Source: Dissertation Abstracts International, Volume: 38-05, Section: B, page: 2209. / Thesis (Ph.D.)--The Florida State University, 1977.

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Single crystals of l-asparagine monohydrate and partially deuterated l-asparagine were x-irradiated at 4.2K, 77K, and room temperature by a 3Mev Van de Graaff electron accelerator. Several free radical species were produced by the x-irradiation and were studied by X-band ESR and ENDOR from 4.2K to 300K. X-irradiation at 77K produced two anion radicals, radicals I and III, with the unpaired spin at the carboxyl, and amide end of the molecule, respectively. Production of III must be less probable than I, since the ESR spectra of III appear to be less intense. X-irradiation at 77K also produced one cation radical (II), the decarboxylation radical. The ESR spectra of radical I are the most intense. Hyperfine tensors were determined for hydrogen ENDOR lines belonging to radicals I, II, and III. In addition, ENDOR lines for one nitrogen and two deuterium lines were observed. Tensors were determined for the nitrogen and one of the deuterium nuclei. These nitrogen and deuterium couplings were needed to explain the ESR spectra of radical II. There was probably another radical present at 77K, but there was not enough information to identify it. Radicals I, II, and III were also produced by x-irradiation at 4.2K. New unidentified ENDOR lines appeared after warming to 128K. Radicals I, II, and III were still observed at this temperature, but the ESR spectra have changed somewhat. After warming to 150K, radical I's ESR spectrum was not observed. Radical VI, the deamination radical, appears to begin to grow in at this temperature. Upon warming to 210K, radical II began decay by hydrogen abstraction to form radical IV which was identified in an earlier room temperature study. Three new ENDOR lines, though not completely followed through all orientations, combine correctly to predict the ESR spectral width along the c axis. Radical VI's ESR spectra became stronger after / warming to room temperature. For x-irradiation (of deuterated samples) at 300K, radical VI's spectra was much weaker than radical IV's, but for x-irradiation at 77K followed by warming to 300K radical VI's spectra was almost as intense as radical IV's spectra. / Source: Dissertation Abstracts International, Volume: 46-09, Section: B, page: 3105. / Thesis (Ph.D.)--The Florida State University, 1985.

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Graduation date: 1968

Solar radiation intensities, incident to the sea surface off the Oregon coast, are measured and compared. Simplification of some physical and biological problems can be anticipated if the average radiation received over a broad segment of ocean can be accurately indicated by the amount recorded at the land station. The area of ocean over which the study was made extends the length of the Oregon coast and 165 miles to sea. The measurements were made during the months of June, July, August, and September 1963 with an Eppley total radiation pyrheliometer. A division of the study area into Newport and three zones parallel to the coast separated the data into comparative groups. Clear sky radiation values, assumed constant with longitude, are used as bases for comparison. For each value of observed radiation, a corresponding clear sky value was calculated using standard techniques. Curves, based on a dust-free atmosphere with two cm of precipitable water, are developed to provide these calculated values. Before the recorded values from the zones are compared, their corresponding calculated spectra are adjusted to be identical. This is done by weighting the number of observations in each classification. In all instances, the zone values are adjusted to those of Newport. Comparison is made between mean intensity values, percentages of calculated clear sky values, relative and cumulative frequencies of intensities, and composites of daily traces. Two methods of analysis are employed. One classifies data by intensity level, and the other classifies it by the hour of the day during which it was recorded. Not enough observations were available in the two zones farthest from Newport to provide smooth curves. It is found, however, that there is essentially no change with longitude in observed intensity spectra and means. It is concluded that the average radiation recorded at Newport indicates with some accuracy the average radiation received over the section of ocean in question. / Graduation date: 1965

In radiation therapy it is very important to accurately measure the amount of radiation delivered. The effectiveness of the treatment depends on delivering the dose with an accuracy of 5% or better. The dosimetry in different clinics must also be consistent. For these reasons national and international calibration protocols have been developed. In the US, the American Association of Physicists in Medicine (AAPM) has published several national dosimetry protocols for the calibration of high-energy photon and electron beams. In this study the absorbed dose-to-water determined according to TG-21 and TG-51 protocols, developed by Task Group 21 and Task Group 51 of the Radiation Therapy of AAPM, are compared. The older protocol, TG-21, is based on exposure calibrated ionization chambers using a ⁶⁰Co beam. Many standards laboratories have started to replace exposure standards with those involving absorbed dose-to-water. The new protocol, TG-51, is based on absorbed dose-to-water calibrated ionization chambers using a ⁶⁰Co beam. Also, there are some differences between the beam quality specifiers and data proposed by the two protocols. A comparison between TG-21 and TG-51 protocols was done by determining the radiation dose rate at a designated distance for 6 and 18 MV photon beams, and 16 and 20 MeV electron beams, generated by Clinac a 2100 C linear accelerator. The cylindrical ionization chambers used in this study were Capintec PR-06G and PR-05. The results of the study show a discrepancy between the absorbed dose-to-water determined according to TG-21 and TG-51 protocols of about 1.4% and 1.7% for 6 and 18 MV photon beams, respectively. Absorbed dose-to-water determined according to TG-21 and TG-51 protocols for 16 MeV energy electron beams agree within 1.8%, while the ones of 20 MeV energy beams agree to within 2.4%. The change from exposure to absorbed dose-to-water calibrated ionization chambers has the largest impact on the differences between TG-21 and TG-51 absorbed dose-to-water, while the change in beam quality specifier and stopping power ratios have only a very small effect on these differences. The TG-51 protocol is very simple, minimizing the chance of mistakes, because it starts with absorbed dose-to-water calibration, while the TG-21 is very complex, starting with the calibration for exposure, which is different from the absorbed dose-to-water, the clinical quantity of interest. The TG-51 protocol allows the determination of a more accurate absorbed dose in a ⁶⁰Co beam than the TG-21 protocol since it uses an absorbed dose-to-water calibration factor directly measured, while the exposure based dosimetry system is dependent on external physical data which are not measured in clinics. / Graduation date: 2003

The ability of ionizing radiation to enhance colon carcinogenesis and the role of diet in this process has not been documented. We hypothesized that radiation would enhance the formation of aberrant crypt foci, ACF, known precursor lesions to colon cancer, by suppressing apoptosis and upregulating proliferation in colonocytes. Diets contained a combination of fish oil or corn oil and either pectin or cellulose. We exposed 40 male Sprague-Dawley rats to 1 Gy ionizing radiation (1 GeV Fe) 10 d prior to injection with AOM. Colons were resected at the promotion stage of carcinogenesis (7 wk post initial injection) and assayed for ACF and apoptosis. Radiation treatment increased (P=0.0327) the incidence of high multiplicity ACF (foci with four or more aberrant crypts) and decreased (P=0.0340) the apoptotic index compared to non-irradiated rats. Radiation also resulted in an increase (P<0.0001) in the proliferative index compared to the nonirradiated rats. The fish oil containing diets resulted in fewer (P=0.0002) high-multiplicity ACF compared to the corn oil treatment. Dietary pectin significantly increased (P=0.0204) the apoptotic index compared to cellulose treatment. These data suggest that ionizing radiation can work synergistically with AOM and increase the formation of high-multiplicity ACF, upregulate cellular proliferation and decrease apoptosis in colonocytes. The data also suggest that diets containing fish oil and pectin may protect against colon cancer by increasing apoptosis and reducing the formation of high multiplicity ACF.

Recent events have underscored the need for the United States government to provide streamlined emergency response procedures and subsequent dose estimations for personnel responding to incidents involving radioactive material. Indeed, the National Council on Radiation Protection and Measurements Report No. 138 (NCRP 2001) indicates that exposures received by first responders will be important for a number of reasons, including planning for the appropriate use of key personnel in an extended emergency situation. In response, the Department of Homeland Security has published Protective Action Guides (DHS 2006) to help minimize these exposures and associated risks. This research attempts to provide some additional radiological exposure knowledge so that an Incident Commander, with limited or no information, can make more informed decisions about evacuation, sheltering-in-place, relocation of the public, turn-back levels, defining radiation hazard boundaries, and in-field radiological dose assessments of the radiation workers, responders, and members of the public. A method to provide such insight begins with providing a model that describes the physics of radiation interactions, radiation source and geometry, collection of field measurements, and interpretation of the collected data. A Monte Carlo simulation of the model is performed so that calculated results can be compared to measured values. The results of this investigation indicate that measured organ absorbed doses inside a tissue equivalent phantom compared favorably to the derived organ absorbed doses measured by the Panasonic thermoluminescence dosimeters and with Monte Carlo ‘N’ Particle modeled results. Additionally, a Victoreen 450P pressurized ion chamber measured the integrated dose and these results compared well with the Panasonic right lateral TLD. This comparison indicates that the Victoreen 450P ionization chamber could potentially serve as an estimator of real-time effective dose and organ absorbed dose, if energy and angular dependence corrections could be taken into account. Finally, the data obtained in this investigation indicate that the MCNP model provided a reasonable method to determine organ absorbed dose and effective dose of a simulated Radiological Dispersal Device in an Inferior-Superior geometry with Na99mTcO4 as the source of radioactive material.

The ability of ionizing radiation to enhance colon carcinogenesis and the role of diet in this process has not been documented. We hypothesized that radiation would enhance the formation of aberrant crypt foci, ACF, known precursor lesions to colon cancer, by suppressing apoptosis and upregulating proliferation in colonocytes. Diets contained a combination of fish oil or corn oil and either pectin or cellulose. We exposed 40 male Sprague-Dawley rats to 1 Gy ionizing radiation (1 GeV Fe) 10 d prior to injection with AOM. Colons were resected at the promotion stage of carcinogenesis (7 wk post initial injection) and assayed for ACF and apoptosis. Radiation treatment increased (P=0.0327) the incidence of high multiplicity ACF (foci with four or more aberrant crypts) and decreased (P=0.0340) the apoptotic index compared to non-irradiated rats. Radiation also resulted in an increase (P<0.0001) in the proliferative index compared to the nonirradiated rats. The fish oil containing diets resulted in fewer (P=0.0002) high-multiplicity ACF compared to the corn oil treatment. Dietary pectin significantly increased (P=0.0204) the apoptotic index compared to cellulose treatment. These data suggest that ionizing radiation can work synergistically with AOM and increase the formation of high-multiplicity ACF, upregulate cellular proliferation and decrease apoptosis in colonocytes. The data also suggest that diets containing fish oil and pectin may protect against colon cancer by increasing apoptosis and reducing the formation of high multiplicity ACF.