Phase I trial of stereotactic MR-guided online adaptive radiation therapy (SMART) for the treatment of oligometastatic or unresectable primary malignancies of the abdomen

Henke, Lauren E.; Kashani, Rojano; Robinson, Clifford G.; Curcuru, Austen; DeWees, T.A.; Bradley, Jeffrey D.; Green, Olga; Michalski, Jeff M.; Mutic, Sasa; Parikh, Parag J.; Olsen, Jeffrey R.

doi:10.1016/j.radonc.2017.11.032

Cited by 355 publications

(399 citation statements)

References 34 publications

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“…Adaptive MRgRT plans prioritized strict OAR constraints even at the expense of PTV coverage. However, if favorable OAR anatomy was noted during adaptive treatment, dose escalation to improve PTV coverage could be performed while maintaining OAR constraints . In some cases, an adaptive plan could be generated to treat above the prescription dose.…”

Section: Methodsmentioning

confidence: 99%

“…However, if favorable OAR anatomy was noted during adaptive treatment, dose escalation to improve PTV coverage could be performed while maintaining OAR constraints. [14][15][16][17] In some cases, an adaptive plan could be generated to treat above the prescription dose. For patients receiving >15 fractions of treatment, nonadaptive MRgRT was delivered using conventional treatment planning with no adjustment for daily internal anatomy.…”

Section: Methodsmentioning

confidence: 99%

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Using adaptive magnetic resonance image‐guided radiation therapy for treatment of inoperable pancreatic cancer

et al. 2019

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Background Adaptive magnetic resonance imaging‐guided radiation therapy (MRgRT) can escalate dose to tumors while minimizing dose to normal tissue. We evaluated outcomes of inoperable pancreatic cancer patients treated using MRgRT with and without dose escalation. Methods We reviewed 44 patients with inoperable pancreatic cancer treated with MRgRT. Treatments included conventional fractionation, hypofractionation, and stereotactic body radiation therapy. Patients were stratified into high‐dose (biologically effective dose [BED 10 ] >70) and standard‐dose groups (BED 10 ≤70). Overall survival (OS), freedom from local failure (FFLF) and freedom from distant failure (FFDF) were evaluated using Kaplan‐Meier method. Cox regression was performed to identify predictors of OS. Acute gastrointestinal (GI) toxicity was assessed for 6 weeks after completion of RT. Results Median follow‐up was 17 months. High‐dose patients (n = 24, 55%) had statistically significant improvement in 2‐year OS (49% vs 30%, P = 0.03) and trended towards significance for 2‐year FFLF (77% vs 57%, P = 0.15) compared to standard‐dose patients (n = 20, 45%). FFDF at 18 months in high‐dose vs standard‐dose groups was 24% vs 48%, respectively ( P = 0.92). High‐dose radiation (HR: 0.44; 95% confidence interval [CI]: 0.21‐0.94; P = 0.03) and duration of induction chemotherapy (HR: 0.84; 95% CI: 0.72‐0.98; P = 0.03) were significantly correlated with OS on univariate analysis but neither factor was independently predictive on multivariate analysis. Grade 3+ GI toxicity occurred in three patients in the standard‐dose group and did not occur in the high‐dose group. Conclusions Patients treated with dose‐escalated MRgRT demonstrated improved OS. Prospective evaluation of high‐dose RT regimens with standardized treatment parameters in inoperable pancreatic cancer patients is warranted.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Using adaptive magnetic resonance image‐guided radiation therapy for treatment of inoperable pancreatic cancer

et al. 2019

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“…Stereotactic MR-guided adaptive radiation therapy has been demonstrated to provide an accurate and robust online adaptive solution for SBRT treatment using an MR-guided Co-60 therapy system [3,7,14]. However, due to the limitation of Cobalt source size and MLC leaf resolution, MR-guided stereotactic radiosurgery (MRgSRS) for intracranial treatment is not feasible on the Cobalt unit.…”

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confidence: 99%

Evaluation of a magnetic resonance guided linear accelerator for stereotactic radiosurgery treatment

Wen

Kim

Doemer

et al. 2018

Radiotherapy and Oncology

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Introduction: The purpose of this study was to investigate the systematic localization accuracy, treatment planning capability, and delivery accuracy of an integrated magnetic resonance imaging guided Linear Accelerator (MR-Linac) platform for stereotactic radiosurgery. Materials and methods: The phantom for the end-to-end test comprises three different compartments: a rectangular MR/CT target phantom, a Winston–Lutz cube, and a rectangular MR/CT isocenter phantom. Hidden target tests were performed at gantry angles of 0, 90, 180, and 270 degrees to quantify the systematic accuracy. Five patient plans with a total of eleven lesions were used to evaluate the dosimetric accuracy. Single-isocenter IMRT treatment plans using 10–15 coplanar beams were generated to treat the multiple metastases. Results: The end-to-end localization accuracy of the system was 1.0 ± 0.1 mm. The conformity index, homogeneity index and gradient index of the plans were 1.26 ± 0.22, 1.22 ± 0.10, and 5.38 ± 1.44, respectively. The average absolute point dose difference between measured and calculated dose was 1.64 ± 1. 90%, and the mean percentage of points passing the 3%/1 mm gamma criteria was 96.87%. Conclusions: Our experience demonstrates that excellent plan quality and delivery accuracy was achievable on the MR-Linac for treating multiple brain metastases with a single isocenter.

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“…The field of radiotherapy has progressed towards the goal of visualizing internal anatomy in real time during irradiation in order to validate targeting, shrink treatment margins, and enable precise dose escalation. Tracking soft tissue motion has recently proven possible using integrated magnetic resonance image guided radiotherapy (MR‐IGRT) systems, and online adaptive planning on these systems has become clinically feasible . Early approaches combined magnetic resonance imaging (MRI) with Co‐60 radioactive sources, while more recent and complex systems incorporate MRI with medical linear accelerators (MR‐linacs) …”

Section: Introductionmentioning

confidence: 99%

“…Tracking soft tissue motion has recently proven possible using integrated magnetic resonance image guided radiotherapy (MR-IGRT) systems, and online adaptive planning on these systems has become clinically feasible. [1][2][3][4] Early approaches combined magnetic resonance imaging (MRI) with Co-60 radioactive sources, [4][5][6] while more recent and complex systems incorporate MRI with medical linear accelerators (MR-linacs). [7][8][9] One of the primary technical challenges of MR-IGRT systems is the presence of a strong transverse magnetic field, which in the case of an MR-linac affects the electronic generation of x-rays, as well as the behavior of dose-depositing secondary electrons.…”

Section: Introductionmentioning

confidence: 99%

Optical imaging method to quantify spatial dose variation due to the electron return effect in an MR‐linac

et al. 2019

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Purpose Treatment planning systems (TPSs) for MR‐linacs must employ Monte Carlo‐based simulations of dose deposition to model the effects of the primary magnetic field on dose. However, the accuracy of these simulations, especially for areas of tissue‐air interfaces where the electron return effect (ERE) is expected, is difficult to validate due to physical constraints and magnetic field compatibility of available detectors. This study employs a novel dosimetric method based on remotely captured, real‐time optical Cherenkov and scintillation imaging to visualize and quantify the ERE. Methods An intensified CMOS camera was used to image two phantoms with designed ERE cavities. Phantom A was a 40 cm × 10 cm × 10 cm clear acrylic block drilled with five holes of increasing diameters (0.5, 1, 2, 3, 4 cm). Phantom B was a clear acrylic block (25 cm × 20 cm × 5 cm) with three cavities of increasing diameter (3, 2, 1 cm) split into two halves in the transverse plane to accommodate radiochromic film. Both phantoms were imaged while being irradiated by 6 MV flattening filter free (FFF) beams within a MRIdian Viewray (Viewray, Cleveland, OH) MR‐linac (0.34 T primary field). Phantom A was imaged while being irradiated by 6 MV FFF beams on a conventional linac (TrueBeam, Varian Medical Systems, San Jose, CA) to serve as a control. Images were post processed in Matlab (Mathworks Inc., Natick, MA) and compared to TPS dose volumes. Results Control imaging of Phantom A without the presence of a magnetic field supports the validity of the optical image data to a depth of 6 cm. In the presence of the magnetic field, the optical data shows deviations from the commissioned TPS dose in both intensity and localization. The largest air cavity examined (3 cm) indicated the largest dose differences, which were above 20% at some locations. Experiments with Phantom B illustrated similar agreement between optical and film dosimetry comparisons with TPS data in areas not affected by ERE. Conclusion There are some appreciable differences in dose intensity and spatial dose distribution observed between the novel experimental data set and the dose models produced by the current clinically implemented MR‐IGRT TPS.

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Phase I trial of stereotactic MR-guided online adaptive radiation therapy (SMART) for the treatment of oligometastatic or unresectable primary malignancies of the abdomen

Abstract: SMART is clinically deliverable and safe, allowing PTV dose escalation and/or simultaneous OAR sparing compared to non-adaptive abdominal SBRT.

Cited by 355 publications

References 34 publications

Using adaptive magnetic resonance image‐guided radiation therapy for treatment of inoperable pancreatic cancer

Using adaptive magnetic resonance image‐guided radiation therapy for treatment of inoperable pancreatic cancer

Evaluation of a magnetic resonance guided linear accelerator for stereotactic radiosurgery treatment

Optical imaging method to quantify spatial dose variation due to the electron return effect in an MR‐linac

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