Testbed for Quantitative Thermoacoustic Tomography

描述（由申请人提供）：我们建议开发一种用于量化热声计算机断层扫描（TCT）信号强度作为电磁（EM）照射脉冲参数的函数的测试平台。TCT成像一种全新的对比机制：通过热膨胀将EM转换为声压。TCT压力由位于成像视场（FOV）外部的超声换能器测量，但是由传播到FOV中的EM照明的短突发引起的FOV内的热膨胀产生。可以重建TCT压力以提供与组织的EM能量的比吸收率（SAR）相关的图像。SAR是所施加电场强度的函数，|e|和内在组织特性。定量TCT的目标是恢复不依赖于组织的固有性质。|e|应用TCT系统。本提案的目标是量化TCT信号强度，|e|以确保可以在体内稳健地产生强TCT信号。 许多令人鼓舞的光声断层扫描（PAT）研究显示，在皮肤表面2 - 3 cm内和血管内的良好结果，但只有一个临床试验的TCT与深穿透射频（RF）照明已报告。我们将使用软件和硬件的“测试台”，旨在产生TCT压力信号下的受控EM环境，以实现以下具体目标：1。量化TCT声信号强度（帕斯卡（Pa））与RF照明参数：简单测试体模和动物组织标本的峰值功率、载波频率、偏振和脉冲宽度。将对软件测试平台的几何简单体模的分析计算与硬件测试平台的测量进行比较。2.量化对比剂对TCT对比度和S/N的影响。我们将专注于超声中使用的微泡和PAT中使用的纳米粒子。3.将试验台改造为用于体外成像的台式TCT断层扫描系统。该试验台将旋转和平移样品，为层析重建提供圆柱形测量表面。 公共卫生相关性：我们将验证用于软组织诊断医学成像的全新造影剂机制。热声学对于目前成像技术严重不足的应用（如前列腺癌成像）可能是一个布恩。

DESCRIPTION (provided by applicant): We propose to develop a testbed for quantifying thermoacoustic computerized tomography (TCT) signal strength as a function of electromagnetic (EM) illumination pulse parameters. TCT images a completely new contrast mechanism: conversion of EM to acoustic pressures via thermal expansion. TCT pressures are measured by ultrasound transducers located outside of the imaging field of view (FOV) but are generated by thermal expansion inside the FOV caused by the short burst of EM illumination propagated into the FOV. TCT pressures can be reconstructed to provide an image related to the tissue's specific absorption rate (SAR) of EM energy. SAR is a function of both applied electric field strength, |E|, and intrinsic tissue properties. The goal of quantitative TCT is to recover intrinsic tissue properties independent of |E| applied by the TCT system. The goal of this proposal is to quantify TCT signal strength as a function of |E| to ensure strong TCT signal can be generated robustly in vivo. Many encouraging photoacoustic tomography (PAT) studies show good results within 2-3 cm of the skin surface and intravascularly, but only one clinical trial of TCT with deeply penetrating radiofrequency (RF) illumination has been reported. We will use both software and hardware "testbeds" designed to generate TCT pressure signals under a controlled EM environment to achieve the following specific aims: 1. Quantify TCT acoustic signal strength in Pascals (Pa) vs. RF illumination parameters: peak power, carrier frequency, polarization and pulse width for simple test phantoms and animal tissue specimens. Analytical calculations for geometrically simple phantoms from the software testbed will be compared to measurements from the hardware testbed. 2. Quantify effect of contrast agents on TCT contrast and S/N. We will focus on microbubbles used in ultrasound and nanoparticles as used in PAT. 3. Modify the testbed to become a benchtop TCT tomography system for ex vivo imaging. This testbed will rotate and translate specimens, providing cylindrical measurement surfaces for tomographic reconstruction. PUBLIC HEALTH RELEVANCE: We will validate a completely new contrast mechanism for diagnostic medical imaging in soft tissues. Thermoacoustics may be a boon to applications for which current imaging techniques are woefully inadequate, such as prostate cancer imaging.