It is desirable to quantify the distribution of the light fluence rate, the optical properties, the drug concentration, and the tissue oxygenation for photodynamic therapy (PDT) of prostate cancer. We have developed an integrated system to determine these quantities before and after PDT treatment using motorized probes. The optical properties (absorption (μa), transport scattering (μs′), and effective attenuation (μeff) coefficients) of cancerous human prostate were measured in-vivo using interstitial isotropic detectors. Measurements were made at 732 nm before and after motexafin lutetium (MLu) mediated PDT at different locations along each catheter. The light fluence rate distribution was also measured along the catheters during PDT. Diffuse absorption spectroscopy measurement using a white light source allows extrapolation of the distribution of oxygen saturation (StO2), total blood volume ([Hb]t), and MLu concentration. The distribution of drug concentration was also studied using fluorescence from a single optical fiber, and was found to be in good agreement with the values determined by absorption spectroscopy. This study shows significant inter- and intra-prostatic variations in the tissue optical properties and MLu drug distribution, suggesting that a real-time dosimetry measurement and feedback system for monitoring these values during treatment should be considered in future PDT studies.

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Determination of the distribution of light, optical properties, drug concentration, and tissue oxygenation in-vivo in human prostate during motexafin lutetium-mediated photodynamic therapy.

Prostate PDT dosimetry

SUMMARY This paper studies a decision theoretic method for timing medical examinations. The specific model is motivated by screening asymptomatic individuals for hidden disease or risk-increasing conditions. Ideas and strategies may be applied more broadly to problems in which a stochastic process is monitored over time with a costly and possibly faulty data collection procedure. The decision space is modelled as a space of functions, termed screening intensity functions. Results include explicit rules for deciding whether or not an individual of given age and risk factors should be screened for a disease, and for deciding when an individual examined today should be examined again. Breast cancer screening

Timing medical examinations via intensity functions

Many diseases can be prevented or treated if they can be detected early or signaled before their occurrence. Disease early detection and prevention (DEDAP) is thus important for health improvement ...

Marilyn Stromborg

Papers

Screening for early detection.