Prostate PDT dosimetry

Summary 

We provide a review of the current state of dosimetry in prostate photodynamic therapy (PDT). PDT of the human prostate has been performed with a number of different photosensitizers and with a variety of dosimetry schemes. The simplest clinical light dose prescription is to quantify the total light energy emitted per length (J/cm) of cylindrical diffusing fibers (CDF) for patients treated with a defined photosensitizer injection per body weight. However, this approach does not take into account the light scattering by tissue and usually underestimates the local light fluence rate, and consequently the fluence. Techniques have been developed to characterize tissue optical properties and light fluence rates in vivo using interstitial measurements during prostate PDT. Optical methods have been developed to characterize tissue absorption and scattering spectra, which in turn provide information about tissue oxygenation and drug concentration. Fluorescence techniques can be used to quantify drug concentrations and photobleaching rates of photosensitizers.

Abbreviations: ALA, 5-aminolevulinic Acid, BPD-MA, benzoporphyrin derivative monoacid A, CW, continuous wave, FDA, Food and Drug Administration, Hb, hemoglobin, HPD, hematoporphyrin derivative, ISC, intersystem crossing, LS-11, taloporfin sodium, MLu, motexafin lutetium, mTHPC, meso-tetrahydroyphenol chlorin, PC4, silicon pthalocyanine 4, PDT, photodynamic therapy, PpIX, protoporphyrin IX, Tookad, Pd-Bacteriopheophorbide

Keywords: Prostate PDT dosimetry, In vivo, Optical properties, Photosensitizer concentration, Light fluence rate, Cimmino feasibility algorithm, Combinatorial search, Optimization