Is simulation necessary for each high-dose-rate tandem and ovoid insertion in carcinoma of the cervix?
OBJECTIVE
To evaluate the dose variation in high-dose-rate (HDR) intracavitary brachytherapy for cancer of the cervix when treatment planning is performed prior to each applicator insertion versus when the initial plan is used for each treatment.


METHODS
Fourteen patients with carcinoma of the cervix were treated with chemoradiotherapy followed by five intracavitary tandem and ovoid insertions of 600 cGy/fraction. We modified the actual plans to calculate the dose each dose point would have received using only the treatment plan created for the initial fraction.


RESULTS
An increase in the percent dose to the rectum, bladder, and vaginal surface of 5%, cGy (p = 0.038), 6% (p = 0.006), and 11%, respectively, were observed when the initial treatment plan was used versus using the optimized treatment plan for each insertion. The greatest single change resulted in a percent increase of 35%, 30%, and 45% to the rectum, bladder, and vaginal surface points, respectively.


CONCLUSIONS
Increased dose to at-risk structures occurred when individualized treatment planning was not performed. Since a significant increase in dose to the rectum (p = 0.038) and bladder (p = 0.006) was obtained without customized treatment planning, we continue to advocate individualized treatment planning in HDR tandem and ovoid insertions for the treatment of cervix cancer.
Jones
Nathan D
ND
Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah Medical Center, 1950 Circle of Hope, Salt Lake City, UT 84112, USA.
Rankin
Jim
J
Gaffney
David K
DK
D001918:Brachytherapy / Q000379:methods*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011879:Radiotherapy Dosage; D011881:Radiotherapy, Computer-Assisted; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*