FMTXCT Workpackage 2 Project advancement Marco Brambilla Vronique

FMT-XCT Workpackage 2 Project advancement Marco Brambilla Véronique Rebuffel Holger Bruenner Marek Karolczak

Outline • Work-package 2 objectives and tasks • X-ray CT system design (task 2. 1) • Dual-energy XCT system development (task 2. 2) ØXCT prototype development ØOn-bench CT at LETI ØDual energy protocol definition and optimization • Work-package advancement • Revised planning FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 2

WP 2 objectives Hybrid imaging system for small animal XCT FMT XCT module should: • 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 (WP 4). Enhanced contrast XCT strategies: • Dual-energy XCT • Use of X-ray contrast agents PARTNERS: CEA-LETI (No. 2, lead) CEA-LIME (No. 2) VAMP (No. 7) FIHGM (No. 5) + UZH (No. 6) + HMGU (No. 1) FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 3

WP 2 tasks, deliverables & milestones D Year 1 M Year 2 D D M M 7 Deliverables: - D 2. 1 / due month 1: XCT design - D 2. 2 / due month 15: Dual energy prototype - D 2. 3 / due month 15: Dual energy processing software - …D 2. 4 to 2. 7: due month 18, 21, 24 Significant 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 FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 4

Task 2. 1: XCT system design (1/2) Report “WP 2: XCT design”, november 2008, issued by CEA-LETI and VAMP, approved by HMGU, distributed to the Consortium. Remark: this report fulfils most of the objectives of the task 2. 7 « optimal XCT design » , this was decided because of the (long) delivery time of the system key components. • Geometrical configuration • Appropriate X-ray tube and detector • Mechanics • Safety and normative requirements • Electrical design FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 5

Task 2. 1: XCT system design (2/2) Oxford instruments Ultra. Bright 80 Watts power, 20 -90 k. V, down to 13µm focal spot size 400 mm Non-continuous rotation mode. 1200 acquisitions in 4 mn per energy scan. Expected resolution 0. 1 mm Detector: Hamamatsu C 7943 (Cs. I scintil. + CMOS photo. array), 100μm pixel size, 1248 x 1248 pixels, 7 frames per second FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 6

Task 2. 2: XCT prototype development Under development at VAMP. First parts have been constructed and others ordered (parts in stock can be used). Status of detector: up to now, VAMP have not yet received positive feedback from Hamamatsu approving our specifications to the chosen detector FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 7

Task 2. 2: On-bench CT at LETI Versatile tool, in order to help Dual Energy development and validation. Vertical tomographic axis FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 8

Dual-energy imaging / Theory (1/4) X-Rays imaging principle • Radiography source • Measure of x-rays attenuation • i 0 μ = μ(E, material) • Contrast depends on: object i detector Ideal Model (linear detector, no scatter…) • object composition μ • incident beam spectrum • transversed length of each material → l • Tomography • volume reconstruction by means of filtered backprojection algorithm • GL → μ(E, material) • Contrast depends only on object materials FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 9

Dual-energy imaging / Theory (2/4) X-Rays dual energy principle μ = μ(E, material) Image the same object with x-rays of different energies (2 or >) E 1 E 2 Obtain quantitative information on chemical composition of the object Contrast enhancement FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 10

Dual-energy imaging / Theory (3/4) X-Rays dual energy principle • Project (a 1, . . . , an) measurement into (l 1, l 2) representation • (l 1, l 2) basis functions: • in principle: any • in pratice, often: • attenuation spectra of two base materials • projected values: base materials equivalent lengths • Single material images or combined • “closer” basis: • contrast enhancement • noise amplification • Many applications in NDT, security and medicine FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 11

Dual-energy imaging / Theory (4/4) An example: bone/soft tissue separation LE (75 k. V) bone Soft tissue FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 12

Dual-energy protocol for FMT-XCT (1/5) Biological tissues analysis • The absorption curves are all enclosed between those of cortical bone and adipose tissue. • Plexiglass is almost superimposed to adipose tissue. • All the other soft tissues are indeed indistinguishable from water • Breast tissue is the only one which differs from water (probably due to high adipose tissue content) • May adipose tissue act as a contrast agent ? ICRU-44 data of human tissue (hopefully not too different from mouse’s ones) Possible base materials: water and plexiglas. FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 13

Dual-energy protocol for FMT-XCT (2/5) Energy couple determination • Multiparametric problem • x-rays generator k. V and m. A • x-rays filters: material and thickness • 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 • Find a figure of merit to optimize equivalent length contrast • Tried different FOMs and different levels of simulation accuracy → Only very realistic simulations give affordable results • Validate results with phantom and animal study FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 14

Dual-energy protocol for FMT-XCT (3/5) Energy couple determination • RESULTS • Best contrast configuration: • LE: • Generator: 40 k. V-6 m. A • Filter: 60 um Sn • 2. 4 m. As • HE: • Generator: 70 k. V-2 m. A • Filter: 100 um Pb • 0. 8 m. As θ 1 θ 3 θ 2 • Angles: • θ 1, θ 2 ~ 1. 5° • θ 3 ~ 3. 1° FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 15

Dual-energy protocol for FMT-XCT (4/5) Energy couple validation • Mouse measurements • Phantom measurements • 35 mm cylindrical container filled with: • 1 euthanized mouse • 1 quail's leg • 1 Plexiglas cylinder • 1 piece of lamb liver • water • Measurement parameters from optimization • LE: 40 k. V, 6 m. A, 50 um Tin filter • HE: 70 k. V, 2 m. A, 100 um Lead filter • “low” resolution: 360 projections @ 1° step; binned images FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 16

Dual-energy protocol for FMT-XCT (5/5) Energy couple validation • Reconstructed volume • 300 x 420 @ 200 um/voxel FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 17

Task 2. 2: Remaining sub-tasks • Dual-energy data processing • decomposition in data domain or reconstructed volume? • enhanced contrast reconstruction • Dual-energy acquisition protocol • Validate chosen acquisition sequence: • Dual-energy calibration protocol • CEA-LETI bench is different from final prototype • more intense x-rays source • detector with higher resolution but less sensitivity → Repeat optimization process for FMT-XCT system • Evaluate scattering effects • from a first estimation: 15 -20% in projections • assess contrast reduction in reconstructed volumes (both LE & HE) • consider the possibility of using anti-scattering grids FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 18

WP 2: Revised planning To be approved by the Consortium…. FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 19

WP 2: Other tasks • Optimization of the delivered dose (Task 2. 3) • to the animal • flat panel detector → minor problem (no need for scans) • diffused • adequate external shielding already reckoned • main problem: the optical chain → design suitable protections • Minimization of X-ray interference (task 2. 4) Month 18 • Dual-energy contrast (task 2. 5) • Use of X-ray contrast agents (task 2. 6) Month 24 • To provide an optimal XCT design (task 2. 7) CEA-LETI, VAMP, HMGU CEA-LETI, CEA-LIME, HMGU CEA-LETI, FIHGM, UZH, HMGU CEA-LETI, VAMP FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 20

WP 2: Training session • Organized by CEA-LETI in Grenoble • Open to all FMT-XCT partners • Date: ~ second part of june (to be confirmed) • Program to be discussed: • X-ray imaging (theory, experimental demonstration) • Prototype demonstration • Simulation software tool presentation • Tour of facilities (X-ray and optical) • Duration: 1. 5, 2, 2. 5 days ? FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 21

Thanks for you attention FMT-XCT 1 st year meeting – 24 April 2009 - M. Brambilla 22