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In radiotherapy (RT), the treatment is thoroughly planned and optimized to fulfil the goal of delivering a high dose to the target, while sparing as much normal tissue as possible. This implies that the patient position and anatomy should be the same as they were during the planning image acquisition. To achieve this, it is important to have motion management methods for predicting, monitoring, and mitigating patient motion. These methods involve for instance adding extra margins around the target accounting for motion uncertainties, treatment in breath-hold, and imaging before and during beam-on. Ultimately, these techniques enhance treatment accuracy by reducing discrepancies between the planned and delivered dose. The work in this thesis aimed to evaluate and optimize motion management for patients treated with RT.Various motion management techniques were analysed for different treatments and patient groups. Surface imaging (SI) and its potential to improve the workflow was assessed for both our most common patients (breast and prostate cancer patients) treated with conventional RT and for some of our most uncommon patients (canine patients) treated with the emerging RT technique FLASH-RT. The potential dosimetric effect of prostate motion and inadequate motion management in the magnetic resonance linear accelerator (MR-linac) workflow was investigated for three different planning target volume (PTV) margins. The dosimetric effects of different motion management methods were also evaluated for our most uncommon patients, ventricular tachycardia (VT) patients receiving stereotactic body RT (SBRT), by simulating treatment in breath-hold (BH) and treatment in free breathing with and without abdominal compression (AC). The potential of AC to decrease respiratory induced heart motion was also investigated. This thesis demonstrated that SI can improve the initial patient setup accuracy and efficiency and is currently the only feasible motion management option for our F

BACKGROUND: During recent years FLASH radiotherapy (FLASH-RT) has shown promising results in radiation oncology, with the potential to spare normal tissue while maintaining the antitumor effects. The high speed of the FLASH-RT delivery increases the need for fast and precise motion monitoring to avoid underdosing the target. Surface guided radiotherapy (SGRT) uses surface imaging (SI) to render a 3D surface of the patient. SI provides real-time motion monitoring and has a large scanning field of view, covering off-isocentric positions. However, SI has so far only been used for human patients with conventional setup and treatment.PURPOSE: The aim of this study was to investigate the performance of SI as a motion management tool during electron FLASH-RT of canine cancer patients.METHODS: To evaluate the SI system's ability to render surfaces of fur, three fur-like blankets in white, grey, and black were used to imitate the surface of canine patients and the camera settings were optimized for each blanket. Phantom measurements using the fur blankets were carried out, simulating respiratory motion and sudden shift. Respiratory motion was simulated using the QUASAR Respiratory Motion Phantom with the fur blankets placed on the phantom platform, which moved 10 mm vertically with a simulated respiratory period of 4 s. Sudden motion was simulated with an in-house developed phantom, consisting of a platform which was moved vertically in a stepwise motion at a chosen frequency. For sudden measurements, 1, 2, 3, 4, 5, 6, 7, and 10 Hz were measured. All measurements were both carried out at the conventional source-to-surface distance (SSD) of 100 cm, and in the locally used FLASH-RT setup at SSD = 70 cm. The capability of the SI system to reproduce the simulated motion and the sampling time were evaluated. As an initial step towards clinical implementation, the feasibility of SI for surface guided FLASH-RT was evaluated for 11 canine cancer patients.RESU

Purpose: The overall purpose of this master thesis was to investigate if the patient positioning could be improved for breast cancer patients with nodal involvement, using the optical scanning system Catalyst during patient setup. Patient motion during treatment and the effect it has on the dose distribution was also investigated. Materials and Methods: Eleven patients positioned according to the Catalyst and 10 patients positioned according to the conventional laser and skin markings based setup (LBS) were enrolled in this study. To evaluate if positioning was improved with the surface based setup (SBS), the setup deviations arising from matching daily verification images to the reference images were acquired for both positioning methods. The setup deviations were then compared between the different methods by studying the distribution of deviations. The systematic and random setup deviations and PTV margin were also determined for both groups. In total, 127 fractions of patients positioned with LBS and 93 fractions of patients positioned with SBS were analysed. To investigate what impact the offline correction strategy used at Skåne University Hospital (SUS) has on the positioning, the data was analysed both with and without the offline corrections applied. The dosimetric effect of patient motion was evaluated for one patient by analysing recorded motion data during beam delivery by the Catalyst system in terms of isocenter shift. All isocenter shifts that occurred when the beam was on were extracted and added to the original patient position to get the total isocenter shift, including both inter- and intrafractional motion. The mean isocenter shift for each fraction was determined and the isocenter position was shifted in the original treatment plan for each fraction in the treatment planning system (TPS). The dose was then re-calculated for each fraction and summed to one plan that was compared to the original dose distribution. Results: The obtained results ind, Förbättrad positionering av bröstcancerpatienter som genomgår strålbehandling Cirka 30 000 kvinnor får diagnosen cancer varje år i Sverige [1]. Av dessa utgör bröstcancer den vanligaste diagnosen med över 9000 fall per år [2]. Cancern kan vara begränsad till endast bröstet, men kan också ha spridit sig till de intilliggande lymfkörtlarna. Behandling av bröstcancer med körtelengagemang inleds vanligtvis med kirurgi och därefter är det vanligt att patienten även får strålbehandling. Syftet med detta är att, med hjälp av strålningen, eliminera de tumörceller som fortfarande kan finnas kvar efter operationen och på så sätt minska risken för att en ny tumör börjar växa. På Skånes Universitetssjukhus i Lund delas strålbehandlingen för bröstcancerpatienter med körtelengagemang upp på 25 fraktioner. Patienten får en lika stor stråldos vid varje behandlingstillfälle. Innan strålbehandlingen påbörjas genomgår patienten datortomografi., som genom röntgenteknik genererar snittbilder av patienten. Vid detta tillfälle positioneras patienten i en fixation som ska användas under alla kommande behandlingstillfällen. Fixationen säkerställer att patienten ligger still och likadant under hela behandlingen. Utifrån datortomografin görs sedan en stråldosplan, i vilken man bestämmer hur strålningen ska ges och med vilka maskininställningar. Vid strålbehandling är det viktigt att endast tumörområdet bestrålas och att den friska vävnaden skonas i så stor utsträckning som möjligt. En viktig del för att uppnå detta utgörs av att patienten ligger korrekt positionerad varje dag vid behandlingen. Det konventionella sättet att positionera patienten inför behandling är att använda sig av ett laserbaserat koordinatsystem som finns inne i behandlingsrummet samt markeringar som ritas på patientens hud vid datortomografin. När laser och hudmarkeringar sammanfaller antar man att patienten är korrekt positionerad. För att verifiera patientens position tas röntgenbilder på patienten innan behandlingen st

På Danmarks Meteorologiska Institut har två index, TI3 och TI4, utvecklats i syfte att lokalisera riskområden för clear air turbulence (CAT). Indexen är ännu inte i operationellt bruk. Deras samband med andra parametrar i DMI-HIRLAM är inte känt och studeras här genom tre situationsstudier. CAT utgör en fara för flygtrafiken och bra prognoser av detta fenomen är nödvändigt. Att två olika index används motiveras av att de indikerar CAT som har utlösts av olika mekanismer. CAT förekommer framför allt i samband med jetströmmen, där starka vindshear genom Kelvin-Helmholtz-instabilitet och inflexionspunktsinstabilitet ger upphov till turbulens. TI3 är en vidareutveckling av ett annat CAT-index, Turbulence index, vilket bygger på produkten mellan vertikalt vindshear och horisontell deformation. I TI3 har ett beroende på den statiska stabiliteten lagts till. TI4 ska indikera riskområden för CAT då deformationen är liten, där värdet för TI3 blir litet. Detta kan ske främst på den anticyklonala sidan av jetströmmen, där det finns risk för att flödet blir obalanserat och CAT kan utvecklas från direkt eller indirekt shear instabilitet. Tre tillfällen i februari 2012 har valts ut och studerats. Modellens beräkning av indexen har jämförts med dess beräkning av turbulent kinetisk energi (TKE), en parameter som beskriver turbulensens intensitet. För samma situationer har också indexens utseende i två modeller,T15 och SKA, med olika upplösning jämförts. Studien visar att det inte går att se ett klart systematiskt samband mellan indexen och TKE, men ett visst samband ses mellan TI3 och TKE. Detta beror troligtvis på parametriseringen av TKE i DMI-HIRLAM. Undersökningen av hur indexen beror på modellupplösning ger ett ganska väntat resultat med fler detaljer för indexen i SKA. Dock finns tveksamheter kring den stora skillnaden för TI4s utseende i de två modellerna. Innan indexen kan tas i bruk behövs verifiering, vilket försvåras av att observationerna är få och kan vara oprecisa., Two indices, TI3 and TI4, have been presented at the Danish Meteorological Institute with the purpose to indicate clear air turbulence (CAT). The indices are not yet in operative use. The correlation between the indices and other parameters in DMI-HIRLAM is not known and is investigated in three case studies. CAT is a hazard to aviation and accurate prediction of CAT is important. The use of two indices is motivated by the fact that they indicate CAT developed from different mechanisms. CAT occurs mainly in association with the jet stream, where strong wind shears give rise to turbulence through Kelvin-Helmholtz and inflection point instability. TI3 is a further development of an other CAT-index, the Turbulence Index, which is the product of vertical wind shear and horizontal deformation. In TI3 a dependence on the static stability is included. TI4 is made to indicate areas with risk of CAT where the deformation is small, where TI3 has a low value. This happens mainly on the anticyclonic shear side of the jet, where the flow can be unbalanced and CAT can develop from direct or indirect shear instability. Three cases in February 2012 have been selected and analyzed. The indices are compared to the model output of turbulent kinetic energy (TKE), a parameter describing the intensity of the turbulence. Also the structure of the indices in the two numerical models, T15 and SKA, with different resolution is compared for the same cases. The case studies show that a clear systematic correlation between the indices and TKE is not to be seen, but some correlation is observed between TI3 and TKE. This probably has its reason in the parametrization of TKE in DMI-HIRLAM. The result of the investigation of the dependence on model resolution is rather expected, the details in SKA were greater. The difference of TI4 in the two numerical models give rise to questions. Before the indices can be taken into operational use verification is needed, a process that is constrained by the la