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postgraduate thesis: Treatment planning comparison between coplanar and non-coplanar intensity modulated radiation therapy for late-stage nasopharyngeal carcinoma

TitleTreatment planning comparison between coplanar and non-coplanar intensity modulated radiation therapy for late-stage nasopharyngeal carcinoma
Authors
Issue Date2016
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Mok, W. [莫華威]. (2016). Treatment planning comparison between coplanar and non-coplanar intensity modulated radiation therapy for late-stage nasopharyngeal carcinoma. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.
AbstractPurpose/Objective(s): The purpose of this study was to compare the dosimetric difference between coplanar and non-coplanar intensity-modulated radiation therapy (IMRT) for late-stage nasopharyngeal carcinoma (NPC). The potential benefits of non-coplanar IMRT in treatment of late-stage NPC would be highlighted so as to provide radiation oncologist with an alternative option for individual clinical case. Methods: Ten late-stage (Stage III and IV) NPC patients were planned by both 1) non-coplanar IMRT and 2) coplanar IMRT using the 〖Philips Pinnacle〗^3 version 9.6 treatment planning system. Standard 9-field IMRT with each beam separated by 40 degrees would be used for coplanar IMRT. For non-coplanar IMRT, 9 coplanar beams which orientations are the same as that used in coplanar IMRT would be applied and 2 extra non-coplanar beams of 90 degree couch angle would be added. The dose levels of planning target volumes (PTVs) with 70/60/54 Gy in 33 fractions were prescribed and delivered as a simultaneous integrated boost. The homogeneity index, conformity index of PTVs, dose to organs at risk (OARs), such as, brainstem, spinal cord, optic chiasm, optic nerves, lens and temporal lobe and monitor units (MU) would be analyzed. Results: All plans fulfilled the departmental planning criteria. Non-coplanar IMRT showed better homogeneity and PTV coverage than coplanar IMRT. Significant reduction of doses for optic chiasm and right lens were observed in coplanar IMRT when comparing with non-coplanar IMRT. A reduction of maximum dose of optic chiasm by 4.29±4.02 Gy was measured. A reduction of maximum dose of right lens by 0.10±0.11 Gy was obtained. Monitor unit was also found reducing by 131.7±93.1 MU. Conclusion: In late-stage NPC cases, non-coplanar IMRT provided better results in terms of PTV coverage while coplanar IMRT provided better sparing of OARs. Non-coplanar technique could be a feasible choice for cases in which coplanar IMRT could not achieve satisfactory dosimetric results.
DegreeMaster of Medical Sciences
SubjectNasopharynx - Cancer - Radiotherapy
Dept/ProgramDiagnostic Radiology
Persistent Identifierhttp://hdl.handle.net/10722/227893

 

DC FieldValueLanguage
dc.contributor.authorMok, Wa-wai-
dc.contributor.author莫華威-
dc.date.accessioned2016-07-22T23:18:02Z-
dc.date.available2016-07-22T23:18:02Z-
dc.date.issued2016-
dc.identifier.citationMok, W. [莫華威]. (2016). Treatment planning comparison between coplanar and non-coplanar intensity modulated radiation therapy for late-stage nasopharyngeal carcinoma. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR.-
dc.identifier.urihttp://hdl.handle.net/10722/227893-
dc.description.abstractPurpose/Objective(s): The purpose of this study was to compare the dosimetric difference between coplanar and non-coplanar intensity-modulated radiation therapy (IMRT) for late-stage nasopharyngeal carcinoma (NPC). The potential benefits of non-coplanar IMRT in treatment of late-stage NPC would be highlighted so as to provide radiation oncologist with an alternative option for individual clinical case. Methods: Ten late-stage (Stage III and IV) NPC patients were planned by both 1) non-coplanar IMRT and 2) coplanar IMRT using the 〖Philips Pinnacle〗^3 version 9.6 treatment planning system. Standard 9-field IMRT with each beam separated by 40 degrees would be used for coplanar IMRT. For non-coplanar IMRT, 9 coplanar beams which orientations are the same as that used in coplanar IMRT would be applied and 2 extra non-coplanar beams of 90 degree couch angle would be added. The dose levels of planning target volumes (PTVs) with 70/60/54 Gy in 33 fractions were prescribed and delivered as a simultaneous integrated boost. The homogeneity index, conformity index of PTVs, dose to organs at risk (OARs), such as, brainstem, spinal cord, optic chiasm, optic nerves, lens and temporal lobe and monitor units (MU) would be analyzed. Results: All plans fulfilled the departmental planning criteria. Non-coplanar IMRT showed better homogeneity and PTV coverage than coplanar IMRT. Significant reduction of doses for optic chiasm and right lens were observed in coplanar IMRT when comparing with non-coplanar IMRT. A reduction of maximum dose of optic chiasm by 4.29±4.02 Gy was measured. A reduction of maximum dose of right lens by 0.10±0.11 Gy was obtained. Monitor unit was also found reducing by 131.7±93.1 MU. Conclusion: In late-stage NPC cases, non-coplanar IMRT provided better results in terms of PTV coverage while coplanar IMRT provided better sparing of OARs. Non-coplanar technique could be a feasible choice for cases in which coplanar IMRT could not achieve satisfactory dosimetric results.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.subject.lcshNasopharynx - Cancer - Radiotherapy-
dc.titleTreatment planning comparison between coplanar and non-coplanar intensity modulated radiation therapy for late-stage nasopharyngeal carcinoma-
dc.typePG_Thesis-
dc.identifier.hkulb5772810-
dc.description.thesisnameMaster of Medical Sciences-
dc.description.thesislevelMaster-
dc.description.thesisdisciplineDiagnostic Radiology-
dc.description.naturepublished_or_final_version-

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