First demonstration of intrafractional tumor‐tracked irradiation using 2D phantom MR images on a prototype linac‐MR

Yun, Jihyun; Wachowicz, Keith; MacKenzie, M; Rathee, S; Robinson, Don; Fallone, B. G.

doi:10.1118/1.4802735

Cited by 67 publications

(80 citation statements)

References 53 publications

(62 reference statements)

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“…The major efforts include the ViewRay MRIdian MRI-60 Co solution, 20 the Cross Cancer Institute MRI-linac ("in-line" construction) 21 and the Elekta MRI-linac ("transverse" construction) 22 . The major advantage of MRI is superior soft tissue contrast, enabling accurate and robust deformable registrations.…”

Section: Daily In-room Treatment Imagingmentioning

confidence: 99%

Online Adaptive Radiation Therapy

Lim‐Reinders

Keller

Al-Ward

et al. 2017

International Journal of Radiation Oncology*Biology*Physics

163

135

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Section: Daily In-room Treatment Imagingmentioning

confidence: 99%

Online Adaptive Radiation Therapy

Lim‐Reinders

Keller

Al-Ward

et al. 2017

International Journal of Radiation Oncology*Biology*Physics

163

135

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“…Several ambitious efforts are in progress to integrate MRI into a real‐time or near‐real‐time solution for tumor targeting during or immediately prior to radiation delivery. These efforts have produced a number of hybrid MRI‐RT solutions such as the Cross Cancer Institute MRI‐Linac prototypes at the University of Alberta,10 the Australian MRI‐Linac concept headed by Paul Keall's research group,11 the first commercialized Cobalt‐60/MRI solution from the company ViewRay12 and the pre‐commercial Elekta (Elekta AB, Stockholm, Sweden) MRI‐Linac 13…”

Section: Introductionmentioning

confidence: 99%

Magnetic field dose effects on different radiation beam geometries for hypofractionated partial breast irradiation

Kim

Lim‐Reinders

McCann

et al. 2017

J Applied Clin Med Phys

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PurposeHypofractionated partial breast irradiation (HPBI) involves treatment to the breast tumor using high doses per fraction. Recent advances in MRI‐Linac solutions have potential in being applied to HPBI due to gains in the soft tissue contrast of MRI; however, there are potentially deleterious effects of the magnetic field on the dose distribution. The purpose of this work is to determine the effects of the magnetic field on the dose distribution for HPBI tumors using a tangential beam arrangement (TAN), 5‐beam intensity‐modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT).MethodsFive patients who have received HPBI were selected with two patients having bilateral disease resulting in a total of two tumors in this study. Six planning configurations were created using a treatment planning system capable of modeling magnetic field dose effects: TAN, IMRT and VMAT beam geometries, each of these optimized with and without a transverse magnetic field of 1.5 T.ResultsThe heart and lung doses were not statistically significant when comparing plan configurations. The magnetic field had a demonstrated effect on skin dose: for VMAT plans, the skin (defined to a depth of 3 mm) D1cc was elevated by +11% and the V30 by +146%; for IMRT plans, the skin D1cc was increased by +18% and the V30 by +149%. Increasing the number of beam angles (e.g., going from IMRT to VMAT) with the magnetic field on reduced the skin dose.ConclusionThe impact of a magnetic field on HPBI dose distributions was analyzed. The heart and lung doses had clinically negligible effects caused by the magnetic field. The magnetic field increases the skin dose; however, this can be mitigated by increasing the number of beam angles.

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“…If the tumor is implanted with radiopaque fiducial markers, the position can be triangulated using stereoscopic imaging from two or more view angles [10][11][12][13] . Similarly, the tumor can be implanted with electromagnetic transponders 7,14 , or can be monitored in the treatment suite using MRI images 15 . One major drawback of these methods is that they rely on technologies or treatments not commonly available to the majority of radiotherapy centers, or are only available for use in certain tumor sites.…”

Section: Introductionmentioning

confidence: 99%

Calculating tumor trajectory and dose‐of‐the‐day using cone‐beam CT projections

2015

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Purpose: Cone-beam CT (CBCT) projection images provide anatomical data in real-time over several respiratory cycles, forming a comprehensive picture of tumor movement. We developed and validated a method which uses these projections to determine the trajectory of and dose to highly mobile tumors during each fraction of treatment.Methods: CBCT images of a respiration phantom were acquired, the trajectory of which mimicked a lung tumor with high amplitude (up to 2.5 cm) and hysteresis. A template-matching algorithm was used to identify the location of a steel BB in each CBCT projection, and a Gaussian probability density function for the absolute BB position was calculated which best fit the observed trajectory of the BB in the imager geometry. Two modifications of the trajectory reconstruction were investigated: first, using respiratory phase information to refine the trajectory estimation (Phase), and second, using the Monte Carlo (MC) method to sample the estimated Gaussian tumor position distribution. The accuracies of the proposed methods were evaluated by comparing the known and calculated BB trajectories in phantom-simulated clinical scenarios using abdominal tumor volumes.Results: With all methods, the mean position of the BB was determined with accuracy better than 0.1 mm, and root-mean-square (RMS) trajectory errors averaged 3.8±1.1% of the marker amplitude. Dosimetric calculations using Phase methods were more accurate, with mean absolute error less than 0.5%, and with error less than 1% in the highest-noise trajectory. MC-based trajectories prevent the over-estimation of dose, but when viewed in an absolute sense, add a small amount of dosimetric error (<0.1%).Conclusions: Marker trajectory and target dose-of-the-day were accurately calculated using CBCT projections. This technique provides a method to evaluate highly-mobile tumors using ordinary CBCT data, and could facilitate better strategies to mitigate or compensate for motion during SBRT.This manuscript was submitted to Medical Physics

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First demonstration of intrafractional tumor‐tracked irradiation using 2D phantom MR images on a prototype linac‐MR

Cited by 67 publications

References 53 publications

Online Adaptive Radiation Therapy

Online Adaptive Radiation Therapy

Magnetic field dose effects on different radiation beam geometries for hypofractionated partial breast irradiation

Calculating tumor trajectory and dose‐of‐the‐day using cone‐beam CT projections

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