MEASUREMENT OF TUMOR BLOOD FLOW FOLLOWING NEUTRON IRRADIATION (ACTIVATION)

Clinical oncologists and cancer researchers benefit from information on the vascularization or non-vascularization of solid tumors because of blood flow's influence on three popular treatment types: hyperthermia therapy, radiotherapy, and chemotherapy. The objective of this research is the development of a clinically useful tumor blood flow measurement technique. The designed technique is sensitive, has good spatial resolution, in non-invasive and presents no risk to the patient beyond his usual treatment (measurements will be subsequent only to normal patient treatment).^ Tumor blood flow was determined by measuring the washout of positron emitting isotopes created through neutron therapy treatment. In order to do this, several technical and scientific questions were addressed first. These questions were: (1) What isotopes are created in tumor tissue when it is irradiated in a neutron therapy beam and how much of each isotope is expected? (2) What are the chemical states of the isotopes that are potentially useful for blood flow measurements and will those chemical states allow these or other isotopes to be washed out of the tumor? (3) How should isotope washout by blood flow be modeled in order to most effectively use the data? These questions have been answered through both theoretical calculation and measurement.^ The first question was answered through the measurement of macroscopic cross sections for the predominant nuclear reactions in the body. These results correlate well with an independent mathematical prediction of tissue activation and measurements of mouse spleen neutron activation. The second question was addressed by performing cell suspension and protein precipitation techniques on neutron activated mouse spleens. The third and final question was answered by using first physical principles to develop a model mimicking the blood flow system and measurement technique.^ In a final set of experiments, the above were applied to flow models and animals. The ultimate aim of this project is to apply its methodology to neutron therapy patients. ^

Screening for anemia in Red Cross blood donor clinics

Accurate screening for anemia at Red Cross blood donor clinics is essential to maintain a safe national blood supply. Despite the importance of identifying anemia correctly by measurement of hemoglobin or hematocrit (hemoglobin/hematocrit) there is no consensus regarding the efficacy of the current two stage screening method which uses the Readacrit$\sp{\rm tm}$ microhematocrit in conjunction with copper sulfate.^ A cross-sectional study was implemented in which hemoglobin/hematocrit was measured, with the present method and four new devices, on 504 prospective blood donors at a Canadian Red Cross permanent blood donor clinic in London, Canada. Concurrently gathered, venous and capillary blood samples were tested by each device and compared to Coulter S IV$\sp{\rm tm}$ determined venous standard readings. Instrument hemoglobin/hematocrit means were statistically calibrated to the standard ones in order to appraise systematic deviations from the standard. Classification analysis was employed to assess concordance between each instrument and the standard when classifying prospective donors as anemic or non-anemic. This was done both when each instrument was used alone (single stage) and when copper sulfate was used as a preliminary screen (two stage) and simulated over a range of anemia prevalences. The Hemoximeter$\sp{\rm tm}$ and Compur M1000$\sp{\rm tm}$ devices had the highest correlations of hemoglobin measurements with the standard ones for both capillary (n.s.) and venous blood (p $<$.05). Analysis of variance (anova) also showed them to be the most accurate (p $<$.05), as did both single and two stage classification analysis, therefore, they are both recommended. There was a smaller difference between instruments for two stage than for single stage screening; therefore instrument choice is less crucial for the former. The present method was adequate for two stage screening as tested but simulations showed that it would discriminate poorly in populations with a higher prevalence of anemia. The Stat-crit and Readacrit, which measure hematocrit, became less accurate at crucial low hematocrit levels. In light of this finding and the introduction of new, effective and easy to use hemoglobin measuring instruments, the continued use of hematocrit as a surrogate for hemoglobin, is not recommended. ^