English: Title: Treatment: Photodynamic_Therapy: Argon-Ion Laser

Description: Photodynamic therapy (PDT) is a procedure to treat cancer. Patients are injected with a photosensitizer which is a light sensitive drug selectively retained by cancer cells. When exposed to laser light, the photosensitizer in the cancer cells produces a toxic reaction which destroys the tumor. This photo shows an argon-ion laser, the first component of the argon pumped-dye laser (630nm red). This argon-ion laser emits blue-green light at 488/514 nm, and is used to excite a dye in the second component, the dye laser head, where the wavelength is changed to 630nm red. Different photosensitizers absorb light at different wavelengths. Some absorb light most efficiently in the blue light region of the spectrum around 400 nanometers(nm) with lesser absorption in the green and red light range. However, red light at 630 nm penetrates deeper into the tumor tissue (3-8 mm) than green or blue light. For this reason, the majority of PDT work has used 630 nm light. See artwork: GA-17. Subjects (names): Topics/Categories: Treatment -- Photodynamic Therapy Type: Color Slide Source: National Cancer Institute Author: Unknown photographer/artist AV Number: AV-8700-3896 Date Created: 1987 Date Added: 1/1/2001

Reuse Restrictions: None - This image is in the public domain and can be freely reused. Please credit the source and/or author listed above.