A Study Of IMRT Plan Quality Control Method Based On Overlap Volume Histogramand Prior Knowledge

Intensity modulated radiation therapy(IMRT) has many advantages over tradiational radiotherapy technolies,it has been used widely in clinical cancer treatment. However, the IMRT mathmatically forms a large scale optimization problem, which involves a large number of variables. Thus the development of IMRT is computational expensive, resulting in time-consuming, inefficient, and difficult to develop high-quality IMRT plans. So how to assure and improve the quality of IMRT plan and efficiency of the IMRT planning has become one of the most important things in the radiation therapy area.By combining with the prior knowledge and the overlap volume histogram, the quality control method of IMRT plan was studied in this paper. Firstly, we described the current quality control and optimization method of IMRT plan in the clinic. Secondly, according to the relationship between shape distribution and dose distribution in IMRT plans, an IMRT plan quality control model based on shape relationship and prior knowledge was developed. Then, we studied calculation method of the overlap volume histogram(OVH) based on MATLAB, which can be used for the retrieval of shape relationship. Finally, we propsed a quality control method based on OVH and prior IMRT plan knowledge, which can provide effective quality control measurements. What’s more, a method by employing the minimum distance between concerned objects was proposed to improve the retrieval efficiency.To verify the feasibility and availability of the quality control method, we analyzed the performance and retrieval effectiveness of OVH descriptor by clinical nasopharyngeal IMRT plans. The experimental results show that: 1) The calculation method proposed in this paper can efficiently calculate the OVH curves of the clinical IMRT plans. The overlap volume histogram can describe geometry relationship characteristics in a simple way, and it recognizes the shape relations well. 2) The quality control method based on OVH and prior IMRT plan knowledge is feasible, it can find out those IMRT plans which have larger optimization space, after re-optimizing the treatment plan, the doses of their CTV1 are increased, meanwhile the dose of their OARs are reduced. In conclusion, the proposed methods can be used to guarante the high-quality of IMRT treatment planning.