Integrating spheres for improved skin photodynamic therapy

Area of Science:

• Biomedical Optics
• Photomedicine
• Dermatology

Background:

• Photodynamic therapy (PDT) for skin cancer relies on empirical radiant exposures.
• Current PDT protocols do not account for individual skin optical properties, leading to suboptimal treatment outcomes.
• Variable light delivery and long treatment times are limitations in current PDT for superficial skin cancers.

Purpose of the Study:

• To introduce an integrating sphere apparatus to optimize PDT light delivery for superficial skin cancers.
• To enhance treatment efficacy and reduce treatment duration by improving light fluence rate and uniformity.
• To enable patient-specific dosimetry through real-time optical property measurements.

Main Methods:

• Incorporation of an integrating sphere into the PDT irradiation apparatus.
• Measurement of tissue reflectance through a side port of the integrating sphere.
• Calculation of light fluence rate enhancement and approximation of tissue transport albedo and penetration depth.

Main Results:

• The integrating sphere increased light fluence rate by up to 100%, dependent on tissue optical properties.
• Reflectance measurements allowed for pre-treatment estimation of optimal light delivery and patient-specific treatment times.
• Improved beam flatness and reduced penumbra resulted in a more uniform light field.
• Side port reflectance measurements provided data for real-time light dosimetry and penetration depth approximation.

Conclusions:

• Integrating spheres offer a significant improvement for PDT of superficial skin cancers by optimizing light delivery.
• Patient-specific dosimetry and improved light field uniformity can enhance treatment success rates and reduce treatment times.
• The proposed method allows for real-time optical property assessment, advancing PDT precision and efficacy.