Wavelength And Dosimetry Considerations In Photoradiation Therapy (PRT)

The effectiveness of hematoporphyrin derivative (HpD) photoradiation therapy (PRT) will depend on (a) the tumor selectivity of HpD, (b) HpD dosage and the delay time between injection and treatment, (c) spectrum of light source, (d) delivered light dose and (e) the optical characteristics of the tissue. Evaluation of the potential useful wavelength of light for HpD-PRT and thier penetration in different tissues have been evaluated. On a theoretical basis, green light (500-520nm) and violet light (400-420nm) will be useful for treating only superficial lesions less than 0.5mm thick while red light (620-640nm) is the light of choice for treatment at depths greater than 0.5mmfor a cat brain tissue.