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Mismatch can result in artifacts in these areas which

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mismatch can result in artifacts in these areas whichmay influence diagnosis and radiotherapy target defi-nition in this region. There are various gating meth-ods that can be used during image acquisition to min-imize the motion component and essentially acquiretrue, motionless, images of patient anatomy. Gatedor 4D CT (with time being the fourth dimension) canbe used to generate more reliable ACFs and also forradiotherapy treatment planning where gated deliverymethods are being used.Contrast-enhanced CT images can cause inaccu-rate ACFs due to artificially increased attenuationthrough anatomy which contains contrast material.The most obvious way to avoid this problem is toacquire a routine CT with contrast and another non-contrast CT. There is also an option to use softwaretools to correct for these artifacts. For radiotherapyscanning, it is preferred to acquire two separate scans.The attenuation correction CT can be a whole-body,low-dose scan with greater slice thickness if desired.The second CT would be a treatment-planning scanwith thin slices for better resolution and DRR qual-ity. This scan is acquired only through the volumeof interest, thus limiting the number of images andmemory requirements to manipulate these images inthe treatment-planning computer. This second scancan then be contrast enhanced if desired.6.2.5Virtual Simulation SoftwareAs with all software programs, user-friendly, fast,and well-functioning virtual (CT) simulation soft-ware with useful features and tools will be a deter-mining factor for success of a virtual simulation pro-gram. Commercially available programs far surpassin-house written software and are the most efficientapproach to virtual simulation. Several features arevery important when considering virtual simulation/ 3D treatment-planning software:1. Contouring and localization of structures:con-touring and localization of structures is oftenmentioned as one of the most time-consumingtasks in the treatment planning process. Thevirtual simulation software should allow fastuser-friendly contouring process with help ofsemi-automatic or automatic contouring tools.An array of editing tools (erase, rotate, translate,stretch, undo) should be available. An ability toadd margins in three dimensions and to automati-cally draw treatment portals around target vol-umes should be available. An underlining empha-sis should be functionality and efficiency.2. Image processing and display: virtual simulationworkstation must be capable of processing largevolumetric sets of images and displaying them indifferent views as quickly as possible (near real-time image manipulation and display is desired).The quality of reconstructed images is just asimportant as the quality of the original study set.

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Term
Fall
Professor
N/A
Tags
The Land, Medical imaging, radiotherapy, treatment planning, Treatment Volume and Treatment Planning

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