Repositioning accuracy of fractionated stereotactic irradiation: assessment of isocentre alignment for different dental fixations by using sequential CT scanning

Baumert, Brigitta G.; Egli, Peter; Studer, Stephan; Dehing, C; Davis, J. Bernard

doi:10.1016/j.radonc.2004.08.002

Cited by 47 publications

(54 citation statements)

References 24 publications

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“…However, based on the imaging data from the kV on‐board imager, significant shifts were measured sometimes when the patients were set up using only the stereotactic immobilization mask and localization system. Previous studies ( 7 , 10 ) reported large shifts using the BrainLAB mask immobilization, and showed that combining dental mold or upper jaw support with the mask improved the accuracy of patient setup in agreement with this work. Other studies measured the shifts required using the Exac‐Track system for patients who were immobilized using the BrainLAB immobilization mask system ( 7 ) and reported large shifts to correct patient position.…”

Section: Discussionsupporting

confidence: 88%

“…Even with more rigid immobilization systems such as the head ring, ( 9 ) dental molds, or upper jaw supporting system, ( 7 , 10 ) the setup accuracy may be compromised by uncontrolled offsets that result from ring slippage. An independent verification system of the patient setup is important where secondary shifts might be detected and corrected.…”

Section: Discussionmentioning

confidence: 99%

“…A head ring ( 9 ) is usually attached invasively with pins to the patient skull, which provides a reproducible patient setup between simulation and treatment with a positioning accuracy better than 2 mm. Other less invasive immobilization systems such as dental bite blocks, facial or head and neck masks ( 7 , 10 ) are available for use to immobilize stereotactic radiotherapy patients. These systems are more flexible for treatments of lesions with broader dose regimen that include hypofractionated doses; however, the reproducibility and accuracy of patient setup is inferior to the rigid invasive head ring.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the setup accuracy of a stereotactic radiotherapy head immobilization mask system using kV on‐board imaging

Ali

Tubbs

Hibbitts

et al. 2010

J Applied Clin Med Phys

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The purpose of this study was to evaluate setup accuracy and quantify random and systematic errors of the BrainLAB stereotactic immobilization mask and localization system using kV on‐board imaging. Nine patients were simulated and set up with the BrainLAB stereotactic head immobilization mask and localizer to be treated for brain lesions using single and hypofractions. Orthogonal pairs of projections were acquired using a kV on‐board imager mounted on a Varian Trilogy machine. The kV projections were then registered with digitally‐reconstructed radiographs (DRR) obtained from treatment planning. Shifts between the kV images and reference DRRs were calculated in the different directions: anterior‐posterior (A‐P), medial‐lateral (R‐L) and superior‐inferior (S‐I). If the shifts were larger than 2 mm in any direction, the patient was reset within the immobilization mask until satisfying setup accuracy based on image guidance has been achieved. Shifts as large as 4.5 mm, 5.0 mm, 8.0 mm in the A‐P, R‐L and S‐I directions, respectively, were measured from image registration of kV projections and DRRs. These shifts represent offsets between the treatment and simulation setup using immobilization mask. The mean offsets of 0.1 mm, 0.7 mm, and −1.6 mm represent systematic errors of the BrainLAB localizer in the A‐P, R‐L and S‐I directions, respectively. The mean of the radial shifts is about 1.7 mm. The standard deviations of the shifts were 2.2 mm, 2.0 mm, and 2.6 mm in A‐P, R‐L and S‐I directions, respectively, which represent random patient setup errors with the BrainLAB mask. The BrainLAB mask provides a noninvasive, practical and flexible immobilization system that keeps the patients in place during treatment. Relying on this system for patient setup might be associated with significant setup errors. Image guidance with the kV on‐board imager provides an independent verification technique to ensure accuracy of patient setup. Since the patient may relax or move during treatment, uncontrolled and undetected setup errors may be produced with patients that are not well‐immobilized. Therefore, the combination of stereotactic immobilization and image guidance achieves more controlled and accurate patient setup within 2 mm in A‐P, R‐L and S‐I directions.PACS numbers: 87.56.‐v, 87.56.Da

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of the setup accuracy of a stereotactic radiotherapy head immobilization mask system using kV on‐board imaging

Ali

Tubbs

Hibbitts

et al. 2010

J Applied Clin Med Phys

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show abstract

“…Patients are immobilized in Scotch-cast masks. Image guidance with online correction of setup errors in 6 DOF replaced treatment based on external stereotactic coordinates [1,3,18]. The degree of precision achievable with this IGRT technique is mainly limited by the potential of the fixation device to immobilize the patient during treatment.…”

Section: Discussionmentioning

confidence: 99%