No description available.

Errors during radiotherapy treatment can cause severe, and potentially fatal, patient harm. The final check immediately prior to treatment delivery, whereby two radiographers ensure that the dose about to be delivered corresponds with the prescription, is the last defence against error. The aim of this research was to increase understanding of this final treatment check and factors affecting error detection, in order to improve the safety of radiotherapy treatment delivery. The research adopted a mixed methods approach, combining qualitative and experimental studies to investigate the interaction of factors affecting accuracy during the final treatment checks. The qualitative interviews and task analysis pointed to difficulties maintaining attention and variation in how these checks are conducted. The interface used to conduct the final treatment check was also recognised to have usability issues. The laboratory-based experimental studies results indicated that a structured form of double checking, called challenge-response, is most effective at error detection, when compared to single or unstructured double checking. Furthermore, it was found that alternating the roles of challenger and responder, and the order parameters are checked in, significantly increases accuracy during repeated treatment checks. The original contribution of this research was a detailed investigation of a previously understudied aspect of radiotherapy treatment. The results informed the design of an original, evidence and theoretical based two-person checking protocol for use during the final treatment check. Qualitative evaluation indicates that it would be well received as a standardised method of treatment checking. Furthermore, an alternative interface design has been proposed, specifically for use during the final treatment check. This was comparatively tested against the most frequently used software package within the UK and found to have a significant positive impact upon user’s accuracy. An additional output is a series of practice based recommendations to improve accuracy during repeated treatment checking. This research has concluded that implementation of the practice recommendations, checking protocol and interface design should help maintain radiographers’ attention during repeated final treatment checks, thereby preventing errors passing undetected. Future research into the radiotherapy interface design and implementation of the standardised final treatment check protocol have been identified.

The modern day radiotherapy treatments are almost exclusively based on computed tomography (CT) images. The CT images are acquired using x-rays, and therefore reflect the radiation interaction properties of the material. This information is used to perform accurate dose calculation by the treatment planning system, and the data is also well suited for creating digitally reconstructed radiographs for comparing patient set up at the treatment machine where x-ray images are routinely acquired for this purpose. The magnetic resonance (MR) scanner has many attractive features for radiotherapy purposes. The soft tissue contrast as compared to CT is far superior, and it is possible to vary the sequences in order to visualize different anatomical and physiological properties of an organ. Both of these properties may contribute to an increase in accuracy of radiotherapy treatment. Using the MR images by themselves for treatment planning is, however, problematic. MR data reflects the magnetic properties of protons, and thus have no connection to the radiointeraction properties of the material. MRI also has inherent difficulty in imaging bone, which will appear in images as areas of no signal similar to air. This makes both dose calculation and patient positioning at the treatment machine troublesome. There are several clinics that use MR images together with CT images to perform treatment planning. The images are registered to a common coordinate system, a process often described as image fusion. In these cases, the MR images are primarily used for target definition and the CT images are used for dose calculations. This method is now not ideal, however, since the image fusion may introduce systematic uncertainties into the treatment due to the fact that the tumor is often able to move relatively freely with respect to the patients’ bony anatomy and outer contour, especially when the image registration algorithms take the entire patient anatomy in the volume of interest into account. The work presented in the thesis “Integration of MRI into the radiotherapy workflow” aim towards investigating the possibilities of workflows based entirely on MRI without using image registration, as well as workflows using image registration methods that are better suited for targets that can move with respect to surrounding bony anatomy, such as the prostate. / Modern strålterapi av cancer baseras nästan helt på datortomografiska (CT) bilder. CT bilder tas med hjälp av röntgenfotoner, och återger därför hur det avbildade materialet växelverkar med strålning. Denna information används för att utföra noggranna dosberäkningar i ett dosplaneringssystem, och data från CT bilder lämpar sig också väl för att skapa digitalt rekonstruerade röntgenbilder vilka kan användas för att verifiera patientens position vid behandling. Bildgivande magnetresonanstomografi (MRI) har många egenskaper som är intressanta för radioterapi. Mjukdelskontrasten i MR bilder är överlägsen CT, och det är möjligt att i stor utstäckning variera sekvensparametrar för att synliggöra olika anatomiska och funktionella attribut hos ett organ. Dessa bägge egenskaper kan bidra till ökad noggrannhet i strålbehandling av cancer. Att använda enbart MR bilder som planeringsunderlag för radioterapi är dock problematiskt. MR data reflekterar magnetiska attribut hos protoner, och har därför ingen koppling till materialets egenskaper då det gäller strålningsväxelverkan. Dessutom är det komplicerat att avbilda ben med MR; ben uppträder som områden av signalförlust i bilderna, på samma sätt som luft gör. Detta gör det svårt att utföra noggranna dosberäkningar och positionera patienten vid behandling. Många moderna kliniker använder redan idag MR tillsammans med CT under dosplanering. Bilderna registreras till ett gemensamt koordinatsystem i en process som kallas bildfusion. I dessa fall används MR bilderna primärt som underlag för utlinjering av tumör, eller target, och CT bilderna används som grund för dosberäkningar. Denna metod är dock inte ideal, då bildregistreringen kan införa systematiska geometriska fel i behandlingen. Detta på grund av att tumörer ofta är fria att röra sig relativt patientens skelett och yttre kontur, och många bildregistreringsalgoritmer tar hänsyn till hela bildvolymen. Arbetet som presenteras i denna avhandling syftar till att undersöka möjligheterna med arbetsflöden som baseras helt på MR data utan bildregistrering, samt arbetsflöden som använder bildregistrerings-algoritmer som är bättre anpassade för tumörer som kan röra sig i förhållande till patientens övriga anatomi, som till exempel prostatacancer.

Positron emission tomography (PET) is a molecular imaging technique that provides a direct and accurate evaluation of tissue function in vivo. PET of the glucose analogue 18F-fluoro-deoxy-glucose, is increasingly in use to aid in gross target volume delineation in radiotherapy treatment planning (RTP) where it shows reduced inter-observer variability. The aim of this thesis was to develop and investigate a new technique for delineating PET-GTV with sufficient accuracy for RTP. A new technique, volume and contrast adjusted thresholding (VCAT), has been developed to automatically determine the optimum threshold value that measures the true volume on PET images. The accuracy was investigated in spherical and irregular lesions in phantoms using both iterative and filtered back-projection reconstructions and different image noise levels. The accuracy of delineation for the irregular lesions was assessed by comparison with CT using the Dice Similarity Coefficient and Euclidean Distance Transformation. A preliminarily investigation of implementing the newly developed technique in patients was carried out. VCAT proved to determine volumes and delineate tumour boundaries on PET/CT well within the acceptable errors for radiotherapy treatment planning irrespective of lesion contrast, image noise level and reconstruction technique.

No description available.

<p>At the University Hospital of Umeå, NUS, a new radiation treatment department is being built. The purpose of this master thesis is to evaluate the actual radiation protection outside three out of five treatment rooms in the building, including two Varian and one Siemens accelerator, and to verify that the radiation limits for the staff and the general public, stated by the Swedish Radiation Safety Authority, are obeyed.</p><p>The evaluation of the radiation protection shielding is made through measurements. The nominal photon beam energies 6 and 15 MV (dose rates up to 500 MU/min) can be used, which means that both photons and neutrons will contribute to the effective dose. For the photon measurements, two different GM counters have been used and for the neutron measurements a Neutron detector with a polyethylene moderator and a ³He recoil proton counter tube was applied. The thesis also includes a literature study of the photon and neutron energy spectra outside the treatment rooms in order to check that the measurement equipments are suitable to use.</p><p>The measured doses of the radiation shielding are below the radiation limits per week and year but the measurements indicate too high values per hour, i.e. momentary dose rate, at the height of isocenter of the primary walls and at the gap under the door for all three accelerators. The rooms with the Varian accelerators also show too high values per hour at the secondary wall where the door is attached. However, the limiting value per hour is only a recommendation and no extra reinforcement in therefore required. Nevertheless, one should avoid placing a workplace, for example a writing desk, close to the secondary and primary walls.</p>

At the University Hospital of Umeå, NUS, a new radiation treatment department is being built. The purpose of this master thesis is to evaluate the actual radiation protection outside three out of five treatment rooms in the building, including two Varian and one Siemens accelerator, and to verify that the radiation limits for the staff and the general public, stated by the Swedish Radiation Safety Authority, are obeyed. The evaluation of the radiation protection shielding is made through measurements. The nominal photon beam energies 6 and 15 MV (dose rates up to 500 MU/min) can be used, which means that both photons and neutrons will contribute to the effective dose. For the photon measurements, two different GM counters have been used and for the neutron measurements a Neutron detector with a polyethylene moderator and a 3He recoil proton counter tube was applied. The thesis also includes a literature study of the photon and neutron energy spectra outside the treatment rooms in order to check that the measurement equipments are suitable to use. The measured doses of the radiation shielding are below the radiation limits per week and year but the measurements indicate too high values per hour, i.e. momentary dose rate, at the height of isocenter of the primary walls and at the gap under the door for all three accelerators. The rooms with the Varian accelerators also show too high values per hour at the secondary wall where the door is attached. However, the limiting value per hour is only a recommendation and no extra reinforcement in therefore required. Nevertheless, one should avoid placing a workplace, for example a writing desk, close to the secondary and primary walls.

M.Tech. / The aim of this study was to determine the effects of the application of therapeutic reflexology as a complementary medicine, in women with cervical cancer who were receiving radiation therapy with curative intent. Therapeutic reflexology is a therapy that involves stimulating specific reflexes in the hands, feet, body and ears by applying pressure to these reflexes with the thumbs and fingers, using specific techniques. All the body’s organs, glands and other parts of the body are reflected in the feet, body, hands and ears can be stimulated by working over the skin surface with the thumbs and fingers for a specific effect. These specific reflexes have been mapped in miniature on the feet, hands, body and ears (Graham, 1998: 5). Therapeutic reflexology promotes homeostasis within the body, by stimulating reflexes pertaining to organs and glands, and achieving normalisation of organs and glands in the receiver of the treatment. The therapy is non - invasive and non - pharmacological, and has no contra-indications (Graham, 1998: 8). Therapeutic reflexology is often used as a complementary or alternative medicine, yet very little information is available on its effects, which requires further research (Milligan, 2002: 489-96). The number of cancer patients using reflexology as a complementary therapy to allopathic medicine is rapidly rising (Apostolides, 1998: 71-95) It is because of this rise in the number of patients seeking complementary therapy that it is of vital importance that more accurate, results-orientated information is made available to both the patient and the medical practitioner. These findings will allow the patient and medical practitioner to make an informed decision regarding the choices available to complement allopathic medicine, to enhance wellbeing, and achieve better results for the allopathic protocol. A sample group of forty-four women were chosen by simple random selection. Twenty three were treated with therapeutic reflexology, and twenty one were given the placebo treatment for six weeks, while undergoing radiation therapy. The patients chosen for the sample group had stage IIIb as well as stage IIb cervical cancer, and were receiving radiation treatment. The result of the study has been determined by evaluating a questionnaire answered by each patient, after each treatment. The control group who received placebo treatment answered the same questionnaire, formulated in accordance with the Likert Scale, for means of comparison.

Proton radiotherapy is a cancer treatment which has the potential to offer greater cure rates and/or fewer serious side effects than conventional radiotherapy. Its availability in the UK is currently limited to a single low-energy fixed beamline for the treatment of ocular tumours, but a number of facilities designed to treat deep-seated tumours are in development. This thesis focusses on the quantitative use of x-ray computed tomography (CT) images in planning proton radiotherapy treatments. It arrives at several recommendations that can be used to inform clinical protocols for the acquisition of planning scans, and their subsequent use in treatment planning systems. The primary tool developed is a software CT scanner, which simulates images of an anthropomorphic virtual phantom, informed by measurements taken on a clinical scanner. The software is used to investigate the accuracy of the stoichiometric method for calibrating CT image pixel values to proton stopping power, with particular attention paid to the impact of beam hardening and photon starvation artefacts. The strength of the method adopted is in allowing comparison between CT-estimated and exactly-calculated proton stopping powers derived from the same physical data (specified in the phantom), leading to results that are difficult to obtain otherwise. A number of variations of the stoichiometric method are examined, identifying the best-performing calibration phantom and CT tube voltage (kVp). Improvements in accuracy are observed when using a second-pass beam hardening correction algorithm. Also presented is a method for identifying the proton paths where stopping power uncertainties are likely to be greatest. Estimates of the proton range uncertainties caused by CT artefacts and calibration errors are obtained for a range of realistic clinical scenarios. The current practice of including planning margins equivalent to 3.5% of the range is found to ensure coverage in all but the very worst of cases. Results herein suggest margins could be reduced to <2% if the best-performing protocol is followed; however, an analysis specific to the CT scanner and treatment site in question should be carried out before such a change is made in the clinic.

In todays Radiotherapy Treatment Planning, RTP, it is common to use Computed Tomography, CT, together with Magnetic Resonance Imaging, MRI, where CT provides electron density information and a geometrical reference, and where MRI provides superior soft tissue contrast. To sim- plify the workflow and improve treatment accuracy, research groups have demonstrated how to exclude CT and use a MRI-only approach. In this thesis, a method for spatial distortion analysis, ultimately enabling quality assurance, QA, of the spatial accuracy of MRI, was defined, tested and evaluated. A phantom was built to cover the entire clinical Field Of View, FOV, and 6mm-diameter fluid filled paintball markers were placed in a well-defined geometrical pattern within the phantom, and used as positive contrast. The phantom was imaged with a 3D Fast Gradient Echo sequence and a 3D Fast Spin Echo sequence. The markers were identified in the image data by a MATLAB-algorithm, and the location of the center of mass was calculated for each marker and compared to a theoretical reference. The location error was defined as the spatial distortion - a measurement of the spatial accuracy. Imaging parameters were altered and the effect on the spatial accuracy was analyzed. The spatial distortions were successfully measured within the entire (maximal) clinical FOV. It was shown that high readout bandwidth reduced distortions in the frequency encoding direction. These distortions could thus be attributed to B0-inhomogeneities. It was also determined that increasing the readout bandwidth to the maximum value reduced the maximum distortions in the frequency encoding direction to the same level as the maximum distortions in the other two phase-encoding directions of the 3D acquisitions. The voxel size had a very small effect on the spatial accuracy, enabling large voxelsize to be used when imaging the phantom, to decrease the scan time. The method was deemed capable of serving as a basis for QA of the spatial accuracy of large FOV MRI, which is needed in future MRI-only RTP approaches.