Dynamic tracking of soft tissue targets with ultrasound images

Abstract

Apparatus and methods of dynamically tracking a soft tissue target with ultrasound images are described. An apparatus includes an ultrasound imager coupled to a robotic arm. A method includes acquiring a first ultrasound (US) image of a patient with an ultrasound imager, determining a quality metric of the first US image, and adjusting one or more imaging parameters of the ultrasound imager if the quality metric of the acquired first US image is less than a quality threshold.

1 . A method, comprising:
 acquiring a first ultrasound (US) image of a patient with an ultrasound imager;   determining a quality metric of the first US image; and   adjusting one or more imaging parameters of the ultrasound imager if the quality metric of the acquired first US image is less than a quality threshold.   
     
     
         2 . The method of  claim 1 , further comprising:
 defining the quality threshold;   computing the quality metric of the first US image; and   comparing the quality metric of the first US image against the quality threshold to determine if the quality metric of the first US image is less than the quality threshold.   
     
     
         3 . The method of  claim 2 , further comprising registering the first US image with a pre-treatment image, wherein the quality metric is determined based on the registering. 
     
     
         4 . The method of  claim 1 , further comprising:
 comparing the quality metric of the first US image against the quality threshold while adjusting, wherein adjusting further comprises adjusting the one or more imaging parameters until the compared quality metric is greater than the quality threshold.   
     
     
         5 . The method of  claim 4 , wherein adjusting the one or more imaging parameters comprises repositioning the ultrasound imager using a robotic arm coupled to the ultrasound imager. 
     
     
         6 . The method of  claim 4 , wherein adjusting comprises adjusting a pressure applied on the patient by the ultrasound imager. 
     
     
         7 . The method of  claim 4 , wherein adjusting the one or more imaging parameters comprises adjusting one or more of an orientation of the ultrasound imager, a transmit frequency, a receive frequency, a gain, a depth dependent gain, and a dynamic range. 
     
     
         8 . The method of  claim 5 , further comprising:
 acquiring a subsequent US image of the patient with the ultrasound imager at each of a plurality of repositioned positions, each of the plurality of repositioned positions being in a different direction; and   determining a quality metric for each of the subsequent US images;   adjusting the US imager in a direction corresponding to one of the plurality of repositioned positions having an improved quality metric of the subsequent US image.   
     
     
         9 . The method of  claim 5 , wherein adjusting the one or more imaging parameters further comprises manually repositioning the ultrasound imager. 
     
     
         10 . The method of  claim 9 , wherein the ultrasound imager is manually repositioned for a course adjustment and wherein the ultrasound image is repositioned using the robotic arm for a fine adjustment. 
     
     
         11 . An apparatus, comprising:
 an ultrasound imager; and   a robotic arm coupled to the ultrasound imager.   
     
     
         12 . The apparatus of  claim 11 , wherein the robotic arm has multiple degrees of freedom. 
     
     
         13 . The apparatus of  claim 12 , wherein the robotic arm has 5 or more degrees of freedom. 
     
     
         14 . The apparatus of  claim 11 , further comprising a processing device coupled with the robotic arm. 
     
     
         15 . The apparatus of  claim 14 , wherein the processing device is configured to compute adjustments to the positioning of the ultrasound imager to be made with the robotic arm. 
     
     
         16 . The apparatus of  claim 15 , wherein the processing device resides within a treatment delivery system. 
     
     
         17 . A method, comprising:
 receiving a pre-treatment image of patient, the pre-treatment imaging including a soft tissue target;   acquiring, during a treatment delivery patient setup, a reference ultrasound image including the soft tissue target;   acquiring a subsequent ultrasound image, during treatment delivery to the patient, the subsequent ultrasound image including the soft tissue target;   registering the subsequent ultrasound image with either the reference ultrasound image or the pre-treatment image to determine a motion of the soft tissue target; and   adjusting a position of a radiation source to compensate for the motion of the soft tissue target.   
     
     
         18 . The method of  claim 17 , wherein the pre-treatment image is a magnetic resonance (MR) image. 
     
     
         19 . The method of  claim 17 , wherein the pre-treatment image is a fused computerized tomography (CT) and magnetic resonance (MR) image.