Major geometric variations between multiple high-dose-rate applications of brachytherapy in cancer of the cervix: frequency and types of variation.
OBJECTIVE
To evaluate major geometric variations in multiple intracavitary applications for carcinoma of the cervix.


METHODS
Orthogonal radiographs were reviewed of 17 consecutive patients with carcinoma of the cervix treated with 70 applications of high-dose-rate brachytherapy. In seven patients, conscious sedation was used for all applications. In 10 patients, general anesthesia was used for the first application and conscious sedation for subsequent applications. Major geometric variation between applications in axis, length, and slippage in tandem placement and separation, packing, and slippage in colpostats placement were reviewed. A major variation was defined as more than 1.0-cm deviation.


RESULTS
Major variations between applications occurred more commonly in colpostats placement than in tandem placement. For tandems, the rates of variation were 5.7% in axis, 4.3% in length, and 1.4% in slippage. For colpostats, rates of variation were 7.1% in separation, 25.7% in vaginal packing, and 7.1% in slippage. No consistent pattern of variation was found between applications except in vaginal packing.


CONCLUSIONS
Awareness of geometric variations should improve proper placement of intracavitary applicators for brachytherapy.
Kim
R Y
RY
Department of Radiation Oncology, University of Alabama at Birmingham 35233-6832, USA.
Meyer
J T
JT
Plott
W E
WE
Spencer
S A
SA
Meredith
R F
RF
Jennelle
R L
RL
Salter
M M
MM
D000768:Anesthesia, General; D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D002584:Cervix Uteri / Q000000981:diagnostic imaging; D016292:Procedural Sedation; D005260:Female; D006801:Humans; D011859:Radiography; D011879:Radiotherapy Dosage; D002583:Uterine Cervical Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*