Computerized Planning of Cryosurgery: From Model Reconstruction to Cryoprobe Placement Strategies

As a part of an ongoing program to develop computerized tools for surgery, the current study focuses on the design of optimal cryoprobe layouts for prostate cryosurgery. Once a decision to treat the prostate with cryosurgery has been made, its application can be presented as a four-stage process: (i) 3D reconstruction of the target region; (ii) evaluation of the optimum number of cryoprobes and their layout; (iii) insertion of cryoprobes according to that plan; and, (iv) orchestrating cryoprobe operation to achieve the optimum match between the target region and the forming frozen region. Cryosurgical success equals the sum of the successes of each of the above stages. To date, this four-stage process is performed manually, relying upon the cryosurgeon's experience and "rules of thumb". This manuscript reviews recent efforts to develop the necessary building blocks for an integrated computerized surgical tool for prostate cryosurgery, which includes methods for prostate model reconstruction, schemes for bioheat transfer simulation, and optimization techniques for cryoprobe placement; experimental verification of these building blocks are also presented. The emphasis in this line of development is on performing a full-scale planning in less than one minute, while the patient is on the operation table. It can be concluded from the current manuscript that the above goals are achievable. The current manuscript concludes with a review of current challenges in the development of related computerized means.