Time-adjusted internal target volume: a novel approach focusing on heterogeneity of tumor motion based on 4-dimensional computed tomography imaging for radiation therapy planning of lung cancer.

Purpose: To consider nonuniform tumor motion within the internal target volume (ITV) by defining time-adjusted ITV (TTV), a volume designed to include heterogeneity of tumor existence on the basis of 4-dimensional computed tomography (4D-CT).

Methods And Materials: We evaluated 30 lung cancer patients. Breath-hold CT (BH-CT) and free-breathing 4D-CT scans were acquired for each patient.

[Availability of using diaphragm matching in stereotactic body radiotherapy (SBRT) at the time in breath-holding SBRT for liver cancer].

Purpose: Liver image guided radiation therapy (IGRT) based on bone matching risks generating serious target positioning errors for reasons of lack of reproducibility of expiration breath hold. We therefore investigated the feasibility of 3D image matching between planning CT images and pretreatment cone-beam computed tomography (CBCT) images based on diaphragm surface matching.

Method: 27 liver stereotactic body radiotherapy (SBRT) cases in whom trancecatheter arterial chemoembolization (TACE) had been performed in advance of radiotherapy were manually image-matched based on contrast, Lipiodol used in the TACE as the marker of the tumor, and the relative coordinates of the isocenter obtained by contrast matching, defined as the reference coordinate.