1. بسم الله الرحمن الرحيم و قل رب زدنى علماً ﴿و قل رب زدنى علماً﴾ صدق الله العظيم

2. Introduction to Radiotherapy Dr. Ahmed Al Far, M.D. Professor of Radiation Oncology RAD 461

3. What is the Target Volumes?

4. The Target Volumes ◘ ◘ Before Planning: 1.Gross Tumor Volume (GTV): primary tumor + any detectable metastases in LN 2.Clinical Target Volume (CTV): GTV + sub-clinical micro. disease ◘ ◘ During Planning: 1.Planned Target Volume (PTV): CTV + safety margin to account for movement of patient or organ during treatment 2.Organs at Risk: dose limiting normal tissue e.g. spinal cord ◘ ◘ After planning: 1.Treated Volume: enclosed by isodose line (equal or close to PTV) 2.Irradiated Volume : the volume receives 50% of the tumor dose (indicator of the quality of the plan)

5. The Target Volumes Clinical target volume Gross Tumor volume Planning target volume Treated volume Irradiated volume

6. ◘ ◘ Clinical Methods: Clinical examination: inspection, palpation Surgical findings and metal clips at fixed points ◘ ◘ Radiological Methods: Diagnostic x-ray unit: - Comparison with simulator (distance, focus, magnification)? Simulator Unit: Conventional Computed Tomography (CT) Localization of the Target Volumes

7. What is the Simulators?

8. Simulator A diagnostic x-ray machine which: accurately simulates the geometry, optical systems and mechanical movements of a radiotherapy machine. Importance: 1.Localization: the target volume and critical normal tissue with respect to skin marks 2.Simulation: the planned treatment fields with respect to tumor and normal tissue

9. Simulator Z X Y

10. Simulator: Main components Gantry rotation around a horizontal axis Source axis distance (SAD) motion in radial direction Collimator rotation Image intensifier motion in the vertical, longitudinal and radial directions Table movement ( rotation, vertical, longitudinal and lateral) Movement of X-ray field collimators and the wires (ruler)

11. Simulator

12. Shielding Block Tray

13. Localization by conventional simulator

14. Conventional & CT Simulators

15. C.T. Simulator : Uses 1.Localization of tumor and normal tissues 2.Direct determination of body contour in different planes (2D, 3D) 3.Dose calculation in different tissues (pixel density)

16. C.T. Simulator : Specification 1.Wide gantry opening 2.Flat top table 3.Laser system 4.The couch movement 5.Rapid scanning 6.Slice thickness 7.Measurement of CT number 8.Making cuts in different planes

17. Conventional & CT Simulators

18. CT simulation

19. The CT scans are linked with a specialized treatment planning computer providing detailed information which will assist with optimum treatment.

20. Localization by C.T Simulator