Abstract Purpose To investigate and test the feasibility of adaptive 3D image based BT planning for cervix cancer patients in settings with limited access to MRI, using a combination of MRI for the ...first BT fraction and planning of subsequent fractions on CT. Material and methods For 20 patients treated with EBRT and HDR BT with tandem/ring applicators two sets of treatment plans were compared. Scenario one is based on the “gold standard” with individual MRI-based treatment plans (applicator reconstruction, target contouring and dose optimization) for two BT applications with two fractions each. Scenario two is based on one initial MRI acquisition with an applicator in place for the planning of the two fractions of the first BT application and reuse of the target contour delineated on MRI for subsequent planning of the second application on CT. Transfer of the target from MRI of the first application to the CT of the second one was accomplished by use of an automatic applicator-based image registration procedure. Individual dose optimization of the second BT application was based on the transferred MRI target volume and OAR structures delineated on CT. DVH parameters were calculated for transferred target structures (virtual dose from MRI/CT plan) and CT-based OAR. The quality of the MRI/CT combination method was investigated by evaluating the CT-based dose distributions on MRI-based target and OAR contours of the same application (real dose from MRI/CT plan). Results The mean difference between the MRI based target volumes (HR CTVMRI2 ) and the structures transferred from MRI to CT (HR CTVCT2 ) was −1.7 ± 6.6 cm3 (−2.9 ± 20.4%) with a median of −0.7 cm3. The mean difference between the virtual and the real total D90, based on the MRI/CT combination technique was −1.5 ± 4.3 Gy EQD2. This indicates a small systematic underestimation of the real D90. Conclusions A combination of MRI for first fraction and subsequent CT based planning is feasible and easy when automatic applicator-based image registration and target transfer are technically available. The results show striking similarity to fully MRI-based planning in cases of small tumours and intracavitary applications, both in terms of HR CTV coverage and respecting of OAR dose limits. For larger tumours and complex applications, as well as situations with unfavourable OAR topography, especially for the sigmoid, MRI based adaptive BT planning remains the superior method.
To evaluate the predictive value of dose-volume histogram (DVH) parameters for late side effects of the rectum, sigmoid colon, and bladder in image-guided brachytherapy for cervix cancer patients.
A ...total of 141 patients received external-beam radiotherapy and image-guided brachytherapy with or without chemotherapy. The DVH parameters for the most exposed 2, 1, and 0.1 cm(3) (D(2cc), D(1cc), and D(0.1cc)) of the rectum, sigmoid, and bladder, as well as International Commission on Radiation Units and Measurements point doses (D(ICRU)) were computed. Total doses were converted to equivalent doses in 2 Gy by applying the linear-quadratic model (α/β = 3 Gy). Late side effects were prospectively assessed using the Late Effects in Normal Tissues-Subjective, Objective, Management and Analytic score. The following patient groups were defined: Group 1: no side effects (Grade 0); Group 2: side effects (Grade 1-4); Group 3: minor side effects (Grade 0-1); and Group 4: major side effects (Grade 2-4).
The median follow-up was 51 months. The overall 5-year actuarial side effect rates were 12% for rectum, 3% for sigmoid, and 23% for bladder. The mean total D(2cc) were 65 ± 12 Gy for rectum, 62 ± 12 Gy for sigmoid, and 95 ± 22 Gy for bladder. For rectum, statistically significant differences were observed between Groups 1 and 2 in all DVH parameters and D(ICRU). Between Groups 3 and 4, no difference was observed for D(0.1cc). For sigmoid, significant differences were observed for D(2cc) and D(1cc), but not for D(0.1cc) in all groups. For bladder, significant differences were observed for all DVH parameters only comparing Groups 3 and 4. No differences were observed for D(ICRU).
The parameters D(2cc) and D(1cc) have a good predictive value for rectal toxicity. For sigmoid, no prediction could be postulated because of limited data. In bladder, DVH parameters were predictive only for major toxicity.
To investigate the value of dose-volume histogram (DVH) parameters for predicting local control in magnetic resonance (MR) image-guided brachytherapy (IGBT) for patients with cervical cancer.
Our ...study population consists of 141 patients with cervical cancer (Stages IB-IVA) treated with 45-50 Gy external beam radiotherapy plus four times 7 Gy IGBT with or without cisplatin. Gross tumor volume (GTV), high-risk clinical target volume (HRCTV), and intermediate-risk clinical target volume (IRCTV) were contoured, and DVH parameters (minimum dose delivered to 90% of the volume of interest D90 and D100) were assessed. Doses were converted to the equivalent dose in 2 Gy (EQD2) by applying the linear quadratic model (alpha/beta = 10 Gy). Groups were defined for patients with or without local recurrence (LR) in the true pelvis for tumor size at diagnosis (GTV at diagnosis GTVD of 2-5 cm (Group 1) or greater than 5 cm (Group 2) and for tumor size response at IGBT (HRCTV) of 2-5 cm (Group 2a) or greater than 5 cm (Group 2b).
Eighteen LRs were observed. The most important DVH parameters correlated with LR were the D90 and D100 for HRCTV. Mean D90 and D100 values for HRCTV were 86 +/- 16 and 65 +/- 10 Gy, respectively. The D90 for HRCTV greater than 87 Gy resulted in an LR incidence of 4% (3 of 68) compared with 20% (15 of 73) for D90 less than 87 Gy. The effect was most pronounced in the tumor group (Group 2b).
We showed an increase in local control in IGBT in patients with cervical cancer with the dose delivered, which can be expressed by the D90 and D100 for HRCTV. Local control rates greater than 95% can be achieved if the D90 (EQD2) for HRCTV is 87 Gy or greater.
To evaluate the possibility of dose escalation and reduction of fraction number in cervical brachytherapy using a gel spacer.
Twenty patients with uterine cervical cancer treated with image-guided ...adaptive brachytherapy (IGABT) were selected. Hyaluronic acid gel injection (HGI) was performed in the rectovaginal and vesicouterine septum for 10 patients. The other ten patients were not with HGI. Both groups were treated with IGABT involving tandem/ovoid or cylindrical applicators along with additional interstitial needles. Dose distributions approved by radiation oncologists were retrospectively analyzed, and a dose summation of 45 Gy/25 of external beam radiation therapy and IGABT was performed. Dose constraints for D
of bladder, rectum, and sigmoid were 80, 70, and 70 Gy, respectively. Equivalent dose in 2-Gy fractions calculations used α/β = 10 Gy for high-risk clinical target volume (CTV
) D
and α/β = 3 Gy for organs at risks (OARs). As a planning study, dose distribution rescaling was conducted to deliver as much dose to CTV
D
as possible within the dose constraint limitation for OARs when IGABT was performed for four, three, and two fractions in both groups.
The median CTV
D
was >80 Gy in the non-HGI group and >85 Gy in the HGI group for virtual two and three fractions. Rectum D
was significantly lower in the HGI group for three fractions (p < 0.01).
In the HGI group, adequate dose delivery to CTV
could be achieved with a reduced IGABT fraction number while meeting the dose constraints of OARs.
This study surveyed radiation oncologists in Morocco to explore current practices and perspectives on brachytherapy for cervix cancer.
A 37-question survey was conducted in April 2023 among 165 ...Moroccan radiation oncologists using Google Forms.
Of the 93 respondents, 39% treated over 20 patients in 2022 using 3D image-guided brachytherapy (BT) through the HDR technique; 2D techniques were not reported in the last five years. Intracavitary BT is uniformly applied with a tandem and ovoid applicator. Only 14% utilized interstitial needles for hybrid BT. Iridium-192 was the primary radioactive source (63%), followed by cobalt (37%). Ultrasound-guided 47% of applicator insertions. All used CT scans for planning, but only 6% used MRI fusion due to limited availability. Guidelines for target volume and dose prescription were mostly based on GEC-ESTRO recommendations (74%), followed by Manchester Point A (30.4%) and ABS (11%). Over 90% delineated CTV-HR and CTV-IR; 30% delineated GTV. All marked the bladder and rectum, while 52% marked the sigmoid, 5% the small bowel, and 3% the recto-vaginal point. For dosimetry, 12% used ICRU 89 points, 54% used dose-volume histograms (DVH), and 36% used both. Most reported EQD2cc for OARs for the rectum and bladder, with nine still using ICRU point doses. The most common fractionation schema was 7 Gy in four fractions (60%) and 7 Gy in three fractions (55%).
Brachytherapy remains essential for treating cervical cancer in Morocco. Key areas for improvement include MRI fusion-guided brachytherapy, access to advanced applicators, expanding interstitial techniques, and professional training and national referential.
Pain control techniques during high-dose-rate hybrid intracavitary-interstitial brachytherapy (HBT) for cervical cancer vary widely, with many centers opting for general anesthesia (GA) or conscious ...sedation (CS). Here, we describe a single-institutional series of patients treated with HBT and ASA-defined minimal sedation, utilizing oral analgesic and anxiolytic medications in substitution for GA or CS.
The charts of patients who underwent HBT treatments for cervical cancer from June 2018 to May 2020 were retrospectively reviewed. Prior to HBT, all patients underwent an exam under anesthesia (EUA), and Smit sleeve placement under general anesthesia or deep sedation. Oral lorazepam and oxycodone/acetaminophen were administered between 30-90 minutes before HBT procedure for minimal sedation. HBT placement was performed on computed tomography (CT) table, with needle advancement under CT-guidance.
Treatments with minimal sedation were attempted in 63 patients. A total of 244 interstitial implants with 453 needles were placed via CT-guidance. Sixty-one patients (96.8%) tolerated the procedure without any additional intervention, while two patients (3.2%) required the use of epidural anesthesia. None of the patients in the series required a transition to general anesthesia for the procedure. Bleeding, which resolved with short-term vaginal packing, occurred in 22.1% of insertions.
In our series, the treatment of HBT for cervical cancer with minimal sedation was feasible at a high percentage (96.8%). The ability to perform HBT without GA or CS could be a reasonable option to provide image-guided adaptive brachytherapy (IGABT) with limited resources, allowing for more widespread use. Further investigations using this technique are warranted.
To quantify dose delivery errors for high-dose-rate image-guided brachytherapy (HDR-IGBT) using an independent end-to-end dose delivery quality assurance test at multiple institutions. The novelty of ...our study is that this is the first multi-institutional end-to-end dose delivery study in the world.
The postal audit used a polymer gel dosimeter in a cylindrical acrylic container for the afterloading system. Image acquisition using computed tomography, treatment planning, and irradiation were performed at each institution. Dose distribution comparison between the plan and gel measurement was performed. The percentage of pixels satisfying the absolute-dose gamma criterion was reviewed.
Thirty-five institutions participated in this study. The dose uncertainty was 3.6% ± 2.3% (mean ± 1.96σ). The geometric uncertainty with a coverage factor of k = 2 was 3.5 mm. The tolerance level was set to the gamma passing rate of 95% with the agreement criterion of 5% (global)/3 mm, which was determined from the uncertainty estimation. The percentage of pixels satisfying the gamma criterion was 90.4% ± 32.2% (mean ± 1.96σ). Sixty-six percent (23/35) of the institutions passed the verification. Of the institutions that failed the verification, 75% (9/12) had incorrect inputs of the offset between the catheter tip and indexer length in treatment planning and 17% (2/12) had incorrect catheter reconstruction in treatment planning.
The methodology should be useful for comprehensively checking the accuracy of HDR-IGBT dose delivery and credentialing clinical studies. The results of our study highlight the high risk of large source positional errors while delivering dose for HDR-IGBT in clinical practices.
To compare radiation doses achieved by image-guided brachytherapy for locally advanced cervical carcinoma implemented with two different protocols.
Medical records of 117 patients with locally ...advanced cervical carcinoma treated with brachytherapy from 2009 to 2018 at our institution were retrospectively reviewed. All patients had received previous external beam radio/chemotherapy. We performed magnetic resonance image-guided adaptive high-dose-rate brachytherapy delivered by intra-cavitary/interstitial applicators. Dose prescription was 7 Gy for four fractions within two weeks. Original schedule of brachytherapy was two fractions delivered on consecutive days with one applicator insertion; this process was repeated one week later (group 1, 54 patients). From 2015 onwards, another protocol of brachytherapy was mainly used, separately performing applicator insertions for each of the four administered fractions (group 2, 63 patients).
The high-risk clinical target volume (HR-CTV) D
planning aim (PA) of ≥ 85 Gy (hard constraint) was not achieved in 9 cases out of 54 (17%) in group 1 compared with only 2 out of 63 cases (3%) in group 2 (
= 0.022). A difference between the two groups was also found in the fulfillment of PA 90 Gy (soft constraint) (
= 0.027). We conducted a sub-group analysis of target volume groups and observed that the differences were most pronounced with very large tumors (> 50 cm
). In these patients, PA 85 Gy was only fulfilled in 67% cases when treatment involved two applications, but in all cases with four separate applicator insertions (
= 0.010).
In our experience, by performing an applicator insertion for each of the fractions, it is possible to correct the non-optimal position of the applicator immediately, and to deliver better doses for consecutive fractions. As a result, the planning aim is more often achieved, especially for large tumors.
The standard of care for patients with locally advanced cervical cancer is definitive chemoradiation followed by a brachytherapy boost. This review describes the current status and future directions ...of image-guided adaptive brachytherapy for locally advanced cervical cancer.
A systematic search of the PubMed and Clinicaltrials.gov databases was performed, focusing on studies published within the last 10 years. The search queried "cervical cancer AND image-guided brachytherapy OR magnetic resonance imaging (MRI) OR adaptive brachytherapy".
The retroEMBRACE and EMBRACE-I trials have established the use of MRI as the standard imaging modality for brachytherapy application and planning. Quantitative imaging and radiomics have the potential to improve outcomes, with three ongoing prospective studies examining the use of radiomics to further risk-stratify patients and personalize brachytherapy. Another active area of investigation includes utilizing the superior soft tissue contrast provided by MRI to increase the dose per fraction and decrease the number of fractions needed for brachytherapy, with several retrospective studies demonstrating the safety and feasibility of three-fraction courses. For developing countries with limited access to MRI, trans-rectal ultrasound (TRUS) appears to be an effective alternative, with several retrospective studies demonstrating improved target delineation with the use of TRUS in conjunction with CT guidance.
Further investigation is needed to continue improving outcomes for patients with locally advanced cervical cancer treated with image-guided brachytherapy.
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