Grade Sheet – HW #2 Name 1: __________________ /Phone: ______________ Role/contribution: ___________ __________________________ Name 2: __________________ /Phone: ______________ Role/contribution: ___________ __________________________ I/we have adhered to the rules on this homework assignment: ___________________________ (signature)(date)(signature)(date) Problem 110 Problem Problem 2.2.a10 Problem 2.2.b10 Problem 2.2.c10 Problem 320 Problem 420 Problem 520 Totals120

Homework groundrules Work in groups of at most 2 people Do not work with other groups on homework Do not refer to previous years’ homework Include the cover sheet on the homework Both students should sign the honor pledge You should state what each of you did

Image-guided prostate biopsy Consider the problem of prostate biopsy under image guidance. Currently, we are exploring several possible guidance scenarios for this problem: –trans-rectal ultrasound guidance –in-scanner CT guidance –in-scanner MRI guidance Of these modalities: –Ultrasound enables you to see the outline of the prostate and urethra. It does not show cancer directly. Seeds and needles are visible, though rather fuzzily. Bone is visible, but borders are poor. –CT shows bone really well and the outline of the prostate very poorly. It does not show cancer directly. Seeds and needles show up well. –MRI shows prostate and cancer well, but shows bone poorly. Needles and seeds can show up as loss-of-signal areas. Ferromagnetic materials or large metal pieces or coils can cause great imaging problems.

Problem: Plan in MRI, Execute in CT For the CT guided system, we will assume that a preoperative MR scan is available showing the suspected cancer lesions. The intraoperative system resembles the in-scanner system shown in class preoperative intraoperative

Computed Notation & Formula Example prostate MRI images biopsy target MRI scanner pelvis Measured Suppose that we plan to pick out biopsy targets on MRI images

Computed Notation & Formula Example prostate MRI images biopsy target MRI scanner pelvis Measured

Computed Notation & Formula Example prostate MRI images biopsy target MRI scanner pelvis Measured

Computed Notation & Formula Example prostate MRI images biopsy target MRI scanner pelvis Measured

Computed Notation & Formula Example prostate MRI images biopsy target MRI scanner pelvis Measured

Computed Notation & Formula Example prostate MRI images biopsy target MRI scanner pelvis Measured

Computed Notation & Formula Example prostate MRI images biopsy target MRI scanner pelvis Measured

Computed Notation & Formula Example (modified) biopsy target Measured prostate MRI images MRI scanner pelvis Suppose that we plan to use standard biopsy positions defined with respect to the prostate, instead of picking the targets out with respect to the MRI Image

Computed Notation & Formula Example (modified) biopsy target Measured prostate MRI images MRI scanner pelvis

Problem 1 Assume that the surgeon wants to use a standard biopsy pattern defined with respect to the prostate, but wants to know the target coordinates with respect to the pelvis. Draw a diagram similar to the examples (including use of a green multi-segment arrow) showing how this calculation can be performed Give the corresponding formula for F Pelvis,Targ

Problem : CT guided biopsy For the CT guided system, we will assume that a preoperative MR scan is available showing the suspected cancer lesions. The intraoperative system resembles the in-scanner system shown in class

Problem 2: CT-guided Biopsy Some of the pertinent coordinate systems are shown below. There may be others. patient prostate other anatomy cancer MRI imagesbiopsy targets patient prostate other anatomy cancer CT scanner robot base robot needle holder CT images needle tip preoperative biopsy targets intraoperative MRI scanner

Problem 2 (con’d) Question 2.1: Describe a procedure for targeted biopsy of prostate cancer lesions based on the use of preoperative MRI images and intraoperative CT. Your answer should include a discussion of what steps need to be done preoperatively and what steps need to be done intraoperatively. It should include a discussion of the information developed in each step and of how that information will be used in subsequent steps. It should also include a brief discussion of how this information relates to concepts such as “segmentation” and “registration” discussed in class. Hint: A good way to do this is to develop a flow chart and then include a discussion of each step. It also sometimes helps to make a sketch showing the patient, equipment, etc. at key steps. Finally, consider this answer in concert with the answer to question 2.2

Problem 1 (continued) Question 2.2: Using a graphical method similar to that developed in class, show the key relationships between the various coordinate systems needed to perform this procedure. Assign a symbolic name to each relationship (e.g., F robot,needle-holder ). a)Explain how these relationships will be determined and identify the steps in the procedure that will be used to determine them. b)At each step in the procedure, use a graphical means to illustrate what is known and what is not yet known. A preferred way to do this is to use colors or heavy vs thin lines. Please follow the convention from class that dashed lines mean things that change over time and solid lines mean things that are assumed not to change. c)Using the method shown in class, give an expression for F robot,needle-holder that will place the needle tip on a desired biopsy target. E.g., F robot,needle-holder =F a,b F c,b -1 …

Problem 3: Ultrasound Guidance Question 3: Suppose now that the CT system has been replaced with a trans-rectal ultrasound system, and that the robot has been modified to work with this system. –Explain how you would modify your procedure from question 2.1 to enable you to use it in this context. Again, words like “segmentation” and “registration” are likely to be part of the answer. –Show a modified relationship graph for key steps –Hint: pay attention to what shows up well in both MRI and Ultrasound.

Problem 5: Comparison Question 5: Compare the systems described in your answers to questions 1 and 2, using criteria similar to those you used in Homework #1.

Problem 4: No Preop MRI Question 4: Suppose that there is no preoperative MRI. I.e., we have decided that this patient is a candidate for biopsy based on elevated PSA levels. How would this affect your biopsy procedure and system?