Tustin-based Toshiba America Medical Systems, the marketing, distribution, and services arm of Toshiba's diagnostic imaging systems group, said today that it has named Stuart Clarkson as Director of its MR Business Unit. Toshiba said Clarkson will be responsible for tactical and strategic marketing in the unit. Clarkson has previously served at GE Healthcare, and the firm says he has over 25 years of experience in the industry. Toshiba sells CT, X-Ray, Ultrasound, MRI, and other equipment.