A treatment planning study comparing helical tomotherapy with intensity-modulated radiotherapy for the treatment of anal cancer

Abstract

Purpose A planning study to compare helical tomotherapy (HT) and intensity-modulated radiotherapy (IMRT) for the treatment of anal canal cancer. Materials and methods Sixteen (8 males and 8 females) patients with anal cancer previously treated radically were identified. HT and IMRT plans were generated and dosimetric comparisons of the plans were performed. The planning goals were to deliver 54 Gy to the tumor (PTV 54Gy) and 48 Gy to the nodes at risk (PTV Node) in 30 fractions. Results PTVs: HT plans were more homogeneous for both men and women. Male patients: HT vs. IMRT: D max: 55.87 ± 0.58 vs. 59.17 ± 3.24 ( p = 0.036); D min: 52.91 ± 0.36 vs. 44.09 ± 6.84 ( p = 0.012); female patients: HT vs. IMRT: D max: 56.14 ± 0.71 vs. 59.47 ± 0.81 ( p = 0.012); D min: 52.36 ± 0.87 vs. 50.97 ± 1.42 ( p = 0.028). OARs: In general, HT plans delivered a lower dose to the peritoneal cavity, external genitalia and the bladder and IMRT plans resulted in greater sparing of the pelvic bones (iliac crest/femur) for both men and women. Iliac crest/femur: the difference was significant only for the mean V10 Gy of iliac crest in women ( p ⩽ 0.012). External genitalia: HT plans achieved better sparing in women compared to men ( p ⩽ 0.046). For men, the mean doses were 18.96 ± 3.17 and 15.72 ± 3.21 for the HT and IMRT plan, respectively ( p ⩽ 0.017). Skin: both techniques achieved comparable sparing of the non-target skin ( p = NS). Conclusions HT and IMRT techniques achieved comparable target dose coverage and organ sparing, whereas HT plans were more homogeneous for both men and women.