Monte Carlo Methods & Virtual Photonics

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Jonah Booker
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1 Monte Carlo Methods & Virtual Photonics Tuesday-Thursday 9 10:30 Room 3201, Nat. Sci. II Jerry Spanier P220 BLI jspanier@uci.edu Please help yourselves to refreshments at the back of the room and leave your name, affiliation and contact information on the sign-in sheet. L A M M P

2 Classes Posted You may view the first four (9/18, 9/20, 9/25, 9/27) class presentations at Click on lectures Future presentations will also be posted there L A M M P

3 VP Overview Presentation Outline Measurement, Instrument & Therapy Design Solutions Through ATKs Computer as Virtual Laboratory Hybrid Computational Engines L A M M P

4 Virtual Photonics Two Project Design: VP CORE VTS ATKs

5 Summary: The VP Core ATKs: The public face of Virtual Photonics; addresses the major problems facing the biomedical community VTS: For development, testing, standarization, benchmarking of a wide range of computational models & methods needed by the ATKs

6 Virtual Photonics in LAMMP: Goals Consolidate and advance LAMMP s current portfolio of modeling and computation tools to accelerate the development of the other LAMMP cores Leverage this portfolio by designing advanced Application ToolKits for delivery to both the biomedical optics community and general biomedical researchers who utilize biophotonic technologies

7 Virtual Photonics in LAMMP VTS is designed as modular and scalable computational platform that can define, solve, visualize, and analyze relevant forward and inverse radiative transport problems in biomedical optics L A M M P

8 Virtual Photonics in LAMMP ATKs are designed to solve practical problems of broad interest within the R&D community and also support and extend work in our internal LAMMP/BLI user community L A M M P

9 Virtual Photonics in LAMMP Initial ATK projects focus on Small Animal Imaging (SAIATK) and Therapeutic and Diagnostic Fiber Optic Probes (FOPATK) These choices help to ensure continuous evolution and finetuning within BLI (WiFI and DOS/I cores) ensure broad user base in biomedical community

10 Proposed VP Workshops Inaugural 3-day Workshop: design, develop & test basic curriculum early in next LAMMP renewal cycle (internal audience) Years 2-5 of LAMMP renewal (external/internal audiences) Dominant modeling paradigms of VP Diffusive transport, deterministic methods/approaches, including FEM and MC Extensive hands-on use of ATKs L A M M P

11 VTS/ATK Plan Continuing with the car analogy of last time, we are developing, in software, the VTS system with powerful computational models & methods and more special-purpose, user-friendly tools (ATKs) for those in biomedical optics who aren t necessarily computational specialists

12 VTS/ATK Plan Push-Pull relationship between ATKs and VTS: ATKs: Address important questions in other LAMMP cores & the broader biomedical community VTS: Develops, tests, benchmarks the models & methods required to resolve these L A M M P

13 It s a Team Effort To accomplish our goals will require committed specialists, practitioners, and some who just want to enjoy the scenery

14 Measurement, Instrument & Therapy Design We intend to go beyond classical inverse problem-solving L A M M P

15 Measurement, Instrument & Therapy Design We are designing the ATKS to address fundamental problems and questions inspired by work in other LAMMP cores These problems/questions arise in making measurements, designing, fabricating and optimizing optical instruments, and in applying them therapeutically L A M M P

16 Measurement Design Examples How do we optimize design of optical fiber source-detector pairs for (a) tumor inclusion, (b) multilayer, and (c) diffusing probe measurement geometries? (a) (b) (c ) L A M M P

17 Cross Talk Illustration In FD systems, what pair of modulation frequencies provide data with specified tradeoff between μ a, μ s separation & desired SNR?

18 Cross Talk Illustration Spatial frequency domain illustration Figure 7: Graphical presentation of optical property crosstalk. Figure 8: Representation of the interplay between signal sensitivity to optical properties and instrument signal-tonoise.

19 Therapy Design Examples What therapeutic laser wavelength should be used to treat a Port-Wine stain (PWS) of depth D, given measured/approximated PWS optical properties? What LED/laser source power should I use to achieve a minimum photosensitizer light dose during photodynamic therapy, given the PWS depth and point/planar illumination geometry?

20 Therapy Design Examples pmc/dmc (not illustrated here) can address these issues

21 Solutions Through the ATKs Initially we plan two ATKs: Small Animal Imaging (SAIATK) for analysis of fluorescence/bioluminescence imaging within a virtual animal model Fiber Optic Probe (FOPATK) for rational design of optical fiber probes prior to fabrication L A M M P

22 FOPATK GUI m

23 The Virtual Mouse Specify 3-D geometry Optical Properties Assigned to Individual Organs Geometry of mouse internal organs from Digimouse 3-D mouse atlas constructed from co-registered X-ray CT and cryosection data of normal male mouse then voxelized Optical properties from broadband DOS measurements on live mouse L A M M P

24 SAIATK GUI h

25 Computer as Virtual Laboratory Computer experiments are Easy to control Cheap (relatively) Repeatable Clean and MC simulation is close to the physics (easier to connect directly to experiment)

26 Virtually Engineered Tissue Virtual tissue phantoms Easy to fabricate : Small # of inputs Large variety of tissue descriptions (homo, layered, regionwise contant optics, voxelized) Customizable to suit project needs Perfect quality control

27 Detailed VTS Architecture

28 Virtually Engineered Tissue Schematic for selecting tissue properties

29 Horsepower vs Fuel Efficiency VTS/ATK requirements extend power & range of our models & methods Computer simulation of complex live or virtual tissue models places great demands on computation Need for hybrid computational engines L A M M P

30 RTE Models for Microscopy Fluorescence/Bioluminescence RTE solver for virtual mouse studies Forward simulation of fluorescence/bioluminscence emission Adjoint simulation from detectors back to each tissue voxel Coupling determines total fluorescence cycle L A M M P

31 Extending RTE Models with EM Ultimately, we hope to either couple EM to RTE for effective microscopic simulation or extend RTE models by introducing say, Stokes vector representations of polarization effects. We also hope to investigate the EM/RTE interface with EM far-field methods. (We earlier described our explorations at the RTE/diffuse interface with P N, S N models)

32 Fuel Efficiency via Adaptive MC Increased complexity places great demands on computational efficiency E = 1/TV where T = total computation time V = appropriate measure of error For MC, V = variance, making E effectively scalable (with # photons sampled) since V = O(1/T) L A M M P

33 Adaptive MC: 10/4 Class Has potential for vast improvements on conventional MC

34 Efficiency Comparison From previous slide E(conventional) = 10 E(adaptive) = /25 = 4x10 14 E(adap)/E(conv) = 4x10 13 Clearly, the potential for solving problems not currently solvable in practical terms is great. We ll discuss such methods next time.

35 Virtual SNR Interpretation While adaptive methods do not by themselves increase the detected signals, they reduce the statistical uncertainties so much that the virtual SNR is magnified enormously. Model problem analyses indicate that problems that would require years to complete with conventional MC methods can be solved in minutes on contemporary computers using adaptive algorithms.

36 Monte Carlo Methods and Virtual Photonics Acknowledgements: For co-sponsorship: Bruce Tromberg (BLI and LAMMP Director) and Arthur Lander (CCSB Director & Chair, Dev. & Cell Biology) NIH P-41-RR01192 (LAMMP), NSF/DMS , UCOP (LANL) The core Virtual Photonics group : (Vasan Venugopalan, Carole Hayakawa, Katya Bhan, David Cuccia, Albert Cerussi, Tony Durkin) Rong Kong, Martin Ambrose and the entire Friday morning M&C gang L A M M P

Computational benchmarks - proposal - Robert Jeraj

Computational benchmarks - proposal - Robert Jeraj Departments of Medical Physics, Human Oncology and Biomedical Engineering University of Wisconsin Madison, WI Increased importance of computer modeling