Quantitative evaluation of patient setup uncertainty of stereotactic radiotherapy with the frameless 6D ExacTrac system using statistical modeling

Keeling, V; Hossain, Sabbir; Jin, H; Algan, Özer; Ahmad, Salahuddin; Ali, I

doi:10.1120/jacmp.v17i3.5959

Cited by 20 publications

(27 citation statements)

References 24 publications

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“…Here, significant effort is required in order to ensure effective mask immobilization and, in certain cases, even with the mask, large systematic drifts of up to several millimeters from initial setup have been reported (Amelio et al, 2013; Fuss et al, 2004; Murphy, 2009). In a recent study uncertainties as large as 5.84 mm and 2.4 degrees were reported and were found to correspond to cases where patients do not setup appropriately because of the limited manufacturing quality of the mask, loosening or shrinkage of the mask during treatment, or physical changes of the patient's head during treatment due to swelling of the face (Keeling et al, 2016). As a result, treatment interruption for intrafractional patient realignment can occur to ensure proper target coverage.…”

Section: Introductionmentioning

confidence: 99%

Towards frameless maskless SRS through real-time 6DoF robotic motion compensation

Belcher¹,

Liu²,

Chmura³

et al. 2017

Phys. Med. Biol.

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Purpose Stereotactic radiosurgery (SRS) uses precise dose placement to treat conditions of the CNS. Frame-based SRS uses a metal head ring fixed to the patient’s skull to provide high treatment accuracy, but patient comfort and clinical workflow may suffer. Frameless SRS, while potentially more convenient, may increase uncertainty of treatment accuracy and be physiologically confining to some patients. By incorporating highly precise robotics and advanced software algorithms into frameless treatments, we present a novel frameless and maskless SRS system where a robot provides real-time 6DOF head motion stabilization allowing positional accuracies to match or exceed those of traditional frame-based SRS. Methods A 6DOF parallel kinematics robot was developed and integrated with a real-time infrared camera in a closed loop configuration. A novel compensation algorithm was developed based on an iterative closest-path correction approach. The robotic SRS system was tested on six volunteers, whose motion was monitored and compensated for in real-time over 15-minute simulated treatments. The system’s effectiveness in maintaining the target’s 6DOF position within preset thresholds was determined by comparing volunteer head motion with and without compensation. Results Comparing corrected and uncorrected motion, the 6DOF robotic system showed an overall improvement factor of 21 in terms of maintaining target position within 0.5 mm and 0.5 degree thresholds. Although the system’s effectiveness varied among the volunteers examined, for all volunteers tested the target position remained within the preset tolerances 99.0% of the time when robotic stabilization was used, compared to 4.7% without robotic stabilization. Conclusion The pre-clinical robotic SRS compensation system was found to be effective at responding to sub-millimeter and sub-degree cranial motions for all volunteers examined. The system’s success with volunteers has demonstrated its capability for implementation with frameless and maskless SRS treatments, potentially able to achieve the same or better treatment accuracies compared to traditional frame-based approaches.

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Section: Introductionmentioning

confidence: 99%

Towards frameless maskless SRS through real-time 6DoF robotic motion compensation

Belcher¹,

Liu²,

Chmura³

et al. 2017

Phys. Med. Biol.

View full text Add to dashboard Cite

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“…Figures and show the accuracy of the patient setup at a couch angle of 0º for SRS/SRT treatment at our institution. Keeling et al reported that the mean translational XC shifts for each of 49 patient treatments were almost from − 2.5 to + 2.5 mm, and those SD values were much less than 1.0 mm in SRS/SRT with the frameless 6D ExacTrac system . It was suggested that our results were larger than theirs because a localizer box was not used in the CT simulation, and all patients were set up at the isocenter position manually in the SRS/SRT treatments at our institution.…”

Section: Discussionmentioning

confidence: 65%

“…A noninvasive thermoplastic mask (BrainLAB A.G., Heimstetten, Germany) was used to immobilize all patients in SRS/SRT for intracranial lesions. A previous report mentioned descriptions of this thermoplastic mask system . In this study, we did not use a localizer box in the CT simulation, but we marked the CT origin coordinate on the noninvasive thermoplastic mask directly as same as the conventional radiation therapy procedure.…”

Section: Methodsmentioning

confidence: 99%

“…Chang et al reported that the accuracy of the patient setup with cone‐beam computed tomography (CBCT) image guidance was comparable to that with frame‐based radiosurgery systems . The frameless 6D ExacTrac system (BrainLAB A.G., Heimstetten, Germany), which is mainly an integration of an infrared (IR)‐based optical positioning system and a radiographic kV X‐ray imaging system, is one of the advanced IGRT system . Keeling et al evaluated the patient setup accuracy of SRS/SRT with this system of 35 patients with cranial lesions using the positioning shift values in this system.…”

Section: Introductionmentioning

confidence: 99%

“…Keeling et al evaluated the patient setup accuracy of SRS/SRT with this system of 35 patients with cranial lesions using the positioning shift values in this system. They reported that the residual setup errors at a couch angle of 0º after positioning correction were less than 0.3 mm and 0.3º in the translational and rotational directions, respectively . Furthermore, the 6D ExacTrac system can be used even when a couch is rotated using noncoplanar beams.…”

Section: Introductionmentioning

confidence: 99%

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Impact of patient positioning uncertainty in noncoplanar intracranial stereotactic radiotherapy

Tanaka

Oita

Inomata

et al. 2020

J Applied Clin Med Phys

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The aim of this study is to evaluate the patient positioning uncertainty in noncoplanar stereotactic radiosurgery or stereotactic radiotherapy (SRS/SRT) for intracranial lesions with the frameless 6D ExacTrac system. In all, 28 patients treated with SRS/SRT of 70 treatment plans at our institution were evaluated in this study. Two X‐ray images with the frameless 6D ExacTrac system were first acquired to correct (XC) and verify (XV) the patient position at a couch angle of 0º. Subsequently, the XC and XV images were also acquired at each planned couch angle for using noncoplanar beams to detect position errors caused by rotating a couch. The translational XC and XV shift values at each couch angle were calculated for each plan. The percentages of the translational XC shift values within 1.0 mm for each planned couch angle for using noncoplanar beams were 77.86%, 72.26%, and 98.47% for the lateral, longitudinal, and vertical directions, respectively. Those within 2.0 mm were 98.22%, 97.96%, and 99.75% for the lateral, longitudinal, and vertical directions, respectively. The maximum absolute values of the translational XC shifts among all planned couch angles for using noncoplanar beams were 2.69, 2.45, and 2.17 mm for the lateral, longitudinal, and vertical directions, respectively. The overall absolute values of the translational XV shifts were less than 1.0 mm for all directions except for one case in the longitudinal direction. The patient position errors were detected after couch rotation for using noncoplanar beams, and they exceeded a planning target volume (PTV) margin of 1.0–2.0 mm used commonly in SRS/SRT treatment. These errors need to be corrected at each planned couch angle, or the PTV margin should be enlarged.

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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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Quantitative evaluation of patient setup uncertainty of stereotactic radiotherapy with the frameless 6D ExacTrac system using statistical modeling

Cited by 20 publications

References 24 publications

Towards frameless maskless SRS through real-time 6DoF robotic motion compensation

Towards frameless maskless SRS through real-time 6DoF robotic motion compensation

Impact of patient positioning uncertainty in noncoplanar intracranial stereotactic radiotherapy

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

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