Frameless Stereotactic Body Radiotherapy for Lung Cancer Using Four-Dimensional Cone Beam CT Guidance

Sonke, Jan‐Jakob; Rossi, Maddalena; Wolthaus, J.; Herk, Marcel van; Damen, E.; Belderbos, J.

doi:10.1016/j.ijrobp.2008.08.004

Cited by 244 publications

(182 citation statements)

References 26 publications

Supporting

Mentioning

170

Contrasting

Unclassified

Order By: Relevance

“…The largest standard deviation was in craniocaudal direction as expected given this is the axis of greatest respiratory amplitude. Our reported inter/ intrafraction tumor displacements are comparable to previous studies that used stereotactic patient positioning equipment [11,12] and frameless equipment [11,16,17]. Guckenberger et al [12] used stereotactic frame immobilization and demonstrated intrafraction tumor position variation of 0.4 mm ML (SD 1.0), -0.8 mm AP (SD 1.7), and 0.7 mm CC (SD 1.7).…”

Section: Positional Variability With Frameless Patient Setupsupporting

confidence: 85%

Variations of the Tumor Position in Frameless Lung Sbrt: Assessment of Predictive Factors Including Tumor Volume Changes

Schuster¹

2013

J Nucl Med Radiat Ther

View full text Add to dashboard Cite

Purpose: To quantify inter-and intrafractional variations of tumor position and analyze the relationship between these changes and respiratory motion amplitude, volume changes and tumor location, in frameless stereotactic body radiotherapy (SBRT) of lung tumors. Materials and methods:Tumor volumes and bony landmarks were contoured manually by a single physician on 174 pre-and under treatment cone-beam computed tomographies (CBCTs) of 17 patients. The interfraction variation of the tumor position was measured by comparing the centroid position of the tumor relative to bony anatomy of each fraction to the pretreatment CBCT scans. The intrafraction variation was measured by comparing the pretreatment tumor location to under treatment CBCTs for every fraction. Respiratory motion was analyzed on planning 4D fan beam CTs for all patients. The change in tumor volume was determined by comparing the contoured tumor volumes on sequential pretreatment CBCTs. Results:The average interfraction/intrafraction tumor displacementrelative to bony landmark in mm was 0.6 (SD 2.3) /-0.3 (SD 0.7) in mediolateral, -0.7 (SD 3.8) /0.0 (SD 2.1) in anteroposterior, and -0.6 (SD 5.9) /-0.2 (SD 2.3) in craniocaudal direction. Inter-/intrafraction tumor-to-bone variations >3 mm were observed in 60%/14% of scans respectively. On the initial CBCT, the average tumor volume was 9 cm 3 (range 1-37 cm 3 ) with a mean volume reduction over the treatment course of 12% (range, +14% to -54%). Patients with a pretreatment motion amplitude > 9 mm (p=0.002), peripheral tumor location (p=0.04), and volume change >12% (p=0.009) had larger interfraction displacement in lateral direction. Conclusions:Frameless set up is comparable to patient positioning with more elaborate fixation devices. Tumor position variations relative to bony anatomy are an important source of geometric uncertainty providing a rationale for repeated soft tissue-based image guidance, particularly in patients identified in this study to be at higher risk for variations. Central tumor location was defined as within 3 cm of heart, aorta, spinal cord, esophagus and main airways. A total dose of 48-60 Gy was delivered in 4-6 fractions prescribed to PTV covering isodose. The approximate treatment time per fraction was 30 minutes; the duration of the treatment course averaged 10 days (range 8-14 days). All patients completed informed consent which had been approved by the local institutional review board. 4D CT and CBCT acquisitionPatients were immobilized in the supine position with both arms above the head using an AccuFix ArmShuttle (Qfix Systems, Avondale, PA, USA). A free breathing four-dimensional computed tomography (4DCT, Brilliance Big Bore, Philips Medical Systems, Andover, MA) simulation procedure was used for all patients (120 kV, 400 mAs, slice thickness 3 mm). The isocenter was marked with three skin tattoos. The scan range covered the complete thoracic region. For each 4DCT, respiration motion was monitored by tracking the vertical displacement of the upper abdominal wa...

show abstract

Section: Positional Variability With Frameless Patient Setupsupporting

confidence: 85%

Variations of the Tumor Position in Frameless Lung Sbrt: Assessment of Predictive Factors Including Tumor Volume Changes

Schuster¹

2013

J Nucl Med Radiat Ther

View full text Add to dashboard Cite

show abstract

“…This effect was largest for patient 2 and 3, with peak‐to‐peak motion clearly exceeding the photon penumbra for lung tissue (assumed to be approximately 6.4 mm) 36 . GTV cold‐spots were not observed for patient 1, for which the GTV deformation was largest (49% increase compared to volume on reference phase).…”

Section: Discussionmentioning

confidence: 93%

Real‐time 4D dose reconstruction for tracked dynamic MLC deliveries for lung SBRT

et al. 2016

View full text Add to dashboard Cite

PurposeThis study provides a proof of concept for real‐time 4D dose reconstruction for lung stereotactic body radiation therapy (SBRT) with multileaf collimator (MLC) tracking and assesses the impact of tumor tracking on the size of target margins.MethodsThe authors have implemented real‐time 4D dose reconstruction by connecting their tracking and delivery software to an Agility MLC at an Elekta Synergy linac and to their in‐house treatment planning software (TPS). Actual MLC apertures and (simulated) target positions are reported to the TPS every 40 ms. The dose is calculated in real‐time from 4DCT data directly after each reported aperture by utilization of precalculated dose‐influence data based on a Monte Carlo algorithm. The dose is accumulated onto the peak‐exhale (reference) phase using energy‐mass transfer mapping. To investigate the impact of a potentially reducible safety margin, the authors have created and delivered treatment plans designed for a conventional internal target volume (ITV) + 5 mm, a midventilation approach, and three tracking scenarios for four lung SBRT patients. For the tracking plans, a moving target volume (MTV) was established by delineating the gross target volume (GTV) on every 4DCT phase. These were rigidly aligned to the reference phase, resulting in a unified maximum GTV to which a 1, 3, or 5 mm isotropic margin was added. All scenarios were planned for 9‐beam step‐and‐shoot IMRT to meet the criteria of RTOG 1021 (3 × 18 Gy). The GTV 3D center‐of‐volume shift varied from 6 to 14 mm.ResultsReal‐time dose reconstruction at 25 Hz could be realized on a single workstation due to the highly efficient implementation of dose calculation and dose accumulation. Decreased PTV margins resulted in inadequate target coverage during untracked deliveries for patients with substantial tumor motion. MLC tracking could ensure the GTV target dose for these patients. Organ‐at‐risk (OAR) doses were consistently reduced by decreased PTV margins. The tracked MTV + 1 mm deliveries resulted in the following OAR dose reductions: lung V 20 up to 3.5%, spinal cord D 2 up to 0.9 Gy/Fx, and proximal airways D 2 up to 1.4 Gy/Fx.ConclusionsThe authors could show that for patient data at clinical resolution and realistic motion conditions, the delivered dose could be reconstructed in 4D for the whole lung volume in real‐time. The dose distributions show that reduced margins yield lower doses to healthy tissue, whilst target dose can be maintained using dynamic MLC tracking.

show abstract

“…The research for the rule of lung breathing talks about the 4D CT direction ( 30 ) and 4D CBCT direction. ( 31 ) We can combine 4D CT technique for solving this problem so that we can make the planning CT and CBCT in the same phase for improving treatment accuracy.…”

Section: Discussionmentioning

confidence: 99%

Deformable registration using edge‐preserving scale space for adaptive image‐guided radiation therapy

Wang

Yin

et al. 2011

J Applied Clin Med Phys

View full text Add to dashboard Cite

Incorporating of daily cone‐beam computer tomography (CBCT) image into online radiation therapy process can achieve adaptive image‐guided radiation therapy (AIGRT). Registration of planning CT (PCT) and daily CBCT are the key issues in this process. In our work, a new multiscale deformable registration method is proposed by combining edge‐preserving scale space with the multilevel free‐form deformation (FFD) grids for CBCT‐based AIGRT system. The edge‐preserving scale space, which is able to select edges and contours of images according to their geometric size, is derived from the total variation model with the L1 norm (TV‐L1). At each scale, despite the noise and contrast resolution differences between the PCT and CBCT, the selected edges and contours are sufficiently strong to drive the deformation using the FFD grid, and the edge‐preserving property ensures more meaningful spatial information for mutual information (MI)‐based registration. At last, the deformation fields are gained by a coarse to fine manner. Furthermore, in consideration of clinical application we designed an optimal estimation of the TV‐L1 parameters by minimizing the defined offset function for automated registration.Six types of patients are studied in our work, including rectum, prostate, lung, H&N (head and neck), breast, and chest cancer patients. The experiment results demonstrate the significance of the proposed method both quantitatively with ground truth known and qualitatively with ground truth unknown. The applications for AIGRT, including adaptive deformable recontouring and redosing, and DVH (dose volume histogram) analysis in the course of radiation therapy are also studied.PACS numbers: 87.57.Gg, 87.57.Ce, 87.62.+n

show abstract

Frameless Stereotactic Body Radiotherapy for Lung Cancer Using Four-Dimensional Cone Beam CT Guidance

Cited by 244 publications

References 26 publications

Variations of the Tumor Position in Frameless Lung Sbrt: Assessment of Predictive Factors Including Tumor Volume Changes

Variations of the Tumor Position in Frameless Lung Sbrt: Assessment of Predictive Factors Including Tumor Volume Changes

Real‐time 4D dose reconstruction for tracked dynamic MLC deliveries for lung SBRT

Deformable registration using edge‐preserving scale space for adaptive image‐guided radiation therapy

Contact Info

Product

Resources

About