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Patient Specific IMRT Pre-Treatment Verification Using A Commercial Portal Dosimetry Software

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V Chandraraj

C VARATHARAJ1*, E Moretti2, R Manickam3, R Padovani4, (1) APOLLO HOSPITALS, BANGALORE, KARNATAKA, (2) AOU S. Maria della Misericordia, Udine, ,(3) Kidwai Memorial Institute of Oncology, Bangalore, Karnataka, (4) AOU SMM Udine, Udine,

SU-E-T-366 Sunday 3:00:00 PM - 6:00:00 PM Room: Exhibit Hall

Purpose:

To implement the newly developed portal dosimetry software using independent dose prediction algorithm EPIDoseTM and evaluate this new tool for the pretreatment IMRT plan QA of whole pelvis with simultaneous integrated boost (WP-SIB-IMRT) of prostate cases by comparing with routine 2D array detector system (MapCHECKTM).

Methods:

All measurements were performed using 6 MV X-ray beam at CLINAC 600C linear accelerator (Varian Associates, Palo Alto CA, USA) equipped with Millennium120 multileaf collimator (MLC). We have compared the measured doses between the two detectors (EPIDose and MapCHECK) and TPS calculated ones for every split field. In the current investigation gamma value distribution for 104 split fields were analyzed using gamma distributions. In particular, for each split field the following gamma distribution parameters were determined: mean gamma value, gamma delta value, defined as the previous mean gamma value + 1.5 SD and Percentage of points with gamma <1, gamma <1.5 and gamma >2.

Results:
We have investigated 104 split fields using gamma distributions in terms of pre-defined gamma frequency parameters. The mean gamma values are found to be 0.42 (SD:0.06) and 0.44 (SD: 0.06) for the EPIDose and MapCHECK, respectively. The average gamma delta for EPIDose and MapCHECK are found as 0.51 (SD:0.06) and 0.53 (SD: 0.07), respectively. Furthermore, the percentage of points with gamma<1, gamma<1.5 and gamma >2 are 97.4%, 99.3% and 0.56%, respectively for EPIDose and 96.4%, 99.0% and 0.62% for MapCHECK.

Conclusions:
Based on our results obtained with EPIDose and strong agreement with MapCHECK, we may conclude that the EPIDose portal dosimetry system has been successfully implemented and validated with our routine 2D array detector.



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