29 research outputs found
CENSORSHIP MEASURES IN STYRIA IMMEDIATELY AFTER THE PUBLICATION OF KOROÅ EC\u27S SLOVENIAN DECLARATION
Immediately after the introduction of the King Aleksandar KaraÄorÄeviÄ\u27s dictatorship and the censorship became more severe. The press was supposed to subordinate its writing to the efforts of the government or at least avoid mentioning anything that was in contrast with these efforts. Through the press the state wanted to exert an allāencompassing control over the thinking, political viewpoints, as well as emotions of the people. The author argues on the censorship measures in Styria after the publication of KoroÅ”ec\u27s Slovenian declaration in 1932
The dose accumulation and the impact of deformable image registration on dose reporting parameters in a moving patient undergoing proton radiotherapy
INTRODUCTION: Potential changes in patient anatomy during proton radiotherapy may lead to a deviation of the delivered dose. A dose estimate can be computed through a deformable image registration (DIR) driven dose accumulation. The present study evaluates the accumulated dose uncertainties in a patient subject to an inadvertent breathing associated motion. MATERIALS AND METHODS: A virtual lung tumour was inserted into a pair of single participant landmark annotated computed tomography images depicting opposite breathing phases, with the deep inspiration breath-hold the planning reference and the exhale the off-reference geometry. A novel Monte Carlo N-Particle, Version 6 (MCNP6) dose engine was developed, validated and used in treatment plan optimization. Three DIR methods were compared and used to transfer the exhale simulated dose to the reference geometry. Dose conformity and homogeneity measures from International Committee on Radioactivity Units and Measurements (ICRU) reports 78 and 83 were evaluated on simulated dose distributions registered with different DIR algorithms. RESULTS: The MCNP6 dose engine handled patient-like geometries in reasonable dose calculation times. All registration methods were able to align image associated landmarks to distances, comparable to voxel sizes. A moderate deterioration of ICRU measures was encountered in comparing doses in on and off-reference anatomy. There were statistically significant DIR driven differences in ICRU measures, particularly a 10% difference in the relative D(98%) for planning tumour volume and in the 3 mm/3% gamma passing rate. CONCLUSIONS: T he dose accumulation over two anatomies resulted in a DIR driven uncertainty, important in reporting the associated ICRU measures for quality assurance
Prepoznavanje ogroženosti za nastanek raka dojk na mamografskih slikah
Za prehod s populacijskega na personalizirano presejanje za raka dojk je v prvi vrsti potrebno natanÄno prepoznavanje ogroženosti za razvoj raka dojk. Standardni modeli, ki temeljijo na klasiÄnih znaÄilkah, niso najbolj zanesljivi. Z razvojem umetne inteligence, predvsem na podroÄju globokega uÄenja, se je izkazalo, da modeli, ki so nauÄeni na mamografskih slikah, dosegajo signifikantno boljÅ”e rezultate pri napovedovanju ogroženosti. Trenutno je najboljÅ”i model za napovedovanje ogroženosti MIRAI, ki je bil uspeÅ”no validiran na razliÄnih populacijah. A vendar so rezultati Å”e daleÄ od popolnih in možnosti za izboljÅ”ave je ogromno, predvsem na podroÄju razÅ”iritve uporabnosti modela za razliÄne proizvajalce mamografskih aparatov, vkljuÄevanja longitudinalnih sprememb in uporabe segmentiranih slik dojke
Performance evaluation of a very high resolution small animal PET imager using silicon scatter detectors
A very high resolution positron emission tomography (PET) scanner for small animal imaging based on the idea of inserting a ring of high-granularity solid-state detectors into a conventional PET scanner is under investigation. A particularly interesting configuration of this concept, which takes the form of a degenerate Compton camera, is shown capable of providing sub-millimeter resolution with good sensitivity. We present a Compton PET system and estimate its performance using a proof-of-concept prototype. A prototype single-slice imaging instrument was constructed with two silicon detectors 1 mm thick, each having 512 1.4 mm Ć 1.4 mm pads arranged in a 32 Ć 16 array. The silicon detectors were located edgewise on opposite sides and flanked by two non-position sensitive BGO detectors. The scanner performance was measured for its sensitivity, energy, timing, spatial resolution and resolution uniformity. Using the experimental scanner, energy resolution for the silicon detectors is 1%. However, system energy resolution is dominated by the 23% FWHM BGO resolution. Timing resolution for silicon is 82.1 ns FWHM due to time-walk in trigger devices. Using the scattered photons, time resolution between the BGO detectors is 19.4 ns FWHM. Image resolution of 980 Āµm FWHM at the center of the field-of-view (FOV) is obtained from a 1D profile of a 0.254 mm diameter 18F line source image reconstructed using the conventional 2D filtered back-projection (FBP). The 0.4 mm gap between two line sources is resolved in the image reconstructed with both FBP and the maximum likelihood expectation maximization (ML-EM) algorithm. The experimental instrument demonstrates sub-millimeter resolution. A prototype having sensitivity high enough for initial small animal images can be used for in vivo studies of small animal models of metabolism, molecular mechanism and the development of new radiotracers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58094/2/pmb7_10_012.pd
Posodobljena priporoÄila diagnostike in zdravljenja diferenciranega raka Å”Äitnice
no abstractni abstrakt