[Planning target volume : Management of uncertainties, immobilization, image guided and adaptive radiation therapy].

[Planning target volume : Management of uncertainties, immobilization, image guided and adaptive radiation therapy].
Radiologe. 2018 Jun 26;:
Authors: Schwahofer A, Jäkel O
Abstract
CLINICAL/METHODICAL ISSUE: As a standard, today's radiation therapy is based on CT images which are used for therapy planning. These images are obtained once before therapy starts and serve as a basis to obtain the position and shape of the target volume. As the patient has to be positioned anew for each fraction, deviations of the tumor position relative to the radiation field but also internal motion of the tumor may occur. These deviations lead to uncertainties, which are taken into account by adding a safety margin around the clinical target volume (CTV) to create the planning target volume (PTV).
STANDARD RADIOLOGICAL METHODS: As a standard today, CT-based treatment planning is used, where images are obtained once prior to therapy. The information on tumor position and shape, which is obtained from these images, is used throughout the whole cycle of radiation therapy without any change. This cycle may last several weeks.
METHODICAL INNOVATIONS: By repeated imaging of the patient in the treatment position prior to each fraction, the position of the tumor can be assessed and corrected for each fraction.
PERFORMANCE: A reduction of positioning uncertainty may be used to reduce the safety margin. This leads to a decreased v...

Source: Der Radiologe - June 26, 2018 Category: Radiology Authors: Schwahofer A, Jäkel O Tags: Radiologe Source Type: research