Standards Development

Scope

This Technical Specification is relevant to simulation of ultrasonic fields including high pressure fields, for example, those of High Intensity Therapeutic Ultrasound (HITU), and would include the following: input field measurements in water needed for ultrasound transducer characterization, simulation methodology for therapeutic ultrasound high pressure level field predictions for water or other homogeneous or heterogeneous media, acoustic field forward and backward projection methods, validation of nonlinear field simulation, coupling of predicted acoustic output to calculate spatial distributions of tissue heating, and the consideration of sidelobes, pre-focal and post-focal maxima and parameters relevant to scanning transducers and multiple sources.

The basic approach taken in this Technical Specification includes two basic components: an experimental characterization of the output of an ultrasound transducer to define a measurement-based source as a model boundary condition, and simulations of ultrasound propagation from this source to predict the resulting field in water or other media. This specification provides guidance on model selection, benchmark-based evaluation of model performance, application-specific source characterization measurements for a given ultrasound transducer, and application-specific validation measurements of simulation outputs.

Purpose

There is a primary need for measurement-based simulation methods for predicting acoustic fields under conditions in which they cannot be measured directly, including nonlinear high-pressure fields and fields inside tissues. This Technical Specification is necessary because most therapeutic medical applications are designed to cause bioeffects in tissue and there is no widely accepted way of translating nonlinear high- pressure fields measured in water to those estimated to occur in tissue at a target site. A secondary aim of the proposed work is to enable the simulation of temperature elevation caused by a therapeutic ultrasound field. In addition to therapeutic ultrasound (HITU), this technical specification is expected to have wide applicability to other medical ultrasound applications. An aim of the proposed new work is to develop the means of making repeatable, accurate field simulations for devices in all these applications.