Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 248)

This bibliography lists 364 reports, articles and other documents introduced into the NASA scientific and technical information system in July 1983

Samarium-Doped Fluorophosphate and Fluoroaluminate Glasses for High-Dose High-Resolution Dosimetry for Microbeam Radiation Therapy

Microbeam Radiation Therapy (MRT) is an important and developing radiotherapy technique that uses spatially fractionated doses, several orders of magnitude larger than that of the doses used in conventional radiation therapy. Healthy tissue displays remarkable resistance to damage caused from microscopically narrow, fractionated, planar beams of x-rays, while showing preferential damage towards cancerous growths, allowing for a high potential towards the treatment of often inoperable tumours. These synchrotron generated, spatially fractionated, planar beams are referred to as microbeams, and have a thickness of 20 – 50 µm and are separated by distances of 100 – 400 µm. The dose delivered at the center of the microbeam can be on the order of thousands of Grays (Gy), whereas the dose between each microbeam should be kept below tens of Gy. An important aspect of MRT is the spatial distribution of the dose delivered to the patient, which must be accurately measured. Ultimately, both high resolution and large dynamic range dosimetric measurements must be done simultaneously. The objective of this Ph.D. research involves the development and characterization of a dosimetric technique that fulfills the requirements of measuring dose distributions of microbeams. The proposed technique uses the indirect detection of x-rays, where the dose is recorded in a glass plate which can then be readout using a confocal microscopy system. The dose delivered is recorded by using trivalent samarium (Sm3+) doped fluoroaluminate and fluoro-phosphate glasses, where conversion from the trivalent form of samarium to the divalent form (Sm2+) occurs after exposure to x-rays. The extent of this conversion can be readout and digitized with high resolution using a confocal microscopy system that utilizes the easily distinguishable photoluminescent spectra of Sm3+ to Sm2+. The work carried out in this research involves the high resolution recording of microbeam profiles performed at the Canadian synchrotron, using samarium doped glass plates under a variety of irradiation parameters in order to determine their suitability for dosimetric applications. In particular, the dose rate and x-ray energy dependence of these materials is investigated, as well as the determination of the optimum Sm3+ dopant concentration. Further, the confocal measurement technique is investigated, as well as the suitability of ion implantation of samarium ions in order to improve the signal readout. Lastly, the change in dose distributions of microbeams is investigated by performing irradiations over a wide range of monochromatic x-rays, so that the potential effect of the selected energy on MRT treatment planning can be examined

Radiobiology of normal rat lung in Boron Neutron Capture Therapy

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.Includes bibliographical references.Boron Neutron Capture Therapy (BNCT) is a binary cancer radiation therapy that utilizes biochemical tumor cell targeting and provides a mixed field of high and low Linear Energy Transfer (LET) radiation with differing biological effectiveness. This project investigated the radiobiology of normal rat lung in BNCT and measured the relative biological effectiveness factors for the lung. Rat thorax irradiations were carried out with x-rays and neutrons with or without the boron compound boronophenylalanine-fructose (BPA-F). Monte Carlo radiation transport simulations were used to design the rat lung neutron irradiations. Among the neutron beam facilities available for BNCT at the MIT Research Reactor, the thermal neutron beam facility was found to provide a suitable dose distribution for this project. A delimiter was designed and constructed for the rat lung irradiations as a lithiated-polyethylene plate of 1.5 cm thickness with an aperture tapered from 4 to 3 cm in width to expose the lung to the beam and shield adjacent radiosensitive organs. The simulation design was validated with in-phantom measurements using gold foil activation and the dual ion chamber technique. By using a two-field irradiation, a relatively uniform dose distribution could be delivered to the rat lung. The mean lung dose rate was 18.7 cGy/min for neutron beam only irradiation and 37.5 cGy/min with neutrons plus BPA and a blood boron concentration of 18 gg/g.(cont.) The delimiter designed for rat lung irradiation, and another similar delimiter, along with the animal holding box, all designed in this project, also serve as the apparatus for other small animal irradiations and cell irradiations at the thermal neutron facility at the MIT Research Reactor. An open-flow whole-body plethysmography system with fully automated signal processing programs was developed to non-invasively measure rat breathing rates and lung functional damage after lung irradiation. Noise reduction was carried out against high frequencies beyond the range of rat breathing frequency and large amplitude spikes due to abnormal animal movement. The denoised breathing signals were analyzed using the Fast Fourier Transform with a circular moving block in combination with the bootstrap for noise suppression and to allow estimation of the statistical uncertainty (standard deviation) of frequency measurements. The major frequency of the mean frequency spectrum was determined as the breathing frequency. The mean control breathing rate was 176 ± 13 (7.4%) min' (mean ± SD), and breathing rates 20% (- 3 SD) above the control average were considered to be abnormally elevated. The mean standard deviation of all measurements (n = 4269) was 2.4%. The dose responses of different irradiation groups with breathing rate elevation as the biological endpoint were evaluated with probit analysis. Two response phases of breathing rate elevation were observed as the early response phase (100 days). The ED50 values for x-rays, neutrons only, and neutrons plus BPA during the early response phase, and neutrons plus BPA during the late response phase, were 11.5 ± 0.4 Gy, 9.2 + 0.5 Gy, 8.7 ± 0.6 Gy and 6.7 ± 0.4 Gy, respectively.(cont.) The radiobiological weighting factors for the neutron beam (neutrons and photons), thermal neutrons only, %°B dose component during the early response phase, and 10B dose component during the late response phase were 1.24 ± 0.08, 2.2 ± 0.4, 1.4 ± 0.2, and 2.3 + 0.3, respectively. The histological damage to the lung during the late phase was also quantified with a histological scoring system. A set of linear dose response curves with histological damage as the endpoint was constructed. The radiobiological weighting factors for the different dose components were also determined at a degree of lung histological damage corresponding to a median histological score between the baseline (similar to the control) and the maximum. The weighting factors measured, 1.22 ± 0.09 for the thermal neutron beam and 1.9 + 0.2 for the o1B dose component, are consistent with the corresponding weighting factors measured using functional damage. The knowledge gained in these radiobiological studies of the normal rat lung indicates that the lung complications experienced by two patients in the Harvard-MIT clinical trial of BNCT for brain tumors do not appear to be related to the BNCT irradiations. This project is also helpful for evaluating the feasibility of BNCT for lung cancer.by Jingli Liu Kiger.Ph.D

Quantification of Pulmonary Ventilation using Hyperpolarized 3He Magnetic Resonance Imaging

Smoking-related lung diseases including chronic obstructive pulmonary disease (COPD) and lung cancer are projected to have claimed the lives of more than 30,000 Canadians in 2010. The poor prognosis and lack of new treatment options for lung diseases associated with smoking are largely due to the inadequacy of current techniques for evaluating lung function. Hyperpolarized 3He magnetic resonance imaging (MRI) is a relatively new technique, and quantitative measurements derived from these images, specifically the ventilation defect volume (VDV) and ventilation defect percent (VDP) have the potential to provide new sensitive measures of lung function. Here, we evaluate the reproducibility of VDV, and explore the sensitivity of these measurements in healthy young and elderly volunteers, and subjects with smoking-related lung disease (COPD and radiation-induced lung injury (RILI)). Our results show that 3He MRI measurements of ventilation have high short-term reproducibility in both healthy volunteers and subjects with COPD. Additionally, we report that these measurements are sensitive to age-related changes in lung function. Finally, in RILI we show that measurements of lung function derived from 3He MRI are sensitive to longitudinal changes in lung function following treatment, while in COPD we report that using VDP in conjunction with structural measurements of disease (using the apparent diffusion coefficient (ADC) derived from diffusion-weighted images) may provide a new method for phenotyping this smoking-related lung disease

Argonne National Laboratory Reports

Annual report of the Argonne National Laboratory Division of Biological and Medical Research summarizing research an other activities. This report includes the exploration of the toxicological effects of effluents from various forms of energy production with a view to defining hazards and risk assessments for man

Applications of Medical Physics

Applications of Medical Physics” is a Special Issue of Applied Sciences that has collected original research manuscripts describing cutting-edge physics developments in medicine and their translational applications. Reviews providing updates on the latest progresses in this field are also included. The collection includes a total of 20 contributions by authors from 9 different countries, which cover several areas of medical physics, spanning from radiation therapy, nuclear medicine, radiology, dosimetry, radiation protection, and radiobiology

Toxicological profile for ionizing radiation (update)

Prepared by Research Triangle Institute under Contract No. 205-93-0606 to the U.S. Dept. of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry.Chemical manager(s)/author(s): Sam Keith, H. Edward Murray, ATSDR, Division of Toxicology, Atlanta, GA; Wayne Spoo, Research Triangle Institute, Research Triangle Park, NC."September 1999.""Prepared by Research Triangle Institute;prepared for U.S. Department of Health and Human Services Public Health Service Agency for Toxic Substances and Disease Registry."Also available via the World Wide Web (accessed 2003 July 3).Includes bibliographical references (p. 351-396)

Radioisotopes

The book Radioisotopes - Applications in Physical Sciences is divided into three sections namely: Radioisotopes and Some Physical Aspects, Radioisotopes in Environment and Radioisotopes in Power System Space Applications. Section I contains nine chapters on radioisotopes and production and their various applications in some physical and chemical processes. In Section II, ten chapters on the applications of radioisotopes in environment have been added. The interesting articles related to soil, water, environmental dosimetry/tracer and composition analyzer etc. are worth reading. Section III has three chapters on the use of radioisotopes in power systems which generate electrical power by converting heat released from the nuclear decay of radioactive isotopes. The system has to be flown in space for space exploration and radioisotopes can be a good alternative for heat-to-electrical energy conversion. The reader will very much benefit from the chapters presented in this section

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 181

This bibliography lists 223 reports, articles, and other documents introduced into the NASA scientific and technical information system in May 1978