Repositioning accuracy of a commercially available thermoplastic mask system

Fuß, Martin; Salter, Bill J.; Cheek, D; Sadeghi, Amir; Hevezi, James M.; Herman, Terence S.

doi:10.1016/j.radonc.2004.03.003

Cited by 65 publications

(47 citation statements)

References 10 publications

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“…Due to the possibility of patient motion with non‐invasive frameless immobilization systems, imaging techniques must be applied throughout treatment to ensure that dose is delivered and distributed according to the treatment plan. Previous works have found that image‐guided frameless SRS provides a similar level of intrafraction patient motion as frame based SRS, but that a single image acquired pre‐treatment is not sufficient to monitor patient motion 3, 8, 11. This study found average magnitude shifts of less than 0.8 mm for all image acquisitions, with a range of 0.08–3.64 mm, similar to previous works.…”

Section: Discussionmentioning

confidence: 99%

“…To achieve the required levels of setup accuracy, image guidance and a thermoplastic mask attached to the treatment couch are used in place of an invasive head frame. Previous works have shown that intra‐fractional positioning accuracy of mask‐based immobilization systems range from 1.59 ± 0.84 mm to 4.7 ± 1.7 mm using a thermoplastic mask and image guidance from Cone‐beam CT (CBCT), CT simulation, portal images, and biplanar diagnostic x ray 2, 3, 4, 5. These positioning errors are still too large for SRS treatments, due to irradiating critical organs during the treatment.…”

Section: Introductionmentioning

confidence: 99%

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Monitoring frequency of intra‐fraction patient motion using the ExacTrac system for LINAC‐based SRS treatments

Lewis

Snyder

Kim

et al. 2018

J Applied Clin Med Phys

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PurposeThe aim of this study was to investigate the intra‐fractional patient motion using the ExacTrac system in LINAC‐based stereotactic radiosurgery (SRS).MethodA retrospective analysis of 104 SRS patients with kilovoltage image‐guided setup (Brainlab ExacTrac) data was performed. Each patient was imaged pre‐treatment, and at two time points during treatment (1st and 2nd mid‐treatment), and bony anatomy of the skull was used to establish setup error at each time point. The datasets included the translational and rotational setup error, as well as the time period between image acquisitions. After each image acquisition, the patient was repositioned using the calculated shift to correct the setup error. Only translational errors were corrected due to the absence of a 6D treatment table. Setup time and directional shift values were analyzed to determine correlation between shift magnitudes as well as time between acquisitions.ResultsThe average magnitude translation was 0.64 ± 0.59 mm, 0.79 ± 0.45 mm, and 0.65 ± 0.35 mm for the pre‐treatment, 1st mid‐treatment, and 2nd mid‐treatment imaging time points. The average time from pre‐treatment image acquisition to 1st mid‐treatment image acquisition was 7.98 ± 0.45 min, from 1st to 2nd mid‐treatment image was 4.87 ± 1.96 min. The greatest translation was 3.64 mm, occurring in the pre‐treatment image. No patient had a 1st or 2nd mid‐treatment image with greater than 2 mm magnitude shifts.ConclusionThere was no correlation between patient motion over time, in direction or magnitude, and duration of treatment. The imaging frequency could be reduced to decrease imaging dose and treatment time without significant changes in patient position.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Monitoring frequency of intra‐fraction patient motion using the ExacTrac system for LINAC‐based SRS treatments

Lewis

Snyder

Kim

et al. 2018

J Applied Clin Med Phys

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“…Compared to head frames, noninvasive immobilization systems such as thermoplastic masks have been shown to offer patient immobilization inferior to what is required for SRS, but sufficient for fully fractionated stereotactic radiotherapy (FSRT) 7, 8, 9, 10, 11, 12. These immobilization systems have been increasingly used in hypofractionated stereotactic radiotherapy (HF‐SRT), stereotactic radiation delivered in 2 to 5 fractions, but the performance has not been well studied 13…”

Section: Introductionmentioning

confidence: 99%

To frame or not to frame? Cone‐beam CT‐based analysis of head immobilization devices specific to linac‐based stereotactic radiosurgery and radiotherapy

Babic

Lee

Ruschin

et al. 2018

J Applied Clin Med Phys

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PurposeNoninvasive frameless systems are increasingly being utilized for head immobilization in stereotactic radiosurgery (SRS). Knowing the head positioning reproducibility of frameless systems and their respective ability to limit intrafractional head motion is important in order to safely perform SRS. The purpose of this study was to evaluate and compare the intrafractional head motion of an invasive frame and a series of frameless systems for single fraction SRS and fractionated/hypofractionated stereotactic radiotherapy (FSRT/HF‐SRT).MethodsThe noninvasive PinPoint system was used on 15 HF‐SRT and 21 SRS patients. Intrafractional motion for these patients was compared to 15 SRS patients immobilized with Cosman‐Roberts‐Wells (CRW) frame, and a FSRT population that respectively included 23, 32, and 15 patients immobilized using Gill‐Thomas‐Cosman (GTC) frame, Uniframe, and Orfit. All HF‐SRT and FSRT patients were treated using intensity‐modulated radiation therapy on a linear accelerator equipped with cone‐beam CT (CBCT) and a robotic couch. SRS patients were treated using gantry‐mounted stereotactic cones. The CBCT image‐guidance protocol included initial setup, pretreatment and post‐treatment verification images. The residual error determined from the post‐treatment CBCT was used as a surrogate for intrafractional head motion during treatment.ResultsThe mean intrafractional motion over all fractions with PinPoint was 0.62 ± 0.33 mm and 0.45 ± 0.33 mm, respectively, for the HF‐SRT and SRS cohort of patients (P‐value = 0.266). For CRW, GTC, Orfit, and Uniframe, the mean intrafractional motions were 0.30 ± 0.21 mm, 0.54 ± 0.76 mm, 0.73 ± 0.49 mm, and 0.76 ± 0.51 mm, respectively. For CRW, PinPoint, GTC, Orfit, and Uniframe, intrafractional motion exceeded 1.5 mm in 0%, 0%, 5%, 6%, and 8% of all fractions treated, respectively.ConclusionsThe noninvasive PinPoint system and the invasive CRW frame stringently limit cranial intrafractional motion, while the latter provides superior immobilization. Based on the results of this study, our clinical practice for malignant tumors has evolved to apply an invasive CRW frame only for metastases in eloquent locations to minimize normal tissue exposure.

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“…These techniques, however, do not fixate the head but merely immobilize it with a tendency to fixation [e.g. 66,98,153,160]. The concept remains the same: to pin down the skull and with that the target, since its position has a strong relation to the skull.…”

Section: Non-invasive Framesmentioning

confidence: 99%

NCS Report 25: Process management and quality assurance for intracranial stereotactic treatment

Heukelom¹,

Hoffmans-Holtzer²,

Marijnissen³

et al. 2015

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Repositioning accuracy of a commercially available thermoplastic mask system

Cited by 65 publications

References 10 publications

Monitoring frequency of intra‐fraction patient motion using the ExacTrac system for LINAC‐based SRS treatments

Monitoring frequency of intra‐fraction patient motion using the ExacTrac system for LINAC‐based SRS treatments

To frame or not to frame? Cone‐beam CT‐based analysis of head immobilization devices specific to linac‐based stereotactic radiosurgery and radiotherapy

NCS Report 25: Process management and quality assurance for intracranial stereotactic treatment

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