%0 Journal Article
%T A prospective observational study evaluating two patient immobilisation methods in lung stereotactic radiotherapy.
%A Boisbouvier S
%A Martel-Lafay I
%A Tanguy R
%A Ayadi-Zahra M
%J Cancer Radiother
%V 28
%N 3
%D 2024 Jun 12
%M 38871604
%F 1.217
%R 10.1016/j.canrad.2023.08.012
%X <B>OBJECTIVE: </B>The main objective of this study was to assess inter- and intrafraction errors for two patient immobilisation devices in the context of lung stereotactic body radiation therapy: a vacuum cushion and a simple arm support.<BR><B>METHODS: </B>Twenty patients who were treated with lung stereotactic body radiation therapy in supine position with arms above their head were included in the study. Ten patients were setup in a vacuum cushion (Bluebag™, Elekta) and ten other patients with a simple arm support (Posirest™, Civco). A pretreatment four-dimensional cone-beam computed tomography and a post-treatment three-dimensional cone-beam computed tomography were acquired to compare positioning and immobilisation accuracy. Based on a rigid registration with the planning computed tomography on the spine at the target level, translational and rotational errors were reported.<BR><B>RESULTS: </B>The median number of fractions per treatment was 5 (range: 3-10). Mean interfraction errors based on 112 four-dimensional cone-beam computed tomographies were similar for both setups with deviations less than or equal to 1.3mm in lateral and vertical direction and 1.2° in roll and yaw. For longitudinal translational errors, mean interfraction errors were 0.7mm with vacuum cushion and -3.9mm with arm support. Based on 111 three-dimensional cone-beam computed tomographies, mean lateral, longitudinal and vertical intrafraction errors were -0.1mm, -0.2mm and 0.0mm respectively (SD: 1.0, 1.2 and 1.0mm respectively) for the patients setup with vacuum cushion, and mean vertical, longitudinal and lateral intrafraction errors were -0.3mm, -0.7mm and 0.1mm respectively (SD: 2.3, 1.8 and 1.4mm respectively) for the patients setup with arm support. Intrafraction errors means were not statistically different between both positions but standard deviations were statistically larger with arm support.<BR><B>CONCLUSIONS: </B>The results of our study showed similar inter and intrafraction mean deviations between both positioning but a large variability in intrafraction observed with arm support suggested a more accurate immobilization with vacuum cushion.