In vivo light dosimetry for motexafin lutetium-mediated PDT of recurrent breast cancer.
OBJECTIVE
To measure the fluence at tissue surface for patients in our Phase II clinical trial of motexafin lutetium (MLu)-mediated chest wall photodynamic therapy for recurrent breast carcinoma and to compare it to the calculated irradiance.


METHODS
The spatial and time dependence of light fluence (rate) was monitored in vivo on the chest wall surface using isotropic detectors in five patients. Patients were given MLu either 4 mg/kg with light at 18 hours or 5 mg/kg with light at 24 hours using an irradiance of 150 J/cm(2) at 730 nm, with an incident fluence rate of 75 mW/cm(2). The ratio of fluence rate to the incident fluence rate was determined at the center of the treatment field. This ratio was used to estimate the effective attenuation coefficient, mu (eff).


RESULTS
The mean and standard deviation of the ratio for all patients was 1.6 +/- 0.2. The corresponding range of mu (eff) was between 0.87 and 2.1 cm(-1), assuming reduced scattering coefficient, mu (s) = 4 cm(-1).


CONCLUSIONS
A conversion factor was determined to convert the irradiance to fluence rate on the tissue surface. However, the fluence (or the ratio) on patient surface varied by 70% due to the heterogeneity of optical properties. This supports the use of real-time in vivo dosimetry during photodynamic therapy.
Dimofte
Andreea
A
Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-4283, USA.
Zhu
Timothy C
TC
Hahn
Stephen M
SM
Lustig
Robert A
RA
D000328:Adult; D001940:Breast / Q000528:radiation effects; D001943:Breast Neoplasms / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008027:Light; D008665:Metalloporphyrins / Q000627:therapeutic use*; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011874:Radiometry; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D035441:Thoracic Wall / Q000528:radiation effects; D013997:Time Factors
D008665:Metalloporphyrins; D017319:Photosensitizing Agents; C102825:motexafin lutetium