@Article{Zhang2013,
journal="Journal of Contemporary Brachytherapy",
issn="1689-832X",
volume="5",
number="4",
year="2013",
title="Original paperThree-dimensional dosimetric considerations from different point A definitions in cervical cancer 
low-dose-rate brachytherapy",
abstract=" Purpose : To investigate the dosimetric difference due to the different point A definitions in cervical cancer low-dose-rate (LDR) intracavitary brachytherapy.    Material and methods:  Twenty CT-based LDR brachytherapy plans of 11 cervical patients were retrospectively reviewed. Two plans with point As following the modified Manchester system which defines point A being 2 cm superior to the cervical os along the tandem and 2 cm lateral (A os ), and the American Brachytherapy Society (ABS) guideline definition in which the point A is 2 cm superior to the vaginal fornices instead of os (A ovoid ) were generated. Using the same source strength, two plans prescribed the same dose to A os  and A ovoid . Dosimetric differences between plans including point A dose rate, treatment volume encompassed by the prescription isodose line (TV), and dose rate of 2 cc of the rectum and bladder to the prescription dose were measured.    Results : On average A ovoid  was 8.9 mm superior to A os  along the tandem direction with a standard deviation of 5.4 mm. With the same source strength and arrangement, A os  dose rate was 19% higher than A ovoid  dose rate. The average TV(A ovoid ) was 118.0 cc, which was 30% more than the average TV(A os ) of 93.0 cc. D 2cc /D(Aprescribe) increased from 51% to 60% for rectum, and increased from 89% and 106% for bladder, if the prescription point changed from A os  to A ovoid .   Conclusions : Different point A definitions lead to significant dose differences. Careful consideration should be given when changing practice from one point A definition to another, to ensure dosimetric and clinical equivalency from the previous clinical experiences.",
author="Zhang, Miao
and Chen, Ting
and Kim, Leonard H.
and Nelson, Carl
and Gabel, Molly
and Narra, Venkat
and Haffty, Bruce
and Yue, Ning J.",
pages="222--226",
doi="10.5114/jcb.2013.38836",
url="http://dx.doi.org/10.5114/jcb.2013.38836"
}