Use of Flattening Filter Free Photon Beams for Off-axis Targets in Conformal Arc Stereotactic Body Radiation Therapy

Smith, A.; Kim, Siyong; Serago, Christopher F.; Hintenlang, Kathleen M.; Ko, Stephen; Vallow, Laura A.; Peterson, Jennifer; Hintenlang, David E.; Heckman, Michael G.; Buskirk, Steven J.

doi:10.14316/pmp.2014.25.4.288

Cited by 3 publications

(12 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, OAG FFF treatment plans are dosimetrically comparable to CAG plans . The disadvantage of OAG plans is that they require longer treatment delivery times compared to CAG FFF plans, related to the off‐axis distance of the PTV . A further potential concern of OAG is the magnification of misalignment errors in the collimator or couch rotations at the off‐axis position.…”

Section: Introductionmentioning

confidence: 99%

“…This then requires large lateral couch shifts to be applied to relocate the patient in the off‐centered couch position following verification. OAG, on the other hand, positions the isocenter at the midline of the patient, thus eliminating clearance issues and enables the patient setup to be verified in the treatment position . Furthermore, OAG FFF treatment plans are dosimetrically comparable to CAG plans .…”

Section: Introductionmentioning

confidence: 99%

“…OAG, on the other hand, positions the isocenter at the midline of the patient, thus eliminating clearance issues and enables the patient setup to be verified in the treatment position . Furthermore, OAG FFF treatment plans are dosimetrically comparable to CAG plans . The disadvantage of OAG plans is that they require longer treatment delivery times compared to CAG FFF plans, related to the off‐axis distance of the PTV .…”

Section: Introductionmentioning

confidence: 99%

“…A further potential concern of OAG is the magnification of misalignment errors in the collimator or couch rotations at the off‐axis position. However, these potential errors (<0.5° at the isocenter) were not found to have a clinically significant effect on dose distributions for OAG conventional (flattened) or FFF plans …”

Section: Introductionmentioning

confidence: 99%

“…16,18 The disadvantage of OAG plans is that they require longer treatment delivery times compared to CAG FFF plans, related to the off-axis distance of the PTV. 16 A further potential concern of OAG is the magnification of misalignment errors in the collimator or couch rotations at the off-axis position. However, these potential errors (<0.5°at the isocenter) were not found to have a clinically significant effect on dose distributions for OAG conventional (flattened) or FFF plans.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Improvement of off‐axis SABR plan verification results by using adapted dose reconstruction algorithms for the Octavius 4D system

et al. 2018

View full text Add to dashboard Cite

The errors in QA phantom measurements due to dose reconstruction at off-axis target geometry have been demonstrated for conformal arcs and clinical VMAT SABR plans. A novel software solution implemented by the vendor to allow accurate pass rates has been tested. This solution enables high-resolution arrays with small active detection areas to be used for quality assurance of SABR treatment plans in the off-axis treatment position.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Improvement of off‐axis SABR plan verification results by using adapted dose reconstruction algorithms for the Octavius 4D system

et al. 2018

View full text Add to dashboard Cite

show abstract

Delivery efficiency and susceptibility to setup uncertainties of flattening filter free lung SBRT: influence of isocentre geometry and treatment modality

Tyler

Dowdell

2018

Phys. Med. Biol.

View full text Add to dashboard Cite

Flattening filter free (FFF) photon beams are frequently used in stereotactic body radiation therapy (SBRT) treatments of lung lesions due to favourable dosimetric characteristics and comparable plan quality to conventional flattened beams. For peripheral targets, the treatment isocentre may remain close to the patient midline to minimise collision risks, which we denote as off-axis geometry (OAG). This study used a cohort of ten patients to investigate the sensitivity of OAG SBRT lung plans to offsets in the isocentre position and compared it to those where the isocentre is placed at the centre of the target volume, i.e. central axis geometry (CAG). Comparisons were made for SBRT treatment plans using 3D conformal radiotherapy (3DCRT) and volumetric modulated arc therapy (VMAT). No statistically significant difference was found between OAG and CAG for SBRT treatments delivered with either 3DCRT or VMAT techniques in terms of plan quality metrics. Planned monitor units for 3DCRT plans were significantly less (p < 0.001) using CAG compared to OAG for this patient cohort, suggesting more efficient treatment delivery. These significant differences in delivery efficiency based on isocentre geometry were not observed in the VMAT plans. The susceptibility of 3DCRT and VMAT plans to systematic setup uncertainties of 1 mm and 2 mm was not significantly influenced by choice of isocentre geometry. OAG and CAG based treatments are equally robust to systematic uncertainties in isocentre positioning.

show abstract

Improving Delivery Accuracy of Stereotactic Body Radiotherapy to a Moving Tumor Using Simplified Volumetric Modulated Arc Therapy

et al. 2016

View full text Add to dashboard Cite

PurposeTo develop a simplified volumetric modulated arc therapy (VMAT) technique for more accurate dose delivery in thoracic stereotactic body radiation therapy (SBRT).Methods and MaterialsFor each of the 22 lung SBRT cases treated with respiratory-gated VMAT, a dose rate modulated arc therapy (DrMAT) plan was retrospectively generated. A dynamic conformal arc therapy plan with 33 adjoining coplanar arcs was designed and their beam weights were optimized by an inverse planning process. All sub-arc beams were converted into a series of control points with varying MLC segment and dose rates and merged into an arc beam for a DrMAT plan. The plan quality of original VMAT and DrMAT was compared in terms of target coverage, compactness of dose distribution, and dose sparing of organs at risk. To assess the delivery accuracy, the VMAT and DrMAT plans were delivered to a motion phantom programmed with the corresponding patients’ respiratory signal; results were compared using film dosimetry with gamma analysis.ResultsThe plan quality of DrMAT was equivalent to that of VMAT in terms of target coverage, dose compactness, and dose sparing for the normal lung. In dose sparing for other critical organs, DrMAT was less effective than VMAT for the spinal cord, heart, and esophagus while being well within the limits specified by the Radiation Therapy Oncology Group. Delivery accuracy of DrMAT to a moving target was similar to that of VMAT using a gamma criterion of 2%/2mm but was significantly better using a 2%/1mm criterion, implying the superiority of DrMAT over VMAT in SBRT for thoracic/abdominal tumors with respiratory movement.ConclusionWe developed a DrMAT technique for SBRT that produces plans of a quality similar to that achieved with VMAT but with better delivery accuracy. This technique is well-suited for small tumors with motion uncertainty.

show abstract

Use of Flattening Filter Free Photon Beams for Off-axis Targets in Conformal Arc Stereotactic Body Radiation Therapy

Cited by 3 publications

References 18 publications

Improvement of off‐axis SABR plan verification results by using adapted dose reconstruction algorithms for the Octavius 4D system

Improvement of off‐axis SABR plan verification results by using adapted dose reconstruction algorithms for the Octavius 4D system

Delivery efficiency and susceptibility to setup uncertainties of flattening filter free lung SBRT: influence of isocentre geometry and treatment modality

Improving Delivery Accuracy of Stereotactic Body Radiotherapy to a Moving Tumor Using Simplified Volumetric Modulated Arc Therapy

Contact Info

Product

Resources

About