{"id":{"repo_id":"buffalo","oai_identifier":"oai:ubir.buffalo.edu:10477/78640"},"canonical_url":"https://search.dev.ndltd.org/etd/buffalo/oai:ubir.buffalo.edu:10477/78640","repository":{"repo_id":"buffalo","name":"Buffalo","base_url":"https://ubir.buffalo.edu/oai/request"},"display":{"title":"On Tumor Motion, Delineation Strategies, and Respiratory Induced Density Variations Associated with Stereotactic Lung Radiotherapy","abstract":"Ph.D.","abstract_html":"Ph.D.","abstract_has_math":false,"creators":["Mohatt, Dennis"],"institution":"State University of New York at Buffalo","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Malhotra, Harish","Radiology"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2018,"date_issued":"2018-10-26T02:57:17Z","date_published":"2018-10-26T02:57:17Z","updated_at":"2026-07-27T19:05:14Z","subjects":["biophysics","physiology"],"languages":["eng"],"rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10477/78640","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Malhotra, Harish","Radiology"]},{"key":"dc:creator","label":"Author","values":["Mohatt, Dennis"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-10-26T02:57:17Z","2018","2018-08-10 18:09:36"]},{"key":"dc:publisher","label":"Institution","values":["State University of New York at Buffalo"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation","Text"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["biophysics","physiology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/10477/78640"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Ph.D.","Stereotactic lung radiotherapy exploits the use of an ablative dose which demands the highest levels of precision and accuracy in every aspect of the treatment planning and delivery process. Hence, motion management, implementation of very small tumor margins, and the accuracy of the dose distribution predicted by the treatment planning system are of paramount importance in reducing patient risk of long term morbidity. In our first study, a quantitative assessment of lung tumor motion was made for 65 patients under abdominal compression using four-dimensional computed tomography (4DCT) imaging. In this clinical study, we have shown that the range of lung tumor mobility to be lobe location dependent, and increases as we are near the lower lobes of the lungs towards the diaphragm. We also found a strong correlation for the Right Upper Lobe (RUL) lesions between the ranges of tumor movement with respect to respiratory cycle. Our second study entailed an investigation into the range dependence of target delineation strategies for stereotactic lung radiotherapy. The purpose of this study was to evaluate alternative target segmentation strategies with respect to the 10 phase “gold standard” benchmark. In clinical scenarios for lung tumor displacements up to 2 cm, we found best conformance using the Free Breathing (FB)-Augmented technique comparable to the 10 phase benchmark, followed by the Maximum Intensity Projection (MIP) approach, then Average Intensity Projection (AIP), and finally FB. For PTV structures based on the delineation of the single phase FB image set, we have shown even with 10 mm superior-inferior margin [5 mm axial] yields suboptimal tumor coverage potentially leading to errors in dose delivery. Finally, our third study focused on the technical and dosimetric implications of respiratory induced density variations in a heterogeneous lung phantom. Again, we utilized 4DCT imaging to generate AIP, FB, and MIP image sets as basis to distinguish between different representations in target density. We also introduced a fourth dataset for dose computation based on a novel phase weighted density (PWD) technique. In the most extreme case scenario, the mean CT difference between FB and MIP datasets was found to be greater than 200 HU, however, the dose difference between CT datasets is small and could not be quantified with ion chamber. In brief, the PWD technique demonstrating slightly better conformity over AIP and FB based computations (gamma 3%, 1mm). As verified in previous studies, our results confirm a clear advantage in terms delivery accuracy and relative decrease in calculated lung dose when using Acuros XB over the Analytic Anisotropic Algorithm (AAA)."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["On Tumor Motion, Delineation Strategies, and Respiratory Induced Density Variations Associated with Stereotactic Lung Radiotherapy"]}]}],"canonical_facts":{"dc:contributor":["Malhotra, Harish","Radiology"],"dc:creator":["Mohatt, Dennis"],"dc:date":["2018-10-26T02:57:17Z","2018","2018-08-10 18:09:36"],"dc:description":["Ph.D.","Stereotactic lung radiotherapy exploits the use of an ablative dose which demands the highest levels of precision and accuracy in every aspect of the treatment planning and delivery process. Hence, motion management, implementation of very small tumor margins, and the accuracy of the dose distribution predicted by the treatment planning system are of paramount importance in reducing patient risk of long term morbidity. In our first study, a quantitative assessment of lung tumor motion was made for 65 patients under abdominal compression using four-dimensional computed tomography (4DCT) imaging. In this clinical study, we have shown that the range of lung tumor mobility to be lobe location dependent, and increases as we are near the lower lobes of the lungs towards the diaphragm. We also found a strong correlation for the Right Upper Lobe (RUL) lesions between the ranges of tumor movement with respect to respiratory cycle. Our second study entailed an investigation into the range dependence of target delineation strategies for stereotactic lung radiotherapy. The purpose of this study was to evaluate alternative target segmentation strategies with respect to the 10 phase “gold standard” benchmark. In clinical scenarios for lung tumor displacements up to 2 cm, we found best conformance using the Free Breathing (FB)-Augmented technique comparable to the 10 phase benchmark, followed by the Maximum Intensity Projection (MIP) approach, then Average Intensity Projection (AIP), and finally FB. For PTV structures based on the delineation of the single phase FB image set, we have shown even with 10 mm superior-inferior margin [5 mm axial] yields suboptimal tumor coverage potentially leading to errors in dose delivery. Finally, our third study focused on the technical and dosimetric implications of respiratory induced density variations in a heterogeneous lung phantom. Again, we utilized 4DCT imaging to generate AIP, FB, and MIP image sets as basis to distinguish between different representations in target density. We also introduced a fourth dataset for dose computation based on a novel phase weighted density (PWD) technique. In the most extreme case scenario, the mean CT difference between FB and MIP datasets was found to be greater than 200 HU, however, the dose difference between CT datasets is small and could not be quantified with ion chamber. In brief, the PWD technique demonstrating slightly better conformity over AIP and FB based computations (gamma 3%, 1mm). As verified in previous studies, our results confirm a clear advantage in terms delivery accuracy and relative decrease in calculated lung dose when using Acuros XB over the Analytic Anisotropic Algorithm (AAA)."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/10477/78640"],"dc:language":["eng"],"dc:publisher":["State University of New York at Buffalo"],"dc:rights":["Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.","Copyright retained by author."],"dc:subject":["biophysics","physiology"],"dc:title":["On Tumor Motion, Delineation Strategies, and Respiratory Induced Density Variations Associated with Stereotactic Lung Radiotherapy"],"dc:type":["Dissertation","Text"]},"updated_at":"2026-07-27T19:05:14Z"}