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4D: Experience of the Centre Léon Bérard, Lyon
S10
SFPM Annual Meeting 2011
TOPIC: IGRT/4D REFRESHER COURSE Overview of positioning techniques using Image Guided Radiotherapy T. GEVAERT, D. VERELLEN, K. TOURNEL, B. ENGELS, M. DUCHATEAU, T. REYNDERS, T. DEPUYDT, M. BOUSSAER, K. POELS and M. DE RIDDER Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium
Progress in radiotherapy is guided by the need to realize improved dose distributions (increasing the therapeutic dose to the lesion while minimizing dose to the surrounding critical structures) and the ability to reduce the treatment volume toward the target volume while still ensuring coverage of that target volume in all dimensions. The limited ability to control for the location of a tumor compromises the accuracy with which radiation can be delivered to tumor-bearing tissue. The resultant requirement for larger treatment volumes to accommodate target uncertainty restricts the radiation dose because more surrounding normal tissue is exposed. The introduction of image-guided radiotherapy (IGRT) has enabled knowledge of the exact position of the tumor and control of organ motion during treatment. As a result treatment
volumes can be optimized and dose escalation can be performed, achieving maximal tumor control with minimal complications. IGRT aims at frequent imaging in the treatment room during a course of radiotherapy, with decisions made on the basis of this information. The concept is not new, but recent developments and clinical implementations of IGRT drastically improved the quality of radiotherapy and broadened its possibilities. In general IGRT solutions can be classified in planar imaging (EPID, kV X-ray), volumetric imaging using ionising radiation (kV- and MV- based CT) or non-radiographic techniques. Furthermore, IGRT allows revision of dose fractionation schedules and exploring new treatment strategies as well as new indication in radiotherapy.
TOPIC: IGRT/4D REFRESHER COURSE ´on Be ´rard, Lyon 4D: Experience of the Centre Le M. AYADI Centre Le´on Be´rard, Unite´ De Physique, 28 Rue Laennec, 69008
Tumor motion management has become a big challenge in radiotherapy for tumors in lung, liver, kidney (etc.) because it can potentially provide an increase of tumor local control while sparing normal tissues. Four-Dimensional Computed Tomography (4D-CT), or respiration-correlated CT, is a key imaging device for motion management. Indeed, it allows a sequence of CT image sets acquisition over consecutive segments of a breathing cycle and consequently to give an accurate knowledge of lung deformation and tumor properties (volume, position and amplitude). 4D-CT can be used for the different treatment strategies that compensate for tumor motion: “the Internal Target Volume (ITV) strategy”, “the Gating”, “the Mid-position strategy” and the “Tracking”. A specific CT image set, derived from the 4D-CT and adapted to the treatment strategy can be used.
In 2006, our radiotherapy department has been equipped with the Brillance Big Boreä (Philips). After the optimization of the CT acquisition parameters using a moving phantom, we designed a workflow for using 4D-CT in clinical routine and contouring moving tumors on specific CT image sets. The 4D-CT contribution was also clinically evaluated with different studies. For example, the evaluation of the abdominal compression efficiency using 4D-CT allowed us to remove the compression for tumors located in the upper lobe of the lung. The optimization of 4D-CT scan parameters for irregular breathing cycles and the implementation of the Midposition strategy for patients with a T2-T3 Nx lung tumor are still work in progress.
SFPM Annual Meeting 2011
TOPIC: IGRT/4D REFRESHER COURSE Overview of positioning techniques using Image Guided Radiotherapy T. GEVAERT, D. VERELLEN, K. TOURNEL, B. ENGELS, M. DUCHATEAU, T. REYNDERS, T. DEPUYDT, M. BOUSSAER, K. POELS and M. DE RIDDER Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium
Progress in radiotherapy is guided by the need to realize improved dose distributions (increasing the therapeutic dose to the lesion while minimizing dose to the surrounding critical structures) and the ability to reduce the treatment volume toward the target volume while still ensuring coverage of that target volume in all dimensions. The limited ability to control for the location of a tumor compromises the accuracy with which radiation can be delivered to tumor-bearing tissue. The resultant requirement for larger treatment volumes to accommodate target uncertainty restricts the radiation dose because more surrounding normal tissue is exposed. The introduction of image-guided radiotherapy (IGRT) has enabled knowledge of the exact position of the tumor and control of organ motion during treatment. As a result treatment
volumes can be optimized and dose escalation can be performed, achieving maximal tumor control with minimal complications. IGRT aims at frequent imaging in the treatment room during a course of radiotherapy, with decisions made on the basis of this information. The concept is not new, but recent developments and clinical implementations of IGRT drastically improved the quality of radiotherapy and broadened its possibilities. In general IGRT solutions can be classified in planar imaging (EPID, kV X-ray), volumetric imaging using ionising radiation (kV- and MV- based CT) or non-radiographic techniques. Furthermore, IGRT allows revision of dose fractionation schedules and exploring new treatment strategies as well as new indication in radiotherapy.
TOPIC: IGRT/4D REFRESHER COURSE ´on Be ´rard, Lyon 4D: Experience of the Centre Le M. AYADI Centre Le´on Be´rard, Unite´ De Physique, 28 Rue Laennec, 69008
Tumor motion management has become a big challenge in radiotherapy for tumors in lung, liver, kidney (etc.) because it can potentially provide an increase of tumor local control while sparing normal tissues. Four-Dimensional Computed Tomography (4D-CT), or respiration-correlated CT, is a key imaging device for motion management. Indeed, it allows a sequence of CT image sets acquisition over consecutive segments of a breathing cycle and consequently to give an accurate knowledge of lung deformation and tumor properties (volume, position and amplitude). 4D-CT can be used for the different treatment strategies that compensate for tumor motion: “the Internal Target Volume (ITV) strategy”, “the Gating”, “the Mid-position strategy” and the “Tracking”. A specific CT image set, derived from the 4D-CT and adapted to the treatment strategy can be used.
In 2006, our radiotherapy department has been equipped with the Brillance Big Boreä (Philips). After the optimization of the CT acquisition parameters using a moving phantom, we designed a workflow for using 4D-CT in clinical routine and contouring moving tumors on specific CT image sets. The 4D-CT contribution was also clinically evaluated with different studies. For example, the evaluation of the abdominal compression efficiency using 4D-CT allowed us to remove the compression for tumors located in the upper lobe of the lung. The optimization of 4D-CT scan parameters for irregular breathing cycles and the implementation of the Midposition strategy for patients with a T2-T3 Nx lung tumor are still work in progress.