Organ motion in linac-based SBRT for glottic cancer
Abstract Purpose The purpose of this study is to evaluate inter- and intra-fraction organ motion as well as to quantify clinical target volume (CTV) to planning target volume (PTV) margins to be adopted in the stereotactic treatment of early stage glottic cancer. Methods and materials Stereotactic b...
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doaj-3e92287b99d7405fb5f35bf0093530042021-06-13T11:57:00ZengBMCRadiation Oncology1748-717X2021-06-011611710.1186/s13014-021-01833-2Organ motion in linac-based SBRT for glottic cancerAnnarita Perillo0Valeria Landoni1Alessia Farneti2Giuseppe Sanguineti3Department of Radiation Oncology, IRCSS Regina Elena National Cancer InstituteDepartment of Medical Physics, IRCSS Regina Elena National Cancer InstituteDepartment of Radiation Oncology, IRCSS Regina Elena National Cancer InstituteDepartment of Radiation Oncology, IRCSS Regina Elena National Cancer InstituteAbstract Purpose The purpose of this study is to evaluate inter- and intra-fraction organ motion as well as to quantify clinical target volume (CTV) to planning target volume (PTV) margins to be adopted in the stereotactic treatment of early stage glottic cancer. Methods and materials Stereotactic body radiotherapy (SBRT) to 36 Gy in 3 fractions was administered to 23 patients with early glottic cancer T1N0M0. Patients were irradiated with a volumetric intensity modulated arc technique delivered with 6 MV FFF energy. Each patient underwent a pre-treatment cone beam computed tomography (CBCT) to correct the setup based on the thyroid cartilage position. Imaging was repeated if displacement exceeded 2 mm in any direction. CBCT imaging was also performed after each treatment arc as well as at the end of the delivery. Swallowing was allowed only during the beam-off time between arcs. CBCT images were reviewed to evaluate inter- and intra-fraction organ motion. The relationships between selected treatment characteristics, both beam-on and delivery times as well as organ motion were investigated. Results For the population systematic (Ʃ) and random (σ) inter-fraction errors were 0.9, 1.3 and 0.6 mm and 1.1, 1.3 and 0.7 mm in the left-right (X), cranio-caudal (Y) and antero-posterior (Z) directions, respectively. From the analysis of CBCT images acquired after treatment, systematic (Ʃ) and random (σ) intra-fraction errors resulted 0.7, 1.6 and 0.7 mm and 1.0, 1.5 and 0.6 mm in the X, Y and Z directions, respectively. Margins calculated from the intra-fraction errors were 2.4, 5.1 and 2.2 mm in the X, Y and Z directions respectively. A statistically significant difference was found for the displacement in the Z direction between patients irradiated with > 2 arcs versus ≤ 2 arcs, (MW test, p = 0.038). When analyzing mean data from CBCT images for the whole treatment, a significant correlation was found between the time of delivery and the three dimensional displacement vector (r = 0.489, p = 0.055), the displacement in the Y direction (r = 0.553, p = 0.026) and the subsequent margins to be adopted (r = 0.626, p = 0.009). Finally, displacements and the subsequent margins to be adopted in Y direction were significantly greater for treatments with more than 2 arcs (MW test p = 0.037 and p = 0.019, respectively). Conclusions In the setting of controlled swallowing during treatment delivery, intra-fraction motion still needs to be taken into account when planning with estimated CTV to PTV margins of 3, 5 and 3 mm in the X, Y and Z directions, respectively. Selected treatments may require additional margins.https://doi.org/10.1186/s13014-021-01833-2Organ motionDaily CBCT imagingSBRTGlottic cancer |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Annarita Perillo Valeria Landoni Alessia Farneti Giuseppe Sanguineti |
spellingShingle |
Annarita Perillo Valeria Landoni Alessia Farneti Giuseppe Sanguineti Organ motion in linac-based SBRT for glottic cancer Radiation Oncology Organ motion Daily CBCT imaging SBRT Glottic cancer |
author_facet |
Annarita Perillo Valeria Landoni Alessia Farneti Giuseppe Sanguineti |
author_sort |
Annarita Perillo |
title |
Organ motion in linac-based SBRT for glottic cancer |
title_short |
Organ motion in linac-based SBRT for glottic cancer |
title_full |
Organ motion in linac-based SBRT for glottic cancer |
title_fullStr |
Organ motion in linac-based SBRT for glottic cancer |
title_full_unstemmed |
Organ motion in linac-based SBRT for glottic cancer |
title_sort |
organ motion in linac-based sbrt for glottic cancer |
publisher |
BMC |
series |
Radiation Oncology |
issn |
1748-717X |
publishDate |
2021-06-01 |
description |
Abstract Purpose The purpose of this study is to evaluate inter- and intra-fraction organ motion as well as to quantify clinical target volume (CTV) to planning target volume (PTV) margins to be adopted in the stereotactic treatment of early stage glottic cancer. Methods and materials Stereotactic body radiotherapy (SBRT) to 36 Gy in 3 fractions was administered to 23 patients with early glottic cancer T1N0M0. Patients were irradiated with a volumetric intensity modulated arc technique delivered with 6 MV FFF energy. Each patient underwent a pre-treatment cone beam computed tomography (CBCT) to correct the setup based on the thyroid cartilage position. Imaging was repeated if displacement exceeded 2 mm in any direction. CBCT imaging was also performed after each treatment arc as well as at the end of the delivery. Swallowing was allowed only during the beam-off time between arcs. CBCT images were reviewed to evaluate inter- and intra-fraction organ motion. The relationships between selected treatment characteristics, both beam-on and delivery times as well as organ motion were investigated. Results For the population systematic (Ʃ) and random (σ) inter-fraction errors were 0.9, 1.3 and 0.6 mm and 1.1, 1.3 and 0.7 mm in the left-right (X), cranio-caudal (Y) and antero-posterior (Z) directions, respectively. From the analysis of CBCT images acquired after treatment, systematic (Ʃ) and random (σ) intra-fraction errors resulted 0.7, 1.6 and 0.7 mm and 1.0, 1.5 and 0.6 mm in the X, Y and Z directions, respectively. Margins calculated from the intra-fraction errors were 2.4, 5.1 and 2.2 mm in the X, Y and Z directions respectively. A statistically significant difference was found for the displacement in the Z direction between patients irradiated with > 2 arcs versus ≤ 2 arcs, (MW test, p = 0.038). When analyzing mean data from CBCT images for the whole treatment, a significant correlation was found between the time of delivery and the three dimensional displacement vector (r = 0.489, p = 0.055), the displacement in the Y direction (r = 0.553, p = 0.026) and the subsequent margins to be adopted (r = 0.626, p = 0.009). Finally, displacements and the subsequent margins to be adopted in Y direction were significantly greater for treatments with more than 2 arcs (MW test p = 0.037 and p = 0.019, respectively). Conclusions In the setting of controlled swallowing during treatment delivery, intra-fraction motion still needs to be taken into account when planning with estimated CTV to PTV margins of 3, 5 and 3 mm in the X, Y and Z directions, respectively. Selected treatments may require additional margins. |
topic |
Organ motion Daily CBCT imaging SBRT Glottic cancer |
url |
https://doi.org/10.1186/s13014-021-01833-2 |
work_keys_str_mv |
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