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Title: On the use of volumetric-modulated arc therapy for single-fraction thoracic vertebral metastases stereotactic body radiosurgery

Abstract

To retrospectively evaluate quality, efficiency, and delivery accuracy of volumetric-modulated arc therapy (VMAT) plans for single-fraction treatment of thoracic vertebral metastases using image-guided stereotactic body radiosurgery (SBRS) after RTOG 0631 dosimetric compliance criteria. After obtaining credentialing for MD Anderson spine phantom irradiation validation, 10 previously treated patients with thoracic vertebral metastases with noncoplanar hybrid arcs using 1 to 2 3D-conformal partial arcs plus 7 to 9 intensity-modulated radiation therapy beams were retrospectively re-optimized with VMAT using 3 full coplanar arcs. Tumors were located between T2 and T12. Contrast-enhanced T1/T2-weighted magnetic resonance images were coregistered with planning computed tomography and planning target volumes (PTV) were between 14.4 and 230.1 cc (median = 38.0 cc). Prescription dose was 16 Gy in 1 fraction with 6 MV beams at Novalis-TX linear accelerator consisting of micro multileaf collimators. Each plan was assessed for target coverage using conformality index, the conformation number, the ratio of the volume receiving 50% of the prescription dose over PTV, R50%, homogeneity index (HI), and PTV-1600 coverage per RTOG 0631 requirements. Organs-at-risk doses were evaluated for maximum doses to spinal cord (D{sub 0.03} {sub cc}, D{sub 0.35} {sub cc}), partial spinal cord (D{sub 10%}), esophagus (D{sub 0.03} {sub cc} andmore » D{sub 5} {sub cc}), heart (D{sub 0.03} {sub cc} and D{sub 15} {sub cc}), and lung (V{sub 5}, V{sub 10}, and maximum dose to 1000 cc of lung). Dose delivery efficiency and accuracy of each VMAT-SBRS plan were assessed using quality assurance (QA) plan on MapCHECK device. Total beam-on time was recorded during QA procedure, and a clinical gamma index (2%/2 mm and 3%/3 mm) was used to compare agreement between planned and measured doses. All 10 VMAT-SBRS plans met RTOG 0631 dosimetric requirements for PTV coverage. The plans demonstrated highly conformal and homogenous coverage of the vertebral PTV with mean HI, conformality index, conformation number, and R{sub 50%} values of 0.13 ± 0.03 (range: 0.09 to 0.18), 1.03 ± 0.04 (range: 0.98 to 1.09), 0.81 ± 0.06 (range: 0.72 to 0.89), and 4.2 ± 0.94 (range: 2.7 to 5.4), respectively. All 10 patients met protocol guidelines with maximum dose to spinal cord (average: 8.83 ± 1.9 Gy, range: 5.9 to 10.9 Gy); dose to 0.35 cc of spinal cord (average: 7.62 ± 1.7 Gy, range: 5.4 to 9.6 Gy); and dose to 10% of partial spinal cord (average 6.31 ± 1.5 Gy, range: 3.5 to 8.5 Gy) less than 14, 10, and 10 Gy, respectively. For all 10 patients, the maximum dose to esophagus (average: 9.41 ± 4.3 Gy, range: 1.5 to 14.9 Gy) and dose to 5 cc of esophagus (average: 7.43 ± 3.8 Gy, range: 1.1 to 11.8 Gy) were kept less than protocol requirements 16 Gy and 11.9 Gy, respectively. In a similar manner, all 10 patients met protocol compliance criteria with maximum dose to heart (average: 4.62 ± 3.5 Gy, range: 1.3 to 10.2 Gy) and dose to 15 cc of heart (average: 2.23 ± 1.8 Gy, range: 0.3 to 5.6 Gy) less than 22 and 16 Gy, respectively. The dose to the lung was retained much lower than protocol guidelines for all 10 patients. The total number of monitor units was, on average, 6919 ± 1187. The average beam-on time was 11.5 ± 2.0 minutes. The VMAT plans demonstrated dose delivery accuracy of 95.8 ± 0.7%, on average, for clinical gamma passing rate with 2%/2 mm criteria and 98.3 ± 0.8%, on average, with 3%/3 mm criteria. All VMAT-SBRS plans were considered clinically acceptable per RTOG 0631 dosimetric compliance criteria. VMAT planning provided highly conformal and homogenous dose distributions for the lower-dose vertebral PTV and the spinal cord as well as organs-at-risk such as esophagus, heart, and lung. Higher QA pass rates and shorter beam-on time suggest that VMAT-SBRS is a clinically feasible, fast, and effective treatment option for patients with thoracic vertebral metastases.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
OSTI Identifier:
22685185
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Dosimetry; Journal Volume: 42; Journal Issue: 1; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 62 RADIOLOGY AND NUCLEAR MEDICINE; ACCURACY; BEAMS; COLLIMATORS; COMPARATIVE EVALUATIONS; COMPLIANCE; COMPUTERIZED TOMOGRAPHY; DELIVERY; ESOPHAGUS; GY RANGE; HEART; IMAGES; IRRADIATION; LINEAR ACCELERATORS; LUNGS; METASTASES; MONITORS; NEOPLASMS; PATIENTS; PHANTOMS; PLANNING; QUALITY ASSURANCE; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY; RECOMMENDATIONS; SPINAL CORD; SURGERY; VALIDATION; VERTEBRAE; QUALITY MANAGEMENT

Citation Formats

Pokhrel, Damodar, E-mail: damodar.pokhrel@uky.edu, Sood, Sumit, McClinton, Christopher, Shen, Xinglei, Badkul, Rajeev, Jiang, Hongyu, Mallory, Matthew, Mitchell, Mellissa, Wang, Fen, and Lominska, Christopher. On the use of volumetric-modulated arc therapy for single-fraction thoracic vertebral metastases stereotactic body radiosurgery. United States: N. p., 2017. Web. doi:10.1016/J.MEDDOS.2016.12.003.
Pokhrel, Damodar, E-mail: damodar.pokhrel@uky.edu, Sood, Sumit, McClinton, Christopher, Shen, Xinglei, Badkul, Rajeev, Jiang, Hongyu, Mallory, Matthew, Mitchell, Mellissa, Wang, Fen, & Lominska, Christopher. On the use of volumetric-modulated arc therapy for single-fraction thoracic vertebral metastases stereotactic body radiosurgery. United States. doi:10.1016/J.MEDDOS.2016.12.003.
Pokhrel, Damodar, E-mail: damodar.pokhrel@uky.edu, Sood, Sumit, McClinton, Christopher, Shen, Xinglei, Badkul, Rajeev, Jiang, Hongyu, Mallory, Matthew, Mitchell, Mellissa, Wang, Fen, and Lominska, Christopher. Sat . "On the use of volumetric-modulated arc therapy for single-fraction thoracic vertebral metastases stereotactic body radiosurgery". United States. doi:10.1016/J.MEDDOS.2016.12.003.
@article{osti_22685185,
title = {On the use of volumetric-modulated arc therapy for single-fraction thoracic vertebral metastases stereotactic body radiosurgery},
author = {Pokhrel, Damodar, E-mail: damodar.pokhrel@uky.edu and Sood, Sumit and McClinton, Christopher and Shen, Xinglei and Badkul, Rajeev and Jiang, Hongyu and Mallory, Matthew and Mitchell, Mellissa and Wang, Fen and Lominska, Christopher},
abstractNote = {To retrospectively evaluate quality, efficiency, and delivery accuracy of volumetric-modulated arc therapy (VMAT) plans for single-fraction treatment of thoracic vertebral metastases using image-guided stereotactic body radiosurgery (SBRS) after RTOG 0631 dosimetric compliance criteria. After obtaining credentialing for MD Anderson spine phantom irradiation validation, 10 previously treated patients with thoracic vertebral metastases with noncoplanar hybrid arcs using 1 to 2 3D-conformal partial arcs plus 7 to 9 intensity-modulated radiation therapy beams were retrospectively re-optimized with VMAT using 3 full coplanar arcs. Tumors were located between T2 and T12. Contrast-enhanced T1/T2-weighted magnetic resonance images were coregistered with planning computed tomography and planning target volumes (PTV) were between 14.4 and 230.1 cc (median = 38.0 cc). Prescription dose was 16 Gy in 1 fraction with 6 MV beams at Novalis-TX linear accelerator consisting of micro multileaf collimators. Each plan was assessed for target coverage using conformality index, the conformation number, the ratio of the volume receiving 50% of the prescription dose over PTV, R50%, homogeneity index (HI), and PTV-1600 coverage per RTOG 0631 requirements. Organs-at-risk doses were evaluated for maximum doses to spinal cord (D{sub 0.03} {sub cc}, D{sub 0.35} {sub cc}), partial spinal cord (D{sub 10%}), esophagus (D{sub 0.03} {sub cc} and D{sub 5} {sub cc}), heart (D{sub 0.03} {sub cc} and D{sub 15} {sub cc}), and lung (V{sub 5}, V{sub 10}, and maximum dose to 1000 cc of lung). Dose delivery efficiency and accuracy of each VMAT-SBRS plan were assessed using quality assurance (QA) plan on MapCHECK device. Total beam-on time was recorded during QA procedure, and a clinical gamma index (2%/2 mm and 3%/3 mm) was used to compare agreement between planned and measured doses. All 10 VMAT-SBRS plans met RTOG 0631 dosimetric requirements for PTV coverage. The plans demonstrated highly conformal and homogenous coverage of the vertebral PTV with mean HI, conformality index, conformation number, and R{sub 50%} values of 0.13 ± 0.03 (range: 0.09 to 0.18), 1.03 ± 0.04 (range: 0.98 to 1.09), 0.81 ± 0.06 (range: 0.72 to 0.89), and 4.2 ± 0.94 (range: 2.7 to 5.4), respectively. All 10 patients met protocol guidelines with maximum dose to spinal cord (average: 8.83 ± 1.9 Gy, range: 5.9 to 10.9 Gy); dose to 0.35 cc of spinal cord (average: 7.62 ± 1.7 Gy, range: 5.4 to 9.6 Gy); and dose to 10% of partial spinal cord (average 6.31 ± 1.5 Gy, range: 3.5 to 8.5 Gy) less than 14, 10, and 10 Gy, respectively. For all 10 patients, the maximum dose to esophagus (average: 9.41 ± 4.3 Gy, range: 1.5 to 14.9 Gy) and dose to 5 cc of esophagus (average: 7.43 ± 3.8 Gy, range: 1.1 to 11.8 Gy) were kept less than protocol requirements 16 Gy and 11.9 Gy, respectively. In a similar manner, all 10 patients met protocol compliance criteria with maximum dose to heart (average: 4.62 ± 3.5 Gy, range: 1.3 to 10.2 Gy) and dose to 15 cc of heart (average: 2.23 ± 1.8 Gy, range: 0.3 to 5.6 Gy) less than 22 and 16 Gy, respectively. The dose to the lung was retained much lower than protocol guidelines for all 10 patients. The total number of monitor units was, on average, 6919 ± 1187. The average beam-on time was 11.5 ± 2.0 minutes. The VMAT plans demonstrated dose delivery accuracy of 95.8 ± 0.7%, on average, for clinical gamma passing rate with 2%/2 mm criteria and 98.3 ± 0.8%, on average, with 3%/3 mm criteria. All VMAT-SBRS plans were considered clinically acceptable per RTOG 0631 dosimetric compliance criteria. VMAT planning provided highly conformal and homogenous dose distributions for the lower-dose vertebral PTV and the spinal cord as well as organs-at-risk such as esophagus, heart, and lung. Higher QA pass rates and shorter beam-on time suggest that VMAT-SBRS is a clinically feasible, fast, and effective treatment option for patients with thoracic vertebral metastases.},
doi = {10.1016/J.MEDDOS.2016.12.003},
journal = {Medical Dosimetry},
number = 1,
volume = 42,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}
  • Twenty-three targets in 16 patients treated with stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT) were analyzed in terms of dosimetric homogeneity, target conformity, organ-at-risk (OAR) sparing, monitor unit (MU) usage, and beam-on time per fraction using RapidArc volumetric-modulated arc therapy (VMAT) vs. multifield sliding-window intensity-modulated radiation therapy (IMRT). Patients underwent computed tomography simulation with site-specific immobilization. Magnetic resonance imaging fusion and optical tracking were incorporated as clinically indicated. Treatment planning was performed using Eclipse v8.6 to generate sliding-window IMRT and 1-arc and 2-arc RapidArc plans. Dosimetric parameters used for target analysis were RTOG conformity index (CI{sub RTOG}), homogeneity indexmore » (HI{sub RTOG}), inverse Paddick Conformity Index (PCI), D{sub mean} and D5-D95. OAR sparing was analyzed in terms of D{sub max} and D{sub mean}. Treatment delivery was evaluated based on measured beam-on times delivered on a Varian Trilogy linear accelerator and recorded MU values. Dosimetric conformity, homogeneity, and OAR sparing were comparable between IMRT, 1-arc RapidArc and 2-arc RapidArc plans. Mean beam-on times {+-} SD for IMRT and 1-arc and 2-arc treatments were 10.5 {+-} 7.3, 2.6 {+-} 1.6, and 3.0 {+-} 1.1 minutes, respectively. Mean MUs were 3041, 1774, and 1676 for IMRT, 1-, and 2-arc plans, respectively. Although dosimetric conformity, homogeneity, and OAR sparing were similar between these techniques, SRS and SBRT fractions treated with RapidArc were delivered with substantially less beam-on time and fewer MUs than IMRT. The rapid delivery of SRS and SBRT with RapidArc improved workflow on the linac with these otherwise time-consuming treatments and limited the potential for intrafraction organ and patient motion, which can cause significant dosimetric errors. These clinically important advantages make image-guided RapidArc useful in the delivery of SRS and SBRT to intracranial and extracranial targets.« less
  • Purpose: Stereotactic body radiation therapy (SBRT) has been proposed for the palliation of painful vertebral bone metastases because higher radiation doses may result in superior and more durable pain control. A phase III clinical trial (Radiation Therapy Oncology Group 0631) comparing single fraction SBRT with single fraction external beam radiation therapy (EBRT) in palliative treatment of painful vertebral bone metastases is now ongoing. We performed a cost-effectiveness analysis to compare these strategies. Methods and Materials: A Markov model, using a 1-month cycle over a lifetime horizon, was developed to compare the cost-effectiveness of SBRT (16 or 18 Gy in 1 fraction)more » with that of 8 Gy in 1 fraction of EBRT. Transition probabilities, quality of life utilities, and costs associated with SBRT and EBRT were captured in the model. Costs were based on Medicare reimbursement in 2014. Strategies were compared using the incremental cost-effectiveness ratio (ICER), and effectiveness was measured in quality-adjusted life years (QALYs). To account for uncertainty, 1-way, 2-way and probabilistic sensitivity analyses were performed. Strategies were evaluated with a willingness-to-pay (WTP) threshold of $100,000 per QALY gained. Results: Base case pain relief after the treatment was assumed as 20% higher in SBRT. Base case treatment costs for SBRT and EBRT were $9000 and $1087, respectively. In the base case analysis, SBRT resulted in an ICER of $124,552 per QALY gained. In 1-way sensitivity analyses, results were most sensitive to variation of the utility of unrelieved pain; the utility of relieved pain after initial treatment and median survival were also sensitive to variation. If median survival is ≥11 months, SBRT cost <$100,000 per QALY gained. Conclusion: SBRT for palliation of vertebral bone metastases is not cost-effective compared with EBRT at a $100,000 per QALY gained WTP threshold. However, if median survival is ≥11 months, SBRT costs ≤$100,000 per QALY gained, suggesting that selective SBRT use in patients with longer expected survival may be the most cost-effective approach.« less
  • Purpose: To retrospectively evaluate quality, efficiency and delivery accuracy of intensity modulated arc therapy (IMAT) plans for thoracic-vertebral metastases using stereotactic body radiotherapy (SBRT). Methods: After obtaining approval of RPC-benchmark plan, seven previously treated thoracic-vertebral metastases patients with non-coplanar hybrid arcs(NC-HA)using 1–2 3D-dynamic conformal partial-arcs plus 7–9 IMRT-beams were re-optimized with IMAT using 3 full co-planar arcs. Tumors were located between T2–T7. T1/T2-weighted MRI images were co-registered with planning-CT. PTVs were between 24.3–240.1cc(median=48.1cc). Prescription was 30Gy in 5 fractions with 6-MV beams at Novalis-TX consisting of HD-MLC.Plans were compared for target coverage:conformality index(CI),homogeneity index(HI),PTVD90. Organs-at-risks(OARs)was evaluated for spinal cord(Dmax, D0.35cc,more » and D1.2cc), esophagus(Dmax and D5cc),heart(Dmax, D15cc)and lung(V5 and V10). Dose delivery efficiency and accuracy of each IMAT plan was assessed via quality assurance(QA) plan. Beam-on time was recorded and a gamma index was used to compare agreement between planned and measured doses. Results: SBRT IMAT plans resulted in superior CI(1.02 vs. 1.36, p=0.05) and HI (0.14 vs. 0.27, p=0.01). PTVD90 was improved but statistically insignificant (31.0 vs. 30.4Gy, p=0.38). IMAT resulted in statistically significant improvements in OARs sparing: esophagus max(22.5 vs. 27.0Gy, p=0.03), esophagus 5cc (17.6 vs. 21.5Gy, p=0.02) and heart max(13.1 vs. 15.8Gy, p=0.03). Spinal cord,lung V5 and V10 were lower but statistically insignificant. Average total MU and beam-on time were 2598±354 vs. 3542±495 and 4.7±0.6 min vs. 7.1±1.0min for IMAT vs. NC-HA (without accounting for couch kicks time for NC-HA). IMAT plans demonstrated an accurate dose delivery of 95.5±1.0% for clinical gamma passing-rate of 2%/2mm criteria on MapCHECK, that was comparable to NC-HA plans. Conclusion: IMAT plans provided highly conformal and homogeneous dose distributions to target and reduced OARs doses compared to NC-HA. Total MU was reduced by a factor of 1.4 and subsequently decreased treatment times significantly - potentially minimizing intra-fraction motion error and owing to patient comfort. SBRT using IMAT planning for single fraction thoracic-vertebrae metastases will be investigated.« less
  • Purpose: This study evaluates a novel algorithm that can be used with any treatment planning system for simple and rapid generation of stereotactic radiosurgery (SRS) plans for treating multiple brain metastases using a single isocenter dynamic conformal arc (DCA) approach. This technique is compared with a single isocenter volumetric modulated arc therapy (VMAT) technique in terms of delivery time, conformity, low dose spread and delivery accuracy. Methods: Five patients, with a total of 37 (5 – 11) targets were planned using a previously published method for generating optimal VMAT plans and using the proposed DCA algorithm. All planning target volumesmore » (PTVs) were planned to 20 Gy, meeting a minimum 99% coverage and maximum 135 % hot spot for both techniques. Quality assurance was performed using radiochromic film, with films placed in the high dose regions of each PTV. Normal tissue volumes receiving 12 Gy and 6 Gy (V12 and V6) were computed for each plan. Conformity index (CI) and gamma evaluations (95% of points passing 4%/0.5mm) were computed for each PTV. Results: Delivery times, including beam on and table rotation times, were comparable: 17 – 22 minutes for all deliveries. V12s for DCA plans were (18.5±15.2 cc) vs. VMAT (19.7±14.4 cc). V6s were significantly lower for DCA (69.0±52.0 cc) compared with VMAT (154.0±91.0 cc) (p <<0.05). CIs for VMAT targets were (1.38±0.50) vs. DCA (1.61±0.41). 36 of 37 DCA planned targets passed gamma tests, while 29 of 37 VMAT planned targets passed. Conclusion: Single isocenter DCA plans were easily achieved. The evaluation suggests that DCA may represent a favorable technique compared with VMAT for multiple target SRS by reducing dose to normal tissue and more accurately depicting deliverable dose.« less
  • Purpose: A planning study was performed comparing volumetric modulated arcs, RapidArc (RA), fixed beam IMRT (IM), and conformal radiotherapy (CRT) with multiple static fields or short conformal arcs in a series of patients treated with hypofractionated stereotactic body radiation therapy (SBRT) for solitary or oligo-metastases from different tumors to abdominal lymph nodes. Methods and Materials: Fourteen patients were included in the study. Dose prescription was set to 45 Gy (mean dose to clinical target volume [CTV]) in six fractions of 7.5 Gy. Objectives for CTV and planning target volume (PTV) were as follows: Dose{sub min} >95%, Dose{sub max} <107%. Formore » organs at risk the following objectives were used: Maximum dose to spine <18 Gy; V{sub 15Gy} <35% for both kidneys, V{sub 36Gy} <1% for duodenum, V{sub 36Gy} <3% for stomach and small bowel, V{sub 15Gy} <(total liver volume - 700 cm{sup 3}) for liver. Dose-volume histograms were evaluated to assess plan quality. Results: Planning objectives on CTV and PTV were achieved by all techniques. Use of RA improved PTV coverage (V{sub 95%} = 90.2% +- 5.2% for RA compared with 82.5% +- 9.6% and 84.5% +- 8.2% for CRT and IM, respectively). Most planning objectives for organs at risk were met by all techniques except for the duodenum, small bowel, and stomach, in which the CRT plans exceeded the dose/volume constraints in some patients. The MU/fraction values were as follows: 2186 +- 211 for RA, 2583 +- 699 for IM, and 1554 +- 153 for CRT. Effective treatment time resulted as follows: 3.7 +- 0.4 min for RA, 10.6 +- 1.2 min for IM, and 6.3 +- 0.5 min for CRT. Conclusions: Delivery of SBRT by RA showed improvements in conformal avoidance with respect to standard conformal irradiation. Delivery parameters confirmed logistical advantages of RA, particularly compared with IM.« less