As a part of an ongoing effort to develop computerized training tools for cryosurgery, the current study presents a proof-of-concept for a computerized tool for cryosurgery tutoring. The tutoring system lists geometrical constraints of cryoprobes placement, simulates cryoprobe insertion, displays a rendered shape of the prostate, enables distance measurements, simulates the corresponding thermal history, and evaluates the mismatch between the target region shape and a pre-selected planning isotherm. The quality of trainee planning is measured in comparison with a computer-generated planning, created for each case study by previously developed planning algorithms. Two versions of the tutoring system have been tested in the current study: (i) an unguided version, where the trainee can practice cases in unstructured sessions, and (ii) an intelligent tutoring system (ITS), which forces the trainee to follow specific steps, believed by the authors to potentially shorten the learning curve. While the tutoring level in this study aims only at geometrical constraints on cryoprobe placement and the resulting thermal histories, it creates a unique opportunity to gain insight into the process outside of the operation room. Posttest results indicate that the ITS system maybe more beneficial than the non-ITS system, but the proof-of-concept is demonstrated with either system.

Purpose As a part of an ongoing effort to develop computerized training tools for cryosurgery, this study presents a scheme to geometrically deform a 3D organ template in order to generate clinically relevant prostate models. The objective for creating deformed models is to develop a database for computerized training. This study further presents compiled literature data on the likelihood of cancer tumor growth in the prostate and its relationship to the prostate shape. Methods Cryosurgery is typically performed on patients with localized prostate cancer, found in stages T3 or earlier. The analysis is restricted to cancer originating from the peripheral zone of the prostate as majority of cancer cases are found within this region. The distribution of geometric features, likely to be found in prostates at stage T3, is determined using tumor growth patterns that attribute to changes in the prostate surface. The extended free-form deformation (EFFD) method is applied on a 3D prostate template to create localized surface changes that resemble cancerous prostates. Results Deformed prostate models were generated using the process of: (1) selecting the desired deformation parameters—extra capsular extension (ECE) range and location, and (2) manipulating the lattice control points until the deformed prostate model's ECE length and transverse span fall within the pre-selected ranges. Conclusions EFFD is an efficient method to rapidly generate prostate models for the application of computerized training of cryosurgery. While the selected criteria for deformation do not lead to a unique shape, since the contours of the deformed body are randomly selected, they do lead to shapes resembling cancer growth, as various growth histories can lead to different ECE shapes of the same maximum extension.

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A proof-of-concept for an advanced-level computerized training tool for cryosurgery is demonstrated, based on three-dimensional cryosurgery simulations and a variable insertion-depth strategy for cryoprobes. The objective for system development is twofold: to identify a cryoprobe layout in order to best-match a planning isotherm with the target region shape, and to verify that cryoprobe placement does not violate accepted geometric constraints. System validation has been performed by collecting training data from 17 surgical residents, having no prior experience or advanced knowledge of cryosurgery. This advanced-level study includes an improved training-session design, in order to enhance knowledge dissemination and elevate participant motivation to excel. In terms of match between a planning isotherm and the target region shape, results of this demonstrate trainee performance improvement from 4.4% in a pretest to 44.4% in a posttest over a course of 50 minutes of training. In terms of combined performance, including the above geometrical match and constraints on cryoprobe placement, this study demonstrates trainee performance improvement from 2.2% in the pretest to 31.1% in the posttest. Given the relatively short training session and the lack of prior knowledge, these improvements are significant and encouraging. These results are of particular significance, as they have been obtained from a surgical resident population, which are exposed to the typical stress and constraints in advanced surgical education.

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