Dosimetric Coverage of the External Anal Sphincter by 3-Dimensional Conformal Fields in Rectal Cancer Patients Receiving Neoadjuvant Chemoradiation: Implications for the Concept of Sphincter-Preserving Radiation Therapy
Figure 5
A patient with a rectal cancer located 2.7 cm above the EAS. (a) The original RT field covered 4 cm inferior to the gross tumor. (b) The EAS can be spared from radiation treatment easily by reducing the inferior border superiorly by 2 cm. (c) Axial CT image through the EAS shows that no draining lymph nodes need to be covered. (d) Coronal scout view shows the level of axial image (red line). Solid red: gross tumor; green: EAS.
