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Radiotherapy

Goal Maximum dose to Tumor minimum dose to critical normal tissues

Conventional Portal for T3 Supraglottic Cancer

3D Conformal Radiotherapy/IMRT Process

• 3D CRT (developed in early 1990s)/IMRT (late 90s) • A CT data set of the ROI of the patient is obtained • Images Transferred to the contouring workstation

(target volumes delineated along with OARs, dose prescription given)

• Images transferred to TPS (Treatment planning)• Plan evaluation, Plan Approval, Plan

implementation (sent to treatment unit)

IMRT(Intensity Modulated Radiotherapy)

• Advanced form of 3DCRT

• High Degree of conformity and sparing of critical structures

CRT VS IMRT8

Conformal: can’t avoid

some level of doses to the

normal tissues

IMRT: sculpt the doses

(isodoses) to the tumor,

avoiding the normal

tissues.

IGRT(Image Guided Radio Therapy)

• Verification of Treatment Set up with Image Guidance

DRR from TPS is Matched with Treatment Port Film (From EPID). Any set-up errors are corrected before Start of Treatment

Planning CT scan is matched with Cone Beam CT scan generated on the machine (Auto-corrected)

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