Simultaneous radiosurgery for multiple brain metastases: technical overview of the UCLA experience

Abstract Purpose/objective(s) To communicate our institutional experience with single isocenter radiosurgery treatments for multiple brain metastases, including challenges with determining planning target volume (PTV) margins and resulting consequences, image-guidance translational and rotational to...

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Autores principales:	Nzhde Agazaryan, Steve Tenn, Chul Lee, Michael Steinberg, John Hegde, Robert Chin, Nader Pouratian, Isaac Yang, Won Kim, Tania Kaprealian
Formato:	article
Lenguaje:	EN
Publicado:	BMC 2021
Materias:	Medical physics. Medical radiology. Nuclear medicine R895-920 Neoplasms. Tumors. Oncology. Including cancer and carcinogens RC254-282
Acceso en línea:	https://doaj.org/article/e40b2eada0d54af3a628b25df1f1b790
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spelling	oai:doaj.org-article:e40b2eada0d54af3a628b25df1f1b7902021-11-21T12:14:12ZSimultaneous radiosurgery for multiple brain metastases: technical overview of the UCLA experience10.1186/s13014-021-01944-w1748-717Xhttps://doaj.org/article/e40b2eada0d54af3a628b25df1f1b7902021-11-01T00:00:00Zhttps://doi.org/10.1186/s13014-021-01944-whttps://doaj.org/toc/1748-717XAbstract Purpose/objective(s) To communicate our institutional experience with single isocenter radiosurgery treatments for multiple brain metastases, including challenges with determining planning target volume (PTV) margins and resulting consequences, image-guidance translational and rotational tolerances, intra-fraction patient motion, and prescription considerations with larger PTV margins. Materials/methods Eight patient treatments with 51 targets were planned with various margins using Elements Multiple Brain Mets SRS treatment planning software (Brainlab, Munich, Germany). Forty-eight plans with 0 mm, 1 mm and 2 mm margins were created, including plans with variable margins, where targets more than 6 cm away from the isocenter were planned with larger margins. The dosimetric impact of the margins were analyzed with V5Gy, V8Gy, V10Gy, V12Gy values. Additionally, 12 patient motion data were analyzed to determine both the impact of the repositioning threshold and the distributions of the patient translational and rotational movements. Results The V5Gy, V8Gy, V10Gy, V12Gy volumes approximately doubled when margins change from 0 to 1 mm and tripled when change from 0 to 2 mm. With variable margins, the aggregated results are similar to results from plans using the lower of two margins, since only 12.2% of the targets were more than 6 cm away from the isocenter. With 0.5 mm re-positioning threshold, 57.4% of the time the patients are repositioned. Reducing the threshold to 0.25 mm results in 91.7% repositioning rate, due to limitations of the fusion algorithm and actual patient motion. The 90th percentile of translational movements in all directions is 0.7 mm, while the 90th percentile of rotational movements in all directions is 0.6 degrees. Median translations and rotations are 0.2 mm and 0.2 degrees, respectively. Conclusions Based on the data presented, we have switched our modus operandi from 2 to 1 mm PTV margins, with an eventual goal of using 0.5 and 1.0 mm variable margins when an automated margin assignment method becomes available. The 0.5 mm and 0.5 degrees repositioning thresholds are clinically appropriate with small residual patient movements.Nzhde AgazaryanSteve TennChul LeeMichael SteinbergJohn HegdeRobert ChinNader PouratianIsaac YangWon KimTania KaprealianBMCarticleMedical physics. Medical radiology. Nuclear medicineR895-920Neoplasms. Tumors. Oncology. Including cancer and carcinogensRC254-282ENRadiation Oncology, Vol 16, Iss 1, Pp 1-9 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medical physics. Medical radiology. Nuclear medicine R895-920 Neoplasms. Tumors. Oncology. Including cancer and carcinogens RC254-282
spellingShingle	Medical physics. Medical radiology. Nuclear medicine R895-920 Neoplasms. Tumors. Oncology. Including cancer and carcinogens RC254-282 Nzhde Agazaryan Steve Tenn Chul Lee Michael Steinberg John Hegde Robert Chin Nader Pouratian Isaac Yang Won Kim Tania Kaprealian Simultaneous radiosurgery for multiple brain metastases: technical overview of the UCLA experience
description	Abstract Purpose/objective(s) To communicate our institutional experience with single isocenter radiosurgery treatments for multiple brain metastases, including challenges with determining planning target volume (PTV) margins and resulting consequences, image-guidance translational and rotational tolerances, intra-fraction patient motion, and prescription considerations with larger PTV margins. Materials/methods Eight patient treatments with 51 targets were planned with various margins using Elements Multiple Brain Mets SRS treatment planning software (Brainlab, Munich, Germany). Forty-eight plans with 0 mm, 1 mm and 2 mm margins were created, including plans with variable margins, where targets more than 6 cm away from the isocenter were planned with larger margins. The dosimetric impact of the margins were analyzed with V5Gy, V8Gy, V10Gy, V12Gy values. Additionally, 12 patient motion data were analyzed to determine both the impact of the repositioning threshold and the distributions of the patient translational and rotational movements. Results The V5Gy, V8Gy, V10Gy, V12Gy volumes approximately doubled when margins change from 0 to 1 mm and tripled when change from 0 to 2 mm. With variable margins, the aggregated results are similar to results from plans using the lower of two margins, since only 12.2% of the targets were more than 6 cm away from the isocenter. With 0.5 mm re-positioning threshold, 57.4% of the time the patients are repositioned. Reducing the threshold to 0.25 mm results in 91.7% repositioning rate, due to limitations of the fusion algorithm and actual patient motion. The 90th percentile of translational movements in all directions is 0.7 mm, while the 90th percentile of rotational movements in all directions is 0.6 degrees. Median translations and rotations are 0.2 mm and 0.2 degrees, respectively. Conclusions Based on the data presented, we have switched our modus operandi from 2 to 1 mm PTV margins, with an eventual goal of using 0.5 and 1.0 mm variable margins when an automated margin assignment method becomes available. The 0.5 mm and 0.5 degrees repositioning thresholds are clinically appropriate with small residual patient movements.
format	article
author	Nzhde Agazaryan Steve Tenn Chul Lee Michael Steinberg John Hegde Robert Chin Nader Pouratian Isaac Yang Won Kim Tania Kaprealian
author_facet	Nzhde Agazaryan Steve Tenn Chul Lee Michael Steinberg John Hegde Robert Chin Nader Pouratian Isaac Yang Won Kim Tania Kaprealian
author_sort	Nzhde Agazaryan
title	Simultaneous radiosurgery for multiple brain metastases: technical overview of the UCLA experience
title_short	Simultaneous radiosurgery for multiple brain metastases: technical overview of the UCLA experience
title_full	Simultaneous radiosurgery for multiple brain metastases: technical overview of the UCLA experience
title_fullStr	Simultaneous radiosurgery for multiple brain metastases: technical overview of the UCLA experience
title_full_unstemmed	Simultaneous radiosurgery for multiple brain metastases: technical overview of the UCLA experience
title_sort	simultaneous radiosurgery for multiple brain metastases: technical overview of the ucla experience
publisher	BMC
publishDate	2021
url	https://doaj.org/article/e40b2eada0d54af3a628b25df1f1b790
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Simultaneous radiosurgery for multiple brain metastases: technical overview of the UCLA experience

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