BOSTON (AP) _ Polaroid Corp. announced Tuesday it was developing equipment for hospitals to take electronic pictures, as the company tries to compete more in the medical business while continuing to look beyond instant photography.

''This is a complete and total departure in some ways,'' said Len Aberbach, Polaroid's director of medical imaging.

Polaroid, based in Cambridge, said its electronic imaging technology for hospitals is in the developmental stage and will be available for sale in 1991. The company gave a preview of its plans this week in Chicago at the annual meeting of the Radiological Society of North America.

The new imaging system is designed to record images from electronic diagnostic tools in hospitals, giving doctors pictures of internal organs and other body parts.

Like traditional Polaroid systems, the new system will record images that are instantly available and require no processing equipment or darkroom facilities. But unlike other Polaroid materials, the technology will not rely on light-sensitive film.

Also, the company said, the system will provide pictures as sharp and as detailed as those processed in conventional photography and doctors will be able to enhance the images.

''The new system is the forerunner of an era of electronic imaging for Polaroid, an era of new imaging devices and new media that we, with our instant photography heritage, are particularly well suited for,'' I. MacAllister Booth, president and chief executive officer of the company, said in a prepared statement.

Polaroid built its success around instant photography, but recently the company has been moving into other ventures, including conventional film.

The strategy comes as the company tries to rebuild profits after the last fiscal year, when Polaroid lost $22.6 million while fending off a hostile takeover bid.

Part of the company's new approach is to promote the use of instant photography for businesses, such as real estate, insurance, auto body repair and architects.

Polaroid for years has marketed its products to medical professionals, Aberbach said in an interview from Chicago. Ophthalmologists have used standard Polaroid film to take instant pictures of patients' retinas, while plastic surgeons have used it for photos of people's faces.

But Aberbach said Polaroid was unable to maintain a strong position in the medical market because the company did not offer the technology to meet hospitals' specific needs.

Polaroid's medical-related sales exceed $100 million, Aberbach said, but the overall market for medical diagnostic imaging has about $13 billion in sales annually.

But while the company is targeting the medical field for its new technology, Polaroid officials said other groups, such as graphics designers, might be able to use applications of the system in the future.