In cervical cancer patients who had three-dimensional (3D) high-dose-rate (HDR) brachytherapy, researchers sought to ascertain the dosage connection between point B and metastatic lymph nodes.

About 30 cervical cancer patients with lymph node metastases who underwent 3D HDR brachytherapy at Liaoning Cancer Hospital and Institute between May 2019 and November 2020 were the subjects of a retrospective analysis. A Fletcher applicator was used to administer brachytherapy at the recommended dosage of 28 Gy/4 f. The MIM system combined delineation pictures of the brachytherapy target and computed tomography images of the external irradiation target. On the MIM system, the point B dose for the brachytherapy target area and the minimum dose received by 90% of the volume (D90) were read. The study examined 78 metastatic lymph nodes from 30 cervical cancer patients, including para-aortic, common, external, internal, iliac, obturator, and inguinal lymph nodes. The difference in the equivalent dosage between each group of metastatic lymph nodes and point B was investigated using paired t-tests and Pearson correlation coefficient analysis.

The average equivalent dosage at point B was 6.69±1.08 Gy. Point B and the para-aortic, common iliac, external iliac, internal iliac, and inguinal lymph nodes showed substantial dosage differences (P<0.05), with a weakly positive association (r<0.4). Obturator lymph nodes and point B did not receive significantly different doses, and there was a positive association (r=0.65) between the two.

Compared to para-aortic and inguinal lymph node doses, 3D HDR brachytherapy dramatically increased pelvic lymph node doses in cervical cancer patients with lymph node metastases. Only the dosage to the obturator lymph nodes was comparable to that at point B, with a slightly positive correlation. The dose at point B significantly exceeded the mean dose to the pelvic lymph nodes.