Ultrasound is the least costly imaging modality by far and is the modality of choice in obstetrics, due to absence of radiation exposure. Unfortunately, a significant amount of training is required to physically perform ultrasound scanning and to make diagnostic decisions based on ultrasound images. Furthermore, training opportunities are relative costly. Thus, ultrasound training simulators have the potential for providing valuable alternative training opportunities. This has led to the development of a low cost training system that a student or health care professional can personally own, carry and use with a laptop/PC.
More … The design approach behind the low-cost personal ultrasound simulator has been to make as much as possible of the scanning experience software-based, thus making the system compact, adaptable and inexpensive, while still retaining the psycho-motor aspects of actual US training. By building the simulator around a standard laptop computer or PC, the cost will be lowered to the point of making personal ownership of the simulator feasible. The hardware components consist of curved compliant scan surface mimicking a generic body surface, a sham transducer with 5 degrees of freedom (DoF) tracking, and a laptop or PC, as seen in the figure below. The PC displays two images: (i) a rendering of the body surface unique to the selected 3D image volume (the virtual subject) and of a transducer following the movements of the sham transducer (the virtual transducer) and (ii) a B-mode image, which is a slice of the selected 3D image volume and is determined by the position and orientation of the sham transducer.
The unique implementation of the tracking system is key to deliver a low-cost solution to psycho-motor training. It operates without the use of position or orientation calibration or the use of an external reference, thus lowering both cost and weight. This system has 5 DoF and is comprised of a 2 DoF positional sub-system, tracking the location of the sham transducer on the curved scan surface by optical means, and 3 DoF orientational sub-system in the form of a low-cost IMU. Optical tracking is created by imprinting the scan surface with the Anoto Dot Pattern, a form of digital paper with fine dots placed in an offset grid pattern. An Anoto IR camera, contained in a pen-like housing, is placed in the sham transducer.
A teaching instrument such as an ultrasound training simulator is only as valuable as the built-in instructional tools. The diagnostic obstetrics ultrasound simulator will have modules, each containing a set of related tasks (e.g. biometric measurements). However, before the student begins the practice part of a given module, there is an instructional component in the form of a set of short narrated videos, one per task, pre-recorded by an instructor using the physical scan surface and the sham transducer. Each video will describe all the steps, observations and landmarks associated with a given task.
(a): Scan surface with Anoto dot pattern (footprint 12”x10”) and sham transducer.
(b): Laptop display showing Virtual Subject and Virtual Transducer, the corresponding image, and the US console.