Treatment planning and delivery using temperature uncertainty maps
A method and programmable computer system calculates and displays the regions where the temperature can be reliably measured in a thermal therapy procedure. The clinician or automated control system then can make an informed decision to treat these regions or plan a treatment to avoid them based on the sensitivity of surrounding structures to unintended heating.
1. A method for delivering thermal therapy to a target volume within a patient's body, comprising:
determining a target volume for delivery of thermal therapy thereto;
in a computer, storing a plurality of phase images captured using a magnetic resonance imaging (MRI) device;
in said computer, creating a reference phase image of a portion of said patient's body using data corresponding to the plurality of phase images captured using said MRI device, wherein each phase image used in creating the reference phase image comprises a plurality of pixels, each pixel having a corresponding phase, and said reference phase image is created by calculating an average phase over several reference images for each pixel in the phase image;
in said computer, creating at least one measurement image of said portion of said patient's body using data corresponding to one or more of said phase images captured using said MRI device;
in a computer, generating at least one uncorrected temperature of the portion of said patient's body using said at least one measurement image and said reference phase image, wherein said at least uncorrected temperature is uncorrected for a phase drift;
using said computer, correcting for said phase drift in at least one temperature map, such that said temperature map includes corrected temperatures;
using said computer, calculating a temperature uncertainty map in a region of said target volume using said at least one temperature map of said corrected temperatures;
using said computer, determining a treatment plan based at least in part on said temperature uncertainty map; and
using a thermal therapy applicator comprising an ultrasound transducer array, delivering a thermal therapy dose to said target volume according to said treatment plan, wherein said treatment plan avoids a region in said target volume having a temperature uncertainty above a temperature uncertainty threshold.
2. The method of claim 1 , further comprising, using said computer, determining a plurality of reference points in said temperature uncertainty map.
3. The method of claim 1 , further comprising, using said computer, generating an output image corresponding to said temperature uncertainty map and displaying said output image of said temperature uncertainty map.
4. The method of claim 1 , further comprising, using said computer, indicating any portions of said temperature uncertainty map that exceed said temperature uncertainty threshold.
5. The method of claim 4 , further comprising, using said computer, generating an output signal depending at least in part on whether a portion of the target volume being treated is at a location where said temperature uncertainty threshold has been exceeded.
6. The method of claim 1 , further comprising, using said computer, calculating a weighted sum of phase differences across all channels and scaling said weighted sum so as to determine temperatures in slices corresponding to said channels.
7. The method of claim 1 , wherein calculating the temperature uncertainty map comprises
calculating a standard deviation of the corrected temperatures for each pixel across a plurality of measurement images.
8. The method of claim 7 , wherein each uncorrected temperature in each said measurement image is generated by calculating a difference between a measured phase and a reference phase at each pixel, multiplied by a constant.