An evaluation of the BrainLAB 6D ExacTrac/Novalis Tx System for image-guided intracranial radiotherapy

Montgomery, Claire; Collins, Mark

doi:10.1017/s1460396917000139

Cited by 4 publications

(3 citation statements)

References 27 publications

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“…However, this technique does not allow automatic registration but only visual verification by juxtaposing the contour of the target volume on the acquired 2D image. The effective dose delivered to the patient is of the order of 2 mSv per pair of images for the Exactrac system 11 compared with 10 to 20 mSv for a kV-CBCT scan. 22 The benefit of tracking the movement of the target is such that we can accept this extra dose.…”

Section: Discussionmentioning

confidence: 99%

“…This system allows to verify the patient's position in 6 directions of freedom (longitudinal, lateral, vertical, pitch, yaw, and roll) from two kV-2D oblique acquisitions made from 2 X-ray sources and 2 detectors installed on the floor and ceiling of the treatment room respectively. This device is described, for example, in detail by Montgomery et al 11 …”

Section: Introductionmentioning

confidence: 99%

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ExacTrac X-Ray 6D Imaging During Stereotactic Body Radiation Therapy of Spinal and Nonspinal Metastases

Hadj Henni,

Gensanne,

Bulot

et al. 2023

Technol Cancer Res Treat

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The objective was to investigate the possibility of using ExacTrac X-ray (ETX) for 6D image guidance in stereotactic body radiation therapy (SBRT) of bone metastasis and to propose a patient management protocol. The analyses were first obtained from measurements on a pelvic phantom and on 19 patients treated for bone metastasis. The phantom study consisted of applying known offsets and evaluating the ETX level of accuracy, where results were compared with kV-cone beam computed tomography (kV-CBCT). Two groups of patients, 10 spinal and 9 nonspinal SBRT cases, were analyzed to evaluate ETX imaging for different bone localisations. A comparison was made between kV-CBCT and ETX prior to the treatment fractions. During treatments, two other kV-CBCT/ETX image pairs were also acquired and a total of 224 shifts were compared. A second study, using the ETX monitoring module, analyzed the intrafraction motion of 8 other patients. In the phantom study, the root mean square (RMS) of the translational and rotational discrepancies between ETX and kV-CBCT were < 0.6 mm and < 0.4°, respectively. For both groups of patients, the RMS of the discrepancies observed between the two imaging systems were greater than the phantom experiment while still remaining < 1 mm and < 0.7°. In the nonspinal group, three patients (2 scapulas and 1 humerus) did not have consistent shift values with ETX due to a lack of anatomical information. When ETX monitoring was used during irradiation, the setup errors measured were on average less than 1 mm/1°. The results obtained validated the use of ETX for 6D image guidance during bone SBRT. Real-time tracking of the target position improves the accuracy of the irradiation. This strategy allowed for faster correction of out-of-tolerance positioning errors. The registration of bone lesions with poor anatomical information is a limitation of this 2D-kV imaging system.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

ExacTrac X-Ray 6D Imaging During Stereotactic Body Radiation Therapy of Spinal and Nonspinal Metastases

Hadj Henni,

Gensanne,

Bulot

et al. 2023

Technol Cancer Res Treat

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“…To address the challenges with spinal SBRT, kV image-based motion tracking techniques have been developed over the past decades (Ho et al 2007, Jin et al 2008, Furweger et al 2011, Gurney-Champion et al 2013, Montgomery and Collins 2017, Kim et al 2018aand 2018b, Bertholet et al 2019, Kaur et al 2019, Roggen et al 2020, Graeper et al 2021. For examples, the X-sight spine tracking system on the CyberKnife platform (Accuray Inc., Sunnyvale, CA) and the ExacTrac system (BrainLAB AG, Feldkirchen, Germany), both employ kV image pairs for quantitative motion tracking (Ho et al 2007, Jin et al 2008, Furweger et al 2011, Montgomery and Collins 2017. Nevertheless, these systems require either a dedicated machine or additional equipment beyond the standard linear accelerators.…”

Section: Introductionmentioning

confidence: 99%

Markerless motion tracking with simultaneous MV and kV imaging in spine SBRT treatment—a feasibility study

Cai

Fan

et al. 2023

Phys. Med. Biol.

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Objective: Motion tracking with simultaneous MV-kV imaging has distinct advantages over single kV systems. This research is a feasibility study of utilizing this technique for spine SBRT through phantom and patient studies. Approach: A clinical spine SBRT plan was developed using 6xFFF beams and nine sliding-window IMRT fields. The plan was delivered to a chest phantom on a linear accelerator. Simultaneous MV-kV image pairs were acquired during beam delivery. KV images were triggered at predefined intervals, and synthetic MV images showing enlarged MLC apertures were created by combining multiple raw MV frames with corrections for scattering and intensity variation. DRR templates were generated using high-resolution CBCT reconstructions (isotropic voxel size (0.243mm)3) as the reference for 2D-2D matching. 3D shifts were calculated from triangulation of kV-to-DRR and MV-to-DRR registrations. To evaluate tracking accuracy, detected shifts were compared to known phantom shifts as introduced before treatment. The patient study included a T-spine patient and an L-spine patient. Patient datasets were retrospectively analyzed to demonstrate the performance in clinical settings. Main Results: The treatment plan was delivered to the phantom in five scenarios: no shift, 2mm shift in one of the longitudinal, lateral and vertical directions, and 2mm shift in all the three directions. The calculated 3D shifts agreed well with the actual couch shifts, and overall, the uncertainty of 3D detection is estimated to be 0.3mm. The patient study revealed that with clinical patient image quality, the calculated 3D motion agreed with the post-treatment cone beam CT. It is feasible to automate both kV-to-DRR and MV-to-DRR registrations using a mutual information-based method, and the difference from manual registration is generally less than 0.3mm. Significance: The MV-kV imaging-based markerless motion tracking technique was validated through a feasibility study. It is a step forward toward effective motion tracking and accurate delivery for spinal SBRT.

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Patient Positioning in Radiotherapy

Guo

Müller-Polyzou

Chen

et al. 2020

2020 IEEE International Symposium on Medical Measurements and Applications (MeMeA)

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An evaluation of the BrainLAB 6D ExacTrac/Novalis Tx System for image-guided intracranial radiotherapy

Cited by 4 publications

References 27 publications

ExacTrac X-Ray 6D Imaging During Stereotactic Body Radiation Therapy of Spinal and Nonspinal Metastases

ExacTrac X-Ray 6D Imaging During Stereotactic Body Radiation Therapy of Spinal and Nonspinal Metastases

Markerless motion tracking with simultaneous MV and kV imaging in spine SBRT treatment—a feasibility study

Patient Positioning in Radiotherapy

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