Dosimetric Validation of Physical and Biological Indexes from the Dose-Volume Histogram for Evaluation of ۳D-CRT and IMRT Techniques with VMAT Treatment Plan Techniques in Cervical Tumors from In-House Developed Software

Introduction:This study aims to investigate the Normal Tissue Complication Probability (NTCP) and Tumor Control Probability (TCP) of cervical cancer from Niemierko radiobiological model and compared with Lyman-Kutcher-Butcher (LKB) model’s effective volume parameter in three different planning techniques such as ۳-Dimensional Conformal Radiation Therapy (۳D-CRT), Intensity Modulated Radiotherapy (IMRT) and Volumetric Arc Therapy (VMAT).Material and Methods:Twenty patients were selected with Grade II and Grade III and the treatment plan was initially generated for ۳D-CRT, IMRT and VMAT. The physical dose from each voxel in radiotherapy treatment planning was extracted through a dose volume histogram (DVH) text file from in-built software developed using python program.  Software was developed by freely available python integration with an integrated Oracle database to store the outcome results with user-friendly graphical user interface for editing the radiological parameter values and viewing the DVH graph. The dosimetricconformalities parameters such as homogeneity index (HI) and conformity index (CI) along with radiobiological parameters such as TCP, NTCP and effective volume (Veff) were compared with three different planning techniques.Results:The IMRT and VMAT dose delivery techniques improve the efficiency of the treatment of cervical cancer with good coverage of target volume as well as low irradiation of Organ at Risk (OARs) compared with ۳D-CRT.Conclusion: There is no significant difference in effective volume for IMRT and VMAT, which proportionally increases with the advanced planning techniques, causes insignificant complication probability to normal tissues. Other conformalities parameters were showing good agreement for all the three techniques.

Keywords:

NTCP , TCP , conformity index , VMAT , IMRT