As filed with the U.S. Securities and Exchange Commission on December 29, 2025. Registration No. 333-291237 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO. 1 TO FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 QT Imaging Holdings, Inc. (Exact Name of Registrant as Specified in its Charter) (State or Other Jurisdiction of Incorporation or Organization) Delaware 6770 85-1728920 (Primary Standard Industrial Classification Code No.) (I.R.S. Employer Identifi ...