KEYWORDS: Monte Carlo methods, Polymers, Ionization, Chemical analysis, Chemical reactions, Optical testing, Optical simulations, Radiation dosimetry, Algorithm development, Computer simulations, Polymerization, Magnetic resonance imaging, Photon transport
The purpose of this study was to estimate an impact on radical effect in the proton beams using a combined approach
with physical data and gel data. The study used two dosimeters: ionization chambers and polymer gel dosimeters.
Polymer gel dosimeters have specific advantages when compared to other dosimeters. They can measure chemical
reaction and they are at the same time a phantom that can map in three dimensions continuously and easily.
First, a depth-dose curve for a 210 MeV proton beam measured using an ionization chamber and a gel dosimeter.
Second, the spatial distribution of the physical dose was calculated by Monte Carlo code system PHITS: To verify of the
accuracy of Monte Carlo calculation, and the calculation results were compared with experimental data of the ionization
chamber. Last, to evaluate of the rate of the radical effect against the physical dose.
The simulation results were compared with the measured depth-dose distribution and showed good agreement. The
spatial distribution of a gel dose with threshold LET value of proton beam was calculated by the same simulation code.
Then, the relative distribution of the radical effect was calculated from the physical dose and gel dose. The relative
distribution of the radical effect was calculated at each depth as the quotient of relative dose obtained using physical and
gel dose. The agreement between the relative distributions of the gel dosimeter and Radical effect was good at the proton
beams.
We developed a secure system that minimizes staff workload and secures safety of a medical information system.
In this study, we assess the legal security requirements and risks occurring from the use of digitized data. We then analyze the security measures for ways of reducing these risks. In the analysis, not only safety, but also costs of security measures and ease of operability are taken into consideration. Finally, we assess the effectiveness of security measures by employing our system in small-sized medical institution. As a result of the current study, we developed and implemented several security measures, such as authentications, cryptography, data back-up, and secure sockets layer protocol (SSL) in our system. In conclusion, the cost for the introduction and maintenance of a system is one of the primary difficulties with its employment by a small-sized institution. However, with recent reductions in the price of computers, and certain advantages of small-sized medical institutions, the development of an efficient system configuration has become possible.
KEYWORDS: Information security, Computer security, Network security, Picture Archiving and Communication System, Surgery, Systems modeling, Electroluminescence, Data storage, Magnetic resonance imaging, Control systems
The target of our study is to analyze the level of necessary security requirements, to search for suitable security measures and to optimize security distribution to every portion of the medical practice. Quantitative expression must be introduced to our study, if possible, to enable simplified follow-up security procedures and easy evaluation of security outcomes or results. Using fault tree analysis (FTA), system analysis showed that system elements subdivided into groups by details result in a much more accurate analysis. Such subdivided composition factors greatly depend on behavior of staff, interactive terminal devices, kinds of services provided, and network routes. Security measures were then implemented based on the analysis results. In conclusion, we identified the methods needed to determine the required level of security and proposed security measures for each medical information system, and the basic events and combinations of events that comprise the threat composition factors. Methods for identifying suitable security measures were found and implemented. Risk factors for each basic event, a number of elements for each composition factor, and potential security measures were found. Methods to optimize the security measures for each medical information system were proposed, developing the most efficient distribution of risk factors for basic events.
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