Analysis of radiation transport in biological tissues using a deterministic code, partisin 4.0

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ANALYSIS OF RADIATION

TRANSPORT IN BIOLOGICAL TISSUES USING A DETERMINISTIC CODE,

PARTISIN 4.0

ANALYSIS OF RADIATION

TRANSPORT IN BIOLOGICAL TISSUES USING A DETERMINISTIC CODE,

PARTISIN 4.0

Murat AYDIN

Nuclear Research Section

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General Objective of Tomography

Constructing the image

to diagnose

inhomogeneties or morphological changes

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What is optical tomograhy?

Optical tomograhy is a form of computed tomograhy that creates a digital volumetric model of an object by

reconstructing images made from light transmitted and scattered through an object

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Optical Tomography

• Advantages_Advantages

• Reduction of invasiveness Reduction of invasiveness

• Better treatments at reduced costBetter treatments at reduced cost • Inexpensive and portable systemInexpensive and portable system

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Why NIR Photons?

 NIR Wavelength 600-1300 nm _{NIR Wavelength 600-1300 nm}

Absorption coefficient 0.001 – 0.01 mm-1_{Absorption coefficient 0.001 – 0.01 mm-1} Scattering coefficient 10 – 100 mm-1 _{Scattering coefficient 10 – 100 mm-1}

UV

UV NLNL

NIR

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The Forward and Inverse

Photon Propagation Problem

The Forward and Inverse

Photon Propagation Problem



Forward problem:

_{Forward problem:}



properties + source responses



Inverse problem

:

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Forward vs. inverse problem

Incident light and object optical properties Output light intensity

Knowing the cause Predict the effect  Forward problem (usually well-posed problem)

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Forward vs. inverse problem

 Inverse problem _{Inverse problem}_{(usually ill-posed problem)}_{(usually ill-posed problem)}

Knowing the effect

Knowing the effect Predict the causePredict the cause

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PARTISN 4.0

 A_A modular computer program package designed to solve _{modular computer program package designed to solve}

the time-independent or dependent multigroup discrete

ordinates form of the Boltzmann transport equation in

several different geometries.

 3₃ distinct modules: the Input Module_{distinct modules: the Input Module}(₍input_input processing_processing)₎, _,

the Solver Module

the Solver Module((the transport equation solvingthe transport equation solving)), and , and the Edit Module

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Solution Methods

 _{The Solver Module contains one, two, and three-}_{The Solver Module contains one, two, and}

three-dimensional solvers in a single module.

dimensional solvers in a single module.

 In addition to the diamond-differencing method, the Solver _{In addition to the diamond-differencing method, the Solver}

Module also has Adaptive Weighted Diamond-Differencing

(AWDD), Linear Discontinuous (LD), and Exponential

Discontinuous (ED) spatial differencing methods

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Sample Forward Problems

(Problem 1)

Sample Forward Problems

(Problem 1)

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Optical Properties of Tissue

Like Media

Optical Properties of Tissue

Like Media

Material µ_s (cm–1 ) µ a (cm–1 ) 1 7 0.02 2 7.22 2.63 3 3.67 0.07

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Planes Passing Tthrough The

Medium

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Scalar Fluency Rate Distribution Along the Planes (Problem 1)

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Angular Fluency Rate Distribution Along the Right Side of the Medium Angular Fluency Rate Distribution Along the Right Side of the Medium

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Problem 2

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Scalar Fluence Rate Distribution

Along the Planes for Problem 2

Scalar Fluence Rate Distribution

Along the Planes for Problem 2

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Angular Fluence Rate Distribution Along

the Right Side of the Medium for Problem 2 Angular Fluence Rate Distribution Along

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Comparison of Scalar Fluence Rates

at Detector Surface

Comparison of Scalar Fluence Rates

at Detector Surface

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 T_This _hisstudy_study has aimed to review a deterministic _{has aimed to review a deterministic}

code PARTISN for forward problems in

scattering media such as biological tissue.

 This is the first step to construct the images of _{This is the first step to construct the images of}

biological tissues using near infrared light (NIR).

 Next, Henyey–Greenstein scattering phase _{Next, Henyey–Greenstein scattering phase}

function will be implemented into the code and,

inverse problem will be solved.inverse problem will be solved.