Comparison between isotropic and nonisotropic dosimetry systems during intraperitoneal photodynamic therapy.
OBJECTIVE
On-line monitoring of light fluence during intraperitoneal photodynamic therapy (IP PDT) is crucial for safe light delivery. A flat photodiode-based dosimetry system is compared with an isotropic detector-based system in patients undergoing IP PDT.


METHODS
Flat photodiodes and spherical detectors were placed side by side in the abdomen, for simultaneous light dosimetry in 19 patients. Tissue phantom experiments were performed to provide a preliminary estimate of the tissue optical properties of the peritoneum.


RESULTS
The conversion factor between systems for 630-nm light was found to be 1.7 +/- 0.12. The mu(eff) of the tissues in the abdomen is estimated to vary between 0.5 cm(-1) to 1.4 cm(-1) assuming a mu(s)' = 7 cm(-1).


CONCLUSIONS
The measured conversion factor should allow for comparison of light fluences with future clinical protocols that use an isotropic-based detector system. Differences in the optical properties of the underlying tissues may contribute to the variability in light measurements.
Vulcan
T G
TG
Department of Physics and Astronomy University of Pennsylvania, Philadelphia, Pennsylvania 19104-4283, USA.
Zhu
T C
TC
Rodriguez
C E
CE
Hsi
A
A
Fraker
D L
DL
Baas
P
P
Murrer
L H
LH
Star
W M
WM
Glatstein
E
E
Yodh
A G
AG
Hahn
S M
SM
D002985:Clinical Protocols; D017323:Dihematoporphyrin Ether / Q000008:administration & dosage*; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000188:drug therapy* / Q000601:surgery; D006414:Hematoporphyrin Photoradiation / Q000379:methods*; D006801:Humans; D008297:Male; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000601:surgery; D017319:Photosensitizing Agents / Q000008:administration & dosage*; D012509:Sarcoma / Q000188:drug therapy* / Q000601:surgery; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000379:methods
D017319:Photosensitizing Agents; D017323:Dihematoporphyrin Ether