Grade Sheet – 600.145 HW #2 Problem 1.1 20 Problem 1.2.a 10 Name 1: __________________ Email/Phone: ______________ Role/contribution: ___________ __________________________ Name 2: __________________ Email/Phone: ______________ Role/contribution: ___________ __________________________ Problem 1.1 20 Problem 1.2.a 10 Problem 1.2.b Problem 1.2.c Problem 2 Problem 3 Problem 4 Totals 110 I/we have adhered to the rules on this homework assignment: ___________________________ ___________________________ (signature) (date) (signature) (date)

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 brachytherapy 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 1: 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 preoperative patient other anatomy prostate cancer MRI images biopsy targets patient other anatomy CT images cancer CT scanner biopsy targets prostate robot needle holder robot base intraoperative needle tip

Problem : CT guidance 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 1: CT-guided Biopsy preoperative patient Some of the pertinent coordinate systems are shown below. There may be others. other anatomy prostate cancer MRI scanner MRI images biopsy targets patient other anatomy CT images cancer CT scanner biopsy targets prostate robot needle holder robot base intraoperative needle tip

Problem 1 (con’d) Question 1.1: 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 1.2

Problem 1 (continued) Question 1.2: 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., Frobot,needle-holder). Explain how these relationships will be determined and identify the steps in the procedure that will be used to determine them. 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. Using the method shown in class, give an expression for Frobot,needle-holder that will place the needle tip on a desired biopsy target. E.g., Frobot,needle-holder=Fa,b •Fc,b-1 •…

Problem 2: Ultrasound Guidance Question 2: 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 1.1 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 3: Comparison Question 3: 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?