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18 Cards in this Set
- Front
- Back
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What is 3D treatment planning?
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3D treatment planning is based on 3D anatomic information, uses 3D doses distributions, and designs and delivers treatment plans that conform as closely as possible to the planned target volume in terms of adequate dose to the tumor and minimum possible dose to normal tissue.
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What are DRRs and what slice thickness gives you the best DRR for the amount of slices you make?
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DRRs are Digitally Reconstructed Radiographs.
A slice thickness of 2 to 10 mm is commonly used. Thinner slices for tumor localization and larger slices for regions outside the tumor volume. |
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What is spiral CT?
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Allows for continuous rotation of the x-ray tube as the patient is translated through the scanner aperture.
Substantially reduces the overall scanning time and therefore allows acquisition of a large number of thin slices required for high-quality CT images and DRRs. |
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What is the most common type of imaging for treatment planning?
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CT is the most commonly used imaging procedure for treatment planning.
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What data is given for MRI?
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MRI shows proton density distribution.
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What is image registration?
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A process of correlating different image data sets to identify corresponding structures or regions.
Facilitates comparison of images from one study to another and fuses them into on data set that could be used for treatment planning. |
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What is meant by beam aperture design?
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Beam aperture design is the task of designing field shapes depending on margins between the CTV and PTV.
Designing beam aperture is aided by the BEV capability of the 3D treatment planning system. |
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What is field multiplicity and collimation?
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Combination of multileaf collimators and independent jaws provides almost unlimited capability of designing multiple fields of any shape. Tangents and critical structures can be viewed in the BEV configuration individually for each field.
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How do you optimize a treatment plan and what methods do you take?
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Treatment plans can be optimized iteratively by using multiple fields, beam modifiers (e.g., wedges and compensators, etc.) beam weights, and appropriate beam directions.
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What is a cumulative DVH?
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The cumulative DVH is a plot of the volume of a given structure receiving a certain dose or higher as a function of dose. This is the most common method to display dose to structures in a 3D CRT treatment plan.
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What is a differential DVH?
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The differential DVH is a plot of volume receiving a dose within a specified dose interval as a function of dose. The differential form of DVH shows the extent of dose variation within a given structure.
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What is meant by the V20 for lung plans?
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The volume of lung receiving 20 Gy
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What is a dose algorithm?
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Dose calculation algorithms are mathematical methods to calculate dose distribution.
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What is the Clarkson algorithm used for?
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Used for the calculation of absorbed dose at a point in a patient.
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What is the Pencil Beam algorithm used for?
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Electron calculations.
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What is the Convolution/Superimposition algorithm used for?
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Convolution-Superposition is currently the most accurate model-based algorithm.
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What is the Monte Carlo algorithm used for?
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Direct Monte Carlo is the most accurate method for treatment planning, but currently it is not feasible because it requires prohibitively long computational times.
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What is a kernel?
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The spatial distribution of the energy imparted by a photon interacting at a point in a medium.
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