Objective:

We aimed to compare four field radiotherapy techniques with three field radiotherapy technique with enhanced dynamic wedges (EDW) in patients with stomach cancer who underwent postoperative chemo-radiotherapy.

Material and Methods:

Ten consecutive stomach cancer patients who underwent total/ subtotal gastrectomy and lymph node dissection were included to the study. For each patient, two different treatment plans were created for the tumor bed and regional lymph nodes. Three field and four field plans were compared for the doses in the planning target volume (PTV), the organ at risk (OAR) volumes (including kidneys, liver, spleen and spinal cord), the dose homogeneity index (DHI), and the monitor unit counts (MU) required for the treatment. Student-t test was used for statistical analysis.

Results:

There was no difference between two techniques in terms of DHI (p:0.576). The mean dose received by the liver was significantly reduced with three field technique (p<0.001); whereas the mean doses of the kidneys, spleen and spinal cord were decreased with four field technique (p values were 0.007, 0.021 and <0.001 respectively). The dose to %10, %30, %40 and %50 of the total liver volume were significantly reduced with three field technique (p values were 0.026, 0.009, 0.001 and <0.001 respectively). The MU counts required for the treatment was significantly lower with four filed technique (p<0.001).

Conclusion:

There weren’t any difference in terms of dose homogeneity in the PTV and DHI between four field technique and three field techniques with EDW in patients with stomach cancer who underwent radiotherapy to the tumor bed and regional lymph nodes. It was expected to need more MU in the three field technique with EDW. The liver dose was significantly reduced with three field technique. Therefore it is more convenient to choose three field techniques with EDW in patients with known liver disease.

Keywords: Dose volume histograms, stomach cancer, radiotherapy