This paper focuses on the evaluation of a prototype for a computer-based tutoring system for prostate cryosurgery, while reviewing its key building blocks and their benchmark performance. The tutoring system lists geometrical constraints of cryoprobe placement, displays a rendered shape of the prostate, simulates cryoprobe insertion, 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 computergenerated plan, created for each case study by a previously developed planning algorithm, known as bubble-packing. While the tutoring level in this study aims only at geometrical constraints on cryoprobe placement and the resulting thermal history, it creates a unique opportunity to gain insight into the process outside of the operation room. System validation of the tutor has been performed by collecting training data from surgical residents, having no prior experience or advanced knowledge of cryotherapy. Furthermore, the system has been evaluated by graduate engineering students having no formal education in medicine. In terms of match between a planning isotherm and the target region shape, results demonstrate medical residents’ performance improved from 4.4% in a pretest to 37.8% in a posttest over a course of 50 minutes of training (within 10% margins from a computer-optimized plan). Comparing those results with the performance of engineering students indicates similar results, suggesting that planning of the cryoprobe layout essentially revolves around geometric considerations.
This study presents a prototype design of an ultra-miniature, wireless, battery-less, and implantable temperature-sensor,
with applications to thermal medicine such as cryosurgery, hyperthermia, and thermal ablation. The design aims at a
sensory device smaller than 1.5 mm in diameter and 3 mm in length, to enable minimally invasive deployment through a
hypodermic needle. While the new device may be used for local temperature monitoring, simultaneous data collection
from an array of such sensors can be used to reconstruct the 3D temperature field in the treated area, offering a unique
capability in thermal medicine. The new sensory device consists of three major subsystems: a temperature-sensing core,
a wireless data-communication unit, and a wireless power reception and management unit. Power is delivered wirelessly
to the implant from an external source using an inductive link. To meet size requirements while enhancing reliability and
minimizing cost, the implant is fully integrated in a regular foundry CMOS technology (0.15 μm in the current study),
including the implant-side inductor of the power link. A
temperature-sensing core that consists of a
proportional-to-absolute-temperature (PTAT) circuit has been designed and characterized. It employs a microwatt chopper stabilized op-amp
and dynamic element-matched current sources to achieve high absolute accuracy. A second order sigma-delta (Σ-Δ)
analog-to-digital converter (ADC) is designed to convert the temperature reading to a digital code, which is transmitted
by backscatter through the same antenna used for receiving power. A high-efficiency multi-stage differential CMOS
rectifier has been designed to provide a DC supply to the sensing and communication subsystems. This paper focuses on
the development of the all-CMOS temperature sensing core circuitry part of the device, and briefly reviews the wireless
power delivery and communication subsystems.
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.
Carcinoma of the breast continues to be the second major cause of death in women in the US today, with 180,000 new cases detected annually in the US. One third of these carcinomas are 1 cm in size or less. The current techniques of surgical resection require operating rooms, anesthesia, cosmetic concerns and cost. The benefits of cryosurgery for the treatment of visceral tumors has stimulated the investigation of this approach for carcinomas of the breast. Here within is a work-in-progress report of our research program to evaluate a cryodevice and techniques for breast cryosurgery.
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