Wayne State | Department of Surgery (313) 745-8778

Ultrasound Simulator

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Increasingly, medical students learn ultrasound skills at simulation centers in medical school. Portable ultrasound machines are used on crude, short-lived,` gel-and-noodles models of the abdomen. The machines are expensive, and the models are time consuming for the surgeon-teacher to build and therefore expensive also. Measuring/monitoring the students as they practice requires direct expert observation and manual recording of performance and is therefore expensive. Teaching by demonstration requires one-on-one learner to educator.

Solution: The Department is developing an ultrasound simulator with a dummy probe whose position is tracked with 6 degrees of freedom as it is manipulated in contact with a physical model of the abdomen. The coordinate data stream will be used to interrogate a virtual digitized model of the abdomen, resulting in an image that varies in real time with the probe position.

Development stage: We have created a bit array (cube)-based data model for the virtual abdomen, and are in the process of (1) connecting an ultrasound transponder to a CNC machine to reference the data points and (2) creating an algorithm that factors in pitch, roll, and yaw, to determine what view is presented to the user.

Competition: There are some available simulators. Their images are still-frame displays triggered by application of an electromagnetic sensing dummy probe to a physical model containing magnetic targets. The probe is not continuously tracked, only limited pre-stored images are triggered for display at each target site (usually transverse and sagittal). The experience is static and unrealistic. No probe manipulation skills are taught

In addition, fully functioning ultrasound devices may become cheap and small enough that simulators are not needed. But even so, they lack the advantage of being embedded with an academic medical institution that is developing curriculum at the same time as it is building and validating pedagogic measurement metrics and models and standards. MEP and its partners will offer a service that includes not just the simulator but also the curriculum and even the distance teaching of the subject. Doctors tend to be unwilling to teach in simulation labs; they prefer to teach in the OR, so they ought to welcome a system that relieves them of an onerous and often evaded duty.

Supporting work: The team working on the ultrasound simulator has developed a simulation system to teach surgical students the skills they need to pass the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) exam in the Fundamentals of Laparoscopic Surgery (FLS.) The system is in use and produced such good results for the first class that used it, that non-FLS-trained students from prior classes asked to be trained on the system after seeing their juniors doing better than them in laparoscopy.

The FLS system could be used to identify then specify and measure the skill set needed for laparoscopic surgery. Right now FLS is task-oriented (tie a knot, etc.) But the tasks have no natural link to anatomy. The important skills include (for example) manual dexterity and the handling of a difficult field of view, etc., in the anatomical and physiological context. That, and not the disembodied knot, is what makes and defines a surgeon. Analysis of the video automatically recorded as students train will enable the identification of valid skills.