Docent degrees

1. Title: Phongs Belysningsmodell - hur den förbättrats genom åren 
   The Phong Illumination Model - How it has been Improved through the Years 
   Anders Hast 
   Date: 100209 
   Abstract: The Classical illumination model presented by B.T. Phong in the early seventies have been the most widely used in the computer graphics area. It is both fast and simple since the idea is to produce a visually plausible result rather than one based on exact physics. More advanced illumination models are based on the behaviour of different materials and these become more and more popular but still the model by Phong is often used in scientific visualization, computer games and in the production of animated movies. The different parts of the model will be discussed together with important improvements and variants that have been done by others as well as by the presenter and his colleagues. 
   Comment: The docent lecture was held in Swedish. 
   

2. Title: Ugly Yet Informative vs. Fine-looking but Frozen Information - Which One Should be the Future of PET Imaging 
   Pasha Razifar
   Date: 100915 
   Abstract: Positron emission tomography (PET) is a non-invasive imaging modality and an excellent exploratory tool, based on ``tracing'' molecules labelled with a positron emitting radionuclide, called ``tracer''. One of the main strengths of PET is its ability to depict and illustrate metabolic, physiological and biological interaction of the administered tracer with target(s) of interest in either a sector or whole body of a living creature, as image volumes.

   A decade ago this functional information provided by PET was coupled with excellent anatomical information provided by Computed Tomography (CT), introducing a new and powerful duo-modality intended to improve the diagnosis value and to fulfil the drawbacks of using two separate imaging modalities, especially in the field of Oncology. Furthermore, one of the revolutions and at the same time one of the "curses'' on PET when introducing this excellent duo-modality was, and still is, the frequent use of Fluorodeoxyglucose (FDG) when performing whole body static PET/CT. Due to short scanning time and good image quality this approach has become a golden standard tool for tumour imaging. However, when performing static imaging the fourth dimension, time, is frozen and this approach generates a "univariate'' image volume, which illustrates only the mean tracer distribution of the administered tracer during the scanning time. This deflates the key strength of the PET, the exploratory dimension, which is based on "tracing a molecule labelled with a positron emitting radionuclide''. Moreover, static imaging requires a good knowledge about the kinetic behaviour, affinity and the specificity of the administered tracer which requisites many experiments and years of experience.

   On the other hand a dynamic PET imaging (where a sector is scanned sequentially during different time points called frames) generates sequential image volumes which have poorer image quality compared with images obtained when performing static imaging. However, these sequential image volumes can be regarded as multivariate image volumes from which physiological, biochemical and functional information can be "traced'' and derived by analyzing the distribution and kinetics of the administrated radiolabelled molecules. This implies that each of the image volumes displays/contains part of a kinetic information representing physiological behaviour of the administered tracer during different time points (the 4-th dimension). Due to presence of the fourth dimension, dynamic image volumes could be quantified and analysed using several approaches/methods such as graphical modelling, parametric images, pixel-wise modelling, and multivariate image analysis.

   The important question still remains: What are scientists looking for when they are utilizing an excellent imaging tool such as PET? Ugly yet informative or fine-looking but frozen information? 
   Comment: The docent lecture was held in English.