Volumetric modulated arc therapy (VMAT) is an efficient and conformal radiation therapy technique. It accomplishes this by dynamically varying multi-leaf collimator (MLC) positions, dose rates and gantry velocity. This work investigated the effect of varying the maximum MLC speed and maximum dose rate on the quality, efficiency and accuracy of treatment plans. The Pinnacle3 SmartArc treatment planning software was used to generate plans on prostate and head and neck (H&N) sites. A range of maximum MLC leaf speeds (0.55 cm/s to 2.20 cm/s) and maximum dose rates (200 MU/min to 600 MU/min) restrictions were applied to each plan to investigate their effect on the treatment quality, efficiency and accuracy. Each plan had their monitor units (MU) per fraction, delivery time, mean dose rate and leaf speed analysed. The dose volume histogram (DVH) data was used in the assessment of the conformity, homogeneity and plan quality. The treatments were delivered on Varian iX accelerator equipped with 120-leaf millennium MLC. Quality assurance measurements were performed using the ArcCHECK™ 3D diode array and results were assessed based on gamma analysis of dose fluence maps, beam delivery statistics and Dynalog data. The number of VMAT fields was found to be a key factor in how significant the maximum MLC leaf speed affected the plan parameters investigated. Single arc treatments were shown to have lower MU, dose rate and plan quality, while also exhibiting a slight increase in estimated delivery time. For dual arc treatments, MU, delivery time, dose rate and plan quality were largely independent of the maximum MLC speed allowed. The QA showed that higher MLC leaf speeds were prone to an increase in the discrepancy between planned and delivered control point (CP) fluence and higher MLC positioning errors. None of these were at a clinically significant level, and the overall fluence distribution and point dose comparisons were independent of maximum MLC leaf speed. The only clinically significant effect that modulation of the maximum dose rate had was on the delivery time. Lower maximum dose rates resulted in longer treatment delivery, which is an important consideration in minimising the intra-fractional motion during treatment. The results of the MLC leaf speed evaluation showed that the lower the maximum leaf speed the more accurate the delivered treatment, -however the quality of the plan is reduced. This indicates that there could be an optimum maximum MLC leaf speed which produces high quality plans that can be accurately delivered. Based on this work a maximum MLC leaf speed of 1.38 cm/s was shown to have no reduction in plan quality however it showed improvement in delivery accuracy. There was no justification found for reducing the maximum dose rate below the recommended 600 MU/min.

Ultraviolet (UV) radiation has several effects on human health as well as other biological and chemical systems. The radiation can be weighted with the erythemal action spectrum and then converted to the dimensionless UV Index, which is designed to indicate the detrimental 'sunburning power' of the radiation for public heath purposes. A global view of the erythemally weighted irradiance from the Ozone Monitoring Instrument (OMI) on board the Aura spacecraft has been available since July, 2004. However, ground-based validation and correction of the satellite data are still required. In this thesis, the erythemal dose rates at local solar noon taken from the satellite were compared to ground-based data measured by spectroradiometers or broadband radiometers in two different climate areas: the Tropics and midlatitudes. This seeks to redress the lack of data and satellite validation for the Tropics, and also allows comparison with previous work in midlatitudes. The validation results show that the satellite data overestimates the ground-based data by 9%-32% at the cleanest site, with a much higher discrepancy at polluted sites. Using a radiative transfer model confirmed that the positive bias in the satellite data was mainly caused by aerosol absorption that is not taken into account in the satellite retrieval algorithm. Therefore, two empirical methods were introduced in order to correct the OMI UV data for absorbing aerosols under clear sky conditions. These methods required aerosol optical depth and aerosol single scattering, or aerosol absorption optical depth, as input parameters. The methods improved the OMI UV data by up to 30% depending on site and input data source. For cloudy conditions aerosol data is usually not available either from ground-based or satellite-based measurements; however, the effect of cloud is usually far greater than that of aerosol, and some of the aerosol effect (scattering) is intrinsically included in the cloud correction. A further empirical model for cloudy conditions was derived to reduce bias of the OMI UV data with respect to ground-based data. The method only requires the OMI UV data as an input. The cloudy model reduced the bias by about 13%-30% depending on site, and gave similar results even when used with clear sky data. Since ground-based data is sparse, the final goal of the work was to produce a corrected map of UV index for the whole of Thailand, based only on data available from satellite, which gives full regional coverage. Issues with availability and quality of satellite data meant that the best results were achieved by using only the cloudy sky correction, for all conditions. The resulting daily noontime UV Index maps of Thailand were assessed against ground-based data for independent years. The corrected UV Index was within ±2 compared with ground-based data for all sites, compared to discrepancies of up to 4 UV Index for uncorrected data.

Brachytherapy is a form of radiotherapy in which radioactive sources are placed at short distances from, or even inside the target volume. The use of high dose rate brachytherapy is a widely accepted and clinically proven treatment for some stages of prostate cancer. The aim of this project was to investigate potential improvements on two of the most important aspects of high dose rate (HDR) and pulsed dose rate (PDR) prostate brachytherapy - prostate definition and treatment delivery verification. The use of magnetic resonance (MR) imaging in addition to the conventional computed tomography (CT) imaging methods currently used routinely for brachytherapy planning may provide some benefit in accurately defining the prostate and surrounding critical structures. The methods used in this project involved analysis of data sets provided by two Radiation Oncologists. The results presented showed inter-observer and intra-observer variations in the size and shape of the prostate, as well as analysis of the dosimetric differences that may be reported due to the differences in prostate size and shape. The results also included analysis of critical structure dosimetry - dose to the surrounding radio-sensitive rectum and urethra. In summary, the results showed that the prostate was defined to be smaller using MR imaging than CT, however the consistency between Oncologists was not significantly improved using MR imaging. MR imaging may be useful in reducing the dose to normal tissue surrounding the prostate and in obtaining better coverage of the smaller target volume, without compromising the critical structures. The use of LiF:Mg,Ti thermoluminescent dosimeters (TLDs) is a potential avenue for in vivo dose verification of an HDR or PDR prostate brachytherapy treatment plan. This project included a phantom study of these TLDs with the aim to determine their feasibility for clinical use. Cylindrical TLD rods (6 mm length x 1 mm diameter) were used, as these fit inside the brachytherapy needles implanted into the prostate, and therefore had potential to be used clinically to verify the dose delivered in the prostate. This study was extended to include determination of a correction factor to allow an independent radiation source (6 MV photon beam from a linear accelerator) to be used to obtain control readings for this relative dosimetric method. The results showed these TLDs to be a promising in vivo dosimeter for prostate brachytherapy with potential errors in the order of 4%. Their potential lies in the fact that they could detect and flag significant calculation errors in treatment plans, and they utilise equipment used routinely for external beam radiotherapy dosimetry in many treatment facilities, reducing the cost of implementing such a procedure.

A braquiterapia de alta taxa de dose é uma das modalidades mais utilizadas em braquiterapia para o tratamento de câncer. Os diversos avanços tecnológicos, bem como a evolução das técnicas de tratamento tornaram a braquiterapia de alta taxa de dose uma das modalidades de estado da arte para o tratamento de alguns cânceres. Parte deste avanço é creditada à melhoria na acurácia e na prescrição de dose absorvida recomendada ao paciente, ao longo dos anos. Este avanço permite que atualmente seja possível realizar os cálculos dosimétricos, por meio de sistemas de planejamento computadorizado, considerando as heterogeneidades dos pacientes, tais como: tecidos e órgãos com composições diferentes da água (meio de referência em radioterapia), contorno do paciente individualizado, introdução de aplicadores, dentre outros. Tais avanços demandam o controle de qualidade destas ferramentas, com objetivo de assegurar que todo o processo de tratamento seja satisfatório e acurado. Até o momento, a comunidade carece de um sistema experimental capaz de avaliar, considerando os níveis de incerteza, se os sistemas de planejamento computadorizados são aptos a considerar a heterogeneidade dos tratamentos. Neste trabalho, apresentamos o desenvolvimento de medidas experimentais em um objeto simulador, com capacidade de mensurar as diferenças introduzidas pela heterogeneidade por meio de três técnicas dosimétricas experimentais: termoluminescência, filmes radiocrômicos e ionométrica. Os resultados experimentais foram comparados com as simulações de Monte Carlo e com um sistema de planejamento computadorizado comercial, apto a realizar correções de heterogeneidade em braquiterapia. Discutimos as principais etapas de desenvolvimento deste objeto simulador, seus resultados experimentais e as comparações com os demais sistemas. As conclusões e as etapas futuras deste projeto também são apresentadas. / High dose rate brachytherapy is one of the most widely used modalities in brachytherapy for cancer treatment The various technological advances and the development of treatment techniques have made high dose rate brachytherapy as one of the state of the art methods for the treatment of some cancers. Part of this progress is credited to the improvement in the accuracy and absorbed dose prescription recommended to patients over the years. This advance currently allows the possibility of performing dosimetric calculations, by means of computerized planning systems, considering the heterogeneity of patients, such as: tissues and organs with different water compositions (reference medium in radiotherapy), individualized patient\'s contour and introduction of applicators, among others. Such advances require quality control of these tools, in order to ensure that the entire treatment process is satisfactory and accurate. Nowadays, the community needs an experimental system capable of evaluating, since the uncertainty levels if the computerized planning systems are able to consider the heterogeneity of treatments. In this project, we present the development of experimental measurements into a phantom, capable of measuring the differences introduced by heterogeneity through three experimental dosimetric techniques: thermoluminescence, radiochromic films and ionometric. The experimental results were compared with the Monte Carlo simulations and a commercial treatment planning system able to perform correction of heterogeneity in brachytherapy. We discuss the main stages of development of this phantom, their experimental results and comparisons with other systems. The conclusions and future steps to complete this project are also presented.

A braquiterapia de alta taxa de dose é uma das modalidades mais utilizadas em braquiterapia para o tratamento de câncer. Os diversos avanços tecnológicos, bem como a evolução das técnicas de tratamento tornaram a braquiterapia de alta taxa de dose uma das modalidades de estado da arte para o tratamento de alguns cânceres. Parte deste avanço é creditada à melhoria na acurácia e na prescrição de dose absorvida recomendada ao paciente, ao longo dos anos. Este avanço permite que atualmente seja possível realizar os cálculos dosimétricos, por meio de sistemas de planejamento computadorizado, considerando as heterogeneidades dos pacientes, tais como: tecidos e órgãos com composições diferentes da água (meio de referência em radioterapia), contorno do paciente individualizado, introdução de aplicadores, dentre outros. Tais avanços demandam o controle de qualidade destas ferramentas, com objetivo de assegurar que todo o processo de tratamento seja satisfatório e acurado. Até o momento, a comunidade carece de um sistema experimental capaz de avaliar, considerando os níveis de incerteza, se os sistemas de planejamento computadorizados são aptos a considerar a heterogeneidade dos tratamentos. Neste trabalho, apresentamos o desenvolvimento de medidas experimentais em um objeto simulador, com capacidade de mensurar as diferenças introduzidas pela heterogeneidade por meio de três técnicas dosimétricas experimentais: termoluminescência, filmes radiocrômicos e ionométrica. Os resultados experimentais foram comparados com as simulações de Monte Carlo e com um sistema de planejamento computadorizado comercial, apto a realizar correções de heterogeneidade em braquiterapia. Discutimos as principais etapas de desenvolvimento deste objeto simulador, seus resultados experimentais e as comparações com os demais sistemas. As conclusões e as etapas futuras deste projeto também são apresentadas. / High dose rate brachytherapy is one of the most widely used modalities in brachytherapy for cancer treatment The various technological advances and the development of treatment techniques have made high dose rate brachytherapy as one of the state of the art methods for the treatment of some cancers. Part of this progress is credited to the improvement in the accuracy and absorbed dose prescription recommended to patients over the years. This advance currently allows the possibility of performing dosimetric calculations, by means of computerized planning systems, considering the heterogeneity of patients, such as: tissues and organs with different water compositions (reference medium in radiotherapy), individualized patient\'s contour and introduction of applicators, among others. Such advances require quality control of these tools, in order to ensure that the entire treatment process is satisfactory and accurate. Nowadays, the community needs an experimental system capable of evaluating, since the uncertainty levels if the computerized planning systems are able to consider the heterogeneity of treatments. In this project, we present the development of experimental measurements into a phantom, capable of measuring the differences introduced by heterogeneity through three experimental dosimetric techniques: thermoluminescence, radiochromic films and ionometric. The experimental results were compared with the Monte Carlo simulations and a commercial treatment planning system able to perform correction of heterogeneity in brachytherapy. We discuss the main stages of development of this phantom, their experimental results and comparisons with other systems. The conclusions and future steps to complete this project are also presented.

BACKGROUND High dose rate Intraluminal Brachytherapy (HDRILBT) is one of the most used palliative treatment options for advanced esophageal cancer. The present study evaluates the role of additional chemotherapy in improving dysphagia free survival (DFS) and overall survival (OS) in patients with inoperable advanced esophageal cancer treated with brachytherapy. MATERIAL and METHODS 132 patients with advanced metastatic esophageal cancer with total or near total dysphagia were given HDRILBT to a dose of 18 Gray (Gy) in 3 fractions on alternate days. Intraluminal brachytherapy alone was performed on 98 patients. 34 patients received Epirubicin, 5-Fluorouracil, and Cisplatin (ECF) chemotherapy regimen after HDRILBT. The mean age of the whole group was 65 years (HDRILBT-71.41, HDRILBT+ECF-59.98; p<0.0001). Male: Female was 101:31 (HDRILBT 72:26; HDRILBT +ECF 29:5; p>0.05). The location incidence was GEJ: Lower Esophagus: Mid Esophagus: Cervical Esophagus 24:81:17:5 respectively; for the whole group HDRILBT- 17:57:16:4; HDRILBT+ECF-7:24:1:1; p>0.05. 78 patients presented with co-morbidities (cardiac) (HDRILBT- 59; HDRILBT+ECF- 19; p>0.05). 74 patients presented with distant metastasis (54 with HDRILBT and 20 with HDRILBT+ECF; p>0.05). The ECOG scores were as follows 0:1:2:3:4 15:52:51:12:2 (HDRILBT- 10:35:41:10:2; HDRILBT+ECF- 5:17:10:2:0; p=0.0014). All patients completed 3 fractions of HDRILBT. 34 patients received additional chemotherapy with ECF regimen. Selection of patients was done by the medical oncologist. Statistical analysis of data was done using the SAS statistical analysis software system. Univariate and multivariate analysis was done using the log rang test. RESULTS Patients who received additional ECF were younger (p< 0.001) and with a better performance status than those who received HDRILBT alone (p=0.0014). Mean DFS was higher for patients who had further chemotherapy treatment (232 days) vs. patients who had HDRILBT only (155 days) (p>0.05). The mean OS for HDRILBT + ECF was 266 days (p = 0.0010) compare with HDRILBT alone which was 155 days, when the effect of 10 prognostic factors was analyzed for DFS and OS. Only additional ECF after brachytherapy impacted on DFS while age (p<0.001) and performance status (p=0.0014) impacted on overall survival on univariate analysis. On multivariate analysis tumor length and nodal presentation (p<0.000) impacted on OS. The incidence of stricture and fistulae were similar. Chemotherapy related side effects: gastrointestinal tract (25 patients), neurotoxicities (2) and nephrotoxicities (2) were seen as a result of 5-FU and Cisplatin respectively. 18 patients completed at least 3 cycles of ECF. CONCLUSION Additional chemotherapy with ECF after HDRILBT improves the DFS and OS in selected patients with advanced esophageal cancer. These patients tend to be younger with better performance status, small tumor length and nodal metastasis. The incidence of complications is similar with more than 50% patients completing at least 3 cycles of chemotherapy. / Thesis / Master of Science (MSc)

Yes

Für die Therapie maligner intranasaler Neoplasien beim Hund existieren nur mäßig be-friedigende Behandlungsstrategien. Als Therapiemodalität der Wahl wird die Radiothe-rapie angesehen, die gegenwärtig v.a. in Form einer perkutanen Bestrahlung (Telethe-rapie) mit aufwendigen, bis zu 20 Fraktionen umfassenden Protokollen kurativer Intenti-on angewendet wird. Die erreichbaren Überlebenszeiten sind meist limitiert durch das Auftreten eines Rezidivs des Nasentumors innerhalb des Bestrahlungsfeldes, sodass eine Erhöhung der applizierten Gesamtdosis nötig erscheint. Dies ist jedoch im Rahmen einer Teletherapie aufgrund nicht vertretbarer akuter Nebenwirkungen nicht möglich. Alternativ steht die Brachytherapie zur Verfügung, die aufgrund ihrer physikalischen Charakteristika zur besseren Schonung des umliegenden Normalgewebes beiträgt. Ge-genwärtig existieren keine anderen Untersuchungen zur Anwendung der fraktionierten High-Dose-Rate-Brachytherapie bei Nasentumoren des Hundes. Ziel dieser Studie war es daher, die Durchführbarkeit dieser Therapiemodalität beim Hund erstmals zu unter-suchen und die akuten und chronischen Nebenwirkungen sowie die erzielbare progres-sionsfreie Zeit und die Überlebenszeit zu dokumentieren. Im Zeitraum von 2001 bis 2007 gingen 18 Hunde in die Studie ein. Das diagnostische Vorgehen beinhaltete neben einer klinischen Untersuchung und der Röntgenuntersu-chung von Nase und Thorax auch die kernspintomographische Beurteilung der Nasen-höhlen und eine nachfolgende Rhinoskopie inklusive Biopsie. Die Therapie bestand aus zwei wöchentlichen Fraktionen, bei denen in Vollnarkose über einen in der Nasenhöhle applizierten Katheter mithilfe des Radioisotops 192Iridium jeweils 5 Gy appliziert wurden. Die damit über vier Wochen erreichte Gesamtdosis lag bei 40 Gy, und entsprach damit der biologischen Effizienz einer perkutan applizierten konventionell fraktionierten Ge-samtdosis von circa 60 Gy. Im Anschluss an die Therapie wurden die Hunde monatlich klinisch untersucht und die auftretenden Nebenwirkungen anhand des Radiation Morbi-dity Scores der VRTOG beschrieben. Es wurden außerdem weiterführende Untersu-chungen in Form von MRT, Rhinoskopie und Biopsie durchgeführt. Die aufgetretenen Nebenwirkungen waren mit denen in der Literatur nach Teletherapie beschriebenen vergleichbar, beziehungsweise fielen im Bereich von Augen und Maulschleimhaut ge-ringer aus. Nebenwirkungen im Bereich der Haut traten in Form von Alopezie, Hyper-pigmentation oder Leukotrichie auf. Im Bereich der Nasenschleimhaut zeigten fast alle Hunde eine leichte chronische Rhinitis. Als problematische Nebenwirkungen traten bei drei Patienten Osteoradionekrosen auf, die einer aufwendigeren chirurgischen Versor-gung bedurften. Die mediane progressionsfreie Zeit lag bei 13 Monaten, die mediane Überlebenszeit bei 17 Monaten. Die Adenokarzinome wiesen die längste Überlebens-zeit auf, dies war jedoch aufgrund der insgesamt kleinen Patientenzahl nicht signifikant. Ein Zusammenhang zwischen dem Tumorstadium und der progessionsfreien Zeit oder Überlebenszeit bestand nicht. Bei dem beschriebenen Protokoll handelt es sich um eine unter klinischen Bedingungen praktikable Therapieform, die mit ihren insgesamt acht Fraktionen für Besitzer und Tier wesentlich weniger belastend ist als teletherapeutische kurative Protokolle mit 12-20 Fraktionen. Gleichzeitig gelingt es, eine Gesamtdosis von verhältnismäßig hoher biolo-gischer Effizienz zu applizieren, ohne jedoch stärkere Nebenwirkungen in Kauf nehmen zu müssen. Im Bereich von Auge und Maulschleimhaut sind die Nebenwirkungen sogar geringer. Bei einem kleinen Teil der Patienten treten jedoch auch hier, ebenso wie nach teletherapeutischen Protokollen, problematische chronische Nebenwirkungen auf, die die Lebensqualität der betroffenen Tiere beeinträchtigen und die einer aufwendigeren Therapie zwingend bedürfen. Die mit diesem Protokoll erreichten Remissions- und Ü-berlebenszeiten sind mit denen aus der Literatur vergleichbar bis tendenziell besser. Aufgrund der oben genannten Vorteile erscheint die vorgestellte Therapie daher als Al-ternative zu Teletherapie bei der Behandlung kaniner Nasentumoren durchaus geeig-net. Weitere Studien mit größeren Patientenzahlen unter Einbeziehung einer anders therapierten Kontrollgruppe sind jedoch notwendig

Für die Therapie maligner intranasaler Neoplasien beim Hund existieren nur mäßig be-friedigende Behandlungsstrategien. Als Therapiemodalität der Wahl wird die Radiothe-rapie angesehen, die gegenwärtig v.a. in Form einer perkutanen Bestrahlung (Telethe-rapie) mit aufwendigen, bis zu 20 Fraktionen umfassenden Protokollen kurativer Intenti-on angewendet wird. Die erreichbaren Überlebenszeiten sind meist limitiert durch das Auftreten eines Rezidivs des Nasentumors innerhalb des Bestrahlungsfeldes, sodass eine Erhöhung der applizierten Gesamtdosis nötig erscheint. Dies ist jedoch im Rahmen einer Teletherapie aufgrund nicht vertretbarer akuter Nebenwirkungen nicht möglich. Alternativ steht die Brachytherapie zur Verfügung, die aufgrund ihrer physikalischen Charakteristika zur besseren Schonung des umliegenden Normalgewebes beiträgt. Ge-genwärtig existieren keine anderen Untersuchungen zur Anwendung der fraktionierten High-Dose-Rate-Brachytherapie bei Nasentumoren des Hundes. Ziel dieser Studie war es daher, die Durchführbarkeit dieser Therapiemodalität beim Hund erstmals zu unter-suchen und die akuten und chronischen Nebenwirkungen sowie die erzielbare progres-sionsfreie Zeit und die Überlebenszeit zu dokumentieren. Im Zeitraum von 2001 bis 2007 gingen 18 Hunde in die Studie ein. Das diagnostische Vorgehen beinhaltete neben einer klinischen Untersuchung und der Röntgenuntersu-chung von Nase und Thorax auch die kernspintomographische Beurteilung der Nasen-höhlen und eine nachfolgende Rhinoskopie inklusive Biopsie. Die Therapie bestand aus zwei wöchentlichen Fraktionen, bei denen in Vollnarkose über einen in der Nasenhöhle applizierten Katheter mithilfe des Radioisotops 192Iridium jeweils 5 Gy appliziert wurden. Die damit über vier Wochen erreichte Gesamtdosis lag bei 40 Gy, und entsprach damit der biologischen Effizienz einer perkutan applizierten konventionell fraktionierten Ge-samtdosis von circa 60 Gy. Im Anschluss an die Therapie wurden die Hunde monatlich klinisch untersucht und die auftretenden Nebenwirkungen anhand des Radiation Morbi-dity Scores der VRTOG beschrieben. Es wurden außerdem weiterführende Untersu-chungen in Form von MRT, Rhinoskopie und Biopsie durchgeführt. Die aufgetretenen Nebenwirkungen waren mit denen in der Literatur nach Teletherapie beschriebenen vergleichbar, beziehungsweise fielen im Bereich von Augen und Maulschleimhaut ge-ringer aus. Nebenwirkungen im Bereich der Haut traten in Form von Alopezie, Hyper-pigmentation oder Leukotrichie auf. Im Bereich der Nasenschleimhaut zeigten fast alle Hunde eine leichte chronische Rhinitis. Als problematische Nebenwirkungen traten bei drei Patienten Osteoradionekrosen auf, die einer aufwendigeren chirurgischen Versor-gung bedurften. Die mediane progressionsfreie Zeit lag bei 13 Monaten, die mediane Überlebenszeit bei 17 Monaten. Die Adenokarzinome wiesen die längste Überlebens-zeit auf, dies war jedoch aufgrund der insgesamt kleinen Patientenzahl nicht signifikant. Ein Zusammenhang zwischen dem Tumorstadium und der progessionsfreien Zeit oder Überlebenszeit bestand nicht. Bei dem beschriebenen Protokoll handelt es sich um eine unter klinischen Bedingungen praktikable Therapieform, die mit ihren insgesamt acht Fraktionen für Besitzer und Tier wesentlich weniger belastend ist als teletherapeutische kurative Protokolle mit 12-20 Fraktionen. Gleichzeitig gelingt es, eine Gesamtdosis von verhältnismäßig hoher biolo-gischer Effizienz zu applizieren, ohne jedoch stärkere Nebenwirkungen in Kauf nehmen zu müssen. Im Bereich von Auge und Maulschleimhaut sind die Nebenwirkungen sogar geringer. Bei einem kleinen Teil der Patienten treten jedoch auch hier, ebenso wie nach teletherapeutischen Protokollen, problematische chronische Nebenwirkungen auf, die die Lebensqualität der betroffenen Tiere beeinträchtigen und die einer aufwendigeren Therapie zwingend bedürfen. Die mit diesem Protokoll erreichten Remissions- und Ü-berlebenszeiten sind mit denen aus der Literatur vergleichbar bis tendenziell besser. Aufgrund der oben genannten Vorteile erscheint die vorgestellte Therapie daher als Al-ternative zu Teletherapie bei der Behandlung kaniner Nasentumoren durchaus geeig-net. Weitere Studien mit größeren Patientenzahlen unter Einbeziehung einer anders therapierten Kontrollgruppe sind jedoch notwendig

Published Article / Worldwide, uterine cervical cancer is one of the most frequently occurring cancers in women, with more than 80% of these cases occurring in developing countries. The South African screening policy and screening program, implemented in 2001, attempt to reduce this incidence of cervical cancer in South Africa. It is essential to treat these women with the best modalities available. This retrospective study focused specifically on the curative potential of radiotherapy administered to patients at the Oncology Department, Bloemfontein, since a new modality of high dose-rate intracavitary brachytherapy was implemented in 1994. Late radiation complications were also investigated.