Influence of Rotations on Dose Distributions in Spinal Stereotactic Body Radiotherapy (SBRT)

Gutfeld, Orit; Kretzler, Annette; Kashani, Rojano; Tatro, Daniel; Balter, James M.

doi:10.1016/j.ijrobp.2008.12.025

Cited by 33 publications

(25 citation statements)

References 23 publications

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“…We added translational and rotational targeting errors resulting from our analysis of imaging data to each individual beam. A new beamset was generated by calculating shifted and rotated source and target vectors s 0 i and t 0 i according to equation (2). In the plan file, the original beamset was replaced using these transformed beam coordinates.…”

Section: Impact Of Residual Patient Motion On the Dose Distributionmentioning

confidence: 99%

See 1 more Smart Citation

Patient Motion and Targeting Accuracy in Robotic Spinal Radiosurgery: 260 Single-Fraction Fiducial-Free Cases

Fürweger¹,

Drexler²,

Kufeld³

et al. 2010

International Journal of Radiation Oncology*Biology*Physics

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Section: Impact Of Residual Patient Motion On the Dose Distributionmentioning

confidence: 99%

“…Both inter-and intrafraction motion contribute to the overall geometric error in treatment delivery (1)(2)(3)(4). Image-guided patient setup can minimize the impact of interfraction motion, but efforts to monitor and compensate for intrafraction motion are still limited (5,6).…”

Section: Introductionmentioning

confidence: 99%

Patient Motion and Targeting Accuracy in Robotic Spinal Radiosurgery: 260 Single-Fraction Fiducial-Free Cases

Fürweger¹,

Drexler²,

Kufeld³

et al. 2010

International Journal of Radiation Oncology*Biology*Physics

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“…The quantitative correlation between the amount of rotational errors and their dosimetric consequence is not obvious and there is a wide range of dose effects. (3,(13)(14)(15)(16)(17)(18) For example, during simulation, the simplest approach is to rotate the gantry for roll correction and couch for yaw correction. (13,16,8) Yue et al (9) developed a method to implement all six DOF corrections using combinations of gantry, collimator, and couch rotations achievable with a conventional treatment couch.…”

mentioning

confidence: 99%

“…(14,15) Additionally, for online corrections, both patient repositioning and plan adjustments have been proposed, and CBCT images have been used to evaluate dose impacts on setup errors. (3,17) At present, it is still a challenging task to accurately delineate the tumor and organs, and calculate the dose using CBCT images. (19) At the University of Florida, a frameless biteplate system is used for patient setup and localization for fractionated stereotactic radiotherapy (SRT) of brain tumors.…”

mentioning

confidence: 99%

Dosimetric consequences of rotational setup errors with direct simulation in a treatment planning system for fractionated stereotactic radiotherapy

Peng

Liu

Chen

et al. 2011

J Applied Clin Med Phys

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The purpose was to determine dose‐delivery errors resulting from systematic rotational setup errors for fractionated stereotactic radiotherapy using direct simulation in a treatment planning system. Ten patients with brain tumors who received intensity‐modulated radiotherapy had dose distributions re‐evaluated to assess the impact of systematic rotational setup errors. The dosimetric effect of rotational setup errors was simulated by rotating images and contours using a 3 by 3 rotational matrix. Combined rotational errors of ± 1°,± 3°,± 5° and ± 7° and residual translation errors of 1 mm along each axis were simulated. Dosimetric effects of the rotated images were evaluated by recomputing dose distributions and compared with the original plan. The mean volume of CTV that received the prescription dose decreased from 99.3%± 0.5% (original) to 98.6%± 1.6% (± 1°), 97.0%± 2.0% (± 3°), 93.1%± 4.6% (± 5°), and 87.8%± 14.2% (± 7°). Minimal changes in the cold and hot spots were seen in the CTV. In general, the increase in the volumes of the organs at risk (OARs) receiving the tolerance doses was small and did not exceed the tolerance, except for cases where the OARs were in close proximity to the PTV. For intracranial tumors treated with IMRT with a CTV‐to‐PTV margin of 3 mm, rotational setup errors of 3° or less didn't decrease the CTV coverage to less than 95% in most cases. However, for large targets with irregular or elliptical shapes, the target coverage decreased significantly as rotational errors of 5° or more were present. Our results indicate that setup margins are warranted even in the absence of translational setup errors to account for rotational setup errors. Rotational setup errors should be evaluated carefully for clinical cases involving large tumor sizes and for targets with elliptical or irregular shape, as well as when isocenter is away from the center of the PTV or OARs are in close proximity to the target volumes.PACS number: 87.53.Bn

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“…Dose consequence due to setup errors for various sites has been studied extensively. [13][14][15][16][17][18][19][20][21][22] Some investigators [13][14][15][16][17][18] suggest that the dosimetric influence of small rotational errors is minimal for most cases in head and neck treatment, prostate treatment, and spine treatment, whereas larger rotational errors may dramatically affect clinical target volume (CTV) coverage and=or organs-at-risk (OAR) sparing, such as in cases of irregular target shape and=or OAR positions that are proximate to the target. Our previous study 19 demonstrated similar dosimetric consequences for SRT of intracranial tumors.…”

Section: Introductionmentioning

confidence: 99%

An approach for online evaluations of dose consequences caused by small rotational setup errors in intracranial stereotactic radiation therapy

Lü

Kahler

et al. 2011

Medical Physics

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Purpose: The purpose of this work is to investigate the impact of small rotational errors on the magnitudes and distributions of spatial dose variations for intracranial stereotactic radiotherapy (SRT) treatment setups, and to assess the feasibility of using the original dose map overlaid with rotated contours (ODMORC) method as a fast, online evaluation tool to estimate dose changes (using DVHs) to clinical target volumes (CTVs) and organs‐at‐risks (OARs) caused by small rotational setup errors. Methods: Fifteen intracranial SRT cases treated with either three‐dimensional conformal radiation therapy (3DCRT) or intensity‐modulated radiation therapy (IMRT) techniques were chosen for the study. Selected cases have a variety of anatomical dimensions and pathologies. Angles of ±3° and ±5° in all directions were selected to simulate the rotational errors. Dose variations in different regions of the brain, CTVs, and OARs were evaluated to illustrate the various spatial effects of dose differences before and after rotations. DVHs accounting for rotations that were recomputed by the treatment planning system (TPS) and those generated by the ODMORC method were compared. A framework of a fast algorithm for multicontour rotation implemented by ODMORC is introduced as well. Results: The average values of relative dose variations between original dose and recomputed dose accounting for rotations were greater than 4.0% and 10.0% in absolute mean and in standard deviation, respectively, at the skull and adjacent regions for all cases. They were less than 1.0% and 2.5% in absolute mean and in standard deviation, respectively, for dose points 3 mm away from the skull. The results indicated that spatial dose to any part of the brain organs or tumors separated from the skull or head surface would be relatively stable before and after rotations. Statistical data of CTVs and OARs indicate the lens and cochleas have the large dose variations before and after rotations, whereas the remaining ROIs have insignificant dose differences. DVH comparisons suggest that the ODMORC method is able to estimate the DVH of CTVs fairly accurately (within 1.5% of relative dose differences for evaluation volumes). The results also show that most of the OARs including the brain stem, spinal cord, chiasm, hippocampuses, optic nerves, and retinas, which were relatively distal from the skull and surface, had good agreement (within 2.0% of relative dose differences for 0.1 cc of the volumes) between the ODMORC method and the recomputation, whereas OARs more proximate to the bone‐tissue interface or surface, such as the lenses and cochlea, had larger dose variations (greater than 5.0%) for some cases due to the incapability of the ODMORC to account for scatter contribution variations proximate to interfaces and intrinsic dose calculation uncertainties for ROIs with small volumes. Conclusions: The ODMORC method can be implemented as an online evaluation system for rotation‐induced dose changes of CTVs and most OARs and for other related dose consequence analy...

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Influence of Rotations on Dose Distributions in Spinal Stereotactic Body Radiotherapy (SBRT)

Cited by 33 publications

References 23 publications

Patient Motion and Targeting Accuracy in Robotic Spinal Radiosurgery: 260 Single-Fraction Fiducial-Free Cases

Patient Motion and Targeting Accuracy in Robotic Spinal Radiosurgery: 260 Single-Fraction Fiducial-Free Cases

Dosimetric consequences of rotational setup errors with direct simulation in a treatment planning system for fractionated stereotactic radiotherapy

An approach for online evaluations of dose consequences caused by small rotational setup errors in intracranial stereotactic radiation therapy

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