Accuracy of Intracavitary Applicator Reconstruction for Cervix Cancer Brachytherapy
Date
2019-12-03
Authors
ALMasri, Hussein
Kakinohana, Yasumasa
Toita, Takafumi
Ariga, Takuro
Kasuya, Goro
Murayama, Sadayuki
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
The accuracy of intracavitary applicator reconstruction for cervical cancer was assessed. A homemade phantom that mimics
clinical applicator placement and reference points was used. Three stainless steel (15°, 30°, and 45°) tandems, x-ray markers, and
three reference points were used to compare radiography- and CT-based systems. For CT reconstructions, two Fletcher CT
compatible (15° and 30°) tandems, two ovoids, and two reference points, with and without inserted x-ray markers, were used. A
2.5-mm CT slice thickness was used. To check for inter- and intra-operator variations in CT, only a 30° tandem without x-ray
markers and 1.25-mm CT slice thickness were used. Applicators were reconstructed three times for each image set to verify the
operator reproducibility. A 6 Gy dose was prescribed and normalized at AL-point. Source dwell times were compared to check
for dose variation at A-point. Maximum standard deviations SD (σ) for radiography and CT reconstructions were 0.35 and
0.83mm, respectively. Analysis of variance for the means of 15° and 30° tandems showed no significant difference. Levene’s test
proved insignificant difference for 15° tandem (p value = 0.131), whereas it showed a significant difference for 30° tandem (p
value = 0.011). This phantom study showed that the variance of dwell times between the two methods for 30° tandem was
statistically significant due to increased applicator curvature. CT proves superiority to radiography. X-ray marker method was
more accurate but has less image quality. Inter- and intra-oncologist variations showed good agreement.
Description
Keywords
Brachytherapy , Intracavitary , Radiography , Computed tomography , Catheter reconstruction