Computerized Planning of Cryosurgery Using Cryoprobes and Cryoheaters

Abstract

In a typical minimally invasive cryoprocedure, multiple cryoprobes are inserted into the tissue with the goal of maximizing cryoinjury within a predefined target region, while minimizing cryoinjury to the surrounding tissues. A temperature-controlled electrical heater has been developed recently by this research team, in order to assist in limiting the cryoinjury to the target region. The new device has been termed a 'cryoheater,' and it can work with any cryosurgical cooling technique. A prototype computerized planning tool has been presented recently by this research team, which helps to determine the best locations in which to insert the cryoprobes. This prototype was designed for cryoprobes only. The planning procedure utilized a novel iterative optimization technique, based on a force-field analogy. The combination of cryoheaters with computerized planning is the subject matter of this report. The current report includes a review of cryoheater development, and presents an improved cryosurgery planning tool which incorporates cryoheaters.

Experimental verification of numerical simulations of cryosurgery with application to computerized planning

“…In fact, due to the typical quality of ultrasound imaging, some surface areas of the organ are interpolated based on imaging data, rather than directly extracted from imaging. Given the quality of agreement between experimental data and numerical simulations presented in the current study, the typical quality of organ reconstruction for cryosurgery applications, and the fact that the defect area concept is the key for computerized planning in parallel studies, it is concluded that the numerical technique presented by Rossi et al (2007) is adequate for the purpose of computerized planning of prostate cryosurgery using the prototype algorithms presented by Lung et al (2004), Rabin et al (2004), and Tanaka et al (2006). An image of a cryoprobe, including two enlarged illustrations displaying the cryoprobe design and functionality.…”

“…It follows that uncertainty in estimating the freezing front location in the current study, based on heat transfer simulations, is smaller than the uncertainty in estimating the freezing front location based on ultrasound imaging, in a clinical setup. Furthermore, given the quality of agreement between experimental data and numerical simulations presented in the current study, the typical quality of organ reconstruction for cryosurgery applications, and the fact that the defect area concept is the key for computerized planning in parallel studies , Tanaka et al 2006, it is concluded that the numerical technique presented by Rossi et al (2007) is adequate for the purpose of computerized planning of cryosurgery using the prototype algorithms presented by Lung et al (2004), Rabin et al (2004), andTanaka et al (2006).…”

“…Suboptimal cryoprobe localization may leave areas in the target region untreated, may lead to cryoinjury of healthy surrounding tissues, may require an unnecessarily large number of cryoprobes, may increase the duration of the surgical procedure, and may increase the likelihood of post cryosurgery complications, all of which affect the quality and cost of the medical treatment. Computerized planning tools would help to alleviate these difficulties, which is the subject matter of this ongoing research program at the Biothermal Technology Laboratory Rabin et al 2004;Rabin and Stahovich 2003;Rossi et al 2007;Tanaka et al 2006Tanaka et al , 2007.…”

Key issues in bioheat transfer simulations for the application of cryosurgery planning

“…Towards this goal, the "force-field" algorithm has been developed [5][6], based on a series of heat transfer simulations and an analogy between the resulting temperature field and forces, which may result in cryoprobes displacement between every two consecutive simulations. A "bubble-packing" algorithm was further developed to identify the most efficient initial condition for the force-field method [7].…”

“…the objective to provide results useful for understanding and designing the multi-cryoprobe procedure is commendable, critical evaluation of the Magalov et al [3] report must incorporate recent and relevant literature [4][5][6][7][8][9][10][11][12] not cited by these authors. (A few of the publications cited here were published only after [3] in archival journal, but are nonetheless relevant to the current discussion; those subjects have been widely presented in conferences in the past few years.)…”