Fig. 1.

An 84-year-old man who presented with hepatocellular carcinoma in the S4 region had Child–Pugh B cirrhosis and received a total of 42.5 Gy in 5 fractions (8.5 Gy per fraction). The whole liver volume and planning target volume were 1062 and 61.2 cm³, respectively. The dose contribution lines are shown in physical (a) and biological (b) doses, and are normalized to prescription doses (100%). The original radiotherapy plan was revised to administer 12 fractions using the dose distribution devised for each plan in this study. The dose at each isodose line (white dashed line) was plotted (c); physical and biological doses were both plotted into the graph. The X and Y axes indicate the distance from the isocenter and the doses at each distance, respectively. Vertical solid lines indicate the edges of the planning target volumes. The liver volume that received each absorbed dose is shown in the scatter plot (d), in which the physical (dot) and biological doses (triangle) were plotted. The X and Y axes in the scatter plot indicate the absorbed dose and volume that received each dose, respectively. The mean physical doses for the whole liver and background liver were 8.51 and 5.83 Gy, respectively. Transferred biological doses for the whole liver and background liver were 20.91 and 11.3 Gy, respectively. Finally, the mean physical and biological doses for the liver in each patient were evaluated.