Quoted from https://www.auntminnie.com/index.asp?Sec=sup&Sub=ult&Pag=dis&ItemId=76409&wf=1956:
Philips gets rights to harmonic ultrasound patents
Patent management firm Research Corporation Technologies (RCT) has granted Royal Philips Electronics and its affiliates (including Philips Medical Systems of Andover, MA) a nonexclusive license to ultrasound tissue harmonic imaging (THI) patents owned by
Philips joins Siemens Medical Solutions unit Acuson as a licensee of RCT patents, according to RCT of Tucson, AZ. The company said it's continuing its efforts to license its patents to the ultrasound industry.