Radiation Treatment Planning

Figure 29 shows application of 3D visualization to radiation treatment planning. Using CT and MRI fused scans, 3D dosimetry can be computed for simulated treatment beams

FIGURE 29 3D visualization used in radiation treatment planning. Dosimetry from several simulated treatment beams can be fused with 3D images to shape dose to tumor site. Critical structures such as the spinal cord and optic nerves can be segmented and examined individually to evaluate local dose and determine whether the plan needs to be adjusted.

optical control to selectively image specific parallel sections within the microscopic structure. Multiple image planes can be selected, providing direct volume image acquisition without the need to remove signal from structures outside of the plane of interest. Often these images are acquired using specific fluorescent dyes to selectively image a particular component of the structure under study.

Visualization techniques have been used to examine the morphology and function of neurons from selected ganglia in the mammalian peripheral autonomic nervous system [17,40,64]. To understand neuron physiology, information about a neuron's shape and dimensions is needed to integrate and localize multiple synaptic inputs. The number and location of selective neurotransmitter receptor sites provides valuable information about the potential response of a neuron to a specific neurotransmitter. Such visualization applications may be termed "spatial physiology'' [17,40,64], in which function of microstructures is studied. 3D images of miniature structures, including the ganglia and individual cells contained therein, obtained with 3D microscopy can be appropriately positioned within 3D renderings or models of the body to provide visualizations that span several orders of magnitude in scale space. Figure 30 illustrates such a global framework and context for study of microstructures. This figure shows two successively magnified views (top) at centimeter scale of a portion of the torso model obtained from the Visible Human Male that contains the inferior mesenteric ganglia, and two magnified views (bottom) at micron scale showing individual neuron models within the ganglia as obtained by confocal microscopy. The individual neuron volume models are produced the same way organ models are obtained from medical scanners, previously described. This type of spatial synthesis of micro and gross anatomy renderings demonstrates the potential for a seamless integration of human anatomy and spatial physiologic function from macroscopic to microscopic levels.

positioned to maximize dose to the target (tumor) and minimize dose to critical structures in the treatment field. This is called conformal therapy [4,74], where the beam profiles are actually "shaped" to deliver cancer-killing dose to the irregular tumor volume while sparing eloquent tissues in the treatment field. Critical structures can be segmented and displayed separately with the regional dose superimposed in order to visually evaluate both the efficacy and safety margins of the proposed treatment plan.

FIGURE 29 3D visualization used in radiation treatment planning. Dosimetry from several simulated treatment beams can be fused with 3D images to shape dose to tumor site. Critical structures such as the spinal cord and optic nerves can be segmented and examined individually to evaluate local dose and determine whether the plan needs to be adjusted.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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