Real-time tumor localization with electromagnetic transponders for image-guided radiotherapy applications

The detection of intrafraction organ motion, necessary for the minimization of treatment errors, is a remaining challenge in radiotherapy. A novel technology for the dynamic monitoring of tumor motion uses tumor-implanted electromagnetic (EM) transponders. In the present thesis, concepts and strategies for the use of the EM technology in image-guided radiotherapy (IGRT) are developed. First, the compatibility of the EM technology with the radiotherapy environment is investigated experimentally. Subsequently, a technique is developed that combines EM tumor localization with the x-ray imaging options of IGRT. This technique exploits the unique advantages of EM tumor localization (non-ionizating radiation, three-dimensional target localization) and those of x-ray imaging (volumetric information about organ deformation and rotation, localization of organs at risk). The technique has been applied successfully to the elimination of motion artifacts in cone-beam computed tomography. In addition, the real-time control of a dynamic multileaf collimator based on the EM transponders could be demonstrated. Finally, the EM tumor tracking technology is introduced clinically with a study on prostate motion. The concepts developed in this thesis improve the detection of intrafraction organ motion in IGRT and thus enable the treatment of dynamic target volumes with increased accuracy

Real-time tumor localization with electromagnetic transponders for image-guided radiotherapy applications

The detection of intrafraction organ motion, necessary for the minimization of treatment errors, is a remaining challenge in radiotherapy. A novel technology for the dynamic monitoring of tumor motion uses tumor-implanted electromagnetic (EM) transponders. In the present thesis, concepts and strategies for the use of the EM technology in image-guided radiotherapy (IGRT) are developed. First, the compatibility of the EM technology with the radiotherapy environment is investigated experimentally. Subsequently, a technique is developed that combines EM tumor localization with the x-ray imaging options of IGRT. This technique exploits the unique advantages of EM tumor localization (non-ionizating radiation, three-dimensional target localization) and those of x-ray imaging (volumetric information about organ deformation and rotation, localization of organs at risk). The technique has been applied successfully to the elimination of motion artifacts in cone-beam computed tomography. In addition, the real-time control of a dynamic multileaf collimator based on the EM transponders could be demonstrated. Finally, the EM tumor tracking technology is introduced clinically with a study on prostate motion. The concepts developed in this thesis improve the detection of intrafraction organ motion in IGRT and thus enable the treatment of dynamic target volumes with increased accuracy

Research and Technology, 1989

Selected research and technology activities at Ames Research Center, including the Moffett Field site and the Dryden Flight Research Facility, are summarized. These accomplishments exemplify the Center's varied and highly productive research efforts for 1989

Aerospace Medicine and Biology: A continuing bibliography with indexes

This bibliography lists 319 reports, articles, and other documents introduced into the NASA scientific and technical information system in May 1986

Life Sciences Program Tasks and Bibliography

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1995. Additionally, this inaugural edition of the Task Book includes information for FY 1994 programs. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive Internet web pag

Water productivity indices of the soybean grown on silty clay soil under sprinkler irrigation

The objective of this research was to compare the effects of different irrigation treatments on soybean [Glycine max (L.) Merr.] productivity and water use efficiency on experimental fields of the Maize Research Institute of Zemun Polje(Serbia), in 2007 and 2008. Four irrigation levels were investigated: full irrigation (I100), 65% and 40% of I100 (I65 and I40) and a rain-fed (I0) system. The crop water use efficiency (CWUE, also known as crop water productivity –CWP), irrigation water use efficiency (IWUE) and evapotranspiration water use efficiency (ETWUE) were used to assess the water productivity of each studied treatment. The efficiency of the same treatment differed between the years as it depended on seasonal water availability, weather conditions and their impact on seed yields. Maximum and minimum yields were obtained in the I65 and I0 treatments, averaging 3.41 t ha–1 and 2.26 t ha–1, respectively. Water use efficiency values were influenced by the irrigation levels. In general, CWUE values increased with the increased level of irrigation. In both growing seasons, IWUE and ETWUE decreased with increasing the seasonal water consumption and irrigation depth. On average, treatments I40 and I65 resulted in similar or higher CWUE and ETWUE than I100, in both growing seasons. I65 resulted in the highest IWUE, averaged over the two seasons, while I100 had the lowest IWUE. I65 could be proper for the soybean irrigated in Vojvodina when there is no water shortage and I45 could be used as a good basis for reduced sprinkler irrigation strategy development under water shortage