Compare the design of divisional target plan and single target plan for massive liver cancer

To improve the coverage of irradiation on tumor and resolve the problem of dose shortage at the edge of tumor beside sensitive organs, we will discuss about designing divisional target plans for massive liver cancer. On the stage of designing treatment plans, we divide the Planning Target Volume (PTV) into three sub-targets: PTV1, PTV2 and PTV3. PTV1 and PTV3 are the regions for designing treatment plans, and PTV2 is the spacer region between PTV1 and PTV3. We select two cases of massive liver cancer, adopt the same prescribed dose and dose threshold of sensitive organs, and then design plans for a single target and divisional targets respectively. We will compare and evaluate the results of these two methods. For case 1, the tumor coverage rates of a single target plan and divisional target plan were 66.51% and 99.00%, respectively. For case 2, the tumor coverage rates of a single target plan and divisional target plan were 56.85% and 92%. Through divisional target plans, the tumor coverage of case 1 and 2 improves 32.49% and 35.15%, respectively. So the design of divisional target plan greatly improves the coverage rate of irradiation on tumor, but prolongs the time of treatment.