Program Information
Assessment and Comparison of Homogeneity and Conformity Indexes in Step and Shoot and Compensator Based Intensity Modulated Radiation Therapy (IMRT) and Three Dimensional Conformal Radiation Therapy (3D CRT) in Prostate Cancer
m salimi*, Tehran university of medical sciences, Tehran, Tehran
Presentations
SU-I-GPD-T-343 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: Intensity Modulated Radiation Therapy (IMRT) and Three-Dimensional Conformal Radiation Therapy (3DCRT) are two treatment modalities in prostate cancer which provide acceptable dose distribution in tumor region with sparing surrounding normal tissues. IMRT is based on inverse planning optimization, which intensity of beams is modified by using multi leaf collimators and also compensators with optimum shapes in Step and Shoot (S.A.S) and compensator based method, respectively. In current study, some important parameters in treatment planning compared to each other in recent two IMRT methods and 3DCRT to elucidate the differences between these methods.
Methods: Prescribed dose was 80 Gy for both IMRT procedures and 70 Gy for 3DCRT. Treatment plans of fifteen prostate cancer candidates were compared for target minimum dose, maximum dose, V 76 Gy (for IMRT plans) V 66.5 Gy (for 3DCRT), mean dose, conformity index and homogeneity index.
Results: Dose conformity in compensators based IMRT was better than S.A.S and 3DCRT. The same outcome was achieved for homogeneity index, too. The target coverage was achieved 95% of prescribed dose to 95% of PTV in 3DCRT and 95% of prescribed dose to 98% of PTV in IMRT methods.
Conclusion: IMRT increases maximum dose to tumor region, improves conformity and homogeneity indexes of target volume and also reduces dose to organs at risks.
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