PurposeIn radical radiotherapy for cervical cancer, high-dose-rate (HDR) brachytherapy is commonly used after external beam radiation therapy (EBRT) to deliver a cumulative EQD2 of 80 to 90 Gy to the primary tumor. However, there is less certainty regarding brachytherapy dose contribution to the pelvic lymph nodes. This poses a challenge as to how high a preceding EBRT dose should be prescribed to gross nodal disease, in order to achieve a cumulative tumoricidal effect. Hence, this study aims to quantify brachytherapy dose contribution to individual pelvic nodal groups, using computed tomography (CT) planning with the Manchester system.Material and methodsThis is a single institution retrospective dosimetric study. CT planning datasets from 40 patients who received EBRT followed by intracavitary HDR brachytherapy (5 or 6 Gy fractions) were retrieved. The external iliac (EI), internal iliac (II), and obturator (OB) lymph node groups were contoured on each CT dataset. Applying the initial brachytherapy plan, mean doses to each nodal group were calculated for every patient, and averaged across the respective (5 or 6 Gy) study populations.ResultsWith a brachytherapy dose of 5 Gy to Manchester point A, the mean absolute doses received by the EI, II, and OB groups were 0.79, 1.12, and 1.34 Gy respectively, corresponding to EQD2s (α/β = 10) of 0.71, 1.04, and 1.27 Gy respectively. With a brachytherapy dose of 6 Gy, the mean absolute doses received by the EI, II, and OB groups were 1.16, 1.56, and 1.80 Gy respectively, corresponding to EQD2s of 1.08, 1.49, and 1.77 Gy, respectively.ConclusionsOur study demonstrates that pelvic lymph nodes receive substantial dose contributions from HDR brachytherapy in cervical cancer. This should be taken into account by the radiation oncologist during EBRT planning, and adequate external beam boost doses calculated to achieve cumulative tumoricidal doses to pelvic nodal disease.

Purpose:The aim of the study was to determine the feasibility of interstitial brachytherapy under non-anesthetist-administered moderate sedation, to identify factors influencing the insertion, and the total procedural time.Material and methods: A total of 47 insertions with hybrid intracavitary and interstitial applicators were performed in 23 patients from March 2017 to March 2020. Moderate sedation was achieved with intravenous midazolam and fentanyl administered by non-anesthetist. Insertion time and procedural time was recorded. Univariate and multivariate analysis were performed to evaluate the impact of different factors on insertion and procedural time.Results: A total of 238 needles (range, 2-8 per insertion) were implanted, with an average insertion depth of 30 mm (range, 20-40 mm). The mean doses for midazolam and fentanyl were 3 mg (standard deviation [SD] = 1) and 53.3 mcg (SD = 23.9) per insertion, respectively. The median insertion time was 30 minutes (interquartile range [IQR] = 22-40), and the median total procedural time was 4.3 hours (IQR = 3.6-5.2). First time insertion, insertions performed before 2019, and higher midazolam dose were associated with significantly longer insertion time, whereas longer insertion time, MRIbased planning, and insertions performed before 2019 were associated with significantly longer total procedural time.Conclusions: Outpatient interstitial brachytherapy with non-anesthetist-administered sedation is achievable and well-tolerated. This method may significantly lessen the burden on hospital resources and has the potential to be cost-effective.

No abstract