Yttrium-90 microsphere brachytherapy of the liver exploits the distinctive features of the liver anatomy to treat liver malignancies with beta radiation and is gaining more wide spread clinical use. This report provides a general overview of microsphere liver brachytherapy and assists the treatment team in creating local treatment practices to provide safe and efficient patient treatment. Suggestions for future improvements are incorporated with the basic rationale for the therapy and currently used procedures. Imaging modalities utilized and their respective quality assurance are discussed. General as well as vendor specific delivery procedures are reviewed. The current dosimetry models are reviewed and suggestions for dosimetry advancement are made. Beta activity standards are reviewed and vendor implementation strategies are discussed. Radioactive material licensing and radiation safety are discussed given the unique requirements of microsphere brachytherapy. A general, team-based quality assurance program is reviewed to provide guidance for the creation of the local procedures. Finally, recommendations are given on how to deliver the current state of the art treatments and directions for future improvements in the therapy.
The shielding of positron emission tomography (PET) and PET/CT (computed tomography) facilities presents special challenges. The 0.511 MeV annihilation photons associated with positron decay are much higher energy than other diagnostic radiations. As a result, barrier shielding may be required in floors and ceilings as well as adjacent walls. Since the patient becomes the radioactive source after the radiopharmaceutical has been administered, one has to consider the entire time that the subject remains in the clinic. In this report we present methods for estimating the shielding requirements for PET and PET/CT facilities. Information about the physical properties of the most commonly used clinical PET radionuclides is summarized, although the report primarily refers to fluorine-18. Typical PET imaging protocols are reviewed and exposure rates from patients are estimated including self-attenuation by body tissues and physical decay of the radionuclide. Examples of barrier calculations are presented for controlled and noncontrolled areas. Shielding for adjacent rooms with scintillation cameras is also discussed. Tables and graphs of estimated transmission factors for lead, steel, and concrete at 0.511 MeV are also included. Meeting the regulatory limits for uncontrolled areas can be an expensive proposition. Careful planning with the equipment vendor, facility architect, and a qualified medical physicist is necessary to produce a cost effective design while maintaining radiation safety standards.
This study demonstrates an important advantage of web-based applications to collect and evaluate CAI utilization efficiently and objectively at both the level of the class and the level of the individual student.
A two-year study was conducted to provide summative evaluations of web-based computer-aided instruction (CAI) specifically designed to supplement the laboratory dissections in the medical human anatomy course. Utilization of CAI was analyzed using server statistics, student surveys and network login tables. There was a significant increase in server requests for CAI over the period of the course in both years of the study. In general, student surveys corresponded with the login data for individual students, although several discrepancies showed limitations of the respective methodologies. When course examination scores were compared to the number of CAI logins for individual students, there were statistically significant direct correlations between exam grades and frequency of CAI use. Our findings illustrate the value of combining server statistics with user surveys for evaluations of CAI as an effective supplement for student learning in the anatomy curriculum.
Summary: In the glucose analog method for determining local glucose utilization rates, time courses of tissue and plasma radioactivity are measured and then analyzed in terms of first-order exchange of label between tissue compartments, The rate of glucose utilization is assumed to have a fixed, linear relationship to the analog phos phorylation rate calculated from the fitted rate constants, Accurate estimation of the rate constants requires many hours of dynamic data acquisition, Therefore, techniques assuming a linear relationship between analog phosphor ylation rate and total tissue concentration of label were developed to predict glucose utilization rates from aThe use of glucose analogs for in vivo determi nation of the local rate of glucose utilization is well established (Sokoloff et aI., 1977; Phelps et aI., 1979; Reivich et aI., 1979 Reivich et aI., , 1982. Measured kinetics of labeled analog in the tissue of interest and in arterial plasma can be used to estimate the local rate of hexokinase-catalyzed phosphorylation of the an alog per unit plasma concentration. This rate is as sumed to have a fixed linear relationship to the net utilization of glucose. However, accurate estima tion of the actual analog kinetic rate constants re quires serial measurements of tissue and plasma ra diolabel concentrations over many hours. Serial measurements in the same tissue are clearly impos sible when using methods based on beta labeling and film autoradiography. In these methods, time courses are constructed by averaging the values
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