Implementation and uniformity calibration of LED array for photodynamic therapy

Abstract

Irradiance uniformity is an important parameter for a Photodynamic Therapy (PDT) device. The calibration and verification of a LED array light source based on computer vision technology were implemented and carried out. First, the correlation coefficients between the pulse width modulate value and the irradiance were calibrated. Then, the correction of the actual light center and divergence angle were solved by image processing to reduce errors from each LED lens. Finally, uniformity was optimized according to the irradiance formula of the Lambertian source. The lowest coefficients of variation of irradiance were 4.87% in a [Formula: see text] area and 3.55% in a [Formula: see text] area within the depth range of 8–12[Formula: see text]cm when the expected irradiance was 100[Formula: see text]mW/cm2. This finding indicated that the light source can achieve a more uniform illumination and provide a better therapeutic effect for the PDT of port-wine stains.

Light-emitting diode planar array light source system for defect detection of highly reflective surface

“…To optimize the overall uniformity of the target surface, the nonlinear constraint method is used for optimization calculation. The convergent optimization objective function [10], [11] is constructed as in Equation ( 8):…”

Miniaturized all-in-one microneedle device for point of care light therapy

“…As a result, patients must be strictly shielded from daylight for up to 4-6 weeks after treatment 16 , which is quite inconvenient and reduces the applicability of light therapy. On the other side, direct illumination requires relatively higher light irradiance (usually up to 150-500 mW cm −2 ) [17][18][19] to compensate for energy loss in the stratum corneum, most likely causing immediate pain 20 and tissue damage 21,22 . Moreover, generating wellcontrolled therapeutic light with high irradiance requires specially designed apparatus which usually are bulky and costly, limiting the availability of equipment to central hospitals 23,24 .…”