In-vivoLight dosimetry for pleural PDT.
In-vivolight dosimetry for patients undergoing photodynamic therapy (PDT) is one of the critical dosimetry quantities for predicting PDT outcome. This study examines the relationship between the PDT treatment time and thoracic treatment volume and surface area for patients undergoing pleural PDT. In addition, the mean light fluence (rate) and its accuracy were quantified. The patients studied here were enrolled in Phase II clinical trial of Photofrin-mediated PDT for the treatment of non-small cell lung cancer with pleural effusion. The ages of the patients studied varied from 34 to 69 years old. All patients were administered 2mg per kg body weight Photoprin 24 hours before the surgery. Patients undergoing photodynamic therapy (PDT) are treated with laser light with a light fluence of 60 J/cm2at 630nm. Fluence rate (mW/cm2) and cumulative fluence (J/cm2) was monitored at 7 different sites during the entire light treatment delivery. Isotropic detectors were used forin-vivolight dosimetry. The anisotropy of each isotropic detector was found to be within 30%. The mean fluence rate deliver varied from 37.84 to 94.05 mW/cm2and treatment time varied from 1762 to 5232s. We found a linear correlation between the total treatment time and the treatment area: t (sec) = 4.80 A (cm2). A similar correlation exists between the treatment time and the treatment volume: t (sec) = 2.33 V (cm3). The results can be explained using an integrating sphere theory and the measured tissue optical properties assuming that the saline liquid has a mean absorption coefficient of 0.05 cm-1. Our long term accuracy studies confirmed light fluence rate measurement accuracy of ±10%. The results can be used as a clinical guideline for future pleural PDT treatment.
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
Andreea
A
Dimofte
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
Timothy C
TC
Zhu
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
Jarod C
JC
Finlay
Department of Surgery, University of Pennsylvania, Philadelphia, PA.
Melissa
M
Cullighan
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
Christine E
CE
Edmonds
Department of Surgery, University of Pennsylvania, Philadelphia, PA.
Joseph S
JS
Friedberg
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
Keith
K
Cengel
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA.
Stephen M
SM
Hahn
Light dosimetry; Photofrin; photodynamic therapy