3D Digital Watermarks Protect Transmitted Medical Images

Digital watermarks can determine if volumetric medical images have been altered by hackers or other parties, and what areas have been affected, according to an article published online in the Journal of Digital Imaging.

While tampering of medical images may not cross the minds of many, the increasing use of web-based technology for patient records and the transmission of records over the Internet could leave images vulnerable to hackers, researchers say. Alteration of medical images sent for consultation could result in incorrect diagnosis and treatment of patients.

To reduce the risk of tampering of images occurring, researchers from Nanyang Technological University in Singapore have developed a fully reversible, dual-layer watermarking scheme with tamper detection capability.

The researchers sought to use 3D properties of the volumetric images rather than the previously used 2D techniques. They used public-key cryptography and reversible data-hiding technique to develop their concept of vertical watermarking. If an image has been altered, the altered regions will be highlighted when viewed at the receiving end. The scheme was tested using medical images in DICOM format, as well as against a previously used 2D application. According to the study, there was 100 percent tamper localization accuracy with the newer 3D technique.

The time involved in de-watermarking images is important. This new technique yielded an average reduction of 65 percent in watermarking time and a 72 percent in de-watermarking time for tested images, compared with the 2D technique.

“The results show that the scheme is able to ensure image authenticity and integrity, and to locate tampered regions in the images,” concluded the authors. More research is to follow as the technique is tested in a clinical environment.