Cargando…

Improved Dose Conformity for Adjacent Targets: A Novel Planning Technique for Gamma Knife Stereotactic Radiosurgery

Purpose In the current Gamma Knife (GK) planning system (GammaPlan, version 10.2, Elekta AB, Stockholm, Sweden), multiple adjacent brain metastasis (BMs) had to be planned sequentially if BMs were drawn separately, leading to less conformal target dose in the composite plan due to inter-target dose...

Descripción completa

Detalles Bibliográficos
Autores principales: Xu, Qianyi, Xue, Jinyu, Kubicek, Gregory, Mulvihill, David, Oh, Steven, Goldman, Warren, Turtz, Alan, Kim, Leonard
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Cureus 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6168383/
https://www.ncbi.nlm.nih.gov/pubmed/30310763
http://dx.doi.org/10.7759/cureus.3057
_version_ 1783360345783402496
author Xu, Qianyi
Xue, Jinyu
Kubicek, Gregory
Mulvihill, David
Oh, Steven
Goldman, Warren
Turtz, Alan
Kim, Leonard
author_facet Xu, Qianyi
Xue, Jinyu
Kubicek, Gregory
Mulvihill, David
Oh, Steven
Goldman, Warren
Turtz, Alan
Kim, Leonard
author_sort Xu, Qianyi
collection PubMed
description Purpose In the current Gamma Knife (GK) planning system (GammaPlan, version 10.2, Elekta AB, Stockholm, Sweden), multiple adjacent brain metastasis (BMs) had to be planned sequentially if BMs were drawn separately, leading to less conformal target dose in the composite plan due to inter-target dose contribution and fine-tuning of the shots being quite tedious. We proposed a method to improve target dose conformality and planning efficiency for such cases. Methods and Materials Fifteen patients with multiple BMs treated on the Leksell GK Perfexion system were retrospectively replanned in the Institutional Review Board (IRB) approved study. The recruitment criterion was all the BMs should be entirely encompassed within the maximum dose grid allowed in the GammaPlan. The BMs were first planned sequentially as routine clinic cases. The contours of the BMs were then exported to the VelocityAI (Varian, CA, USA) to generate a composite contour after a union operation, and all the BMs were planned again simultaneously using this composite contour in the GammaPlan. The inverse planning (IP) was employed in both methods with the same treatment time allowed for a fair plan comparison. Dose evaluation was performed in the VelocityAI with all planning magnetic resonance (MR) images, structure set and dose were exported to the VelocityAI. The dosimetery parameters, including conformality index (CI), V20Gy, V16Gy, V12Gy, and V5Gy, were compared between the two methods. Results The planning results from both methods were reviewed qualitatively and quantitatively. The proposed method exhibited superior CI, except for an outlier case with very tiny BMs. The mean and standard deviation (std.) of the Paddick CI for all patients were 0.76±0.11 for the proposed method, comparing to 0.69±0.13 for the sequential method. The V20Gy, V16Gy, V12Gy, and V5Gy for the proposed method were 10.9±0.9%, 9.5±10.2%, 6.2±16.4% and 3.3±21.8%, all lower than those from the sequential method. Conclusions The proposed method showed improved target dose conformality for all cases except for very tiny BMs. Planning efficiency is considerably better with the combined target technique. The improved dose conformality will be beneficial to patients in long term with lowered risk of radiation necrosis after GK stereotactic radiosurgery (SRS).
format Online
Article
Text
id pubmed-6168383
institution National Center for Biotechnology Information
language English
publishDate 2018
publisher Cureus
record_format MEDLINE/PubMed
spelling pubmed-61683832018-10-11 Improved Dose Conformity for Adjacent Targets: A Novel Planning Technique for Gamma Knife Stereotactic Radiosurgery Xu, Qianyi Xue, Jinyu Kubicek, Gregory Mulvihill, David Oh, Steven Goldman, Warren Turtz, Alan Kim, Leonard Cureus Medical Physics Purpose In the current Gamma Knife (GK) planning system (GammaPlan, version 10.2, Elekta AB, Stockholm, Sweden), multiple adjacent brain metastasis (BMs) had to be planned sequentially if BMs were drawn separately, leading to less conformal target dose in the composite plan due to inter-target dose contribution and fine-tuning of the shots being quite tedious. We proposed a method to improve target dose conformality and planning efficiency for such cases. Methods and Materials Fifteen patients with multiple BMs treated on the Leksell GK Perfexion system were retrospectively replanned in the Institutional Review Board (IRB) approved study. The recruitment criterion was all the BMs should be entirely encompassed within the maximum dose grid allowed in the GammaPlan. The BMs were first planned sequentially as routine clinic cases. The contours of the BMs were then exported to the VelocityAI (Varian, CA, USA) to generate a composite contour after a union operation, and all the BMs were planned again simultaneously using this composite contour in the GammaPlan. The inverse planning (IP) was employed in both methods with the same treatment time allowed for a fair plan comparison. Dose evaluation was performed in the VelocityAI with all planning magnetic resonance (MR) images, structure set and dose were exported to the VelocityAI. The dosimetery parameters, including conformality index (CI), V20Gy, V16Gy, V12Gy, and V5Gy, were compared between the two methods. Results The planning results from both methods were reviewed qualitatively and quantitatively. The proposed method exhibited superior CI, except for an outlier case with very tiny BMs. The mean and standard deviation (std.) of the Paddick CI for all patients were 0.76±0.11 for the proposed method, comparing to 0.69±0.13 for the sequential method. The V20Gy, V16Gy, V12Gy, and V5Gy for the proposed method were 10.9±0.9%, 9.5±10.2%, 6.2±16.4% and 3.3±21.8%, all lower than those from the sequential method. Conclusions The proposed method showed improved target dose conformality for all cases except for very tiny BMs. Planning efficiency is considerably better with the combined target technique. The improved dose conformality will be beneficial to patients in long term with lowered risk of radiation necrosis after GK stereotactic radiosurgery (SRS). Cureus 2018-07-27 /pmc/articles/PMC6168383/ /pubmed/30310763 http://dx.doi.org/10.7759/cureus.3057 Text en Copyright © 2018, Xu et al. http://creativecommons.org/licenses/by/3.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Medical Physics
Xu, Qianyi
Xue, Jinyu
Kubicek, Gregory
Mulvihill, David
Oh, Steven
Goldman, Warren
Turtz, Alan
Kim, Leonard
Improved Dose Conformity for Adjacent Targets: A Novel Planning Technique for Gamma Knife Stereotactic Radiosurgery
title Improved Dose Conformity for Adjacent Targets: A Novel Planning Technique for Gamma Knife Stereotactic Radiosurgery
title_full Improved Dose Conformity for Adjacent Targets: A Novel Planning Technique for Gamma Knife Stereotactic Radiosurgery
title_fullStr Improved Dose Conformity for Adjacent Targets: A Novel Planning Technique for Gamma Knife Stereotactic Radiosurgery
title_full_unstemmed Improved Dose Conformity for Adjacent Targets: A Novel Planning Technique for Gamma Knife Stereotactic Radiosurgery
title_short Improved Dose Conformity for Adjacent Targets: A Novel Planning Technique for Gamma Knife Stereotactic Radiosurgery
title_sort improved dose conformity for adjacent targets: a novel planning technique for gamma knife stereotactic radiosurgery
topic Medical Physics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6168383/
https://www.ncbi.nlm.nih.gov/pubmed/30310763
http://dx.doi.org/10.7759/cureus.3057
work_keys_str_mv AT xuqianyi improveddoseconformityforadjacenttargetsanovelplanningtechniqueforgammaknifestereotacticradiosurgery
AT xuejinyu improveddoseconformityforadjacenttargetsanovelplanningtechniqueforgammaknifestereotacticradiosurgery
AT kubicekgregory improveddoseconformityforadjacenttargetsanovelplanningtechniqueforgammaknifestereotacticradiosurgery
AT mulvihilldavid improveddoseconformityforadjacenttargetsanovelplanningtechniqueforgammaknifestereotacticradiosurgery
AT ohsteven improveddoseconformityforadjacenttargetsanovelplanningtechniqueforgammaknifestereotacticradiosurgery
AT goldmanwarren improveddoseconformityforadjacenttargetsanovelplanningtechniqueforgammaknifestereotacticradiosurgery
AT turtzalan improveddoseconformityforadjacenttargetsanovelplanningtechniqueforgammaknifestereotacticradiosurgery
AT kimleonard improveddoseconformityforadjacenttargetsanovelplanningtechniqueforgammaknifestereotacticradiosurgery