Methodology to reduce 6D patient positional shifts into a 3D linear shift and its verification in frameless stereotactic radiotherapy

Sarkar, Biplab; Ray, Jyotirmoy; Ganesh, T; Manikandan, A.; Munshi, Anusheel; Rathinamuthu, Sasikumar; Kaur, Harpreet; Anbazhagan, Satheeshkumar; Giri, U; Roy, Soumya; Jassal, Kanan; Mohanti, Bidhu Kalyan

doi:10.1088/1361-6560/aab231

Cited by 15 publications

(17 citation statements)

References 31 publications

(37 reference statements)

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“…From the treatment approved plan, CT images were pushed to ExacTrac and CBCT workstations for set‐up verification. Details of radiotherapy treatment planning can be found elsewhere …”

Section: Methodsmentioning

confidence: 99%

“…A total of 699 intrafraction images, 361 coplanar, and 338 noncoplanar, were acquired for 51 SRS/SRT patients. Rotational errors were reduced to translational errors using the formula (1‐3 and 1a‐3a) described by Sarkar et al (

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) and (

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→

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Y_{Ex}^{v, i . . j}

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) …”

Section: Methodsmentioning

confidence: 99%

“…Intrafraction positional errors have been calculated using CBCT 12,29,30 stereoscopic x‐ray imaging like ExacTrac, Cyberknife (CK) imaging Synchrony, and surface guidance . Quantification of the intrafraction motion was carried out in terms of translational shifts or translational and rotational shifts and set‐up margins. In CBCT imaging, investigators determined intrafraction motion as the difference between the pre‐ and post‐treatment shifts.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, this study aims to determine rotational positional error corrected intrafraction set‐up margin in coplanar (

S M_{italicCP}^{x}

S M_{italicCP}^{y}

S M_{italicCP}^{z}

), and noncoplanar (

S M_{italicNCP}^{x}

S M_{italicNCP}^{y}

S M_{italicNCP}^{z}

) table positions, using ExacTrac imaging and compares it with the residual set‐up margin obtained from CBCT.…”

Section: Introductionmentioning

confidence: 99%

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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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“…From the treatment approved plan, CT images were pushed to ExacTrac and CBCT workstations for set‐up verification. Details of radiotherapy treatment planning can be found elsewhere …”

Section: Methodsmentioning

confidence: 99%

x_{CB}^{v}

y_{CB}^{v}

z_{CB}^{v}

θ_{CB}^{v}

Ψ_{CB}^{v}

Φ_{CB}^{v}

→

X_{CB}^{v}

Y_{CB}^{v}

Z_{CB}^{v}

) and (

x_{Ex}^{v, i . . j}

y_{Ex}^{v, i . . j}

z_{Ex}^{v, i . . j}

θ_{Ex}^{v, i . . j}

Ψ_{Ex}^{v, i . . j}

Φ_{Ex}^{v, i . . j}

→

X_{Ex}^{v, i . . j}

Y_{Ex}^{v, i . . j}

Z_{Ex}^{v, i . . j}

) …”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Therefore, this study aims to determine rotational positional error corrected intrafraction set‐up margin in coplanar (

S M_{italicCP}^{x}

S M_{italicCP}^{y}

S M_{italicCP}^{z}

), and noncoplanar (

S M_{italicNCP}^{x}

S M_{italicNCP}^{y}

S M_{italicNCP}^{z}

) table positions, using ExacTrac imaging and compares it with the residual set‐up margin obtained from CBCT.…”

Section: Introductionmentioning

confidence: 99%

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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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“…Subsequently CT images, along with the structure set and isocenter information, were pushed to the Monaco (Elekta CMS, Sunnyvale, CA) workstation for VMAT planning. Details of our stereotactic planning strategies can be found in previous articles …”

Section: Methodsmentioning

confidence: 99%

Standardization of volumetric modulated arc therapy‐based frameless stereotactic technique using a multidimensional ensemble‐aided knowledge‐based planning

et al. 2019

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Purpose Aim of this article is to describe a new knowledge‐based planning (KBP) methodology using volumetric modulated arc therapy (VMAT) for stereotactic radiosurgery (SRS) and radiotherapy (SRT) assisted by an ensemble mapping technique for use in a Monte Carlo planning system. Methods Libraries of 121 stereotactic patients were assembled on the basis of eight different parameters (a) tumor laterality, (b) whether planning target volume (PTV) dose coverage challenged by the presence of the organ at risk (OAR), (c) prescription dose and number of fractions, (d) number of PTVs, (e) tumor volume, (f) shortest distance between OAR and PTV (edge to edge distance, or EED), (g) center to center distance between OARs and PTV (CCD), and (h) lateral dimension of external contour (brain). For new patients, the most appropriate library plan was selected on the basis of the above categorization. A KBP plan was created based on this selected library plan with all parameters unchanged keeping the isocenter at the center of PTV. Using the same beam configuration, another independent treatment plan (IP) was generated by an experienced dosimetrist for comparison. IP and KBP were compared for 76 new patients. Results Of 197 patients (121 library and 76 new), 103 (52.3%) were placed in the OAR‐challenged category and 94 were placed in the OAR unchallenged category. The ensemble mapping technique shows that, for an OAR‐challenged patient, picking up the library plan is appropriate. IP was marginally better than KBP in PTV coverage and dose conformity (PCI). Library plans, IP, and KBP offer a mean PCI of 0.77 ± 0.2, 0.79 ± 0.2, and 0.78 ± 0.4, mean PTV‐V99% of 97.3 ± 22.0%, 98.9 ± 14.1%, and 98.2 ± 13.2%, and mean MU of 2403.8 ± 2403.8, 2344.0 ± 2423.6, and 2473.6 ± 2296.8, respectively. Statistically significant differences were observed in the planning time between the IP and KBP plans for both OAR‐challenged (P < 0.001) and ‐unchallenged (P < 0.002) categories. Comparison of optimization and dose calculation time showed a much lower average planning time of 111.0 ± 84.1 min for KBP as against 248.2 ± 96.6 min for IP. Conclusion Validation results for KBP plans indicate the multidimensional ensemble mapping mechanism can accurately pick up the most appropriate library plan. KBP plans, although slightly inferior in their dosimetric quality, fulfill all the required clinical conditions and dose constraints. KBP plans save considerable planning time and are nearly independent of the skill and knowledge of the treatment planner. KBP works well with a Monte Carlo planning system like Monaco.

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Evaluation of intrafraction couch shifts for proton treatment delivery in head‐and‐neck cancer patients: Toward optimal imaging frequency

Biswal

Rodrigues

Yao

et al. 2022

J Applied Clin Med Phys

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Purpose Treatment planning for head‐and‐neck (H&N) cancer, in particular oropharynx, nasopharynx, and paranasal sinus cases, at our center requires noncoplanar proton beams due to the complexity of the anatomy and target location. Targeting accuracy for all beams is carefully evaluated by using image guidance before delivering proton beam therapy (PBT). In this study, we analyzed couch shifts to evaluate whether imaging is required before delivering each field with different couch angles. Methods After the Institutional Review Board approval, a retrospective analysis was performed on data from 28 H&N patients treated with PBT. Each plan was made with two‐to‐three noncoplanar and two‐to‐three coplanar fields. Cone‐beam computed tomography and orthogonal kilovoltage (kV) images were acquired for setup and before delivering each field, respectively. The Cartesian (longitudinal, vertical, and lateral) and angular (pitch and roll) shifts for each field were recorded from the treatment summary on the first two fractions and every subsequent fifth fraction. A net magnitude of the three‐dimensional (3D) shift in Cartesian coordinates was calculated, and a 3D vector was created from the 6 degrees of freedom coordinates for transforming couch shifts in the system coordinate to the beam's‐eye view. Results A total of 3219 Cartesian and 2146 angular shift values were recorded for 28 patients. Of the Cartesian shifts, 2069 were zero (64.3%), and 1150 (35.7%) were nonzero (range, −7 to 11 mm). Of the angular shifts, 1034 (48.2%) were zero, and 1112 (51.8%) were nonzero (range, −3.0° to 3.2°). For 17 patients, the couch shifts increased toward the end of the treatment course. We also found that patients with higher body mass index (BMI) presented increased net couch shifts (p < 0.001). With BMI < 27, all overall net shift averages were <2 mm, and overall maximum net shifts were <6 mm. Conclusions These results confirm the need for orthogonal kV imaging before delivering each field of H&N PBT at our center, where a couch rotation is involved.

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Methodology to reduce 6D patient positional shifts into a 3D linear shift and its verification in frameless stereotactic radiotherapy

Cited by 15 publications

References 31 publications

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

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

Standardization of volumetric modulated arc therapy‐based frameless stereotactic technique using a multidimensional ensemble‐aided knowledge‐based planning

Evaluation of intrafraction couch shifts for proton treatment delivery in head‐and‐neck cancer patients: Toward optimal imaging frequency

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