Fiberproduktionen i världen ökar i takt med att jordens befolkning blir fler, vilket innebär ökad förbrukning av icke-förnyelsebara resurser. Samhällen påverkas även negativt, då avfallshanteringen blir en allt större belastning. Fibertypen som dominerar, och förväntas förtsätta göra det i framtiden, är polyester. Att faktiskt återvinna polyesterfiber är ovanligt. Företaget Teijin har dock utvecklat en metod för kemisk återvinning, från fiber till fiber. Detta sker genom depolymerisation ner till ursprungsmonomererna. Dessa används igen vid framställning av ny PET. Metoden kostsam samtidigt som alternativen mellan denna och energiåtervinning är få. Syftet med detta examensarbete har varit att undersöka potentialen i en alternativ återvinningsmetod. Förhoppningen är att i framtiden kunna utveckla ett mer tids- ocj kostnadseffektivt alternativ i jämförelse med den kemiska återvinningen. Metoden bygger på modifiering av PET genom omförstringsreaktioner under smältbearbetning. Genom att inkorporera segment från alifatiska polyestrar, är önskan att få ett nytt material med lägre smälttemperatur än ursprungsmaterialet. Detta kan vara eftertraktat för flera olika applikationer. Två olika fraktioner av PET, jungfrulig och kasserade polyesterfibrer, har smältbearbetats med PCL, PES eller PTS - vid viktförhållandena PET/alifatisk polyester (mass%) 70/30, 85/15 och 92,5/7,5. Reaktionerna har skett i närvaro av katalysatorn Ti(O Bu)4. De nya materialen analyserades genom DSC och TGA, för att undersöka Tm, samt eventuell viktminskning vid förhöjda temperaturer. Alla prover visade på en lägre smältpunkt i förhållande till ursprungspolyestern. Detta tros bero på omförestring, men en sänkning av molekylvikt har inte kunnat uteslutas. Detta arbete har visat på att omförestring mellan PET och annan polyester leder till sänkning av Tm. Det har kunnat konstateras att detta är en potentiell återvinningsmetod, som bör undersökas vidare. Detta projekt är initierat av Anders Persson, Univeristetslektor vid instutitionen Texiltilhögskolan på Högskolan i Borås.

Treatment response assessment in advanced head and neck cancer patients using Positron Emission Tomography (PET) has potential to provide significant clinical benefit. PET quantification methods can be either static or dynamic. The static approach is simple and is widely used. The simplified dynamic PET quantification method is a promising approach as it provides a reasonable trade-off between accuracy and clinical practicality. This method requires a blood sample which makes it not ideal since the PET quantification accuracy may be compromised due to small activity and volume of the blood sample. The implementation of image-based simplified dynamic PET quantification in head and neck cancer patients requires partial volume correction due to small vessel sizes and limitted PET spatial resolution. The objective of this thesis is to evaluate the accuracy of current PET quantification methods for response assessment in advanced head and neck cancer patients and to develop a novel and robust partial volume correction technique to improve PET quantification. First, the static PET quantification method using fixed size ROI is evaluated. Significant variation in response assessment was observed suggesting that static PET quantification using a fixed-size ROI should be approached with caution in heterogeneous tumours. Second, the accuracy of blood activity measurements and its effect on the accuracy of quantitative response assessment is evaluated. Significant inaccuracies in the blood sample based simplified dynamic PET quantification method are identified. The results support a need to develop an image-based simplified dynamic PET quantification method with partial volume correction. Finally, a novel partial volume correction technique was developed, validated, and its robustness was investigated. In comparison to previously published partial volume correction techniques, it performed better with noisy PET images and it was more robust for errors in PET-CT registration. The partial volume correction technique was also implemented and validated in sinogram space to provide additional advantages such as applicability to iterative reconstructions. The proposed partial volume correction technique enables the use of image-based simplified dynamic PET quantification in advanced head and neck cancer patients. Furthermore, the technique establishes a framework for future research to address the inherent low spatial resolution of PET.

Treatment response assessment in advanced head and neck cancer patients using Positron Emission Tomography (PET) has potential to provide significant clinical benefit. PET quantification methods can be either static or dynamic. The static approach is simple and is widely used. The simplified dynamic PET quantification method is a promising approach as it provides a reasonable trade-off between accuracy and clinical practicality. This method requires a blood sample which makes it not ideal since the PET quantification accuracy may be compromised due to small activity and volume of the blood sample. The implementation of image-based simplified dynamic PET quantification in head and neck cancer patients requires partial volume correction due to small vessel sizes and limitted PET spatial resolution. The objective of this thesis is to evaluate the accuracy of current PET quantification methods for response assessment in advanced head and neck cancer patients and to develop a novel and robust partial volume correction technique to improve PET quantification. First, the static PET quantification method using fixed size ROI is evaluated. Significant variation in response assessment was observed suggesting that static PET quantification using a fixed-size ROI should be approached with caution in heterogeneous tumours. Second, the accuracy of blood activity measurements and its effect on the accuracy of quantitative response assessment is evaluated. Significant inaccuracies in the blood sample based simplified dynamic PET quantification method are identified. The results support a need to develop an image-based simplified dynamic PET quantification method with partial volume correction. Finally, a novel partial volume correction technique was developed, validated, and its robustness was investigated. In comparison to previously published partial volume correction techniques, it performed better with noisy PET images and it was more robust for errors in PET-CT registration. The partial volume correction technique was also implemented and validated in sinogram space to provide additional advantages such as applicability to iterative reconstructions. The proposed partial volume correction technique enables the use of image-based simplified dynamic PET quantification in advanced head and neck cancer patients. Furthermore, the technique establishes a framework for future research to address the inherent low spatial resolution of PET.

PET (positron emission tomography) scans are still in the experimental phase, as one of the newest breast cancer diagnostic techniques. It is becoming the new standard in neurology, oncology and cardiology. PET, like other nuclear medicine diagnostic and treatment techniques, involves the use of radiation. Because of the negative impact of radioactivity to our bodies the radiation doses in PET should be small. The existing computing algorithms for calculating PET images can be divided into two broad categories: analytical and iterative methods. In the analytical approach the relation between the picture and its projections is expressed by a set of integral equations which are then solved analytically. The Fourier backprojection (FBP) algorithm is a numerical approximation of this analytical solution. Iterative approaches use deterministic (ART = Algebraic Reconstructed Technique) or stochastic (EM = Expectation Maximization) algorithms. My proposed kernel density estimation (KDE) algorithm also falls also into the category of iterative methods. However, in this approach each coincidence event is considered individually. The estimate location of the annihilation event that caused each coincidence event is based on the previously assigned location of events processed earlier. To accomplish this, we construct a probability distribution along each coincidence line. This is generated from previous annihilation points by density estimation. It is shown that this density estimation approach to PET can reconstruct an image of an existing tumor using significantly less data than the standard CT algorithms, such as FBP. Therefore, it might be very promising technique allowing reduced radiation dose for patients, while retaining or improving image quality.

Cardiovascular diseases (CVD) remain the number one cause of mortality globally. Compared with autologous vessels, synthetic vascular grafts such as poly (ethylene terephthalate) (PET) vascular grafts are still widely used to replace or bypass diseased arteries. However, PET is susceptible to thrombosis when in contact with blood. In this study, “bioactive”/“bioinert” agents – heparin and poly(ethylene glycol) (PEG) were immobilized covalently on chemically inert PET substrate using a special surface modification technique – surface interpenetrating network (IPN) successfully. The improved haemocompatibility of heparin modified PET surface was proved by a platelet adhesion assay. The PEG modified PET substrate also demonstrated decreased platelet adhesion. Further research has been conducted to immobilize aliphatic chains ended with sulfate and carboxylate groups (existing in heparin) on a model substrate. In vitro thrombus formation test indicated an interesting anticoagulating action between those anionic groups with an optimal ratio in the range of (3:1) and (4.5:1).

PET (positron emission tomography) scans are still in the experimental phase, as one of the newest breast cancer diagnostic techniques. It is becoming the new standard in neurology, oncology and cardiology. PET, like other nuclear medicine diagnostic and treatment techniques, involves the use of radiation. Because of the negative impact of radioactivity to our bodies the radiation doses in PET should be small. The existing computing algorithms for calculating PET images can be divided into two broad categories: analytical and iterative methods. In the analytical approach the relation between the picture and its projections is expressed by a set of integral equations which are then solved analytically. The Fourier backprojection (FBP) algorithm is a numerical approximation of this analytical solution. Iterative approaches use deterministic (ART = Algebraic Reconstructed Technique) or stochastic (EM = Expectation Maximization) algorithms. My proposed kernel density estimation (KDE) algorithm also falls also into the category of iterative methods. However, in this approach each coincidence event is considered individually. The estimate location of the annihilation event that caused each coincidence event is based on the previously assigned location of events processed earlier. To accomplish this, we construct a probability distribution along each coincidence line. This is generated from previous annihilation points by density estimation. It is shown that this density estimation approach to PET can reconstruct an image of an existing tumor using significantly less data than the standard CT algorithms, such as FBP. Therefore, it might be very promising technique allowing reduced radiation dose for patients, while retaining or improving image quality.

Cardiovascular diseases (CVD) remain the number one cause of mortality globally. Compared with autologous vessels, synthetic vascular grafts such as poly (ethylene terephthalate) (PET) vascular grafts are still widely used to replace or bypass diseased arteries. However, PET is susceptible to thrombosis when in contact with blood. In this study, “bioactive”/“bioinert” agents – heparin and poly(ethylene glycol) (PEG) were immobilized covalently on chemically inert PET substrate using a special surface modification technique – surface interpenetrating network (IPN) successfully. The improved haemocompatibility of heparin modified PET surface was proved by a platelet adhesion assay. The PEG modified PET substrate also demonstrated decreased platelet adhesion. Further research has been conducted to immobilize aliphatic chains ended with sulfate and carboxylate groups (existing in heparin) on a model substrate. In vitro thrombus formation test indicated an interesting anticoagulating action between those anionic groups with an optimal ratio in the range of (3:1) and (4.5:1).

This thesis has contributed to the achievement of in-beam PET as a promising clinical monitoring technique. In response to a pressing medical demand, this work has provided a tool for quantification of local dose deviations in case of observed discrepancies between the measured and expected PET images. The implemented interactive approach described in chapter 3 is in clinical use since 2001. It provides the radio-oncologist with a valuable feedback which may allow a prompt reaction in the strategy of the therapy prior to the delivery of the successive treatment fraction in case of significant deviations between planned and actually applied dose. ...

In light of the increasing interest in the syntheses of fluorocarbohydrates as well as in their radiolabelled analogues for use in positron emission tomography (PET), a two- step synthesis of 2-fluoro-2-deoxy-ß-D-allose (2-FDpA) has been developed. The present synthesis employed electrophilic fluorination of 3,4,6-tri-O-acetyl-D-glucal in anhydrous HF (aHF) solvent using F2 and AcOF and was more rapid and efficient than the existing synthesis of 2-deoxy-2-fluoro-D-allose, with a total synthesis time of approximately 45 min, and less laborious. The synthesis proved to be higly regio- and Stereosective, which is often hard to achieve from electrophilic fluorinations. The synthetic route to 2-FDßA was used to obtain the 18F-Iabelled analogue, 2-[18F]FDßA, for the first time with the anticipation that the labelled compound will be of use as a diagnostic agent for the detection and assessment of different tumours as well as for monitoring D-allose metabolism. The overall decay-corrected radiochemical yields (RCY) of the products resulting from radiofluorination of TAG in aHF with [18F]F2 and [18F]AcOF were 33 ±3% and 9 ±2%, respectively, with respect to [18FJF2. The RCY of 33 ±3% is the highest reported for direct fluorinations of TAG using [18FJF2 in any solvent. The radiochemical purities of 2-[18F]FDßA were 96 ±3% and 91 ±8% as determined by radio-HPLC and radio-TLC, respectively. Preliminary in vivo studies using normal rats showed significant differences between the uptake of 2-[18F]FDßA and 2-[18F]FDG, the most commonly used PET radiotracer for detection of various types of cancers. In addition, an animal study with a Polynoma Middle T mouse showed retention of 2-[18F]FDßA in the tumour. The 18F-Iabelling technique was also used as a mechanistic probe for the synthesis of 2-FDßA in the present study. / Thesis / Master of Science (MSc)

This thesis deals with the recycling of polyethylene terephthalate and its subsequent processing into the form of a regranulate meeting the parameters required for food use. A brief description of recycling technology, PET flake quality rating and input material contamination is provided. Additionally, legislation regarding recycling for food purposes is discussed and regranulation technologies are described. The suitability of these technologies for processing specific flake samples has been confirmed. In the experimental part, differences in the regranulate samples are compared using DSC and FT-IR. It has been found that there are no major differences between food quality samples. Tests were carried out on 200 PET bottles (bottle, label), on which the input material was divided into 16 groups. Groups that are unsuitable for recycling with this technology was defined. In addition, contaminants of the final product were examined. Their approximate composition was determined and the relationship between the labels of the bottles at the inlet and the impurities at the outlet was found. Appropriate solutions have been proposed to reduce this contamination