Large In-mask Motion during Frameless Radiosurgery of a Brain Metastasis

Harat, Maciej; Furtak, Jacek

doi:10.1055/s-0037-1604285

Cited by 4 publications

(1 citation statement)

References 13 publications

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“…Relocatable thermoplastic mask systems are commonly used for patient immobilization during Stereotactic Radiosurgery (SRS) and Stereotactic Radiotherapy (SRT) treatments to reduce inter-and intra-fraction motion but do not eliminate it [1][2][3][4][5][6]. A study of 6DOF intrafraction motion reported up to 1.75mm of cranial translation and up to 1.6˚of cranial rotation within the thermoplastic mask [1].…”

Section: Introductionmentioning

confidence: 99%

Six degrees of freedom intrafraction cranial motion detection using a novel capacitive monitoring technique: evaluation with human subjects

Sadeghi

Bastin-Decoste

Robar

2023

Biomed. Phys. Eng. Express

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The purpose of this work is to introduce and evaluate a capacitive monitoring array capable of continuous 6DOF cranial motion detection during high precision radiotherapy. The ring-shaped capacitive array consists of four equally sized conductive sensors positioned at the cranial vertex. The system is modular, non-contact, and provides continuous motion information through the thermoplastic immobilization mask without relying on skin monitoring or use of ionizing radiation. The array performance was evaluated through a volunteer study with a cohort of twenty-five individuals. The study was conducted in a linac suite and the volunteers were fitted with an S-frame thermoplastic mask. Each volunteer took part in one data acquisition session per day for three consecutive days. During the data acquisition, the conductive array was translated and rotated relative to their immobilized cranium in 1-millimetre and 1-degree steps to simulate cranial motion. Capacitive signals were collected at each position at a frequency of 20 Hz. The data from the first acquisition session was then used to train a classifier model and establish calibration equations. The classifier and calibration equations were then applied to data from the subsequent acquisition sessions to evaluate the system performance. The trained classifiers had an average success rate of 92.6% over the volunteer cohort. The average error associated with calibration had a mean value below 0.1 mm or 0.1 deg for all six motions. The capacitive array system provides a novel method to detect translational and rotational cranial motion through a thermoplastic mask.

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Section: Introductionmentioning

confidence: 99%

Six degrees of freedom intrafraction cranial motion detection using a novel capacitive monitoring technique: evaluation with human subjects

Sadeghi

Bastin-Decoste

Robar

2023

Biomed. Phys. Eng. Express

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Technical Note: Rotational positional error corrected intrafraction set‐up margins in stereotactic radiotherapy: A spatial assessment for coplanar and noncoplanar geometry

et al. 2019

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Purpose: The aim of this study is to calculate setup margin based on six-dimensional (6D) corrected residual positional errors from kV cone beam computed tomography (CBCT) and from intrafraction projection kV imaging in coplanar and in noncoplanar couch positions in stereotactic radiotherapy. Methods: Six dimensional positional corrections were carried out before patient treatments, using a robotic couch and CBCT matching. A CBCT and stereoscopic ExacTrac image were acquired posttable position correction. Further, a series of intrafraction ExacTrac images were obtained for the variable couch position. Translational and rotational errors were identified as lateral (X), longitudinal (Y), vertical (Z); roll (Ɵ°), pitch (Φ°) and yaw (Ψ°). A total of 699 intrafraction image sets (361 coplanar and 338 noncoplanar) for 51 SRS/SRT patients were analysed. Rotational errors were corrected in terms of translational coordinates. Residual set-up margins were calculated from CBCT shifts. ExacTrac shifts give residual + intrafraction setup margins as a function of coplanar and noncoplanar couch positions. Results: The average residual positional error obtained from CBCT in X, Y, Z, Ɵ, Φ, Ψ were 0.1 AE 0.4 mm, 0.0 AE 0.6 mm, 0.0 AE 0.5 mm, 0.2 AE 0.8°, 0.1 AE 0.6°and À0.1 AE 0.7°respectively. For ExacTrac, the shits were À0.5 AE 0.9 mm, À0.0 AE 1mm, À0.6 AE 1.0mm, 0.4 AE 0.9°, À0.2 AE 0.6°, and À0.0 AE 0.8°.CBCT calculated linear setup margins in X, Y, Z direction were 0.5, 1.2, and 1 mm respectively. ExacTrac yielded coplanar and noncoplanar linear setup margins were 1.2, 1.3, 1.5, 1.4, 1.5, and 2.1 mm respectively. Conclusion: CBCT-based gross residual set-up margin is equal to 1 mm. ExacTrac calculated residual plus intrafraction setup margin falls within a 2 mm range; attributed to intrafraction patient movement, table position inaccuracies, and poor image fusion in noncoplanar geometry. There could be variations in the required additional margin between centers and between machines, which require further studies.

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A novel intra-fraction motion monitoring system for stereotactic radiosurgery: proof of concept

et al. 2018

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The purpose of this work is to develop a prototype system for continuous, three-dimensional (3D) monitoring of patient cranial motion during stereotactic radiosurgery. Using novel capacitive detector plates, the goal was to provide detection of cranial position inside a thermoplastic immobilizing mask, without relying on skin monitoring or use of ionizing radiation. A novel capacitive detector array was used to detect cranial translations with sub-millimeter accuracy. The array was comprised of four conductive plates arranged around the cranium. One superior plate was positioned at the cranial vertex, two lateral plates were positioned in sagittal planes at the lateral aspects of the cranium and one plate was located in a coronal plane anterior to the face. The system was calibrated by parameterizing a capacitive signal for each dimension as a function of spatial translation. The detector array performance was evaluated with the help of a volunteer in the absence of radiation. Separately, possible effects of electromagnetic interference and irradiation in the linac suite were assessed. Detector plates mounted at 1 cm original distance to the thermoplastic mask can detect sub-millimeter lateral and superior cranial motion. Detection of sub-millimeter anterior motion is possible when the plate is mounted closer to the patient (5-10 mm). No signal interference was observed when the capacitive array was irradiated. Our prototype detector array provides continuous, 3D translation detection with sub-millimeter precision. The signal provides sufficient signal to noise ratio and is stable in linac room environment and in direct radiation beam. The detector plate is sensitive to the position of the cranium inside a mask and offers the advantage of being insensitive to the mask itself. Future work will involve modifying the array to detect patient rotation.

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Large In-mask Motion during Frameless Radiosurgery of a Brain Metastasis

Cited by 4 publications

References 13 publications

Six degrees of freedom intrafraction cranial motion detection using a novel capacitive monitoring technique: evaluation with human subjects

Six degrees of freedom intrafraction cranial motion detection using a novel capacitive monitoring technique: evaluation with human subjects

Technical Note: Rotational positional error corrected intrafraction set‐up margins in stereotactic radiotherapy: A spatial assessment for coplanar and noncoplanar geometry

A novel intra-fraction motion monitoring system for stereotactic radiosurgery: proof of concept

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