This works claims to define, via numerical simulations, magnetic field parameters to perform an effective in situ bone tumor hyperthermia treatment using magnetic scaffolds. A Cole-Cole model to describe the frequency response of the magnetic susceptibility of nanoparticles embedded in novel magnetic biomaterials is explored. The heating phenomena is investigated considering both the ischemic and inflamed state of the fracture gap at the bone/implants interface. Both Osteosarcoma and Fibrosarcoma tumors are analyzed. Magnetic hydroxyapatite and poly-ε-caprolactone scaffolds are investigated. From the thermal analysis, it is found that the fracture behaves as a resistance to heat conduction, therefore strength and frequency of external magnetic field has to be tuned to perform the treatment taking the fracture status into account. Moreover, numerical experiments indicate that low perfused Fibrosarcoma can be treated using moderate-strength field, whereas more intense external fields are required to treat strongly vascularized Osteosarcoma without damaging healthy bone tissue. Magnetic hydroxyapatite stands out to be the most performant and versatile material to treat both tumors. These simulations can be regarded as a starting point to analyze possible clinical use of magnetic scaffolds for in situ bone hyperthermia.

No abstract

Assessing the level of descent of the fetal head in the birth canal during a pelvic examination is a critical skill required by gynecologists and midwifes to avoid injuries for the mother and the newborn. A way to train this ability in a riskless environment is through medical simulation; however, the majority of tools do neither provide visual feedback of the location of the fetus inside the birth canal, nor give the possibility to quantitatively assess this skill. This work aimed at creating a low-cost transducer based on magnetic fields that discriminates between nine levels of descent of the fetal head, namely engagement levels, usable with part-tasks pelvic trainers. Starting with neodymium magnets, we designed a magnetic transducer so that each level was identified by a unique combination of magnetic fields. Three Hall effect sensors detect polarity and intensity of the field generated by 27 permanent magnets, organized in a 9x3 matrix, and each level, corresponding to one row of the matrix, is uniquely encoded by the sensors. The system was theoretically analyzed in simulation, then tested using a customized prototype and finally integrated into an existing birth simulator. The transducer is wireless and avoids any obstruction in the birth canal, as it does not require any power supply to generate magnetic fields and the sensors are connected to the hardware in the fetal manikin. Also, its dimension and ease to install make it usable with many pelvic models, which can be turned into sensorized simulators providing visual feedback and quantitative evaluations.