Potential of a HDR image processing sensor for optimized visualisation in NOTES interventions

Objective of the Study: Since current NOTES endoscopes have a very narrow and poorly illuminated field of view, it is inevitable to optimize the visualization of the operation field and build a basis for further developments in NOTES-surgery. Typical effects are the overexposure of near objects and the underexposure of distant structures, as well as bright areas in the centre and poorly illuminated areas in the periphery. Consistent illumination and sharp clear structures would help for orientation and to ensure safe operation.

Methods and Procedures: In a collaborative research project with viimagic and C.R.S. iiMotion (Villingen-Schwenningen) a new High-Dynamic-Range (HDR) Sensor is developed and adapted to medical problems and irritating effects occurring in minimally-invasive surgery. For this purpose, a first evaluation including different approaches for virtual smoke elimination was implemented by consulting 16 experienced endoscopists. Moreover, the sensor is able to take three or more pictures of different exposure time simultaneously and fuses them to one optimized image in real-time. Due to the increased dynamic range compared to Standard-Dynamic-Range (SDR) cameras, more picture and colour information can be detected and utilized.

Results: HDR image processing provides high potential for medical application. The analysis of the evaluation provides the basis for further optimization of the surgeon's field of vision by the HDR camera system and dedicated software tools. The integrated image processing software improves interfering effects, such as reflections or smoke plumes of HF-devices. The HDR sensor is able to correct over- and underexposure and delivers an optimized image on the screen in real-time.

Conclusions: HDR imaging is a promising tool for improved visualization in medicine, but this technique is in an initial stage for medical application. There are some aspects, which still have to be optimized. One important challenge is colour rendering. In NOTES the natural colouring of human structures is an important feedback for the physician to guarantee safety of the procedure. High-Dynamic-Range camera systems in medicine establish a helpful and promising technique also for NOTES interventions.