Geometric accuracy evaluation of a six-degree-of-freedom (6-DoF) couch with cone beam computed tomography (CBCT) using a phantom and correlation study of the position errors in pelvic tumor radiotherapy

Fu, Caofei; Ma, Changsheng; Shang, Dan; Qiu, Qingtao; Duan, Jianan; Yin, Yong

doi:10.21037/tcr-20-1528

Cited by 6 publications

(5 citation statements)

References 18 publications

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“…Corrections could be applied with the Varian PerfectPitch 6D couch (Varian Medical Systems, Palo Alto, California, USA) for the best repositioning of the bony structures and of the body profile. The quality assurance tests performed on our couch evidenced a setup accuracy of less than 0.2 mm in linear movements (X‐Y‐Z of the couch frame of reference) and less than 1.1° in angular displacements (pitch‐roll‐yaw), similar to the findings of other Authors 20 …”

Section: Methodssupporting

confidence: 88%

“…The quality assurance tests performed on our couch evidenced a setup accuracy of less than 0.2 mm in linear movements (X-Y-Z of the couch frame of reference) and less than 1.1 • in angular displacements (pitch-roll-yaw), similar to the findings of other Authors. 20 Then, a new snapshot was acquired with a ruler positioned near the pupil to calibrate the scale of distance on the next video recordings and to reposition the pupil in the Origin. The patients were carefully instructed to gaze the LED light.…”

Section: Methodsmentioning

confidence: 99%

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An empirical approach to the definition of the target margins in eye radiosurgery

Perrone

Laliscia

Traino

et al. 2023

J Applied Clin Med Phys

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Introduction: A system for stabilizing and monitoring eye movements during LINAC-based photon beam one single fraction stereotactic radiotherapy was developed at our Institution. This study aimed to describe the feasibility and the efficacy of our noninvasive optical localization system that was developed, tested, and applied in 20 patients treated for uveal melanoma. Methods: Our system consisted of a customized thermoplastic mask to immobilize the head, a gaze fixation LED, and a digital micro-camera. The localization procedure, which required the active collaboration of the patient, served to monitor the eye movements during all phases of the treatment, starting from the planning computed tomography up to the administration of radiotherapy, and allowed the operators to suspend the procedure and to interact with the patient in case of large movements of the pupil. Results: Twenty patients were treated with stereotactic radiosurgery (27 Gy in one fraction) for primary uveal melanoma. All patients showed a good tolerance to the treatment; until now, all patients were in local control during the follow up and one died for distant progression 6 months after radiosurgery. Conclusions: This study showed that this noninvasive technique, based on eye position control, is appropriate and can contribute to the success of LINACbased stereotactic radiotherapy. A millimetric safety margin to the clinical target volume was adequate to take account for the organ movement. All patients treated till now showed a good local control; failures in the disease control were due to metastatic spread.

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Section: Methodssupporting

confidence: 88%

Section: Methodsmentioning

confidence: 99%

An empirical approach to the definition of the target margins in eye radiosurgery

Perrone

Laliscia

Traino

et al. 2023

J Applied Clin Med Phys

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“…This leads to improvement in accuracy at the time of treatment. The improved accuracy with 6D couch has been described in various studies [9,10] especially in stereotactic radiotherapy treatment for the central nervous system lesions. [11] The aim of the this study is to analyze the setup errors of patients with GBM treated with IGRT technique using 6D couch corrections, the benefit of applying corrections in 6° of freedom over the conventional three directions and whether any reduction in PTV margin can be done using daily CBCT and 6D couch correction which may help improve therapeutic index.…”

Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Effectiveness of 6D couch with daily cone beam computed tomography in reducing PTV margins for glioblastoma multiforme

Pruthi¹,

Nagpal²,

Pandey³

2022

JNRP

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Objectives: Image-guided radiotherapy maximizes therapeutic index of brain irradiation by reducing setup errors during treatment. The aim of study was to analyze setup errors in the radiation treatment of glioblastoma multiforme and if decrease in planning target volume (PTV), margin is feasible using daily cone beam CT (CBCT) and 6D couch correction. Materials and Methods: Twenty-one patients (630 fractions of radiotherapy) were studied in which corrections were made in 6° of freedom. We determined setup errors, impact of setup errors of initial three fractions CBCT versus rest of the treatment with daily CBCT, and mean difference in setup errors with or without application of 6D couch and volumetric benefit of reduction of PTV margin from 0.5 cm to 0.3 cm. Results: The mean shift in the conventional directions, namely, vertical, longitudinal, and lateral was 0.17 cm, 0.19 cm, and 0.11 cm. There was significant change in vertical shift when first three fractions were compared with rest of the treatment with daily CBCT. When the effect of 6D couch was nullified, all directions showed increased error with longitudinal shift being significant. The number of setup errors of magnitude >0.3 cm was more significant when only conventional shifts were applied as compared with 6D couch. There was significant decrease in volume of brain parenchyma irradiated when margin of PTV was reduced from 0.5 cm to 0.3 cm. Conclusion: Daily CBCT along with 6D couch correction can reduce setup error which allows reduction in PTV margin during radiotherapy planning in turn improving the therapeutic index.

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“…[11][12][13][14][15][16] The Varian 6-DOF PerfectPitch robotic couch recently introduced to clinic by Varian (Varian Medical Systems, Palo Alto, CA, USA) can compensate for such errors if detected. [17][18][19][20] .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the accuracy of a six-degree-of-freedom robotic couch using optical surface and cone beam CT images of an SRS QA phantom

et al. 2023

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Purpose: To assess the accuracy of the Varian PerfectPitch six-degree-of-freedom (6DOF) robotic couch by using a Varian SRS QA phantom. Methods: The stereotactic radiosurgery (SRS) phantom has five tungsten carbide BBs each with 7·5 mm in diameter arranged with the known geometry. Optical surface images and cone beam CT (CBCT) images of the phantom were taken at different pitch, roll and rotation angles. The pitch, roll, and rotation angles were varied from −3 to 3 degrees by inputs from the linac console. A total of 39 Vision RT images with different rotation angle combinations were collected, and the Vision RT software was used to determine the rotation angles and translational shifts from those images. Eight CBCT images at most allowed rotational angles were analysed by in-house software. The software took the coordinates of the voxel of the maximum CT number inside a 7·5-mm sphere surrounding one BB to be the measured position of this BB. Expected BB positions at different rotation angles were determined by multiplying measured BB positions at zero pitch and roll values by a rotation matrix. Applying the rotation matrix to 5 BB positions yielded 15 equations. A linear least square method was used for regression analysis to approximate the solutions of those equations. Results: Of the eight calculations from CBCT images, the maximum rotation angle differences (degree) were 0·10 for pitch, 0·15 for roll and 0·09 for yaw. The maximum translation differences were 0·3 mm in the left–right direction, 0·5 mm in the anterior–posterior direction and 0·4 mm in the superior–inferior direction. Conclusions: The uncertainties of the 6-DOF couch were examined with the methods of optical surface imaging and CBCT imaging of the SRS QA phantom. The rotational errors were less than 0·2 degree, and the isocentre shifts were less than 0·8 mm.

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Geometric accuracy evaluation of a six-degree-of-freedom (6-DoF) couch with cone beam computed tomography (CBCT) using a phantom and correlation study of the position errors in pelvic tumor radiotherapy

Cited by 6 publications

References 18 publications

An empirical approach to the definition of the target margins in eye radiosurgery

An empirical approach to the definition of the target margins in eye radiosurgery

Effectiveness of 6D couch with daily cone beam computed tomography in reducing PTV margins for glioblastoma multiforme

Evaluation of the accuracy of a six-degree-of-freedom robotic couch using optical surface and cone beam CT images of an SRS QA phantom

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