With this type of treatment, three-dimensional computer planning systems are used to deliver radiation that conforms to the shape of the tumor. During the initial planning phase (simulation), a thermoplastic mask is used to immobilize the patient to ensure reproducible, accurate set-ups. CT or MRI is used to localize the tumor. These images are then transferred to a high-speed computer. This allows the physician to contour the normal structures and tumor. A dosimetrist or physicist will then plan the field orientation and optimize the dose distribution. The beams may be shaped using custom-made blocks or collimators. A beam's eye view can be created to determine the orientation of the radiation beams, which helps to tailor the radiation dose around the tumor. Dose-volume histograms can be used to calculate a defined tumor volume that will receive a given percentage of the dose, which allows for the comparison of plans. The 3D-CRT has two main limitations: the accuracy of the results depends heavily on the planner's skills, and multiple iterations are required to develop an optimal plan.
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The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.