Background
Prostate cancer is the most common cancer type amongst the male population, with an estimated 1.2 million cases worldwide in 2022 (https://gco.iarc.who.int/en). To diagnose prostate cancer before it becomes malignant, prostate biopsies are the most prevalent procedure. Most of these procedures are either ultrasound or MRI guided, with MRI being the preferred option for smaller lesions due to its high resolution and detail. To guide the biopsy needle accurately these imaging methods have to be used in real-time. This poses a problem as the nature of MRI scanners does not allow for the use of electronics in the MRI environment due to potential interference or damage to components.
Current solutions to this problem include fully manual devices, which tend to be slower and less accurate than mechanically actuated devices and medical procedures that avoid real-time MRI altogether, therefore also not benefitting from the detailed live-feedback. Another solution is using pneumatics to actuate the biopsy needle. Soteria uses such an approach but their device struggles with applying enough force and reliability.
Challenge
The challenge I will be focusing on is to motorize an existing medical device for prostate biopsies guided by Magnetic Resonance Imaging (MRI). This means replacing the manual knobs, used for adjusting the position of the biopsy needle with motors. The medical device to be modified is the DynaTRIM, developed and manufactured by Philips. Due to the nature of MRI Scanners, no electronics can be used in an MRI environment without risking interference or damage to components. Due to these restraints I will use Pneumatic Stepper-Motors made of a polymer like PLA, and produced using a 3D-printer. Part of the challenge is identifying the dimensions, and force for the pneumatic Stepper Motors that works best in this context, while keeping accuracy and precision high. Additionally, I will have to figure out a way of implementing the chosen motors safely in the system as well as redefining the specifications of the whole device.
Research Question
To guide this project, the main research question has been formulated as:
“How can an existing manually operated prostate biopsy device, such as the DynaTRIM, be motorized using pneumatic stepper motors to achieve the necessary accuracy and precision for remote-controlled MRI-guided prostate biopsies?”
To explore this research question in a structured manner, it has been divided into the following sub-research questions (SRQs):
- SRQ 1: What level of accuracy is necessary for MRI-guided prostate biopsies, and what are the clinical and mechanical tolerances for needle positioning?
- SRQ 2: How can pneumatic stepper motors be integrated into the DynaTRIM system, and what step size and resolution are required to achieve the desired accuracy?
- SRQ 3: How does motorization affect the accuracy and stability of needle positioning, and what mechanisms can be implemented to ensure fail-safe operation in case of motor failure or errors?