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Conference Paper: Dosimetric evaluation of the interplay between LINAC movement and tumor motion in respiratory gated VMAT of lung cancer

TitleDosimetric evaluation of the interplay between LINAC movement and tumor motion in respiratory gated VMAT of lung cancer
Authors
Issue Date2012
PublisherElsevier Inc. The Journal's web site is located at http://www.elsevier.com/locate/ijrobp
Citation
The 54th Annual Meeting of the American Society for Radiation Oncology (ASTRO 2012), Boston, MA., 28 October-1 November 2012. In International Journal of Radiation Oncology - Biology - Physics, 2012, v. 84 n. 3 suppl., p. S766-S767, abstract no. 3458 How to Cite?
AbstractPurpose/Objective(s): Respiratory gated radiation therapy of lung cancer helps to minimize the treated volume and hence treatment side effects. VMAT can reduce the treatment time while producing a highly conformed dose distribution. However, in gated VMAT delivery, the interplay effect between the LINAC movement (MLC and gantry) and tumor motion may result in undesirable hot and cold spots jeopardizing tumor coverage. In this study we investigated the possible dosimetric errors caused by the interplay between the tumor motion and the LINAC movement for gated VMAT lung cancer treatment. Materials/Methods: We studied 2 lung cancer cases prescribed to 60 Gy given in 30 fractions. GTVs were contoured on each of the 10 phases of 4DCT. The end-expiration phase and 3 neighboring phases were chosen for gating (40%-70%). The GTVgating consisted of the volume encompassing GTVs of the 4 phases. 5 mm margin was added to the GTVgating to create the CTVgating and 8 mm margin was added to generate the PTVgating. A highly modulated single arc VMAT plan was derived for each case based on the 50% phase image. The plans aimed to minimize dose to the spinal cord while maintaining PTV coverage. A program was written to segment the arc in the original plan with 177 control points into 88 mini arcs with 3 control points each. Each mini arc spanned about 0.67 second and was assumed to irradiate 1 phase of the gating window during which there should be relatively little movement of the anatomy. Every one in four arcs was then inserted into a VMAT plan irradiating each of the 4 phases, thus generating 4 plans each having 22 mini arcs. Dose calculation was done for each plan on the CT image for the particular phase. The resulting dose from each plan was then mapped to the base phase image (50%) and finally summed with a deformable dose accumulation software. The resulting dose was compared to the original dose distribution. Results: See Table. Conclusion: The dosimetric effect of the interplay between tumor motion and LINAC movement was studied for 2 lung cancer cases. It was found that there was no significant difference in tumor coverage when the original plan was done assuming a static target. The dose to critical structures also remained very close to the original plan. It can be concluded that interplay between LINAC movement and tumor motion will not affect the dosimetric quality of gated VMAT plans for lung cancer.
DescriptionConference Theme: Advancing Patient Care Through Innovation
This journal suppl. entitled: Proceedings of the American Society for Radiation Oncology 54th Annual Meeting
Persistent Identifierhttp://hdl.handle.net/10722/165596
ISSN
2019 Impact Factor: 5.859
2015 SCImago Journal Rankings: 2.274
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorNg, CYen_US
dc.contributor.authorLee, VHFen_US
dc.contributor.authorLeung, TWen_US
dc.date.accessioned2012-09-20T08:20:45Z-
dc.date.available2012-09-20T08:20:45Z-
dc.date.issued2012en_US
dc.identifier.citationThe 54th Annual Meeting of the American Society for Radiation Oncology (ASTRO 2012), Boston, MA., 28 October-1 November 2012. In International Journal of Radiation Oncology - Biology - Physics, 2012, v. 84 n. 3 suppl., p. S766-S767, abstract no. 3458en_US
dc.identifier.issn0360-3016-
dc.identifier.urihttp://hdl.handle.net/10722/165596-
dc.descriptionConference Theme: Advancing Patient Care Through Innovation-
dc.descriptionThis journal suppl. entitled: Proceedings of the American Society for Radiation Oncology 54th Annual Meeting-
dc.description.abstractPurpose/Objective(s): Respiratory gated radiation therapy of lung cancer helps to minimize the treated volume and hence treatment side effects. VMAT can reduce the treatment time while producing a highly conformed dose distribution. However, in gated VMAT delivery, the interplay effect between the LINAC movement (MLC and gantry) and tumor motion may result in undesirable hot and cold spots jeopardizing tumor coverage. In this study we investigated the possible dosimetric errors caused by the interplay between the tumor motion and the LINAC movement for gated VMAT lung cancer treatment. Materials/Methods: We studied 2 lung cancer cases prescribed to 60 Gy given in 30 fractions. GTVs were contoured on each of the 10 phases of 4DCT. The end-expiration phase and 3 neighboring phases were chosen for gating (40%-70%). The GTVgating consisted of the volume encompassing GTVs of the 4 phases. 5 mm margin was added to the GTVgating to create the CTVgating and 8 mm margin was added to generate the PTVgating. A highly modulated single arc VMAT plan was derived for each case based on the 50% phase image. The plans aimed to minimize dose to the spinal cord while maintaining PTV coverage. A program was written to segment the arc in the original plan with 177 control points into 88 mini arcs with 3 control points each. Each mini arc spanned about 0.67 second and was assumed to irradiate 1 phase of the gating window during which there should be relatively little movement of the anatomy. Every one in four arcs was then inserted into a VMAT plan irradiating each of the 4 phases, thus generating 4 plans each having 22 mini arcs. Dose calculation was done for each plan on the CT image for the particular phase. The resulting dose from each plan was then mapped to the base phase image (50%) and finally summed with a deformable dose accumulation software. The resulting dose was compared to the original dose distribution. Results: See Table. Conclusion: The dosimetric effect of the interplay between tumor motion and LINAC movement was studied for 2 lung cancer cases. It was found that there was no significant difference in tumor coverage when the original plan was done assuming a static target. The dose to critical structures also remained very close to the original plan. It can be concluded that interplay between LINAC movement and tumor motion will not affect the dosimetric quality of gated VMAT plans for lung cancer.-
dc.languageengen_US
dc.publisherElsevier Inc. The Journal's web site is located at http://www.elsevier.com/locate/ijrobp-
dc.relation.ispartofInternational Journal of Radiation Oncology - Biology - Physicsen_US
dc.titleDosimetric evaluation of the interplay between LINAC movement and tumor motion in respiratory gated VMAT of lung canceren_US
dc.typeConference_Paperen_US
dc.identifier.emailNg, CY: ngchoryi@hku.hken_US
dc.identifier.emailLee, VHF: vhflee@hku.hken_US
dc.identifier.emailLeung, TW: ltw920@hkucc.hku.hken_US
dc.identifier.authorityLee, VHF=rp00264en_US
dc.description.naturelink_to_OA_fulltext-
dc.identifier.doi10.1016/j.ijrobp.2012.07.2051-
dc.identifier.hkuros210294en_US
dc.identifier.volume84-
dc.identifier.issue3 suppl.-
dc.identifier.spageS766, abstract no. 3458-
dc.identifier.epageS767, abstract no. 3458-
dc.identifier.isiWOS:000310542902455-
dc.publisher.placeUnited Kingdom-
dc.identifier.issnl0360-3016-

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