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Purpose: Concurrent chemoradiotherapy and brachytherapy is the standard of care for locally advanced cervical cancer. Brachytherapy is an integral part of treatment and has improved overall survival. Research is needed to ascertain the planning modalities and schedules to best use resources and optimize treatment time course. We hypothesized that MRI-based brachytherapy when delivered with the described regimen would not prolong, and potentially shorten, overall treatment time as compared with CT-based brachytherapy., Methods and Materials: This study was a single-institution retrospective review within the years 2008 through 2018. Patients with cervical cancer of any stage who underwent definitive chemoradiotherapy and either CT- or MRI-based brachytherapy were included. The primary outcome variable for this study was time (in days). Overall treatment time was defined as the number of days from the first until the last day of radiotherapy. Univariate analysis was performed using Stata statistical software., Results: External beam radiotherapy doses were generally 45-50.4 Gy. CT-based and MRI-based brachytherapy were performed in 55 and 49 patients, respectively. The median treatment time for brachytherapy with CT-based planning was 19.0 days and with MRI-based planning was 9.0 days (p < 0.001). The median treatment time for total radiation therapy with CT-based planning was 53 days, and with MRI-based planning was 50 days (p = 0.781)., Conclusions: This study found that MRI-based brachytherapy, when performed with the proposed regimen, did not prolong overall treatment time and significantly decreased time to complete brachytherapy in comparison with CT-based brachytherapy on nonconsecutive days. This regimen favorably impacts timely completion of treatment and uses MRI resources well within the construct of our institution., (Published by Elsevier Inc.)

Purpose: While some institutions deliver multiple fractions per implant for MRI-based planning, it is common for only one fraction to be delivered per implant with CT-based cervical brachytherapy. The purpose of this study was to compare physician costs, hospital costs, and overall costs for cervical cancer patients treated with either CT-based or MRI-based high-dose-rate (HDR) cervical brachytherapy to determine if MRI-based brachytherapy as described can be financially feasible., Methods and Materials: We identified 40 consecutive patients treated with curative intent cervical brachytherapy. Twenty patients underwent CT-based HDR brachytherapy with five fractions delivered in five implants on nonconsecutive days in an outpatient setting with the first implant placed with a Smit sleeve under general anesthesia. Twenty patients received MRI-based HDR brachytherapy with four fractions delivered in two implants, each with MRI-based planning, performed 1-2 weeks apart with an overnight hospital admission for each implant. We used Medicare reimbursements to assess physician costs, hospital costs, and overall cost., Results: The median cost of MRI-based brachytherapy was $14,248.75 (interquartile range [IQR]: $13,421.32-$15,539.74), making it less costly than CT-based brachytherapy with conscious sedation (i.e., $18,278.85; IQR: $17,323.13-$19,863.03, p < 0.0001) and CT-based brachytherapy with deep sedation induced by an anesthesiologist (i.e., $27,673.44; IQR: $26,935.14-$29,511.16, p < 0.0001). CT-based brachytherapy with conscious sedation was more costly than CT-based brachytherapy with deep sedation (p < 0.001)., Conclusions: MRI-based brachytherapy using the described treatment course was less costly than both methods of CT-based brachytherapy. Cost does not need to be a barrier for MRI-based cervical brachytherapy, especially when delivering multiple fractions with the same application., (Published by Elsevier Inc.)

Purpose: To define the relationship between the Point A prescription dose and the dose delivered to various pelvic lymph node groups during high-dose-rate (HDR) brachytherapy treatment of cervical cancer. In less developed countries, brachytherapy is often done without three-dimensional image guidance, instead relying on plain radiography and prescription to Point A. A defined relationship between Point A dose and lymph node doses would help physicians in these health care settings to more accurately estimate nodal doses., Methods and Materials: Treatment data from 50 fractions of HDR brachytherapy of cervical cancer were reviewed, the pelvic lymph nodes were contoured, and dose-volume histogram parameters were obtained. Dose-volume histogram parameters for each contour were normalized as a percentage of the corresponding Point A dose. All nodal groups were divided into left and right sides, except the presacral nodal group., Results and Conclusions: Mean Point A doses were bilateral (Bil) 5.92 Gy ± 0.58, left (L) 5.93 ± 0.59, and right (R) 5.92 ± 0.59. Mean normalized D90 values for the various lymph node groups were as follows-obturator: Bil 20.3% ± 4.5, L 20.5% ± 4.4, and R 20.2% ± 5.2; external iliac: Bil 9.5% ± 2.9, L 10.0% ± 3.1, and R 9.5% ± 3.0; internal iliac: Bil 12.2% ± 3.5, L 12.1% ± 3.4, and R 12.9% ± 4.7; common iliac: Bil 4.3% ± 1.6, L 4.3% ± 1.6, and R 4.3% ± 1.7; and presacral: 8.7% ± 3.4. These relationships can serve as a useful tool for evaluating lymph node doses during HDR brachytherapy of cervical cancer in facilities performing two-dimensional treatment planning and those with limited resources., (Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to report early outcomes and assess the learning curve in a new MRI-based cervical brachytherapy program., Methods: We accrued 33 patients prospectively, and only patients with ≥3 months' followup (n = 27) were assessed for disease control and toxicity. Eras were defined as first half and second half for the intracavitary (IC)-only era (n = 13 each), and the intracavitary/interstitial (IC/IS) era was separated by difference in applicator availability (n = 7). Dose to 90% of the high-risk clinical target volume (D 90 HR-CTV) and minimum dose to the maximally irradiated 2 cubic centimeters (D 2cc ) to organs at risk were used to assess dosimetry. Statistics were performed with t tests and Kaplan-Meier method., Results: Median followup was 14.7 months. Median treatment duration was 50.5 vs. 57 days for patients treated with external beam radiation therapy at our institution vs. an outside institution (p = 0.03). One-year local control, noncervical pelvic control, distant metastasis-free rate, and overall survival were 84.0%, 96.0%, 78.5%, and 91.3%, respectively. When comparing the first half and second half eras of IC only, there were no differences in median D 90 HR-CTV or D 2cc of the bladder, rectum, or sigmoid. Comparing the entire IC era to the IC/IS era, median D 90 HR-CTV trended higher from 88.0 Gy to 92.9 Gy (p = 0.11). D 2cc rectum decreased from 69.3 Gy to 62.6 Gy (p = 0.01), and D 2cc bladder trended lower from 87.5 Gy to 83.6 Gy (p = 0.09)., Conclusions: There was no significant difference between the first half and second half eras with IC-only MRI-based brachytherapy. Incorporation of an IC/IS applicator generated the greatest dosimetric improvement. Early results of the MRI-based brachytherapy program are favorable., (Published by Elsevier Inc.)

Purpose: To evaluate the dosimetric benefits of MRI-based brachytherapy in small and large high-risk clinical target volume (HR-CTV) in cervical cancer., Methods and Materials: Twenty-eight fractions obtained from sixteen cervical cancer patients treated with MRI-based high-dose-rate brachytherapy with standard tandem and ovoid applicators were used; original fractions were optimized to HR-CTV D 90 . Fractions were separated based on the median volume into small and large (HR-CTV <25 cm 3 or >25 cm 3 ) lesion groups. Retrospective plans prescribed to Point A were created for each fraction. D 0.1 cc , D 2 cc , and International Commission of Radiation Unit and Measurements (ICRU) points were used to compare Point A vs. HR-CTV D 90 plans for bladder, rectum, and sigmoid., Results: In the small lesion group, Point A plans vs. HR-CTV D 90 plans had significantly higher D 0.1 cc , D 2 cc , and ICRU points for bladder, rectum, and sigmoid (p < 0.05). In the large lesion group, there was no significant difference between Point A and HR-CTV D 90 plans for D 0.1 cc , D 2 cc , and ICRU points to the organs at risk (OARs)., Conclusions: The dosimetric advantages to OARs offered by MRI-based brachytherapy with prescription to HR-CTV D 90 compared to Point A is most distinct for patients with smaller HR-CTV (<25 cm 3 ). This study demonstrates sufficient tumor coverage with lower doses to OARs in HR-CTV D 90 vs. Point A plans in the small lesion group. These improvements were not seen in the large lesion group, indicating a lesser dosimetric advantage of HR-CTV D 90 compared to Point A planning when the cervical lesion is >25 cm 3 . Incorporation of interstitial needles for patients with larger HR-CTV is likely the best method to decrease dose to OARs and improve tumor coverage., (Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate dose-volume histograms (DVHs) and dose-surface histograms (DSHs) to analyze bladder distension during cervical brachytherapy., Methods: Twenty brachytherapy fractions from five cervical cancer patients were selected. For each fraction, empty and full (200cc of contrasted saline) bladder simulation CT scans existed, one of which was used to plan treatment. An alternative plan was then created with the unused scan. DVH for each fraction was generated for the bladder, rectum, sigmoid colon, and small bowel. Mean DVH dose, D0.1cc, and D2cc were calculated for each organ at risk. Plans were then exported to a MATLAB-based program to generate a DSH., Results: Full bladder plans showed no difference in bladder D2cc or D0.1cc compared with empty bladder plans; however, bladder mean DVH dose and DSH dose were both significantly reduced. Full bladder plans showed a significant reduction in small intestine D2cc from 2.81 Gy to 1.83 Gy and reduction in D0.1cc from 4.07 Gy to 2.57 Gy (p < 0.05); similarly, sigmoid D2cc was significantly reduced from 4.24 Gy to 3.87 Gy (p < 0.05) and D0.1cc was reduced from 6.12 Gy to 5.61 Gy (p < 0.05) in full bladder plans. Both small intestine and sigmoid also showed reduced mean DVH and DSH dose in full bladder plans. The rectum showed no significant difference in D2cc, D0.1cc, mean DVH, or DSH dose between plans., Conclusions: Bladder distension during cervical brachytherapy significantly reduced dose in all DVH and DSH parameters for sigmoid and small intestine with no change in bladder parameters. It reduces dose to organ at risk, but the correlation to toxicity requires further investigation., (Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)