| dc.description.abstract | Brachytherapy dose specification point A, located 2 cm superior to the external
cervical orifice and 2 cm lateral to the cervical canal, is a geometrical concept
that represents the anatomic position where the uterine artery crosses the
ureter. The study aimed to determine how well the Manchester point A
represents the true anatomical point A (APA). The relationship between high -
risk-clinical target volume (HRCTV) dimensions and the position of APA is also
assessed to discuss the possibilities of individualizing the point-based
brachytherapy. In this quantitative study, diagnostic contrast-enhanced
computed tomographic scans of 48 patients with Carcinoma of the cervix/
endometrium were reviewed retrospectively. The same geometric coordinate
system as Manchester point A was established; APA and HR-CTV were located
and contoured on the CT data. Maximum HR-CTV dimensions on AP projection
and coordinates of APA were recorded to assess correlations. The mean APA of
the sample was at a vertical level of 1.18±0.35 cm from the external-orifice along
the uterine axis and 3.63±0.52 cm laterally to either side. A significant moderate
positive correlation exists between HRCTV dimensions and APA position. An
approximate individualized Point A is defined using this correlation as a
function of HR-CTV dimensions, which can easily be measured from
radiotherapy planning CT scans. The proposed model is useful in a 3D brachytherapy setup for individualized dose recording and can be used in a 2D brachytherapy setup to individualize dose prescription if proven applicability. | en_US |
