The external beam radiotherapy and Image-guided radiotherapy (2) Somvilai Mayurasakorn, MD. Division of Therapeutic Radiology and Oncology, Faculty of Medicine, Chiang Mai University

Imaging techniques for IGRT

Imaging techniques for IGRT On-line EPID IGRT Based on boney landmarks Reported outcomes of EPID - based IGRT are favorable IJROBP2000; 46:400-506

Imaging techniques for IGRT CyberKnife Real-Time Tumor Tracking (RTRT)

Imaging techniques for IGRT Volumetric X-ray imaging Kilovoltage fan-beam CT (kV CT) Kilovoltage cone-beam CT (kV CBCT) Megavoltage cone-beam CT (MV CBCT) Megavoltage fan-beam CT (MV CT) Kilovoltage fan-beam CT (kV CT, commercially available as a peripheral solution by Siemens termed CT-on-rails) Kilovoltage cone-beam CT (kV CBCT, commercially available as integrated solutions for Elekta and Varian linear accelerators (linacs). Megavoltage cone-beam CT (MV CBCT, commercially available as an integrated solution for Siemens linacs) Megavoltage fan-beam CT (MV CT, commercially available as the integrated TomoTherapy solution) Korreman S, Rasch C, McNair H et al. The European Society of Therapeutic Radiology and Oncology–European Institute of Radiotherapy (ESTRO–EIR) report on 3D CT-based in-room image guidance systems: A practical and technical review and guide.Radiotherapy and Oncology 2010; 94:129–144

Helical Tomotherapy Concept for Helical Tomotherapy : Since 1993 Idea proposed by Thomas Rockwell Mackie Research/Prototype (Univ. of Wisconsin) First commercial unit installation at Wisconsin (~2002)

Helical Tomotherapy Helical - radiation rotating around the patient while couch is translating The patient is moved through the machine as a radiation source rotates through 360° Tomotherapy – patient is irradiated “slice by slice”

Helical Tomotherapy A Highly Integrated Platform For IMRT & IGRT Integrated solution for the combination of IGRT and IMRT

Increasing the accuracy of treatment delivery Helical Tomotherapy Benefits from IGRT Use of imaging (MVCT) immediately before or during treatment To ensure that the patient and tumor are in the correct position the robust measurement of set-up accuracy in three dimensions Allows the correction of both random and systematic components of set-up errors Increasing the accuracy of treatment delivery

Helical Tomotherapy Benefits from IMRT Characterised by steep dose gradients Delivering higher doses to the tumor Maintaining acceptable doses to critical OAR Allow for dose escalation Better conformity of an IMRT dose distribution and better normal tissue sparing

Helical Tomotherapy IMRT Helical tomotherapy Arc radiation therapy Fixed- gantry Step and shoot dynamic Arc radiation therapy Slice therapy Correction of both random and systematic components of set-up errors The patient is moved through the treatment unit while the radiation source rotates around the patient Palma et al. Cancer Treatment Reviews 2010;36 :393–399

Potential advantages of arc therapies over standard IMRT Helical Tomotherapy Potential advantages of arc therapies over standard IMRT Improved dose distributions Using arc techniques The target can be treated from all angles Negating the issue of beam angle selection when using fixed beams Palma et al. Cancer Treatment Reviews 2010;36 :393–399

Quality Depends on Number of Beams

Comparisons of isodose distributions NPC patient Comparisons of isodose distributions A dosimetric gain in CI and HI of PTV and sparing of OARs was significantly obtained in HT versus SaS-IMRT T.-F. Lee et al. Radiotherapy and Oncology 89 (2008) 89–96

IMRT and HT: The comparison of isodose distributions of PTV and OARs Lee et al. Radiation Oncology 2010 5:58