In the thesis, we developed and studied a novel polymer delivery system for the DNA-intercalator bearing radioisotope iodine-125. Auger electrons emitting radioisotopes (such as iodine-125 or indium-111) are a potentially effective cancer treatment. Their use as an effective cancer therapy requires that they will be transported within close proximity of DNA, where they induce double-strand breaks leading to the cell death. This type of therapy may be even more beneficial when associated with drug delivery systems. The DNA intercalators proved to be effective carriers for the delivery of Auger electron emitters into DNA. Therefore, the new radioiodinated DNA-intercalating ellipticinium derivatives were synthesized and characterized. These compounds were linked to N-(2-hydroxypropyl) methacrylamide copolymer with narrow molecular weight distribution via acid-sensitive hydrazone linker. The structure of the linker plays a crucial role in the biological effectivity of the delivery system, so it was optimized to be stable at pH 7.4 (representing the pH of blood plasma), whereas in slightly acidic pH in endosomes after the cell internalization, the radioiodine-containing biologically active intercalator is rapidly released from its polymer carrier. The intercalating ability of the active compound was...

Thesis--University of London. / At head of title: Community Dentistry Unit, The London Hospital Medical College Dental School. Includes bibliographical references (p. 248-269).

Thesis--University of London. / At head of title: Community Dentistry Unit, The London Hospital Medical College Dental School. Includes bibliographical references (p. 248-269).

Radiodiagnostics is a relatively young field of medicine the objective of which is imaging of anatomic structures and physiological and pathological processes in order to determine diagnoses or prognoses of diseases. For this purpose radiodiagnostics uses ionizing radiation with both its positive and negative effects. The effects are demonstrated also in healthy cells and healthy tissues of the human organism. A radiation protection system therefore establishes, among other things, limit doses to which individuals working with ionizing radiation may be exposed while performing their jobs. The received doses are kept under control by means of a dosimetric system. Essentially, there are two types of dosimeters: passive and active, i.e. electronic. The purpose of this thesis is to compare results from personal film dosimeters with results obtained from electronic dosimeters DMC 2000 XB made by Merlin Gerin and to determine whether electronic dosimeters are suitable for radiodiagnostics and whether they can replace film dosimeters. I performed the measurements at the radiodiagnostics ward of the hospital Nemocnice Sušice, o.p.s. X-ray assistants in the ward are routinely equipped with personal film dosimeters. In addition to their film dosimeters, they were given personal electronic dosimeters for a period of seven months. They were wearing both types of the dosimeters in compliance with the Decree issued by the State Office for Nuclear Safety (SÚJB) No. 307/2002 Coll., as amended, at the reference place, i.e. on the left upper part of the chest on their clothing. Measurements were conducted on five X-ray assistants and one additional personal electronic dosimeter was used to measure the natural background. I have used results from electronic personal dosimeters to evaluate the collective dose of all workers in the individual months, the total collective dose and the sum of dose equivalents in all months for the individual workers. The collective dose from dose equivalents Hp(10) was stable most of the time and in November and December it was slightly higher. This was due to a higher frequency of surgeries which required presence of an assistant with an X-ray device in the operating room. The highest sum of dose equivalents Hp(10) was found for the worker No. 1 due to his more frequent presence in the operating room. Although the X-ray workers take turns at the workplace regularly they perform their tasks at random. I can definitely exclude that the worker No. 1 was in any way different from the other workers - when it comes to radiation protection all X-ray assistants observe the same principles of radiation protection. For better understanding the thesis also includes information about working activities performed by X-ray assistants. Despite the fact that the measurements using electronic dosimeters several times indicated monthly values of personal dose equivalent Hp(10) higher than 0.1 mSv, the evaluation of the respective film dosimeters from the same period of time indicated values lower than 0.1 mSv or lower than 0.05 mSv. Subsequent investigations have shown that CSOD, s.r.o. is capable of measuring values = 0.01 mSv. The discrepancy between the measured results therefore does not come from the evaluation but from a lower sensitivity of the film dosimeter. The thesis also includes evaluation of advantages and disadvantages of both the types of personal dosimeters. Based on results of the measurements, evaluation of advantages and disadvantages of the two types of personal dosimeters and based on working activities of X-ray assistants I can conclude that the personal electronic dosimeter DMC 2000 XB made by Merlin Gerin is suitable for activities at the radiodiagnostics ward and that it may fully replace the film dosimeter.

Le but de notre travail a été d’évaluer l’effet de la réduction de la dose d’irradiation en TDM multibarrette quant à la performance diagnostique, la confiance de l’observateur dans le diagnostic proposé, la capacité à suggérer un diagnostic alternatif dans quelques pathologies courantes et/ou caractérisées par des situations de faibles contrastes entre les structures anatomiques normales ou pathologiques. Nous avons donc comparé ces paramètres entre des TDM à doses réduites et à doses standard telles que couramment rapportées dans la littérature dans les circonstances suivantes :<p><p>•\ / Doctorat en sciences médicales / info:eu-repo/semantics/nonPublished

The aim of this study is to determination of local diagnostic reference levels for radiodiagnostic examination in the General Teaching Hospital in Prague. Local diagnostic reference levels are used for an evaluation of radiation load which patients receive during medical examinations of specific parts of the human body. The evaluation can be on the level of a hospital and its department or on the level of concrete X-ray machine. The theoretical part describes a ionizing radiation, including its interaction with matter, creating, formation of radiodiagnostic image, legislation during optimization of radiodiagnostic examination, radiological protection and determination of values for radiation dose. The practical part describes the determination of local diagnostic reference levels with the help of entrance surface kerma and the median dose in the mammary gland. Both of these variables are relevant for determination of the risk of adverse effects of ionizing radiation which is applied during radiographic examination. Data for this study was collected with the help of operating diaries and PACS system. It has been rated twenty-six kinds of examinations from twelve mobile and nine stationary (including two mammographs) X-ray machines. All resulting values were statistically processed and compared with...