Intra-fractional patient setup error during fractionated intracranial stereotactic irradiation treatment of patients wearing medical masks: comparison with and without bite block during COVID-19 pandemic

Ohira, Satoshi; Kanayama, Naoyuki; Komiyama, Riho; Ikawa, Toshiki; Toratani, Masayasu; Ueda, Yoshihiro; Washio, Hayate; Miyazaki, Michihiko; Teshima, Teruki

doi:10.1093/jrr/rraa101

Cited by 8 publications

(14 citation statements)

References 27 publications

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“…For example, the fixation ability of a mask with a patient-specific dental bite block attached to the frame was estimated to be comparable to that of the invasive frame method [ 3 , 15 ]. However, a null result was also obtained using the bite-block system by Ohira et al [ 16 ] which implies that the accuracy evaluation at each institution is required before use.…”

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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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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“…The Student’s t‐test showed no statistical difference between the two groups on any three translational and three rotational motion shifts 9 . Ohira et al compared the intrafractional patient setup error with and without a mask, a bite block (BB), during fractionated intracranial stereotactic irradiation (STI) with thermoplastic masks and concluded that the required accuracy for STI can be maintained even without BB 5 . Their strategy for image registration was to correct patient position using CBCT, and bony registration was performed using the MV images at each planned couch angle for non‐coplanar beams.…”

Section: Discussionmentioning

confidence: 99%

“…with thermoplastic masks and concluded that the required accuracy for STI can be maintained even without BB. 5 Their strategy for image registration was to correct patient position using CBCT, and bony registration was performed using the MV images at each planned couch angle for non-coplanar beams. The CBCT requires | 279 spectrum.…”

Section: Discussionmentioning

confidence: 99%

“…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%

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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.

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Intra‐fractional motion error during HyperArc stereotactic radiosurgery on patients with brain metastases: Comparison of open and full‐face clamshell‐style immobilization devices

Ohira

Komiyama

Kanayama

et al. 2022

J Applied Clin Med Phys

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Purpose To compare the intrafractional motion error (IME) during stereotactic irradiation (STI) in patients with brain metastases immobilized using open‐ (Encompass) and full‐face (DSPS) clamshell‐style immobilization devices. Methods Encompass (38 patients) and DSPS (38 patients) were used for patient immobilization, and HyperArc plans with three to four non‐coplanar beams were generated to deliver 25 to 35 Gy in three to five fractions. Cone‐beam computed tomography (CBCT) was performed on patients before and after the treatment. Moreover, the difference in patient position between the two CBCT images was considered as the IME. The margins to compensate for IME were calculated using the van Herk margin formula. Results For Encompass, the mean values of IME in the translational setup were 0.1, 0.2, and 0.0 mm in the anterior–posterior, superior–inferior, and left–right directions, respectively, and the mean values of IME about rotational axes were −0.1, 0.0, and 0.0° for the Pitch, Roll, and Yaw rotations, respectively. For DSPS, the mean values of IME in the translational setup were 0.2, 0.2, and 0.0 mm in the anterior–posterior, superior–inferior, and left–right directions, respectively, and the mean values of IME about rotational axes were −0.1, −0.1, and 0.0° for the Pitch, Roll, and Yaw rotations, respectively. No statistically significant difference was observed between the IME of the two immobilization systems except in the anterior–posterior direction (p = 0.02). Moreover, no statistically significant correlation was observed between three‐dimensional IME and treatment time. The margin compensation for IME was less than 1 mm for both immobilization devices. Conclusions The IME during STI using open‐ and full‐face clamshell‐style immobilization devices is approximately equal considering the adequate accuracy in patient positioning.

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Intra-fractional patient setup error during fractionated intracranial stereotactic irradiation treatment of patients wearing medical masks: comparison with and without bite block during COVID-19 pandemic

Cited by 8 publications

References 27 publications

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

Intra‐fractional motion error during HyperArc stereotactic radiosurgery on patients with brain metastases: Comparison of open and full‐face clamshell‐style immobilization devices

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