A retrospective analysis of setup and intrafraction positional variation in stereotactic radiotherapy treatments

Barnes, Micah; Yeo, Adam; Thompson, Kenton; Phillips, Claire; Kron, Tomas; Hardcastle, Nicholas

doi:10.1002/acm2.13076

Cited by 18 publications

(21 citation statements)

References 20 publications

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“…Barnes et al used a mask system which is similar to BLSRS and retrospectively analyzed intrafractional positional variations in stereotactic treatments. The mean deviation along each axis was ± 0.1 mm and ± 0.1°, which is similar to our results for BLSRS mask (±0.1 mm and ± 0.1°) [15] .…”

Section: Discussionsupporting

confidence: 91%

“…The stereotactic mask systems used in the present work have also been studied by Lesiuk et al, Shah et al and Agazaryan et al They could all show mean deviations smaller than 0.7 mm [12] , [13] , [14] . Barnes et al reported deviations of only 0.1 mm along each axis [15] . Similarly, double mask systems used by Tomihara et al resulted in an average 3D-deviation of 0.2 mm [16] .…”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Intrafractional monitoring of patients using four different immobilization mask systems for cranial radiotherapy

Reitz

Muecke

Mendes

et al. 2022

Physics and Imaging in Radiation Oncology

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 98%

Intrafractional monitoring of patients using four different immobilization mask systems for cranial radiotherapy

Reitz

Muecke

Mendes

et al. 2022

Physics and Imaging in Radiation Oncology

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“…Unlike CBCT, which is capable of imaging at zero couch angles only, stereoscopic x-ray imaging (ExacTrac, BrainLab AG, Germany) and surface guided imaging (SGRT) with no radiation are options to be considered [ 6 , 7 , 17 , 18 ]. According to Barnes et al, 42% of fractions required repositioning when intrafractionally monitored using stereoscopic X-ray imaging because of motion greater than 0.7 mm and 0.7°, which was their action level [ 7 ]. However, the prolonged treatment time required for repetitive imaging and position correction cannot be neglected.…”

Section: Discussionmentioning

confidence: 99%

Combined effect of dose gradient and rotational error on prescribed dose coverage for single isocenter multiple brain metastases in frameless stereotactic radiotherapy

et al. 2021

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Background To evaluate the combined effect of rotational error and dose gradient on target dose coverage in frameless stereotactic radiotherapy. Methods Three spherical targets of different diameters (1, 1.5, and 2 cm) were drawn and placed equidistantly on the same axial brain computed tomography (CT) images. To test the different isocenter-target distances, 2.5- and 5-cm configurations were prepared. Volumetric modulated arc therapy plans were created for different dose gradients from the target, in which the dose gradients were modified using the maximum dose inside the target. To simulate the rotational error, CT images and targets were rotated in two ways by 0.5°, 1°, and 2°, in which one rotation was in the axial plane and the other was in three dimensions. The initial optimized plan parameters were copied to the rotated CT sets, and the doses were recalculated. The coverage degradation after rotation was analyzed according to the target dislocation and 12-Gy volume. Results A shallower dose gradient reduced the loss of target coverage under target dislocation, and the effect was clearer for small targets. For example, the coverage of the 1-cm target under 1-mm dislocation increased from 93 to 95% by increasing the Paddick gradient index from 5.0 to 7.9. At the same time, the widely accepted necrosis indicator, the 12-Gy volume, increased from 1.2 to 3.5 cm3, which remained in the tolerable range. From the differential dose volume histogram (DVH) analysis, the shallower dose gradient ensured that the dose-deficient under-covered target volume received a higher dose similar to that in the prescription. Conclusions For frameless stereotactic brain radiotherapy, the gradient, alongside the margin addition, can be adjusted as an ancillary parameter for small targets to increase target coverage or at least limit coverage reduction in conditions with probable positioning error.

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“…The accuracy of treatment planning and delivery is highly dependent on accurate patient positioning and immobilization to achieve local tumor control and spare normal tissue. Several stereotactic systems have been used to immobilize these patients accurately during treatment 1–8 . Conventionally, invasive immobilization, such as metal frames or rings fixed to the patient’s skull, has been used for patient immobilization and target localization in the SRS/SRT treatment of intracranial lesions 4 .…”

Section: Introductionmentioning

confidence: 99%

“…Several stereotactic systems have been used to immobilize these patients accurately during treatment. [1][2][3][4][5][6][7][8] Conventionally, invasive immobilization, such as metal frames or rings fixed to the patient's skull, has been used for patient immobilization and target localization in the SRS/SRT treatment of intracranial lesions. 4 Noninvasive (frameless) SRS/SRT, such as thermoplastic mask systems, has become a standard immobilization method owing to the advent of image-guided radiotherapy (IGRT) systems.…”

Section: Introductionmentioning

confidence: 99%

Uncertainty in the positioning of patients receiving treatment for brain metastases and wearing surgical mask underneath thermoplastic mask during COVID‐19 crisis

Miura

Hioki²,

Ozawa

et al. 2021

J Applied Clin Med Phys

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Thermoplastic masks, used along with surgical masks, enable immobilization methods to reduce the risk of infection in patients undergoing intracranial stereotactic radiosurgery and stereotactic radiotherapy (SRS/SRT) during the COVID-19 crisis.The purpose of this study was to investigate the feasibility of thermoplastic mask immobilization with a surgical mask using an ExacTrac system. Twelve patients each with brain metastases were immobilized using a thermoplastic mask and a surgical mask and only a thermoplastic mask. Two x-ray images were acquired to correct (XC) and verify (XV) the patient's position at a couch angle of 0°. Subsequently, the XC and XV images were acquired at each planned couch angle for non-coplanar beams. When the position errors were detected after couch rotation for noncoplanar beams, the errors were corrected at each planned couch angle until a clinically acceptable tolerance was attained. The position errors in the translational and rotational directions (vertical, lateral, longitudinal, pitch, roll, and yaw) were retrospectively investigated using data from the ExacTrac system database. A standard deviation of XC translational and rotational position errors with and without a surgical mask in the lateral (1.52 vs 2.07 mm), longitudinal (1.59 vs 1.87 mm), vertical (1.00 vs 1.73 mm), pitch (0.99 vs 0.79°), roll (1.24 vs 0.68°), and yaw (1.58 vs 0.90°) directions were observed at a couch angle of 0°. Most of patient positioning errors were less than 1.0 mm or 1.0°after the couch was rotated to the planned angle for non-coplanar beams. The overall absolute values of the translational and rotational XV position errors with and without the surgical mask were less than 0.5 mm and 0.5°, respectively. This study showed that a thermoplastic mask with a surgical mask is a feasible immobilization technique for brain SRS/SRT patients using the ExacTrac system.

show abstract

A retrospective analysis of setup and intrafraction positional variation in stereotactic radiotherapy treatments

Cited by 18 publications

References 20 publications

Intrafractional monitoring of patients using four different immobilization mask systems for cranial radiotherapy

Intrafractional monitoring of patients using four different immobilization mask systems for cranial radiotherapy

Combined effect of dose gradient and rotational error on prescribed dose coverage for single isocenter multiple brain metastases in frameless stereotactic radiotherapy

Uncertainty in the positioning of patients receiving treatment for brain metastases and wearing surgical mask underneath thermoplastic mask during COVID‐19 crisis

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