Abstract
BackgroundTo assess the intra-fractional dosimetric variations of image-guided brachytherapy of cervical cancer.MethodsA total of 38 fractions (9 patients) undergoing brachytherapy for cervical cancer underwent a CT scanning for treatment planning (planning CT) and a Cone-beam CT (CBCT) scanning immediately prior to delivery (pre-delivery CBCT). The variations of volumes as well as the dosimetric impact from treatment planning to delivery (intra-application) were evaluated. The dose volume histogram parameters including volume, D90 of high-risk clinical target volume (HRCTV) and D2cc of organs at risk (OARs) were recorded.ResultsThe relative differences (mean ± 1SD) of the volume and D90 HRCTV across the two scans were − 2.0 ± 3.3% and − 1.2 ± 4.5%, respectively. The variations of D2cc for bladder, rectum, sigmoid and small intestine are − 0.6 ± 17.1%, 9.3 ± 14.6%, 7.2% ± 20.5% and 1.5 ± 12.6%, respectively. Most of them are statistically nonsignificant except the D2cc for rectum, which showed a significant increase (P = 0.001). Using 5% and 10% uncertainty of physical dose for HRCTV at a 6 Gy × 5 high-dose-rate schedule, the possibility of total equivalent doses in 2 Gy fractions (EQD2) lower than 85 Gy is close to 0% and 3%, respectively. Performing similar simulation at 15% and 20% uncertainty of a 4 Gy physical dose for OARs, the possibility of total EQD2 dose exceeding 75 Gy is about 70%. Less than 1% of the total EQD2 of OARs would exceed 80 Gy.ConclusionsAverage intra-fractional dosimetric variation of HRCTV was small in an interval of less than 1 h, and the possibility of total EQD2 exceeding 85 Gy is higher than 97%. The intra-fractional dosimetric variations of OARs might result in an overdose for OARs in a single fraction or the whole treatment. It is necessary to detect unfavorable anatomical changes by re-imaging and take interventions to minimize applied doses and reduce the risk of complications.
Highlights
Radiotherapy is an essential component of curative treatment of locally advanced cervical cancer, which includes external beam radiotherapy (EBRT) and brachytherapy (BT) [1]
Full list of author information is available at the end of the article
MRI-based 3D-IGBT is the gold standard for cervical cancer [6], CT-based planning provides useful information for discrimination of the organs at risk (OARs), which has a similar effect as MRI [7]
Summary
Radiotherapy is an essential component of curative treatment of locally advanced cervical cancer, which includes external beam radiotherapy (EBRT) and brachytherapy (BT) [1]. MRI-based 3D-IGBT is the gold standard for cervical cancer [6], CT-based planning provides useful information for discrimination of the organs at risk (OARs), which has a similar effect as MRI [7]. The effect of intra-fractional variation remains an issue in 3D-IGBT for cervical cancer [12]. These intra-fractional target and OARs variations might result from changes in location relative to the applicator, variations of shape and/or filling status of OARs, and patient transfer. Several studies have reported the intrafractional dosimetric variations in the 3D-IGBT for cervical cancer, which might require repetitive imaging and predelivery intervention treatment [12,13,14,15]. To assess the intra-fractional dosimetric variations of image-guided brachytherapy of cervical cancer
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
