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Cancer is a leading cause of morbidity and mortality worldwide, with approximately 14 million new cases and 8.2 million cancer related deaths in 2012 [1]. Moreover, the global cancer burden is expected to exceed 20 million new cancer cases by 2025. Understanding the spatial and temporal behaviour of cancer is a crucial precondition to achieve a successful treatment. Because no two cancer cases are the same, every patient should receive a treatment plan designed specifically for her case, in order to improve the patient’s survival chances.
A simplified model for spondylodesis, ie fixation of vertebrae by osteosynthesis, is developed for virtual magnetic resonance imaging (MRI) examinations to numerically calculate energy absorption. This paper presents results of calculated energy absorption in body tissue surrounding titanium rod implants. In general each wire or rod behaves like an antenna in electromagnetic fields. The specific absorption rate (SAR) profile describes dependence of implant size. SAR hotspots appear near the rod edges. Depending of the size of implant fixation SAR is 62%(small fixation) up to 90.95%(large fixation) higher than without implants. In addition, local SAR profile displays local dependency on tissue: SAR is lower between the vertebrae.
Metallic implants in magnetic resonance imaging (MRI) are a potential safety risk since the energy absorption may increase temperature of the surrounding tissue. The temperature rise is highly dependent on implant size. Numerical examinations can be used to calculate the energy absorption in terms of the specific absorption rate (SAR) induced by MRI on orthopaedic implants. This research presents the impact of titanium osteosynthesis spine implants, called spondylodesis, deduced by numerical examinations of energy absorption in simplified spondylodesis models placed in 1.5 T and 3.0 T MRI body coils. The implants are modelled along with a spine model consisting of vertebrae and disci intervertebrales thus extending previous investigations [1], [2]. Increased SAR values are observed at the ends of long implants, while at the center SAR is significantly lower. Sufficiently short implants show increased SAR along the complete length of the implant. A careful data analysis reveals that the particular anatomy, i.e. vertebrae and disci intervertebrales, has a significant effect on SAR. On top of SAR profile due to the implant length, considerable SAR variations at small scale are observed, e.g. SAR values at vertebra are higher than at disc positions.
Upgrade of Bioreactor System Providing Physiological Stimuli
to Engineered Musculoskeletal Tissues
(2017)
A novel central control interface (CCI) is developed to improve the modular bioreactor system with regard to extendability and modifiability in Tissue Engineering (TE) applications. This paper presents the results developed in the project with open-source hardware and the graphical programming system LabVIEW. A new platform independent User Interface was further developed to contribute to the new flexibility of the device.
This study investigates differences between treatment plans generated by Ray Tracing (RT) and Monte Carlo (MC) calculation algorithms in homogeneous and heterogeneous body regions. Particularly, we focus on the head and on the thorax, respectively, for robotic stereotactic radiotherapy and radiosurgery with Cyberknife. Radiation plans for tumors located in the head and in the thorax region have been calculated and compared to each other in 47 cases and several tumor types.
Radiotherapy (RT) treatment planning is based on computed tomography (CT) images and traditionally uses the conventional Hounsfield unit (CHU) range. This HU range is suited for human tissue but inappropriate for metallic materials. To guarantee safety of patient carrying implants precise HU quantification is beneficial for accurate dose calculations in planning software. Some modern CT systems offer an extended HU range (EHU). This study focuses the suitability of these two HU ranges for the quantification of metallic components of active implantable medical devices (AIMD). CT acquisitions of various metallic and non-metallic materials aligned in a water phantom were investigated. From our acquisitions we calculated that materials with mass-density ρ > 3.0 g/cm3 cannot be represented in the CHU range. For these materials the EHU range could be used for accurate HU quantification. Since the EHU range does not effect the HU values for materials ρ < 3.0 g/cm3, it can be used as a standard for RT treatment planning for patient with and without implants.
