Satisfactory Essays
A CT simulator (CT Sim) is a substantial bore CT scanner that is utilized to contour the patient’s body. It has all the features of a treatment device but uses a diagnostic X-ray tube to create projection radiograph. It is used during the pre-treatment phase for localisation of the tumour and verification of the treatment plan. The application of CT Sim involves acquiring volumetric CT images which provides maximum information about tumour and normal tissue localisation and is suited for the sophisticated 3-D treatment planning. The CT numbers can be converted into electron densities which can be used for dose calculations. Furthermore, the CT data is utilized to digitally reconstruct the images, which are then used during the verification stage (DYK & MAH, 2004).
This assignment will mainly focus on the SOMATOM Definition AS (SD-AS) CT Sim by Siemens. SD-AS is an open CT system which allows both diagnostic scans and radiotherapy planning scans (SIEMENS, 2012) .This investigation will focus on the mechanical features used for radiotherapy planning and verification. It will investigate why this machine is more suitable for utilization by the radiographers and the patients compared to other simulation modalities.
A CT Sim is made up of three main components, CT scanner, laser system and virtual simulation application (NEEDHAM, 2009). CT scanner is an X-ray machine which produces a transverse image of the patient’s body. The scanner has a "doughnut" shaped gantry, which contains an X-ray tube. The process of X-ray production is described below:
Filament is connected to low tension supply compared to cathode and anode, which are connected to high tension supply, this triggers thermoionic emission (cathode...

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...ecise contour needed to for dose calculations, treatment field planning and creating DRR’s. When compared with the other simulators, virtual simulation is superior regarding the precision of patients marking, quality of the reference images and the time efficiency for the patients and radiographer. It also offers images and DRRs to be viewed in multiple planes making it easier for radiotherapist whilst planning.
SD-AS is a great machine with all the application of a CT Sim and a diagnostic scanner. It allows all kinds of patient like bariatric and paediatric to have their treatment planned. The virtual system for SD-AS provides technical features needed for high resolution and fast scanning. Some specific features in syngo VSim such as BEV and FOV makes it more users friendly and easier to use, while other features like motion sensor reduce errors during planning.
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