Max sample size 4-5 cm 10 cm 1 mm File size 16 Go 32 Go 64 Go or more Scan time 10 min to 1 hour 10 min to 1 hour 1 s to few minutes

6 The synchrotron lights

7 The synchrotron facilities vs lab devices very high x-ray intensity fast scan time the sample chamber is huge (but the scanned area is not larger than for the lab tools) access after a proposal short time experiments huge data to manage (1-4 To /j) very tiring

8 3D hydraulic network observation New information about the vessels network

9 0 r Embolism measurements CAVITRON Vulnerability curve P50 Cochard et al 2005 Increasing tension and measurement of the loss of conductivity The big issue: not available for long vessels species

10 Embolism observation and measurments Pinus sylvestris Douglas 200 µm 100 µm Walnut tree

11 What did we learn about embolism process thanks to X-ray tomography? Few experiments using synchrotron radiations or our Nanotom (Clermont-Ferrand)

12 Experiments using synchrotron light and living trees

13 Experiments using synchrotron light and living trees light stimulation, fan, root stress => tension in hydraulic conduits

14 Live embolism spreading observation (poplar tree) 3H 3H 3H 3H 10 min / scan using synchrotron radiation (Swiss Light Source) Loss of conductivity (%) y=100/(1+exp(a*(x-b))), r 2 =0.993 a=-4.50, b= Pressure (MPa) Poiseuille s law 3H 3H 3H 3H

15 Live embolism spreading observation (oak tree) 3H 3H Cavitron X-ray images Loss of conductivity (%) y=100/(1+exp(a*(x-b))), r 2 =0.89 a=-1.2, b= Pressure (MPa)

16 -1 MPa -3 MPa Laurus: long vessels species -6 MPa 100% embolized 80 Percent xylem embolism Percent Percent xylem Percent xylem embolism xylem xylem embolism embolism 100 Salleo & Lo Gullo 1993 Indirect Salleo et methods al 2000 Hacke Dehydration & Sperry Trifilo Salleo et 2014a & Lo Gullo 1993 Trifilo Salleo et 2014b 100 et al 2000 Salleo Hacke Salleo et 1996 & Lo Sperry Gullo Tyree et Trifilo Salleo et et al al 2000 Salleo 1998 & Lo 2014a Gullo 1993 Hacke Hacke & Sperry & Sperry Trifilo Salleo et al b 80 Salleo Salleo Trifilo et 2004 et et al al a Salleo Air injection Tyree Trifilo et al 2006 et et al al b Trifilo et al 2014a Salleo Salleo et 2009 et al 1996 Trifilo Tyree Salleo et et al al b 80 Cochard 2002 Salleo et al dehydration Salleo Tyree et al Salleo Trifilo et et et al al al a centrifugation Cochard Salleo Trifilo et et 2002 al al b dehydration Salleo Salleo et et al al centrifugation Cochard Salleo Tyree et 2002 al Centrifugation dehydration Salleo et al centrifugation Cochard Salleo et 2002 al 2004 dehydration Salleo et al centrifugation Salleo et al Direct micro-ct Cochard dehydration 20 centrifugation Xylem pressure, MPa Xylem -4 pressure, -3 MPa Xylem pressure, MPa Xylem -4 pressure, -3 MPa Xylem pressure, MPa Hacke & Sperry Salleo & Lo Gullo 1993 Hacke & Sperry 2003 Long vessel species, with big vessels do not show R shaped vulnerability curve and can be very resistant! Hacke Hacke & Sperry Sperry Hacke & Sperry 2003 Hacke & Sperry 2003 (Cochard, Delzon and Badel, submitted)

17 Embolism start Douglas Poplar (Dalla Salda et al, unpublished) At the annual ring level, embolism is not a random process!

18 Embolism spreading -1.5 MPa -2.5 MPa? Data for modelling at the cell arrangement level Torres, Badel, Cochard et al in prep) At the cell level, lonely seeds of embolism start more or less randomly; then spreading occurs in radial direction. Question: how?

19 Freeze/thaw induced embolism Freezing box Cryo-stat AEcum (%) < T < Temperature ( C) Acoustic recording during X-ray scan Charra Vaskou, Badel, Charrier, Mayr, Ameglio, in prep) Time (sec) Air temperature Air temperature of control chamber Stem temperature AEcum

20 Conclusion - Prospect X-ray observation may over-estimate the embolism but never under-estimate it! Great opportunity to look inside living trees under stress Visualization will help to understand the mechanism. X-ray tomography is becoming a reference method for embolism evaluation! Need to ensure the tree health is not impacted by the x-ray radiations Need to improve the sample environments for stresses control (cold, heat, RH%, light) We always want more : higher resolution with larger field of view and faster scans.

21 Thank you and if you do not have a synchrotron, you re welcome in Clermont-Ferrand ALIMENTATION AGRICULTURE E Piaf NVIRONNEMENT

22 detector The spatial resolution X-ray spot Warning: the spatial resolution given by the manufacturer does not indicate the blurring The spot size is cruxial pixel resolution = det ector resolution G X-ray spot blurred pixel = spot size G Same resolutions (given by the manufacturer!!) Detector resolution scan time small spot low x-ray intensity

23 Quantitative resolution 1 mm niveau de gris mm niveau de gris position (pixel) position (pixel)

24 Embolism visualisation Pinus needle Olive tree leaf Charra-Vaskou et al, 2012 ALIMENTATION AGRICULTURE ENVIRONNEMENT