A dose volume histogram based correction factor for dosimetric comparison of radiotherapy treatment plans: preliminary study

Abstract

Author(s): M. Boopathi, D. Khanna*, P. Mohandass, P. Venkatraman, K. Kanakavel, C. Narmada and S.Vignesh

Purpose: Objective of this present study is to assess the correlation factor kDVH (Dose Volume Histogram) for the Verisoft PTW software for different clinical sites. Materials and methods: Utilizing a simple dose reconstruction method in OCTAVIUS® 4D phantom, the measured dose in the array is 3D reconstructed. The DVH derived from Treatment Planning System (TPS) is compared with the DVH generated in Verisoft software from the measurement. To match these obtained histograms, user defined correction factor available in Verisoft application. The present study is intended to obtain a constant value that could be helpful in the comparison between the TPS DVH with the Verisoft generated DVH for all the clinical manifestations. In the present study, 9 cases, 10 cases, 11 cases and 10 cases of Oesophagus, Brain, Rectum and Head & Neck respectively total 40 cases have been taken for the calculation of this correction. With 1.000 kDVH default value, maximum dose for all the structures were examined in VeriSoft PTW software. The average values in the TPS for DVH and maximum values for VeriSoft were obtained for all the given structures in the different cases. Results: The results of DVH derived from TPS compared with Varisoft generated DVH for all four clinical sites. The comparison results of mean and maximum dose of target and OAR volumes did not show any significant dose difference (p>0.05). In addition, mean deviation factor obtained was <1% which ensure that the derived constant value does not does not disturb the software calculation but enhances the quality of the DVH as like TPS DVH. Therefore, user can trust the use of kDVH in the Verisoft Software to improve the DVH Calculation. The value of kDVH was evaluated for both Neck & Head and Rectum cases such as 1.000 and 1.022. From the results obtained, it was found that 1.022 kDVH (constant value) would be better that can match the correction factor for Measured Verisoft DVH and TPS DVH. Conclusion: The average kDVH value 1.022 is derived and this value will act as the baseline for comparing and calculating TPS with Verisoft PTW software.

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