Planning and control for magnetic resonance guided radiation therapy

Abstract

Magnetic resonance (MR) guided radiation therapy (MRgRT) enables control over the delivery of radiation based on patient motion indicated by MR imaging (MRI) images captured during radiation delivery. A method for MRgRT includes: simultaneously using one or more radiation therapy heads to deliver radiation and an MRI system to perform MRI; using a processor to determine whether one or more gates are triggered based on at least a portion of MRI images captured during the delivery of radiation; and in response to determining that one or more gates are triggered based on at least a portion of the MRI images captured during the delivery of radiation, suspending the delivery of radiation.

What is claimed is: 
     
         1 . A method for magnetic resonance (MR) guided radiation therapy (MRgRT), the method comprising:
 simultaneously using one or more radiation therapy heads to deliver radiation and an MR imaging (MRI) system to perform MM;   using a processor to determine whether one or more gates are triggered based on at least a portion of MRI images captured during the delivery of radiation; and   in response to determining that one or more gates are triggered based on at least a portion of the MRI images captured during the delivery of radiation, suspending the delivery of radiation.   
     
     
         2 . The method of  claim 1 , wherein the one or more gates includes a spatial gate that is triggered when one of a region of interest (ROI) and an organ at risk (OAR) shifts across the spatial gate during the delivery of radiation. 
     
     
         3 . The method of  claim 2 , wherein the one or more gates further includes a temporal gate that is triggered when the one of the ROI and the OAR remains across the spatial gate for a length of time exceeding the temporal gate. 
     
     
         4 . The method of  claim 1 , further comprising:
 in response to determining that one or more gates are not triggered based on at least a portion of the MM images captured during the delivery of radiation, continuing to simultaneously use the one or more radiation therapy heads to deliver radiation and the MRI system to perform MRI.   
     
     
         5 . The method of  claim 1 , further comprising:
 determining whether patient motion exceeds one or more interlock thresholds based on at least a portion of the MRI images captured during the delivery of radiation; and   in response to determining that patient motion exceeds one or more interlock thresholds based on at least a portion of the MRI images captured during the delivery of radiation, suspending the delivery of radiation.   
     
     
         6 . The method of  claim 1 , further comprising:
 determining whether one or more conditions causing the suspension of radiation delivery is resolved; and   in response to determining that the one or more conditions causing the suspension of radiation delivery is resolved, recommencing the delivery of radiation.   
     
     
         7 . The method of  claim 1 , wherein radiation delivery is performed based at least in part on a first treatment plan. 
     
     
         8 . The method of  claim 7 , further comprising generating the first treatment plan by:
 receiving at least one MRI image set;   defining one or more anatomical structures;   generating a prescription; and   generating a delivery configuration.   
     
     
         9 . The method of  claim 8 , wherein defining the one or more anatomical structures comprises using the processor to automatically contour one or more of a region of interest (ROI) and an organ at risk (OAR). 
     
     
         10 . The method of  claim 7 , further comprising computing an actual dose of radiation delivered. 
     
     
         11 . The method of  claim 10 , wherein the actual dose of radiation is computed based on at least one of the MRI images captured during the delivery of radiation and one or more suspensions of radiation delivery due the triggering of the one or more gates. 
     
     
         12 . The method of  claim 10 , further comprising generating a second treatment plan based at least in part on the actual dose of radiation delivered. 
     
     
         13 . The method of  claim 12 , wherein generating the second treatment plan comprises modifying at least one of a prescription and a delivery configuration comprising the first treatment plan. 
     
     
         14 . The method of  claim 13 , wherein the prescription includes one or more of a radiation dose to be delivered to a region of interest (ROI), a margin for expansion, a dose-volume constraint for an organ at risk (OAR), a temporal gate, and a spatial gate; and wherein the delivery configuration include at least one of an isocenter placement, radiation beam configuration, intensity modulated radiation therapy (IMRT) configurations, and conformal radiation therapy (CRT) configurations. 
     
     
         15 . A magnetic resonance (MR) guided radiation therapy (MRgRT) system, comprising:
 an MRgRT apparatus comprising one or more radiation therapy heads and an MR imaging (MRI) system, wherein the MRgRT apparatus is configured to simultaneously use the one or more radiation therapy heads to deliver radiation and the MRI system to perform MM; and   a processor coupled to the MRgRT apparatus and configured to:
 determine whether one or more gates are triggered based on at least a portion of MRI images captured during the delivery of radiation; and 
 in response to determining that one or more gates are triggered based on at least a portion of the MRI images captured during the delivery of radiation, suspend the delivery of radiation. 
   
     
     
         16 . The system of  claim 15 , wherein the one or more gates includes a spatial gate that is triggered when one of a region of interest (ROI) and an organ at risk (OAR) shifts across the spatial gate during the delivery of radiation. 
     
     
         17 . The system of  claim 16 , wherein the one or more gates further includes a temporal gate that is triggered when the one of the ROI and the OAR remains across the spatial gate for a length of time exceeding the temporal gate. 
     
     
         18 . The system of  claim 15 , wherein the processor is further configured to:
 in response to determining that one or more gates are not triggered based on at least a portion of the MM images captured during the delivery of radiation, continue to simultaneously use the one or more radiation therapy heads to deliver radiation and the MRI system to perform MRI.   
     
     
         19 . The system of  claim 15 , wherein the processor is further configured to:
 determine whether patient motion exceeds one or more interlock thresholds based on at least a portion of the MRI images captured during the delivery of radiation; and   in response to determining that patient motion exceeds one or more interlock thresholds based on at least a portion of the MRI images captured during the delivery of radiation, suspend the delivery of radiation.   
     
     
         20 . The system of  claim 15 , wherein the processor is further configured to:
 determining whether one or more conditions causing the suspension of radiation delivery is resolved; and   in response to determining that the one or more conditions causing the suspension of radiation delivery is resolved, recommencing the delivery of radiation.   
     
     
         21 . The system of  claim 15 , wherein the MRgRT apparatus performs radiation delivery based at least in part on a first treatment plan. 
     
     
         22 . The system of  claim 21 , wherein the processor is further configured to generate the first treatment plan by:
 receiving at least one MRI image set;   defining one or more anatomical structures;   generating a prescription; and   generating a delivery configuration.   
     
     
         23 . The system of  claim 22 , wherein to define the one or more anatomical structures, the processor is configured to automatically contour one or more of a region of interest (ROI) and an organ at risk (OAR). 
     
     
         24 . The system of  claim 21 , wherein the processor is further configured to compute an actual dose of radiation delivered. 
     
     
         25 . The system of  claim 24 , wherein the processor is configured to compute the actual dose of radiation based on at least one of the MRI images captured during the delivery of radiation and one or more suspensions of radiation delivery due the triggering of the one or more gates. 
     
     
         26 . The system of  claim 24 , wherein the processor is further configured to generate a second treatment plan based at least in part on the actual dose of radiation delivered. 
     
     
         27 . The system of  claim 26 , wherein to generate the second treatment plan, the processor is configured to modify at least one of a prescription and a delivery configuration comprising the first treatment plan. 
     
     
         28 . The system of  claim 27 , wherein the prescription includes one or more of a radiation dose to be delivered to a region of interest (ROI), a margin for expansion, a dose-volume constraint for an organ at risk (OAR), a temporal gate, and a spatial gate; and wherein the delivery configuration include at least one of an isocenter placement, radiation beam configuration, intensity modulated radiation therapy (IMRT) configurations, and conformal radiation therapy (CRT) configurations. 
     
     
         29 . A method of magnetic resonance (MR) guided radiation therapy (MRgRT), comprising:
 receiving a plurality of MR imaging (MRI) images captured by an MRI system during a delivery of radiation by one or more radiation therapy heads;   determining, based on a least a portion of the MRI images, whether one or more gates are triggered; and   in response to determining that the one or more gates are triggered based on at least a portion of the MRI images, causing the one or more radiation therapy heads to suspend delivery of radiation.   
     
     
         30 . The method of  claim 29 , wherein the one or more gates includes a spatial gate that is triggered when one of a region of interest (ROI) and an organ at risk (OAR) shifts across the spatial gate during the delivery of radiation. 
     
     
         31 . The method of  claim 30 , wherein the one or more gates further comprises a temporal gate that is triggered when the one of the ROI and the OAR remains across the spatial gate for a length of time exceeding the temporal gate. 
     
     
         32 . The method of  claim 29 , further comprising:
 in response to determining that one or more gates are not triggered based on at least a portion of the MM images captured during the delivery of radiation, continuing to simultaneously use the one or more radiation therapy heads to deliver radiation and the MRI system to perform MRI.   
     
     
         33 . The method of  claim 29 , further comprising:
 determining whether patient motion exceeds one or more interlock thresholds based on at least a portion of the MRI images captured during the delivery of radiation; and   in response to determining that patient motion exceeds one or more interlock thresholds based on at least a portion of the MRI images captured during the delivery of radiation, suspending the delivery of radiation.   
     
     
         34 . The method of  claim 29 , wherein the radiation delivery is performed based at least in part on a first treatment plan. 
     
     
         35 . The method of  claim 34 , further comprising:
 computing an actual dose of radiation delivered based on at least one of the MRI images captured during the delivery of radiation and one or more suspensions of radiation delivery due the triggering of the one or more gates; and   generating a second treatment plan based at least in part on the actual dose of radiation delivered.