Accuracy evaluation of a six‐degree‐of‐freedom couch using cone beam <scp>CT</scp> and IsoCal phantom with an in‐house algorithm

Driewer, J; Wang, Shuo; Li, Sicong; Zhu, Xiaofeng; Zheng, Dandan; Cao, Yejie; Zhang, Jiaju; Jamshidi, A; Cox, Brett; Knisely, Jonathan; Potters, Louis; Klein, Eric E.

doi:10.1002/mp.12342

Cited by 10 publications

(9 citation statements)

References 27 publications

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“…Theoretically, the 6-DoF couch united with kilovoltage cone beam computed tomography (kV-CBCT) can further reduce setup errors. This may lead to a potential situation that decreases the clinical target volume (CTV) to planning target volume (PTV) margins ( 9 , 10 ).…”

Section: Introductionmentioning

confidence: 99%

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

Fu¹,

Ma²,

Shang³

et al. 2020

Transl Cancer Res TCR

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Background: To assess the position accuracy of the six-degree-of-freedom (6-DoF) couch based on cone beam computed tomography (CBCT) and exploit the correlation of the six degrees errors.Methods: CT scans of an anthropomorphic phantom and patients were obtained at 3 mm slice thicknesses using a Philips scanner at the head, first supine and prostrate positions. An Eclipse Treatment Planning System was used to create a treatment plan. Different levels of known position errors were introduced to simulate patient position status for the anthropomorphic phantom. CBCT datasets for each position were acquired and registered to original CT datasets to evaluate the accuracy of the 6-DoF couch and determine the setup errors of patients. The setup errors of 200 CBCT datasets from 14 patients with pelvic tumors were analyzed. The correlations between six degrees position errors were finally extracted.Results: For the phantom study, the difference between known introduced errors and the setup errors were almost negligible. The deviation (mean ± one standard deviation) in registration methods were (0.01±0.

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Section: Introductionmentioning

confidence: 99%

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

Fu¹,

Ma²,

Shang³

et al. 2020

Transl Cancer Res TCR

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show abstract

“…There is also a treatment machine, called tomotherapy, which can correct only three translational and one rotational axes . Zhang et al investigated the rotational accuracy of the 6DoF couch with cone‐beam CT, and they reported that the mean rotational errors ± SD for pitch, roll, and yaw angles were 0.028 ± 0.032°, −0.043 ± 0.058°, and −0.009 ± 0.033°, respectively. The rotational accuracy of our prototype device was measured using two different methods (the digital goniometer and cone‐beam CT), which is almost equivalent to the results reported by Zhang et al as shown in Result section 3.B.…”

Section: Discussionmentioning

confidence: 99%

“…Zhang et al investigated the rotational accuracy of the 6DoF couch with cone‐beam CT, and they reported that the mean rotational errors ± SD for pitch, roll, and yaw angles were 0.028 ± 0.032°, −0.043 ± 0.058°, and −0.009 ± 0.033°, respectively. The rotational accuracy of our prototype device was measured using two different methods (the digital goniometer and cone‐beam CT), which is almost equivalent to the results reported by Zhang et al as shown in Result section 3.B. Moreover, the repeatability was less than the detection limit of the digital goniometer, as described in Result section 3.A.…”

Section: Discussionmentioning

confidence: 99%

Development of twist‐correction system for radiotherapy of head and neck cancer patients

Shimizu

Sasaki

Aoyama

et al. 2019

J Applied Clin Med Phys

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To propose a concept for correcting the twist between the head and neck and the body frequently occurring in radiotherapy patients and to develop a prototype device for achieving this. Furthermore, the operational accuracy of this device under no load was evaluated. We devised a concept for correcting the twist of patients by adjustment of the three rotation (pitch, roll, and yaw) angles in two independent plates connected by a joint (fulcrum). The two plates (head and neck plate and body plate) rotate around the fulcrum by adjusting screws under each of them. A prototype device was created to materialize this concept. First, after all adjusting screws were set to the zero position, the rotation angle of each plate was measured by a digital goniometer. Repeatability was evaluated by performing 20 repeated measurements. Next, to confirm the rotational accuracy of each plate of the prototype device, the calculated rotation angles for 20 combinations of patterns of traveled distances of the adjusting screws were compared with those measured by the digital goniometer and cone‐beam computed tomography (CT). The repeatability (standard deviation: SD) of the pitch, roll, and yaw angles of the head and neck plate was 0.04°, 0.05°, and 0.03°, and the repeatability (SD) of the body plate was 0.05°, 0.04°, and 0.04°, respectively. The mean differences ± SD between the calculated and measured pitch, roll, and yaw angles for the head and neck plate with the digital goniometer were 0.00 ± 0.06°, −0.01 ± 0.06°, and −0.04 ± 0.04°, respectively. The differences for the body plate were −0.03 ± 0.04°, 0.03 ± 0.05°, and 0.02 ± 0.05°, respectively. Results of the cone‐beam CT were similar to those of the digital goniometer. The prototype device exhibited good performance regarding the rotational accuracy and repeatability under no load. The clinical implementation of this concept is expected to reduce the residual error of the patient position due to the twist.

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“…The IsoCal phantom is a hollow cylinder with 16 tungsten-carbide ball bearings (BBs) arranged at a specified position. 15 While the purpose of this phantom is to calibrate between the isocenter and the image center, 16 it was used to determine the gantry angle in this study. The phantom images were acquired by the "triggered imaging" mode using the on-board kV imager at the source-detector distance (SDD) of 150 cm.…”

Section: A | Experimental Setupmentioning

confidence: 99%

Evaluation of gantry angle during respiratory‐gated VMAT using triggered kilovoltage x‐ray image

Miyasaka

Saitoh

Kawachi

et al. 2019

J Applied Clin Med Phys

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Respiratory‐gated volumetric modulated arc therapy (gated VMAT) involves further complexities to the dose delivery process because the gantry rotation must repeatedly stop and restart according to the gating signals. In previous studies, the gantry rotation performances were evaluated by the difference between the plan and the machine log. However, several reports pointed out that log analysis does not sufficiently replicate the machine performance. In this report, a measurement‐based quality assurance of the relation between the gantry angle and gate‐on or gate‐off using triggered kilovoltage imaging and a cylinder phantom with 16 ball bearings is proposed. For the analysis, an in‐house program that estimates and corrects the phantom offset was developed. The gantry angle in static and gated arc delivery was compared between the machine log and the proposed method. The gantry was set every 5 deg through its full motion range in static delivery, and rotated at three speeds (2, 4 and 6 deg s ‐1 ) with different gating intervals (1.5 or 3.0 s) in gated arc delivery. The mean and standard deviation of the angular differences between the log and the proposed method was −0.05 deg ± 0.12 deg in static delivery. The mean of the angular difference was within ±0.10 deg and the largest difference was 0.41 deg in gated arc delivery. The log records the output of the encoder so that miscalibration and mechanical sagging will be disregarded. However, the proposed method will help the users to detect the mechanical issues due to the repeated gantry stops and restarts in gated VMAT.

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Accuracy evaluation of a six‐degree‐of‐freedom couch using cone beam CT and IsoCal phantom with an in‐house algorithm

Cited by 10 publications

References 27 publications

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

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

Development of twist‐correction system for radiotherapy of head and neck cancer patients

Evaluation of gantry angle during respiratory‐gated VMAT using triggered kilovoltage x‐ray image

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