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Light-emitting diodes as a light source for intraoperative photodynamic therapy
M H Schmidt1, D M Bajic, K W Reichert
1Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, USA.
Neurosurgery
|March 1, 1996
Summary
Light-emitting diodes (LEDs) offer a cost-effective alternative for photodynamic therapy (PDT) of brain tumors. Studies show LEDs provide comparable brain stem toxicity to lasers when used with Photofrin, making them suitable for PDT applications.
Area of Science:
- Biomedical Engineering
- Oncology
- Photomedicine
Background:
- Photodynamic therapy (PDT) for brain tumors requires effective and economical light sources.
- Photofrin porfimer sodium is a photosensitizer used in PDT, with optimal absorption in the red spectrum.
- Existing laser light sources can be expensive and may have limitations in specific clinical applications.
Purpose of the Study:
- To investigate the efficacy and safety of light-emitting diode (LED) arrays as a cost-effective light source for PDT of brain tumors.
- To compare the performance of an LED-based light delivery system with traditional laser systems using Photofrin.
Main Methods:
- Development of an inflatable balloon device with an aluminum gallium arsenide LED tip emitting red light (peak 677 nm).
- Use of intralipid within the balloon as a light-scattering medium to ensure uniform light dispersion.
- Comparative analysis of spectral emission, light absorption by Photofrin, and brain stem toxicity in canines between LED and laser light sources.
Main Results:
- The LED source achieved 27.5% of the Photofrin absorption compared to monochromatic 630-nm light, requiring a 3.63-fold increase in light output for equivalent dosing.
- Canine brain stem toxicity studies demonstrated equivalent toxicity signs between LED and laser light at comparable energy and Photofrin doses (maximal tolerated Photofrin dose: 1.6 mg/kg with 100 J/cm2 light energy).
- High light dispersion was observed with the intralipid-filled balloon, indicating effective light delivery.
Conclusions:
- Light-emitting diodes (LEDs) are a suitable and potentially more cost-effective light source for photodynamic therapy of brain tumors using Photofrin.
- LEDs demonstrate comparable safety profiles to lasers in terms of brain stem toxicity.
- LEDs show promise for future PDT applications, particularly with second-generation photosensitizers absorbing closer to the LED emission wavelength.
Keywords:
Non-programmatic