Development of a portable testing chamber to assess imaging performance of laparoscopes in low- and middle-income countries.

Significance: Laparoscopic surgery is generally unavailable in low- and middle-income countries (LMICs) due to the high cost of installation and lack of qualified personnel to maintain and repair equipment. We developed a low-cost, durable, reusable laparoscopic system, called the KeyScope laparoscope, for use in LMICs. To reliably build and service the KeyScope in LMICs, a portable testing chamber (PTC) is needed to assess image performance.

Aim: A PTC was developed to characterize KeyScope laparoscope performance in LMICs.

Approach: Images of standard resolution, color accuracy, distortion, and depth of field (DOF) targets were captured in both a standard optical bench setup (OBS) and the PTC. Measurements from the OBS and PTC were quantified and compared using standard software (ImageJ and Imatest). To further reduce cost, alternative paper imaging targets were identified and compared with standard glass targets. To improve usability, MATLAB applications (apps) were developed to automate image analysis and reduce cost.

Results: The PTC achieved similar results compared to the OBS for the image quality metrics, distortion and DOF. Further, the PTC presented similar results to the OBS for resolution at 4 to 7 cm working distances and improved resolution at periphery working distances of 3 and 10 cm. Color accuracy values were also improved in the PTC compared with those measured in the OBS. The low-cost resolution, color accuracy, and distortion targets resulted in similar image quality results to the standard image quality target. MATLAB apps produced similar results to Imatest and ImageJ software and decreased the time to complete image quality test analysis.

Conclusion: The low-cost portable design of the PTC will facilitate the translation of the KeyScope by enabling accurate and fast characterization of laparoscopic imaging performance in LMICs.