importance of ct-simulator in radiotherapy

importance of ct-simulator in radiotherapy

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  IMPOTRANCE OF CT-SIMULATOR IN RADIOTHERAPY Vipin singh pal B.Sc-Radiotherapy Technology Student
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  Aim • The purposeof this study is to develop a general strategy that allows for design the best and more precise treatment plan and specific ct-simulation protocol based on radiotherapy goal
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  What is ctsimulator • Dedicated CT scanner for use in Radiotherapy treatment simulator and planning are known as CT Simulator. • The CT scanner is used to acquire a volumetric CT-Scan of a patients which represents the “virtual “or digital patients • The ct-simulation software provides virtual representation of the geometric capabilities of a treatment machine
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  Ct-simulator components • X-raytube • Large bore ct-scanner with an opening of up to 85cm • Detectors systems • Collimators and attenuator • Patients couch • Laser • Computer and work station • Control console
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  patients positioning andimmobilization accessories used during ct-simulation and treatments • Thermoplastic orfit cast • Vac- lok • AIO base plate • Knee rest • Head rest • Shoulder traction tube • Foam wedges
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  CT-simulation procedure 1.PATIENT POSITIONINGAND IMMOBLISATION • The precision required for beam delivery • Patient may or may not required an external immoblisation device for their treatment • Immoblisation devices improve the reproducibility and rigidity of the set-up
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  2.REFERENCE MARRKING • Duringthe CT scan a set of reference marks must be placed on the patient so the patient can be positioned on the treatment machine • Anatomical landmark
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  3. SCAN PROTOCOL •Energy select • Slice thickness • Slice spacing • Sprial pitch • Field of view • This protocol depends upon disease and anotomy
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  4.CONTRAST • For severaltreatment sites contrast can be used to help differentiate between tumour and surrounding healthy tissue • I.V. fluid is commonly used as contrast
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  5.Volumetric data aquirefrom 2 ways 3D volumetric data 4D volumetric data • 4d imaging is a complete data set that contains images from each portion of the breathing cycle. • Images used to determine tumor normal organ motion. 3D radiation therapy simulation allows multiple cross sectional CT slices of the patient with a graphic display of the 3D anatomy of both normal tissue and tumour bearing region.
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  RESULT • The CTimages excellent soft tissue contrast allowing for greatly improved tumor localization and defining in comparison to conventional simulator. • Patient contour may be obtained easily from CT data in particular the patients skin contains target and any organs of interest. • Electron density information useful in the calculation of dose inhomogeneity due to the different composition of human tissue. • The target volume and its position are identified with relative case of each CT slice.