FMT-XCT – Workpackage 2 advancement

Marco Brambilla Véronique Rebuffel

Markus MronzMarek Karolczak

FMT-XCT Year 2 meeting 26.03.2010 – Heraklion, Crete

Outline

• Work-package 2 advancement summary• X-ray CT system design• Dual-energy X-ray protocol• Scattered radiation estimation• Absorbed dose estimation• Conclusions• (XPCI proposal)

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

WP 2 Objectives

• provide adequate accommodation of the optical components,

• eliminate X-ray interference with optical components,

• offer improved contrast between organs as is important for optimal use of XCT information as priors in the FMT inversion procedure (WP4).

Hybrid imaging system for small animal

XCT FMT

XCT module should:

Enhanced contrast XCT strategies:

• Dual-energy XCT

• Use of X-ray contrast agents

No Name M.M.

2 CEA-LETI (lead) 51.7

7 CT-Imaging 6

5 FIHGM 18

6 UZH 1

1 HMGU 1

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

WP 2 Deliverables: current stateDeliverables:- D2.1 (mo.1): XCT design - completed

Report “WP2: XCT design”, 11/2008, issued by CEA-LETI and CT-Imagingdistributed to the Consortium.

- D2.2 & 2.3 (mo.15): Dual energy prototype & software - completedPrototype and software demonstrated during Training session (06/2009).Report ready to be delivered.

- D2.4 (mo.18): Preliminary technical specifications - completedBased on LETI lab bench. Report ready to be delivered

- D2.5 (mo.21): Measurements of scattered energy - partially completedBased on LETI lab bench only. Draft report prepared.

- D2.6 (mo.24): Optimal contrast-enhancing strategy - delayed- D2.7 (mo.24): Optimized system design - almost completed

Update from D2.1

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

D2.1

MM

D2.4

D2.5

D2.2,

2.3

D2.6,

2.7

Milestone (n°5) : selection of an appropriate XCT technology for FMT-XCT system (by the executive committee)Month 18: preliminary recommendation / Month 24: official decision

WP 2 Problems

CEA-LETI bench is different from final prototype• more intense x-rays source• different environment

→ Repeat optimization process for FMT-XCT system

→ Repeat measurements (dose, contrast) on FMT-XCT system

Final prototype available only end of May 2010• Defect delivered gantry motor (still waiting !!!)• Problem with the PLC (re-design of the PCB of the PLC)• Time to construct the X-Ray shielding

→ Integrate gantry motor when delivered and finalize the prototype

→ Integration of the FMT chain (more than initially planned) has started at CT-Imaging

CEA-LETI bench not convenient for extensive tests using living mice• vertical position, fixation by forelegs• successive CTs, (Dual energy + with contrast agent), very difficult on a living

mouse

→ Tests planned for D2.6 require a more easily usable bench

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

WP2 Corrective actions and revised planning

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

Final prototype available

@ CT-Imaging

Mo.25 (04/2010)

D 2.5D 2.4 v2

Final prototype @ HMGU

D 2.6D 2.7 v2

M5

Scattering measurementsAdjust DE protocol

Mo.27 (06/2010)

TBDMo 24 (Now)

on test benches on final prototype at CTI on final prototype at HMGU

Comparison of contrast enhancement strategies

D2.5 (mo.21): Measurements of scattered energy → Update current preliminary report

D2.7 (mo.24): Optimized system design → Update current report integrating last changes

D2.6 (mo.24): Optimal contrast-enhancing strategy →

Comparison of on specified living mice.

Refine data analysis procedure and comparison protocolPossible experimental approaches:

→ DE experiments at CEA-LETI, contrast agent ones at FIHGM

→ All experiments at FIHGM

→ All experiments using the final prototype (required)

• Single energy CT• Dual energy CT • Contrast agent CT

Dimensions: 145 cm x 140 cm x 103 cm

Back view Front view

WP2 (2.7) / WP5 (5.3) / Milestone 8XCT final design, gantry development and shielding

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

WP2 (2.7) / WP5 (5.3) / Milestone 8XCT final design, gantry development and shielding

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

XCT 1) X-Ray tube: Oxford UltraBright 80W, 90kV, 13-20µm

2) Detector: Hamamatsu C7942, Csl scintil. + CMOS photo array, 2400 x 2400 pix, 9 f/s @ 4x4 binning

3) Beam modification: collimator, shutter, prefilter for dual energy mode

FMT 4) CCD camera: Princeton Instr. Pixis 1024

5) Filter wheel: FRM 65 (Owis)

6) Scattered X-Ray protection: CCD shutter and shielding

7) Laser positioning: KDT 105 and optical collimator

8) Stray light shielding: PEAK tube with openings for optical path

1

2

3

45

6

7

8

WP2 (2.7) / WP5 (5.3) / Milestone 8XCT final design, gantry development and shielding

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

XCT acquistion PC

FMT acquistion PC

FMT Laser stage control

PLC Master

Animal bed

Gantry motor

Gantry position

InterlockIO‘s

PLC Slave

X-Ray tube

Illumination

X-Ray shutter

CCD shutter

X-Ray prefilter

CDD filter wheel

Detector CCD camera

Network

Block diagram

of the main components

Task 2.2: CT bench at CEA-LETI

Versatile tool, in order to help Dual Energy development and validation.

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

• Results:

• LE:• Generator: 40kV-6mA• Filter: 60um Sn• 2.4 mAs

• HE:• Generator: 70kV-2mA• Filter: 100um Pb• 0.8 mAs

Dual-energy protocol for FMT-XCT

Energy couple determination

• Multi-parametric problem

• x-rays generator kV and mA

• x-rays filters

• duration of irradiation for LE and HE acquisitions

• By means of a simulation software:

• simulated all the dual energy chain trying different combinations of the parameters

• find the combination with best figure of merit

• Tried different FOMs and different levels of simulation accuracy

• Validate results with phantom and animal study

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

DE protocol validation (1/2)

Observations:

• Little contrast between organs

• Contrast between soft tissues/adipose tissue

• High level of noise (mainly in HE)

• Same type of contrast in LE/HE

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

DE protocol validation (2/2)

Mou

se 1

Mou

se 2

Mou

se 3

to distinguish adipose from other soft tissues

Feasible:

Easy:

to distinguish bones from soft tissues

Very difficult:

to identify organs

High energy does not add significant information

(unless very high dose@ both energies)

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

Beam hardening estimation

• Stronger attenuation of lower part of the spectrum

→ (in radiographs) attenuation not linear any more against object thickness→ (in tomography) cupping artifacts

Radiography: → good linearity at both LE and HE

LE Tomography: → Negligible cupping

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

→ Very limited beam hardening influence

Absorbed dose

Low energy High energy

Dose rate [mGy/min]Single radiography

(300ms exposure) [mGy]

Full tomographic scan (3’20’’ duration)

[mGy]Dose rate [mGy/min]

Single radiography (300ms exposure)

[mGy]

Full tomographic scan (3’20’’ duration)

[mGy]

Abdomen 93.93 0.47 312.8 14.78 0.07 49.0Chest 65.40 0.33 217.8 10.25 0.05 34.1Mean 77.56 0.39 258.3 12.16 0.06 40.5

lIIIIa exp100

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

Scattered X-ray measure for CCD shielding

Scattered field depends on the bench

→ Not possible to estimate shielding geometry

→ Possible to estimate shielding thickness

mmcmcm

I

I

kVevPbt e

45.2245.049.24

)10log(

log)70,(

1

1

6

0

tkVevPbI

I e )70,(exp0

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

Parameter optimization for final prototype

• Optimization by simulation using datasheet parameters• Simulation prarameters:

• source:• Oxford Instr. UltraBright u-focus• 13um focal spot size• 20-90kV anodic voltage range• 2mA maximum anodic current• W anode

• detector:• Hamamatsu C7942 (same as CEA-LETI bench)

• geometry:• source-obj. dist.: 20cm• obj.-detector dist.: 20cm

Optimal configurationLow energy:

• 35kV• 2mA• 50um tin filter

High energy:• 70kV• 1.25mA• 50um lead filter

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

• Better contrast than CEA-LETI bench• To be verified experimentally on final prototype !

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

Conclusions and perspectives

• Prototype construction almost completed• Prototype testing planned• Dual energy protocol developed and tested (to be confirmed)

• Most relevant information (and dose) in low energy data

• Preliminary scattered radiation measurements performed• Optimal contrast enhancement strategy not yet defined

Conclusions

Perspectives

• Scarce information contribution from high energy data• Dual energy protocol not suggested• Low energy acquisition only

• We propose at no additional man-months:• Different X-ray contrast enhancement technique investigation→ X-rays phase contrast imaging

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete

Thank you

WP 2 Remaining and corrective actions

- D2.5 (mo.21): Measurements of scattered energy - Month 27

- X-ray measurements on the final prototype (first experiments done by CT-Imaging)

- Optimization of the CCD camera shielding

- D2.7 (mo.24): Optimized system design - Month 27

- Update of the prepared report integrating last changes

- D2.6 (mo.24): Optimal contrast-enhancing strategy - Month 30 to be discussed

Comparison of on specified living mice.

Possible experimental approaches:

-> X-ray experiments at CEA-LETI, contrast agent ones at FIHGM

-> All experiments at FIHGM

-> All experiments using the final prototype (required)

Refine data analysis procedure and comparison protocol

• Single energy CT• Dual energy CT • Contrast agent CT

M.Brambilla - FMT-XCT year 2 Meeting – 26.03.2010, Crete