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

2. Imaging techniques for IGRT

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

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

5. 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

6. 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)

7. 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”

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

9. 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

10. 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

11. 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

12. 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

13. Quality Depends on Number of Beams

14. 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

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