How tissue optics affect dosimetry of photodynamic therapy

Steven Jacques

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

We describe three lessons learned about how tissue optics affect the dosimetry of red to near-infrared treatment light during PDT, based on working with Dr. Tayyaba Hasan. Lesson 1 - The optical fluence rate φ near the tissue surface exceeds the delivered irradiance (E). A broad beam penetrates into tissue to a depth (z) as φ=Eke , with an attenuation constant μ and a backscatter term k. In tissues, k is typically in the range 3-5, and 1/μ equals δ, the 1/e optical penetration depth. Lesson 2 - Edge losses at the periphery of a uniform treatment beam extend about 3δ from the beam edge. If the beam diameter exceeds 6δ, then there is a central zone of uniform fluence rate in the tissue. Lesson 3 - The depth of treatment is linearly proportional to S (and the melanin content of pigmented epidermis in skin) while proportional to the logarithm of all other factors, such as irradiance, exposure time, or the photosensitizer properties (concentration, extinction coefficient, quantum yield for oxidizing species). The lessons illustrate how tissue optics play a dominant role in specifying the treatment zone during PDT.

Original languageEnglish (US)
Article number051608
JournalJournal of Biomedical Optics
Volume15
Issue number5
DOIs
StatePublished - Sep 2010

Fingerprint

Photodynamic therapy
Dosimetry
dosimeters
therapy
Optics
optics
Tissue
irradiance
fluence
Melanin
melanin
Light extinction
epidermis
Photosensitizing Agents
Photosensitizers
lessons learned
Melanins
Quantum yield
logarithms
Skin

Keywords

  • Dosimetry
  • Optical properties
  • Photodynamic therapy
  • Tissue optics

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biomaterials
  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

Cite this

How tissue optics affect dosimetry of photodynamic therapy. / Jacques, Steven.

In: Journal of Biomedical Optics, Vol. 15, No. 5, 051608, 09.2010.

Research output: Contribution to journalArticle

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