Evaluation of system accuracy and PTV margins for SBRT in lung and liver using Novalis Tx™ adaptive gating and Exactrac^® 6D system

Target volume is of main concern for irradiation of tumors affected by the respiratory motion such as in lung and liver. With reduction of the target volume decreased complication rates of organs at risk is expected. Stereotactic body radiation therapy (SBRT) is popular choice with ultrahigh doses per fraction (6 to 30 Gy), in a hypo fractionated regimen of five or fewer fractions. To deliver such high doses per fraction respiratory motion need to be account during the course of radiotherapy. We used Novalis Tx^TM ExacTrac^® Adaptive Gating technique for increasing accuracy in dose delivery and to reduce the target volume