Computed tomography versus magnetic resonance imaging-based contouring in cervical cancer brachytherapy: results of a prospective trial and preliminary guidelines for standardized contours

Effective timing of hyaluronate gel injection in image-guided adaptive brachytherapy for uterine cervical cancer: a proposal of the 'adjusted dose score'

Hyaluronate gel injection (HGI) in the rectovaginal septum and vesicovaginal septum is effective in the setting of high-dose-rate image-guided adaptive brachytherapy (IGABT) for cervical cancer. We aimed to retrospectively investigate optimal conditions for HGI to achieve optimal dose distribution with a minimum number of HGI. We classified 50 IGABT plans of 13 patients with cervical cancer who received IGABT both with and without HGI in the rectovaginal septum and vesicovaginal septum into the following two groups: plan with (number of plans = 32) and plan without (number of plans = 18) HGI. The irradiation dose parameters of high-risk clinical target volume (CTVHR) and organs at risk per fraction were compared between these groups. We also developed the adjusted dose score (ADS), reflecting the overall irradiation dose status for four organs at risk and CTVHR in one IGABT plan and investigated its utility in determining the application of HGI. HGI reduced the maximum dose to the most exposed 2.0 cm3 (D2.0 cm3) of the bladder while increasing the minimum dose covering 90% of CTVHR and the percentage of CTVHR receiving 100% of the prescription dose in one IGABT plan without causing any associated complications. An ADS of ≥2.60 was the optimum cut-off value to decide whether to perform HGI. In conclusion, HGI is a useful procedure for improving target dose distribution while reducing D2.0 cm3 in the bladder in a single IGABT plan. The ADS can serve as a useful indicator for the implementation of HGI.

A Novel Positive-Contrast Magnetic Resonance Imaging Line Marker for High-Dose-Rate (HDR) MRI-Assisted Radiosurgery (MARS)

Magnetic resonance imaging (MRI) can facilitate accurate organ delineation and optimal dose distributions in high-dose-rate (HDR) MRI-Assisted Radiosurgery (MARS). Its use for this purpose has been limited by the lack of positive-contrast MRI markers that can clearly delineate the lumen of the HDR applicator and precisely show the path of the HDR source on T1- and T2-weighted MRI sequences. We investigated a novel MRI positive-contrast HDR brachytherapy or interventional radiotherapy line marker, C4:S, consisting of C4 (visible on T1-weighted images) complexed with saline. Longitudinal relaxation time (T1) and transverse relaxation time (T2) for C4:S were measured on a 1.5 T MRI scanner. High-density polyethylene (HDPE) tubing filled with C4:S as an HDR brachytherapy line marker was tested for visibility on T1- and T2-weighted MRI sequences in a tissue-equivalent female ultrasound training pelvis phantom. Relaxivity measurements indicated that C4:S solution had good T1-weighted contrast (relative to oil [fat] signal intensity) and good T2-weighted contrast (relative to water signal intensity) at both room temperature (relaxivity ratio > 1; r2/r1 = 1.43) and body temperature (relaxivity ratio > 1; r2/r1 = 1.38). These measurements were verified by the positive visualization of the C4:S (C4/saline 50:50) HDPE tube HDR brachytherapy line marker on both T1- and T2-weighted MRI sequences. Orientation did not affect the relaxivity of the C4:S contrast solution. C4:S encapsulated in HDPE tubing can be visualized as a positive line marker on both T1- and T2-weighted MRI sequences. MRI-guided HDR planning may be possible with these novel line markers for HDR MARS for several types of cancer.

The prognostic effect of tumor volume, reduction ratio, and cumulative doses on external beam radiotherapy with central-shielding method and image-guided adaptive brachytherapy for cervical cancer

Objective

To evaluate the prognostic effect of tumor volume at diagnosis, tumor reduction ratio during external beam radiotherapy (EBRT) with central-shielding method, and cumulative minimal dose to 90% of the high-risk clinical target volume (CTVHR D90) on combined EBRT and image-guided adaptive brachytherapy (IGABT) for cervical cancer.

Methods

Consecutive patients who underwent definitive radiotherapy or concurrent chemoradiotherapy for cervical cancer at Gunma University Hospital between January 2010 and December 2019 were retrospectively reviewed. Tumor volume at diagnosis and reduction ratio were calculated using magnetic resonance imaging at diagnosis and before the first IGABT session. The cumulative dose of EBRT and IGABT was calculated as an equivalent dose in 2 Gy fractions (EQD2). Optimal cutoff values were determined according to a receiver operating characteristic curve. Treatment outcomes were evaluated using the Kaplan-Meier method and compared using the log-rank test and Cox proportional hazards regression.

Results

A total of 254 patients were included in the analysis. The median follow-up for all patients was 57 (2-134) months. The 5-year overall survival (OS) was 81.9%, progression-free survival (PFS) was 71.3%, and local control (LC) was 94.5%. The patients were divided into four groups according to tumor volume at diagnosis and reduction ratio. The group with tumor volume at diagnosis ≥ 34.1 cm3 and reduction ratio < 68.8% showed significantly worse OS, PFS, and LC than the other three groups (All p < 0.05). In this group, the patients with a cumulative CTVHR D90 < 69.6 GyEQD2 showed significantly worse PFS and LC (p = 0.042 and p = 0.027, respectively). In the multivariate analysis of OS, adenocarcinoma/adenosquamous carcinoma, International Federation of Gynecology and Obstetrics 2009 stage III/IV, and a reduction ratio of < 68.8% were independent significant poor prognostic factors (p = 0.045, p = 0.009 and p = 0.001, respectively). In the univariate analysis of LC, a reduction ratio of < 68.8% was the only poor prognostic factor (p = 0.041).

Conclusion

The patients with large and poorly responding tumors had significantly worse prognoses in terms of OS, PFS, and LC, suggesting that dose escalation should be considered for such tumors.

Evaluating outcomes and toxicities for a newly implemented MRI-based brachytherapy program for cervical cancer

OBJECTIVE

We report an updated analysis of the outcomes and toxicities of MRI-based brachytherapy for locally advanced cervical cancer from a U.S. academic center.

METHODS

A retrospective review was performed on patients treated with MRI-based brachytherapy for cervical cancer. EBRT was standardly 45 Gy in 25 fractions with weekly cisplatin. MRI was performed with the brachytherapy applicator in situ. Dose specification was most commonly 7 Gy for 4 fractions with optimization aim of D90 HR-CTV EQD2 of 85-95 Gyα/β=10 Gy in 2 implants each delivering 2 fractions.

RESULTS

Ninety-eight patients were included with median follow up of 24.5 months (IQR 11.9-39.8). Stage IIIA-IVB accounted for 31.6% of cases. Dosimetry results include median GTV D98 of 101.0 Gy (IQR 93.3-118.8) and HR-CTV D90 of 89 Gy (IQR 86.1-90.6). Median D2cc bladder, rectum, sigmoid, and bowel doses were 82.1 Gy (IQR 75.9-88.0), 65.9 Gy (IQR 59.6-71.2), 65.1 Gy (IQR 57.7-69.6), and 55 Gy (IQR 48.9-60.9). Chronic grade 3+ toxicities were seen in the bladder (8.2%), rectosigmoid (4.1%), and vagina (1.0%). Three-year LC, PFS, and OS were estimated to be 84%, 61.7%, and 76.1%, respectively.

CONCLUSION

MRI-based brachytherapy demonstrates excellent local control and acceptable rates of high-grade morbidity. These results are possible in our population with relatively large volume primary tumors and extensive local disease.

Current Status and Future Directions of Image-Guided Adaptive Brachytherapy for Locally Advanced Cervical Cancer

PURPOSE

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.

METHODS

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".

DISCUSSION

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.

CONCLUSIONS

Further investigation is needed to continue improving outcomes for patients with locally advanced cervical cancer treated with image-guided brachytherapy.

Patterns of practice survey for cervical cancer brachytherapy in Morocco

PURPOSE

This study surveyed radiation oncologists in Morocco to explore current practices and perspectives on brachytherapy for cervix cancer.

METHODS AND MATERIALS

A 37-question survey was conducted in April 2023 among 165 Moroccan radiation oncologists using Google Forms.

RESULTS

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%).

CONCLUSIONS

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.

Clinical outcome after high dose rate intracavitary brachytherapy with traditional point 'A' dose prescription in locally advanced carcinoma of uterine cervix: dosimetric analysis from the perspective of computed tomography imaging-based 3-dimensional treatment planning

OBJECTIVE

To analyze tumour response and toxicity with respect to cumulative radiotherapy dose to target and organs at risk (OARs) with computed tomography (CT)-based image guided adaptive brachytherapy planning for locally advanced carcinoma cervix.

METHODS

Patients were treated with two-dimensional concurrent chemoradiotherapy to whole pelvis followed by intracavitary brachytherapy (ICBT) with dose prescription to point 'A'. CT image-based delineation of high-risk clinical target volume (HR-CTV), urinary bladder, rectum and sigmoid colon was done with generation of dose-volume histogram (DVH) data and optimization of doses to target and OARs. Follow up assessments were done for response of disease and toxicity with generation of data for statistical analysis.

RESULTS

One hundred thirty-six patients were enrolled in the study. Delineated volume of HR-CTV ranged from 20.9 to 37.1 mL, with median value of 30.2 mL. The equivalent dose in 2 Gy per fraction (EQD2) for point 'A' ranged from 71.31 to 79.75 Gy with median value of 75.1 Gy and EQD2 HR-CTV D90 ranged from 71.9 to 89.7 Gy with median value of 85.1 Gy. 69.2% of patients showed complete response and after median follow-up of 25 months, 50 patients remained disease free, of whom, 74.0% had received ≥85 Gy to HR-CTV D90 versus 26.0% receiving <85 Gy to HR-CTV D90.

CONCLUSION

s Amidst the unavailability of magnetic resonance imaging facilities in low middle income countries, incorporation of CT-image based treatment planning into routine practice for ICBT provides the scope to delineate volumes of target and OARs and to generate DVH data, which can prove to be a better surrogate for disease response and toxicity.

High-Dose-Rate Three-Dimensional Image-Guided Adaptive Brachytherapy (3D IGABT) for Locally Advanced Cervical Cancer (LACC): A Narrative Review on Imaging Modality and Clinical Evidence

Background: Brachytherapy (BT) is a critical component of radiotherapy for locally advanced cervical cancer (LACC), and it has rapidly developed in recent decades. Since the advent of three-dimensional image-guided adaptive brachytherapy (3D-IGABT), magnetic resonance imaging (MRI) has emerged as the primary modality for image guidance. Meanwhile, other imaging modalities, such as computed tomography, 18F-fluorodeoxyglucose positron emission tomography, ultrasound, and their combinations have also been widely studied. Materials and methods: We reviewed studies on different imaging modalities utilized for target delineation and planning. Emerging techniques in IGABT like real-time image guidance and 3D printing were also included. We summarized research on their feasibility and concentrated on their clinical outcomes. Results: MRI-guided BT was the gold standard, and CT-guided BT was the most widely applied. Other modalities have shown feasibility and promising efficacy in dosimetry studies and preliminary outcomes. The longer-term clinical outcomes associated with these approaches require further elucidation. Conclusions: As 3D-IGABT was validated by promising clinical outcomes, the future of BT for LACC is expected to progress toward the refinement of more effective image-guided procedures. Moreover, achieving operational consensus and driving technological advancements to mitigate the inherent limitations associated with different imaging modes remain essential.

Recent Advances and Adaptive Strategies in Image Guidance for Cervical Cancer Radiotherapy

The standard of care for locally advanced cervical cancer is external beam radiotherapy (EBRT) with simultaneous chemotherapy followed by an internal radiation boost. New imaging methods such as positron-emission tomography and magnetic resonance imaging have been implemented into daily practice for better tumor delineation in radiotherapy planning. The method of delivering radiation has changed with technical advances in qualitative imaging and treatment delivery. Image-guided radiotherapy (IGRT) plays an important role in minimizing treatment toxicity of pelvic radiation and provides a superior conformality for sparing the organs at risk (OARs) such as bone marrow, bowel, rectum, and bladder. Similarly, three-dimensional image-guided adaptive brachytherapy (3D-IGABT) with computed tomography (CT) or magnetic resonance imaging (MRI) has been reported to improve target coverage and reduce the dose to normal tissues. Brachytherapy is a complementary part of radiotherapy treatment for cervical cancer and, over the past 20 years, 3D-image-based brachytherapy has rapidly evolved and established itself as the gold standard. With new techniques and adaptive treatment in cervical cancer, the concept of personalized medicine is introduced with an enhanced comprehension of the therapeutic index not only in terms of volume (three-dimensional) but during treatment too (four-dimensional). Current data show promising results with integrated IGRT and IGABT in clinical practice and, therefore, better local control and overall survival while reducing treatment-related morbidity. This review gives an overview of the substantial impact that occurred in the progress of image-guided adaptive external beam radiotherapy and brachytherapy.

MucoUp® as a spacer in brachytherapy for uterine cervical cancer: A first-in-human experience

We first used MucoUp®, a hyaluronic acid used in endoscopic resection, as a spacer in brachytherapy. In five cervical cancer patients, MucoUp® insertion increased a 90% dose of the high-risk CTV to over 80 Gy while decreasing the dose of organs at risk. No related adverse events were observed.

Personalized Brachytherapy for a Herlyn-Werner-Wunderlich Syndrome Patient with Endometrial Cancer: A Case Report

Purpose

Endometrial carcinoma (EC) is a common gynecological malignancy. Vaginal cuff brachytherapy (VBT) is an adjuvant treatment for EC. Since a single-channel cylinder sometimes delivers inadequate dose coverage to the vaginal apex, three-dimensional (3D) printing technology can be used to achieve satisfactory dose distribution. Here, we report the first case of an EC patient with Herlyn-Werner-Wunderlich syndrome (HWWS) treated with VBT using 3D-printed applicators.

Case Presentation

Here, we present a case study of an endometrial cancer patient with HWWS who underwent surgery. During adjuvant radiotherapy, 3D-printed applicators were used in VBT. To accomplish the reconstruction of the source pathways on magnetic resonance imaging, catheters with copper sulfate were placed in two 3D-printed applicators. The early tolerance of this treatment was positive. During the 6-month follow-up, locoregional recurrence was not detected.

Conclusion

Our findings strongly indicate that VBT with 3D-printed applicators may be a reasonable treatment option for EC with HWWS.

Adaptive Radiation Therapy: A Review of CT-based Techniques

Adaptive radiation therapy is a feedback process by which imaging information acquired over the course of treatment, such as changes in patient anatomy, can be used to reoptimize the treatment plan, with the end goal of improving target coverage and reducing treatment toxicity. This review describes different types of adaptive radiation therapy and their clinical implementation with a focus on CT-guided online adaptive radiation therapy. Depending on local anatomic changes and clinical context, different anatomic sites and/or disease stages and presentations benefit from different adaptation strategies. Online adaptive radiation therapy, where images acquired in-room before each fraction are used to adjust the treatment plan while the patient remains on the treatment table, has emerged to address unpredictable anatomic changes between treatment fractions. Online treatment adaptation places unique pressures on the radiation therapy workflow, requiring high-quality daily imaging and rapid recontouring, replanning, plan review, and quality assurance. Generating a new plan with every fraction is resource intensive and time sensitive, emphasizing the need for workflow efficiency and clinical resource allocation. Cone-beam CT is widely used for image-guided radiation therapy, so implementing cone-beam CT-guided online adaptive radiation therapy can be easily integrated into the radiation therapy workflow and potentially allow for rapid imaging and replanning. The major challenge of this approach is the reduced image quality due to poor resolution, scatter, and artifacts. Keywords: Adaptive Radiation Therapy, Cone-Beam CT, Organs at Risk, Oncology © RSNA, 2023.

Application of three-dimensional multi-imaging combination in brachytherapy of cervical cancer

BACKGROUND

Three-dimensional (3D) imaging has an important role in brachytherapy and the treatment of cervical cancer. The main imaging methods used in the cervical cancer brachytherapy include magnetic resonance imaging (MRI), computer tomography (CT), ultrasound (US), and positron emission tomography (PET). However, single-imaging methods have certain limitations compared to multi-imaging. The application of multi-imaging can make up for the shortcomings and provide a more suitable imaging selection for brachytherapy.

PURPOSE

This review details the situation and scope of existing multi-imaging combination methods in cervical cancer brachytherapy and provides a reference for medical institutions.

MATERIALS AND METHODS

Searched the literature related to application of three-dimensional multi-imaging combination in brachytherapy of cervical cancer in PubMed/Medline and Web of Science electronic databases. Summarized the existing combined imaging methods and the application of each method in cervical cancer brachytherapy.

CONCLUSION

The current imaging combination methods mainly include MRI/CT, US/CT, MRI/US, and MRI/PET. The combination of two imaging tools can be used for applicator implantation guidance, applicator reconstruction, target and organs at risk (OAR) contouring, dose optimization, prognosis evaluation, etc., which provides a more suitable imaging choice for brachytherapy.

Dose-effect relationship between dose-volume parameters of residual gross tumor volume and clinical prognosis in MRI-guided adaptive brachytherapy for locally advanced cervical cancer: a single-center retrospective study

PURPOSE

To investigate the dose-effect relationship between the dose-volume parameters of residual gross tumor volume (GTV_res) and clinical prognosis in MRI image-guided adaptive brachytherapy (IGABT) of patients with locally advanced cervical cancer in our center.

MATERIALS AND METHOD

The clinical data of 93 patients with locally advanced cervical squamous cell cancer who received external beam radiotherapy (EBRT) combined with IGABT ± chemotherapy in our center were retrospectively analyzed. The disease stage, overall treatment time (OTT), chemotherapy, and the dose-volume parameters D₉₀, D₉₈, and D₁₀₀ of GTV_res, the intermediate-risk clinical target volume (CTV_IR), and the high-risk clinical target volume (CTV_HR) of the patients were statistically analyzed. Kaplan-Meier and uni- and multivariable Cox regression analyses were used to analyze 2‑year overall survival (OS), progression-free survival (PFS), and local control rate (LC). A probit model was employed to assess the dose-effect relationship between the volume and dose-volume parameters of GTV_res and 2‑year OS, PFS, and LC.

RESULTS

The median follow-up time was 19.6 months and 2‑year OS, PFS, and LC were 79.6%, 68.8%, and 94.6%, respectively. CTV_HR D₉₀ was an independent influencing factor for 2‑year PFS (P = 0.041); GTV_resBT1 volume was an independent factor for 2‑year OS, PFS, and LC (P < 0.001). The probit model showed that at GTV_resBT1 volume < 32.86 cm³, the expected 2‑year LC was > 90%; at GTV_res D₉₈ > 129.12 Gy_EQD2, the expected 2‑year OS was > 90%.

CONCLUSION

Both the volume and dose-volume parameters of GTV_res are promising predictors in assessment of IGABT prognosis of cervical cancer.

Phase I/II prospective clinical trial for the hybrid of intracavitary and interstitial brachytherapy for locally advanced uterine cervical cancer

OBJECTIVE

The purposes of this trial were to demonstrate the feasibility and effectiveness of the hybrid of intracavitary and interstitial brachytherapy (HBT) for locally advanced cervical cancer patients in the phase I/II prospective clinical trial.

METHODS

Patients with FIGO stage IB2-IVA uterine cervical cancer pretreatment width of which was ≥5 cm measured by magnetic resonance imaging were eligible for this clinical trial. The protocol therapy included 30-30.6 Gy in 15-17 fractions of whole pelvic radiotherapy concurrent with weekly CDDP, followed by 24 Gy in 4 fractions of HBT and pelvic radiotherapy with a central shield up to 50-50.4 Gy in 25-28 fractions. The primary endpoint of phase II part was 2-year pelvic progression-free survival (PPFS) rate higher than historical control of 64%.

RESULTS

Between October 2015 and October 2019, 73 patients were enrolled in the initial registration and 52 patients proceeded to the secondary registration. With the median follow-up period of 37.3 months (range, 13.9-52.9 months), the 2- PPFS was 80.7% (90% confidence interval [CI]=69.7%-88%). Because the lower range of 90% CI of 2-year PPFS was 69.7%, which was higher than the historical control ICBT data of 64%, therefore, the primary endpoint of this study was met.

CONCLUSION

The effectiveness of HBT were demonstrated by a prospective clinical study. Because the dose goal determined in the protocol was lower than 85 Gy, there is room in improvement for local control. A higher dose might have been needed for tumors with poor responses.

CT-based image-guided brachytherapy in uterine cervical cancer: Effect of tumor dose and volume on local control

BACKGROUND AND PURPOSE

To determine the optimal primary tumor dose for cervical cancer treatment using computed tomography (CT)-based image-guided brachytherapy (IGBT).

MATERIALS AND METHODS

We retrospectively reviewed 171 patients with cervical cancer who underwent both external beam radiation therapy (EBRT) and IGBT between May 2015 and December 2019. Majority of EBRT plan included central shielding technique. CT-based IGBT was performed weekly a median of three times. Magnetic resonance imaging preceded the first and third session of IGBT for target delineation.

RESULTS

The median age of the patients was 64 years (range: 30-91 years). The median follow-up time for living patients was 43 months (range: 6-76 months). The 3-year local control rates according to the International Federation of Gynecology and Obstetrics (FIGO, 2008) stages were 89%, 100%, 92%, 89%, 78%, and 100% for stages IB, IIA, IIB, IIIA, IIIB, and IVA, respectively. The median EBRT dose to the central pelvis and parametrium/pelvic wall was 41.4 Gy and 50.4 Gy, respectively. Patients who received a cumulative 2 Gy equivalent dose (EQD2) (α/β = 10 Gy) of high-risk clinical target volume (HR CTV) D90% ≥ 75 Gy achieved a long-term local control rate of 93%, compared with 80% in those who received <75 Gy (p = 0.02).

CONCLUSION

This is one of the largest CT-based IGBT series examining the treatment of cervical cancer based on the tumor dose-volume relationship. An HR CTV D90% ≥75 Gy was significantly associated with favorable local control in this study.

Commissioning and Dosimetric Results of an Indigenously Developed Intra-Vaginal Template for Interstitial Plus Intracavitary High dose Rate Image-Guided Brachytherapy of Advanced Cervix Cancer

Aim

The goal of this study is to discuss the commissioning and dosimetric parameters achieved during the clinical implementation of an indigenously developed intracavitary (IC) plus interstitial (IS) template for high dose rate (HDR) image-guided brachytherapy (IGBT) in cancer (Ca) cervix. We want to discuss our achieved values of cumulative equi-effective doses (EQD2) for high-risk clinical target volume (HRCTV) and organ at risk (OAR) and compare it with available published results.

Materials and Methods

Medanta anterior oblique/lateral oblique template has a total of 19 needles including the central tandem. For commissioning the template with needles, the indigenously made acrylic phantom was used. Oblique and straight needles were placed inside the acrylic phantom and a computed tomography (CT) scan was performed. Sixteen patients were treated in HDR IGBT using this template after external-beam radiotherapy. The IGBT plans were evaluated based on EQD2 of target coverage i.e., dose received by 98% (D98%_HRCTV), 90% (D90%_HRCTV), and 50% (D50%_HRCTV) volume of HRCTV, and dose received by 2 cc (D2cc) and 0.1 cc (D0.1cc) of OAR using linear quadratic (LQ) radiobiological model.

Results

The autoradiographic in radiochromic film shows that the distance between the needle tip and the middle of the source position is 6 mm. The mean D98%_HRCTV and D90%_HRCTV was 76.8 Gy (range: 70-87.7 Gy, P < 0.01) and 84.49 Gy (range: 76.6-96.7 Gy, P < 0.01), respectively. Mean EQD2 of D2cc of the bladder, rectum, and sigmoid was 85.6 Gy (range: 77.5-99.6 Gy, P < 0.03), 74.3 Gy (range: 70.9-76.7 Gy, P < 0.05), and 58.3 Gy (range: 50.6-67.9 Gy, P = 0.01), respectively. The mean total reference air kerma at a 1 m distance is 0.489cGy (range: 0.391-0.681cGy).

Conclusions

The indigenously developed template could attain satisfactory standards in terms of set parameters for commissioning and acceptable dose volume relations in our clinical use for treating the advanced Ca cervix patients who need IC + IS type of HDR IGBT. The comparative analysis with contemporary applicators was acceptable.

A new technique for performing interstitial implants for gynecologic malignancies using transvaginal ultrasound guidance

Objectives

This study concerns a new technique that aims to achieve precise interstitial brachytherapy of pelvic recurrent tumors under transvaginal ultrasound (US) guidance, enhance the conformity index of the brachytherapy (BT), and improve the curative effect of radiotherapy for gynecological oncology patients with pelvic relapse.

Methods

A real-time transvaginal US-guided interstitial implant device was developed to assist in implant BT. Prior to implant brachytherapy, the size and location of the tumor in the pelvis and the interrelationship with adjacent organs were first assessed with intracavitary ultrasound. The transvaginal US-guided interstitial implant device was then placed on the endoluminal ultrasound probe, the probe was oriented intravaginally to determine a safe needle path, the implant needle was placed into the needle passage of the device, and the implant needle was inserted into the tumor tissue in the direction guided by the ultrasound puncture guide line. After the implant needle was placed in place, the cover of the transvaginal US-guided interstitial implant device was opened perpendicular to the ultrasound probe, and the needle was separated from the ultrasound probe smoothly, and then the cover was re-covered for subsequent implantation.

Results

In this study, 56 patients who underwent real-time transvaginal ultrasound-guided implantation for gynecologic oncology were enrolled, and insertion of 736 implant needles was completed. Among them, 13 patients had recurrent pelvic tumors after cervical cancer surgery and 6 patients had recurrent pelvic tumors after endometrial cancer surgery. Thirty-two patients who underwent radical radiation therapy for cervical cancer did not have adequate regression of parametrial invaded tissue after completion of standard EBRT treatment; and 5 patients had recurrent tumors in the radiation field after previous standard course of pelvic radiotherapy. The accuracy of the implant therapy was improved. The radiotherapy dose for recurrent pelvic masses was successfully increased, and the cumulative dose of external irradiation combined with BT was augmented to 80–100 Gy. The use of a new device for transvaginal implant for recurrent masses located in the lateral wall of the pelvic cavity was successful.

Conclusion

This intravascular US-guided interstitial implant device can realize interstitial implant with the shortest path under transvaginal US guidance. With convenient operation, high precision, and good security, the device not only improves the accuracy of implant therapy, but it also reduces the risks of anesthesia and organ injury, so it is suitable for widespread promotion and use.

Change in image-guided planning strategies over time impacts oncologic and survival outcomes for intracavitary cervical cancer brachytherapy

PURPOSE

Intracavitary cervical brachytherapy (BT) has transitioned from a two-dimensional nonvolumetric (NV) dosimetry system to three-dimensional computed tomography (CT) and/or magnetic resonance imaging (MRI)-based planning techniques. The purpose of this study is to retrospectively evaluate the relative improvements in image-guided planning strategies over time with regards to dosimetry, survival, and toxicity.

METHODS AND MATERIALS

A single site retrospective review of 95 locally advanced cervical cancer patients treated with concurrent chemoradiation and high dose rate BT from 2009 to 2016 were divided into three BT planning groups: point-A based NV dosimetry using CT imaging (n = 37), CT-based volumetric dosimetry (n = 33), and MRI-based volumetric dosimetry (n = 25). Overall survival (OS), progression free survival (PFS), and pelvic control (PC) at 5 years were plotted using Kaplan-Meier curves. Univariate and multivariate (MVA) cox proportional-hazards models calculated hazard-ratios (HZ). Finally, acute and late grade 3-4 toxicities were compared between the cohorts.

RESULTS

Both MRI and CT had significantly less D2cc to bowel (p < 0.001) and sigmoid (p < 0.001) compared to NV-based planning. On MVA, age (<60 vs. ≥60 years) was significant for worse 5-year OS (HZ: 2.48) and PC (HZ: 5.25). MRI, with NV as the reference, had significantly improved 5-year OS (HZ: 0.26), PFS (HZ: 0.34) and PC (HZ: 0.16). There was no significant difference in grade ≥3 toxicities between the cohorts.

CONCLUSIONS

CT and MRI-based 3D planning had significantly less D2cc to bowel and sigmoid. MRI-based planning had significant improvement in 5-year OS, PFS, and LC compared to NV on MVA.

Galalae R. Ultrasound-Guided Brachytherapy for Cervical Cancer - A Tool for Quality Improvement in Brachytherapy?

Nowadays, brachytherapy is one of the major components to treat inoperable cervical cancer. Brachytherapy yields a higher dose to the target (cervix) while sparing normal tissues. Developments of brachytherapy stepped forward in the previous decade by image-guided brachytherapy (IGBT) turning brachytherapy from point-based planning to volume-based planning and IGBT improves the treatment quality for cervical cancer. Magnetic resonance imaging (MRI) or computed tomography (CT) is utilized in brachytherapy and showed promising results internationally. However, in a limited-resource area, the implementation of IGABT is difficult due to many causes (manpower, equipment, or budgets). To improve the quality in limited resources, ultrasound is introduced. The utilization of ultrasound in brachytherapy practice is to prevent uterine perforation during application. With present data, measurement by ultrasound showed the correlation to MRI measurement in uterine dimensions. With these aspects, there are many researches using ultrasound to improve the quality of treatment in brachytherapy, for example, to guide contouring on CT or to support brachytherapy planning. The use of ultrasound improves the quality of brachytherapy in comparison to conventional planning and supports the improvement in brachytherapy for cervical cancer.

Survival outcome of cervical cancer patients treated by image-guided brachytherapy: a 'real world' single center experience in Thailand from 2008 to 2018

The objective of our study was to evaluate the survival outcome of cervical cancer patients treated using image-guided brachytherapy (IGBT). From 2008 to 2018, 341 patients with cervical cancer were treated by radical radiotherapy. IGBT (by computed tomography [CT] or transabdominal ultrasound [TAUS]) was used to treat all of these patients. The characteristic data and patient status after treatment were recorded. All data were evaluated for survival outcome analysis. From a total of 341 patients, 295 patients were analyzed and 46 patients were excluded due to data missing in the survival outcomes. At the median follow-up time of 48 months (IQR 30-80 months), The 4-year local control, progression-free survival and overall survival rates were 89.5%, 74.9% and 69.1%, respectively. For overall survival, the size (> 5 cm), pathology (non-SCCA), stage (stage III-IV by FIGO 2009), lymph node (LN) (presented) and overall treatment time (OTT) (> 56 days) showed statistical significance in univariate analysis while non-SCCA pathology, advanced stage, presented LN and longer OTT showed statistical significance in multivariate analysis. In conclusion, our analysis reports a 4-year overall survival rate of 69.1%. Non-SCCA pathology, advanced stage disease, LN presence and longer OTT showed worse prognostic factors in multivariate analysis.

A novel ultrasound probe calibration method for multimodal image guidance of needle placement in cervical cancer brachytherapy

PURPOSE

Interstitial needles placement is a critical component of combined intracavitary/interstitial (IC/IS) brachytherapy (BT). To ensure precise placement of interstitial needles, we proposed a novel ultrasonic (US) probe calibration method to accurately register the US image in the magnetic resonance imaging (MRI) image and provide multimodal image guidance for needle placement.

METHODS

A wire-based calibration phantom combined with the stylus was developed for the calibration of US probe. The calibration phantom helps to quickly align the imaging plane of the US probe with the fiducial points to obtain US images of these points. The coordinates of fiducial points in US images were located automatically by feature extraction algorithms and were further corrected by the proposed correction method. Ingenious structures were designed on both sides of the calibration phantom to accurately obtain the coordinates of the fiducial points relative to the tracking device. Marker validation and pelvic phantom study were performed to evaluate the accuracy of the proposed calibration method.

RESULTS

In the marker validation, the US probe calibration method with corrected transformation achieves a registration accuracy of 0.694 ± 0.014 mm, and the uncorrected one is 0.746 ± 0.018 mm. In the pelvic phantom study, the needle tip difference was 1.096 ± 0.225 mm and trajectory difference was 1.416 ± 0.284 degrees.

CONCLUSION

The proposed US probe calibration method is helpful to achieve more accurate multimodality image guidance for needle placement.

Salvage image-guided freehand interstitial brachytherapy for pelvic sidewall recurrence after hysterectomy for uterine malignancies

PURPOSE

Pelvic sidewall recurrence after hysterectomy for uterine malignances has a poor prognosis, and the salvage therapy for this type of recurrence is still challenging. The purpose of this study was to investigate the efficacy of freehand high-dose-rate interstitial brachytherapy (HDR-ISBT) through the perineum using transrectal ultrasonography for this disease.

METHODS AND MATERIALS

We retrospectively evaluated 42 patients with pelvic sidewall recurrence after hysterectomy for uterine cervical and endometrial cancers. We investigated patients' characteristics, the 2-year local control and survival rates, and late adverse events of the rectum and bladder.

RESULTS

The 2-year overall survival, local control, and progression-free survival rates were 73.7% (95% confidence interval [CI], 60.8-89.3%), 69.4% (95% CI, 55.4-80.1%), and 37.3% (95% CI, 24.6-56.5%), respectively. In Cox multivariate analysis, tumor size at recurrence (<45 mm vs. ≥45 mm) (p = 0.04) and disease-free periods after hysterectomy (<10 months vs. ≥10 months) (p < 0.01) were significant prognostic factors for overall survival. Lymph node metastasis at recurrence (p < 0.01) was also a significant prognostic factor for progression-free survival. Three patients experienced Grade 3-4 late proctitis (7%).

CONCLUSIONS

Transperineal freehand salvage HDR-ISBT using transrectal ultrasonography was demonstrated to be a curative treatment option for patients with pelvic sidewall recurrence following hysterectomy. Based on the findings of this study, we emphasize the importance of HDR-ISBT for pelvic sidewall recurrence.

Contemporary image-guided cervical cancer brachytherapy: Consensus imaging recommendations from the Society of Abdominal Radiology and the American Brachytherapy Society

PURPOSE

To present recommendations for the use of imaging for evaluation and procedural guidance of brachytherapy for cervical cancer patients.

METHODS

An expert panel comprised of members of the Society of Abdominal Radiology Uterine and Ovarian Cancer Disease Focused Panel and the American Brachytherapy Society jointly assessed the existing literature and provide data-driven guidance on imaging protocol development, interpretation, and reporting.

RESULTS

Image-guidance during applicator implantation reduces rates of uterine perforation by the tandem. Postimplant images may be acquired with radiography, computed tomography (CT), or magnetic resonance imaging (MRI), and CT or MRI are preferred due to a decrease in severe complications. Pre-brachytherapy T2-weighted MRI may be used as a reference for contouring the high-risk clinical target volume (HR-CTV) when CT is used for treatment planning. Reference CT and MRI protocols are provided for reference.

CONCLUSIONS

Image-guided brachytherapy in locally advanced cervical cancer is essential for optimal patient management. Various imaging modalities, including orthogonal radiographs, ultrasound, computed tomography, and magnetic resonance imaging, remain integral to the successful execution of image-guided brachytherapy.

Large volume was associated with increased risk of acute non-hematologic adverse events in the hybrid of intracavitary and interstitial brachytherapy for locally advanced uterine cervical cancer: preliminary results of prospective phase I/II clinical trial

OBJECTIVE

This is the preliminary results of a multi-center prospective clinical trial evaluating the feasibility of the hybrid of intracavitary and interstitial brachytherapy for locally advanced cervical cancer.

METHODS

Patients with FIGO stage IB2, IIA2, IIB, IIIA, IIIB and IVA uterine cervical cancer pretreatment width of which was ≥5 cm measured by MRI were eligible. Protocol therapy consisted of 30-30.6 Gy in 15-17 fractions of whole pelvic radiotherapy concurrent with weekly CDDP, followed by 24 Gy in 4 fractions of hybrid of intracavitary and interstitial and pelvic radiotherapy with central shield up to 50-50.4 Gy in 25-28 fractions. The primary endpoint of phase I part was that the rate of grade ≥ 3 acute non-hematologic adverse events related to hybrid of intracavitary and interstitial would be <10%.

RESULTS

Between October 2015 and October 2019, 74 patients underwent primary registration, with 52 patients eventually proceeding to the secondary registration. The median pretreatment tumor width was 5.7 cm, and FIGO Stages were IB2 10, IIA2 2, IIB 20 and IIIB 20, respectively. The median high-risk clinical target volume D90 was 72.0 Gy (54.8-86.6 Gy, EQD2), rectum D2cc was 53.7 Gy (29.3-80.3 Gy) and bladder D2cc was 69.8 Gy (38.9-84.8 Gy). The rate of grade ≥ 3 non-hematologic adverse events related to hybrid of intracavitary and interstitial was 1.9% (1/52), and 17.3% (9/52) of patients experienced non-hematologic adverse events related to hybrid of intracavitary and interstitial of any grade. In multivariate analysis, high-risk clinical target volume ≥ 35 ml was associated with an increased risk of any grade of acute non-hematologic adverse events related to hybrid of intracavitary and interstitial (P = 0.036).

CONCLUSION

The feasibility and reproducibility of hybrid of intracavitary and interstitial were demonstrated from a multi-center prospective clinical trial.

Clinical Outcomes of MRI-Guided Adaptive Brachytherapy for Each Fraction in Locally Advanced Cervical Cancer: A Single Institution Experience

Purpose

This study aims to evaluate clinical outcomes of MRI-guided adaptive brachytherapy (MR-IGABT) for each brachytherapy fraction in patients with locally advanced cervical cancer (LACC).

Methods and Materials

A retrospective analysis was performed on 97 consecutive patients with LACC treated with 44.0–50.4 Gy external beam radiotherapy (EBRT) ± concurrent platinum-containing chemotherapy followed by 4 × 7 Gy MR-IGABT between September 2014 and April 2019. Intracavitary (IC)/interstitial (IS)/hybrid intracavitary and interstitial (IC/IS) brachytherapy was used in MR-IGABT. Brachytherapy planning and dose reporting followed the GEC-ESTRO recommendations. Clinical outcomes including overall survival (OS), cancer-specific survival (CSS), progression-free survival (PFS), local control (LC), and treatment-related toxicity evaluated by the RTOG criteria were analyzed. Kaplan–Meier and univariable and multivariable Cox regression analyses were used to analyze the prognostic factor.

Results

Median follow-up was 21.1 months. Median dose to 90% (D₉₀) of the high-risk clinical target volume (HR-CTV) was 91.7 Gy (range 76.7~107.2 Gy). Two-year OS, CSS, PFS, and LC were 83.5%, 84.1%, 71.1%, and 94.8%, respectively. Four patients (4.1%) suffered from grade 3 late gastrointestinal radiation toxicity, and no other grade 3 or greater radiation toxicity occurred. Initial HR-CTV was an independent factor of OS (p = 0.001, HR = 1.018/cm³), PFS (p = 0.012, HR = 1.012/cm³), and LC (p = 0.011, HR = 1.028/cm³). The HR-CTV D₉₀ (p = 0.044, HR = 0.923/Gy) was an independent factor of PFS. Age was an independent factor of LC (p = 0.010, HR = 1.111/year).

Conclusion

For patients with LACC, MR-IGABT was effective and safe. It showed favorable LC, OS, and minimal toxicity. Moreover, initial HR-CTV, HR-CTV D₉₀, and age were significant prognostic factors.

Management of stage I and II cervical cancer: a review

In the modern era, cervical cancer treatment has become more multidisciplinary in nature. Accurate and precise staging based on clinical and radiographic findings, as well as identification of pathologic and molecular risk factors, may alter treatment recommendations. Additionally, the body of evidence guiding optimal treatment recommendations continues to grow. Multiple specialists including gynecologic oncologists, radiation oncologists, medical oncologists, radiologists, pathologists, and other ancillary staff, often with subspecialty experience in gynecology or cancer care, now staff multidisciplinary gynecologic oncology teams. This review highlights the basis of multidisciplinary treatment of early-stage cervical cancer, with a focus on surgical interventions, the role of adjuvant therapy, and indications for definitive chemoradiation. We specifically focus on the treatment of cervical cancer from stage IA1 (microinvasive disease) to stage IIB (parametrial involvement without involvement of pelvic sidewall). The staging manuals referenced in this review include the International Federation of Gynecology and Obstetrics (FIGO) 2018 staging as well as the updated American Joint Committee on Cancer (AJCC) 9th edition (2021).

Clinical advantage and outcomes of computed tomography-based transvaginal hybrid brachytherapy performed only by sedation without general or saddle block anesthesia

BACKGROUND

Three-dimensional image-guided brachytherapy is the standard of care in cervical cancer radiotherapy. In addition, the usefulness of the so-called "hybrid brachytherapy (HBT)" has been reported, which involves the addition of needle applicators to conventional intracavitary brachytherapy for interstitial irradiation.

AIM

To evaluate the clinical outcomes of CT-based HBT consisting of transvaginal insertion of needle applicators (CT-based transvaginal HBT) and only intravenous sedation without general or saddle block anesthesia.

METHODS AND RESULTS

This is a retrospective chart review of patients who received definitive radiotherapy, including CT-based transvaginal HBT, between February 2012 and July 2019. The inclusion criteria were as follows: (i) histologically diagnosed disease, (ii) untreated cervical cancer, (iii) International Federation of Gynecology and Obstetrics (FIGO) stage IB1-IVA disease in the 2008 FIGO staging system, and (iv) patients who underwent CT-based transvaginal HBT at least once in a series of intracavitary brachytherapy. Overall, 54 patients fulfilled the eligibility criteria in the present study. The median follow-up period was 32 (IQR, 19-44) months. No patient complained of symptoms such as persistent bleeding or abdominal pain after the treatment. The 3-year local control (LC), disease-free survival, and overall survival rates for all 54 patients were 86.6%, 60.3%, and 90.7% (95% CI [81.3%-100.0%]), respectively. The 3-year LC rate was 87.7% in patients with FIGO III-IVA and 90.4% in tumor size >6.0 cm. The incidence rate of late adverse events, grade ≥3, in the rectum and bladder was 0% and 1.8%, respectively. In the dose-volume histogram analyses, transvaginal HBT increased the dose of HR-CTV_D90 by ~7.5% without significantly increasing the dose of organs at risk.

CONCLUSION

Considering the favorable clinical outcomes, CT-based transvaginal HBT may be a good option for treating cervical cancer.

Laminaria tent insertion in preplanning MRI for CT-based cervical cancer brachytherapy

PURPOSE

Preplanning magnetic resonance imaging (MRI) is routinely used in image-guided adaptive brachytherapy (IGABT) for cervical cancer. However, a preplanning MRI performed without an applicator does not have good accuracy of image fusion with a planning computed tomography (CT) performed with an applicator. This study aimed to evaluate the efficacy of laminaria tent insertion during pre-planning MRI for cervical cancer brachytherapy (BT).

METHODS AND MATERIALS

Sixteen patients with cervical cancer were enrolled in the study. Images obtained from a single preplanning MRI performed with a laminaria tent inserted into the cervix were fused with images from the planning CT performed with an applicator during each BT session. The alignment between the high-risk clinical target volume on MRI (HR-CTVMRI) and planning CT (HR-CTVCT) was assessed. Image fusion accuracy was classified as follows: maximum misalignment between HR-CTVMRI and HR-CTVCT <5 mm was excellent, 5-10 mm as available, and >10 mm as not available. Image fusion accuracy was reviewed by two radiation oncologists.

RESULTS

Fifty-nine BT sessions were analyzed. Fusion images for 39 (66%) sessions were categorized as excellent, and those for the remaining 12 (20%) sessions were available, and 8 (14%) were not available. Complications reported after laminaria tent insertion were grade-1 fever for 5 (8%) BT sessions in 5 patients and grade-1 pain for 8 (13%) sessions in 5 patients.

CONCLUSION

Laminaria tent insertion during pre-planning MRI may improve the accuracy of image fusion with planning CT and may help delineate the HR-CTV in CT-based IGABT for cervical cancer.

High-Dose-Rate Interstitial Brachytherapy for Deeply Situated Gynecologic Tumors Guided by Combination of Transrectal and Transabdominal Ultrasonography: A Technical Note

Background and Purpose

High-dose-rate interstitial brachytherapy (HDR-ISBT) is recommended to obtain a better local tumor control for uterine cancer patients in specific situations such as bulky lesions, an extension to the lateral parametrium, or tumors with irregular shapes. Our group uses real-time transrectal ultrasonography (TRUS) to guide freehand interstitial needle insertion. Occasionally, target tumors locate deeper beyond the rectum and cannot be visualized by TRUS. CT can guide needles to deeply located tumors, but in such cases, repeated image obtainment is required to achieve ideal needle localization. In this report, we present nine cases of patients who underwent HDR-ISBT for deeply situated tumors guided by a combination of transrectal and transabdominal ultrasonography (TR/TA-US).

Material and Methods

Nine uterine cancer patients whose tumors were located deeper than the reach of TRUS and underwent HDR-ISBT guided by TR/TA-US were presented. All nine cases had no distal organ metastasis and underwent external beam radiation therapy (EBRT) to the pelvic region for 45–50.4 Gy in 25–28 fractions followed by boost HDR-ISBT for deeply situated tumors guided by TR/TA-US.

Results

There were seven cervical cancer and two endometrial cancer patients: six with extensive uterine corpus invasion, one cervical cancer with massive pelvic lymph node metastasis, one cervical cancer with postoperative pelvic recurrence, and one with left ovarian direct tumor invasion. The median follow-up period was 15 months (range 3–28 months). The average clinical target volume at the time of first HDR-ISBT was 131 ml (range 44–335 ml). The linear distance from the vaginal entrance to the deepest part of the tumor at first time brachytherapy of nine cases was 14.0 (9.0–17.0) cm. HDR-ISBT dose fractionation was 24–30 Gy in four or five fractions. Seven out of nine cases had no local recurrence in the follow-up period. One had local in-field recurrence 25 months after HDR-ISBT. Another case with carcinosarcoma could not obtain local control and underwent salvage hysterectomy for a residual uterine tumor 11 months after HDR-ISBT. Four cases had extra-field recurrence in lymph nodes or distant organs.

Conclusions

In brachytherapy for gynecologic malignancies, deeply situated tumors located out of reach of TRUS may obtain favorable local control by HDR-ISBT guided with TR/TA-US.

Dosimetric impact of target definition in brachytherapy for cervical cancer – Computed tomography and trans rectal ultrasound versus magnetic resonance imaging

•

This study evaluated the dosimetric impact of target volume delineation in Computed Tomography (CT) with assistance from Trans Rectal Ultrasound (TRUS) as compared to Magnetic Resonance Imaging (MRI) image-based brachytherapy for cervical cancer.

•

No statistically significant systematic difference was found between MRI and CT for target structures.

•

However, considerable variations were seen on individual patient level which needs to be considered during clinical practice, which also needs further investigations.

•

Current findings provide useful information to optimally utilize various imaging modalities for brachytherapy planning.

•

Although, CT + TRUS based delineation of target volume, appear promising, MRI remains the gold standard.

Background and Purpose

Magnetic Resonance Imaging (MRI) based target definition in cervix brachytherapy is limited by its availability, logistics and financial implications, therefore, use of computed tomography (CT) and Trans Rectal UltraSonography (TRUS) has been explored. The current study evaluated the dosimetric impact of CT + TRUS based target volumes as compared to gold standard MRI.

Methods and Materials

Images of patients (n = 21) who underwent TRUS followed by MRI and CT, were delineated with High-Risk Clinical Target Volume in CT (CTV_HR-CT) and in MRI (CTV_HR-MR). CTV_HR-CT was drawn on CT images with TRUS assistance. For each patient, two treatment plans were made, on MRI and CT, followed by fusion and transfer of CTV_HR-MR to the CT images, referred as CTV_HR-MRonCT. The agreement between CTV_HR-MRonCT and CTV_HR-CT was evaluated for dosimetric parameters (D₉₀, D₉₈ and D₅₀; Dose received by 90%, 98% and 50% of the volumes) using Bland-Altman plots, linear regression, and Pearson correlation.

Results

No statistically significant systematic difference was found between MRI and CT. Mean difference (±1.96 SD) of D₉₀, D₉₈ and D₅₀ between CTV_HR-MRonCT and CTV_HR-CT was 2.0, 1.2 and 5.6 Gy respectively. The number of patients who have met the dose constraints of D₉₀ > 85 Gy were 90% and 80% in MR and in CT respectively, others were in the borderline, with a minimum dose of 80 Gy. The mean ± SD dose-difference between MR and CT plans for bladder was significant (5 ± 13 Gy; p = 0.12) for D_0.1cm3, while others were statistically insignificant.

Conclusion

CT + TRUS based delineation of CTV_HR appear promising, provide useful information to optimally utilize for brachytherapy planning, however, MRI remains the gold standard.

Point-Based Brachytherapy in Cervical Cancer With Limited Residual Disease: A Low- and Middle-Income Country Experience in the Era of Magnetic Resonance-Guided Adaptive Brachytherapy

PURPOSE

To evaluate the clinical outcomes in patients with cervical cancer with limited residual disease at brachytherapy (BT) treated with point-based dose prescription.

METHODS

Patients with locally advanced squamous cell carcinoma of the cervix treated with computed tomography (CT)-based intracavitary BT were considered for analysis. Patients with good response to external beam radiotherapy and limited residual disease suitable for intracavitary BT alone were included. Postapplication CT scans were performed before each fraction and individual plans were made for each session. The dose per fraction was 9Gy high dose rate, prescribed to point-A. Two sessions were planned, 1 week apart. The organs at risk were contoured, and cumulative dose-volume histograms were computed. Local control, pelvic control, disease-free survival, and overall survival were evaluated and late toxicities were documented.

RESULTS

Four hundred ninety patients were included. Overall, 79.8% had International Federation of Gynecology and Obstetrics (FIGO) stage IB2 to IIB disease and 20.2% had stage III to IVA disease. Median dose at point A (EQD2_10Gy) was 74.4 Gy (interquartile range [IQR] 72.3-74.5 Gy) and median D_2cc (EQD2_3Gy) for bladder, rectum, and sigmoid were 82.5 Gy (IQR, 65.5-90.8 Gy), 66.5 Gy (IQR, 60.7-75.7 Gy), and 54.1 Gy (IQR, 50.5-77.3 Gy), respectively. At a median follow-up of 62 (IQR, 33-87) months, the 5-year local and pelvic control rates were 90.1% and 88.3%, respectively. The 5-year disease-free survival was 80% and overall survival was 88%. Rates of grade 3-4 bladder and rectosigmoid toxicities were 6.93% and 4.08%, respectively.

CONCLUSION

In patients with limited residual disease at BT, point-based dose prescription with CT planning results in good local control and acceptable toxicity. In a resource-constrained setting, patients may be triaged to receive point-based BT or magnetic resonance imaging–guided adaptive BT depending on the extent of residual disease.

Point-based brachytherapy can be utilized in cervical cancer with limited residual disease after external RT

Comparative dosimetry of brachytherapy treatment planning between a volume-based plan by CT and a point-based plan by TAUS in CT datasets for brachytherapy

Aim:

To evaluate comparative dosimetry of brachytherapy treatment planning between a volume-based plan by computed tomography (CT) and a point-based plan by transabdominal ultrasound (TAUS) in CT datasets for brachytherapy.

Materials and methods:

From 2019 to 2021, 59 different datasets of CT images were collected from 38 patients treated by intracavitary brachytherapy with tandem ovoid or tandem ring applicators. At that time, TAUS was performed to prevent uterine perforation and to evaluate topography of the cervix during application. In volume-based planning by CT, the target dose was used to keep the dose at 90% of high-risk clinical target volume (HR-CTV), to give a dose of at least 7Gy, while in the point-based plan by TAUS, the target dose was used to keep the minimum dose to eight cervix reference points (measured by TAUS), to give a dose of at least 7Gy. The doses to targets and organs at risk were evaluated and compared between volume-based planning by CT and the point-based plan by TAUS.

Results:

Of 59 fractions, a tandem ovoid applicator was used in 48 fractions (81·3%). In the volume-based plan by CT, the mean doses to HR-CTV(D90), intermediate-risk clinical target volume (IR-CTV)(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 7·0, 3·9, 4·9, 2·9 and 3·3 Gy, respectively, while in the point-based plan by TAUS, the mean doses to HR-CTV(D90), IR-CTV(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 8·2, 4·6, 5·9, 3·4 and 3·9 Gy, respectively. The percentages of mean dose differences between TAUS and CT of HR-CTV(D90), IR-CTV(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 17·7, 19·5, 20·5, 19·5, 21·3 and 19·8%, respectively. With the target dose to the point-based plan by TAUS (7 Gy to the cervix reference points), this was close to D98 of HR-CTV with a mean percentage of difference of 0·6%.

Findings:

The point-based plan by TAUS showed higher values to targets and organs at risk than the volume-based plan by CT. With the point-based plan by TAUS, it was close to D98 of HR-CTV.

Quantitative and qualitative application of clinical drawings for image-guided brachytherapy in cervical cancer patients

Purpose

Clinical drawings are integral part of image-guided adaptive brachytherapy (IGABT) of cervical cancer. It was used in EMBRACE study protocol as a useful tool. In our study clinical drawings from EMBRACE study were modified to include scales in all the dimensions for more accurate representation of various tumor related volumes. The aim of the present study was to understand patterns of tumor regression and relationship between gross tumor at diagnosis (GTVD) and high-risk clinical target volume (CTV-T_HR)/intermediate-risk clinical target volume (CTV-T_IR) in brachytherapy (BRT), using modified clinical drawings.

Material and methods

42 cervical cancer patients, staged as FIGO IIB-IIIB according to EMBRACE study, were enrolled. Advanced schematic 3D mapping diagram (3D-MD) in axial, coronal, and sagittal orientations, with a measurement scale (grid with 10 mm distance) for precise assessment and documentation was applied (through MRI at diagnosis and during brachytherapy). Dimensions, including height, width, and thickness as well as volumes (GTVD, CTV-T_HR and CTV-T_IR) were compared both qualitatively and quantitatively.

Results and conclusions

We found qualitative and quantitative correlation of the dimensions of final CTV-T_HR with initial GTVD. Meticulous mapping of tumor volumes can provide useful insights to CTV-T_HR volume during brachytherapy.

Evaluation of tumor response three months after concomitant chemoradiotherapy with high dose rate brachytherapy as a definitive treatment modality for locally advanced cervical cancer

OBJECTIVE

Radiotherapy remains an essential part of the management of locally advanced cervical cancer. Post-treatment surveillance allows for tumor response assessment and early detection of progressive prosecutions or local recurrences that may benefit from salvage treatment. The objective of this work is to assess the effectiveness of this therapeutic modality.

MATERIALS METHODS

This is a retrospective study of 69 patients treated with concomitant radiation chemotherapy followed by high dose rate intracavitary brachytherapy. The tumor response was assessed by gynecologic physical examination at three months after the end of treatment.

RESULTS

Median age of patients is 54.9 years (33-78 years). The most common histological type is squamous cell carcinoma (89.9%). The average dose received during external radiotherapy is 52.2Gy (46-60Gy). The average dose received during brachytherapy is 27.5Gy (18-28Gy). Three months after completion of treatment, 95.6% of patients had complete tumor remission, and only 4.4% had a tumor residue of 1cm.

CONCLUSION

Radiation chemotherapy with brachytherapy allows for improved short-term local control in cervical cancer.

ACR-ABS-ASTRO practice parameter for the performance of radionuclide-based high-dose-rate brachytherapy

PURPOSE

This practice parameter aims to detail the processes, qualifications of personnel, patient selection, equipment, patient and personnel safety, documentation, and quality control and improvement necessary for an HDR brachytherapy program.

METHODS AND MATERIALS

This practice parameter was revised collaboratively by the American College of Radiology (ACR), the American Brachytherapy Society (ABS), and the American Society for Radiation Oncology (ASTRO).

RESULTS

Brachytherapy is a radiotherapeutic modality in which radionuclide or electronic sources are used to deliver a radiation dose at a distance of up to a few centimeters by surface, intracavitary, intraluminal, or interstitial application. Brachytherapy alone or combined with external beam radiotherapy plays an important role in the management and treatment of patients with cancer. High-dose-rate (HDR) brachytherapy uses radionuclides, such as iridium-192, at dose rates of ≥12 Gy/hr to a designated target point or volume, and it is an important treatment for a variety of malignant and benign conditions. Its use allows for application of high doses of radiation to defined target volumes with relative sparing of adjacent critical structures.

CONCLUSIONS

HDR brachytherapy requires detailed attention to personnel, equipment, patient and personnel safety, and continuing staff education. Coordination between the radiation oncologist and treatment planning staff and effective quality assurance procedures are important components of successful HDR brachytherapy programs.

Increasing Demand on Human Capital and Resource Utilization in Radiation Therapy: The Past Decade

PURPOSE

To quantify the change resource utilization in radiation therapy in the context of advancing technologies and techniques over the last decade.

METHODS AND MATERIALS

Prospectively, the time to complete radiation therapy workflow tasks was captured between January 1, 2020, and December 31, 2020. The institutional task workflows are specific to each technique and broadly organized into 4 categories: 3-dimenstional conformal radiation therapy, intensity modulated radiation therapy, volumetric modulated arc therapy simple, and volumetric modulated arc therapy complex. These discipline-specific task times were used to quantify a resource utilization factor, which is the median time taken to complete all tasks for each category divided by the median time for 3-dimensional conformal radiation therapy treatments. Retrospectively, all plans treated between January 1, 2012, and December 31, 2019, were quantified and categorized. The resource factor was applied to determine resource utilization. For context, institutional staffing levels were captured across the same decade for medical dosimetrists, medical physicists, and radiation oncologists.

RESULTS

This analysis includes 30,229 patient plans in the retrospective data set and 4747 patient plans in the prospective data set. This analysis demonstrates that over this period, patient numbers increased by approximately 45%, whereas time-based human resources increased by almost 150%. The resource allocation factors for 3-dimenstional conformal radiation therapy, intensity modulated radiation therapy, volumetric modulated arc therapy simple, and volumetric arc therapy complex were 1.0, 2.4, 2.9, and 4.3, respectively. Across the 3 disciplines, staffing levels increased from 15 to 17 (13%) for medical dosimetrists, from 10 to 13 (30%) for medical physicists, and from 16 to 23 (44%) for radiation oncologists.

CONCLUSIONS

This work demonstrates the increase in resource utilization due to the introduction of advanced technologies and changes in radiation therapy techniques over the past decade. Human resource utilization is the predominant factor and should be considered with increasing patient volume for operational planning.

Advances in External Beam Radiation Therapy and Brachytherapy for Cervical Cancer

The standard of care for the definitive treatment of locoregionally advanced cervical cancer is external beam radiation therapy (EBRT) with concurrent chemotherapy followed by a brachytherapy boost. Historically, EBRT was delivered via a two-dimensional technique based primarily on bony landmarks. This gave way to three-dimensional conformal radiation therapy, which allows for dose calculation and adjustment based on individual tumour and patient anatomy. Further technological advances have established intensity-modulated radiation therapy (IMRT) as a standard treatment modality, given the ability to maintain tumoricidal doses to target volumes while reducing unwanted radiation dose to nearby critical structures, thereby reducing toxicity. Routine image guidance allows for increased confidence in patient alignment prior to treatment, and the ability to visualise the daily position of the targets and organs at risk has been instrumental in allowing safe reductions in treated volumes. Additional EBRT technologies, including proton therapy and stereotactic body radiation therapy, may further improve the therapeutic index. In the realm of brachytherapy, a shift from point-based dose planning to image-guided brachytherapy has been associated with improved local control and reduced toxicity, with additional refinement ongoing. Here we will discuss these advances, the supporting data and future directions.

Adaptive Radiotherapy in the Management of Cervical Cancer: Review of Strategies and Clinical Implementation

The complex and varied motion of the cervix-uterus target during external beam radiotherapy (EBRT) underscores the clinical benefits afforded by adaptive radiotherapy (ART) techniques. These gains have already been realised in the implementation of image-guided adaptive brachytherapy, where adapting to anatomy at each fraction has seen improvements in clinical outcomes and a reduction in treatment toxicity. With regards to EBRT, multiple adaptive strategies have been implemented, including a personalised internal target volume, offline replanning and a plan of the day approach. With technological advances, there is now the ability for real-time online ART using both magnetic resonance imaging and computed tomography-guided imaging. However, multiple challenges remain in the widespread dissemination of ART. This review investigates the ART strategies and their clinical implementation in EBRT delivery for cervical cancer.

IBS-GEC ESTRO-ABS recommendations for CT based contouring in image guided adaptive brachytherapy for cervical cancer

MR Imaging is regarded asthe gold standardfor Image Gudied Adaptive Brachytherapy (IGABT) for cervical cancer. However, its wide applicability is limited by its availability, logistics and financial implications. Use of alternative imaging like CTand Ultrasound (US) for IGABT has been attempted. In order to arrive at a systematic, uniform and international approach for CT based definition and contouring of target structures, GEC ESTRO, IBS and ABS agreed to jointly develop such recommendations based on the concepts and terms as published in the ICRU Report 89. The minimum requirements are clinical examination & documentation, CT or MR imaging at diagnosis and at a minimum, CT imaging with the applicator in place. The recommendations are based on (i) assessment of the GTV at diagnosis and at brachytherapy, (ii) categorizing the response to external radiation into different clinical remission patterns, (iii) defining various clinico-radiological environments and (iv) definition & delineation of a target on CT imaging at the time of brachytherapy with the applicator in situ. CT based target contouring recommendations based on 4 remission categories within 8 defined environments, aim at improving the contouring accuracy for IGABT using CT, US and MRI as available. For each clinico-radiological environment, there is an attempt to minimize the specific uncertainties in order to arrive at the best possible contouring accuracy. Evaluating feasibility & reproducibility, to achieve a benchmark towards a gold standard MR IGABT and further clinical research including outcomes with CT Based IGABT will become the next steps.

Integration of functional imaging in brachytherapy

Functional imaging allows the evaluation of numerous biological properties that could be considered at all steps of the therapeutic management of patients treated with brachytherapy. Indeed, it enables better initial staging of the disease, and some parameters may also be used as predictive biomarkers for treatment response, allowing better selection of patients eligible for brachytherapy. It may also improve the definition of target volumes with the aim of dose escalations by dose-painting. Finally, it could be useful during the follow-up to assess response to treatment. In this review, we report how functional imaging is integrated at the present time during the brachytherapy procedure, and what are its potential future contributions in the main tumour locations where brachytherapy is recommended. Functional imaging has great potential in the contact of brachytherapy, but still, several issues remain to be resolved before integrating it into clinical practice, especially as a biomarker or in dose painting strategies.

Equivalent dose in 2 Gy (EQD2) to pelvic lymph nodes using volume based prescription for three brachytherapy applicators - a dosimetric retrospective analysis

Background

Pelvic lymph node (PLN) metastasis has been included in the FIGO staging, so there is a need to determine the dose contribution from brachytherapy to ascertain the total delivered dose to the pelvic lymph nodes in cervical cancer. The aim of the study was to calculate the equivalent dose in 2 Gy (EQD2) of the pelvic lymph nodes (PLNs) based on volume prescription using three applicators.

Materials and methods

Forty-one patients who had undergone external beam radiotherapy followed by brachytherapy using tandem ovoids (TO), tandem ring (TR) and TO + free hand interstitial needles (TO + FH) applicators were taken for this study. 26 Gy in 4 fractions was prescribed to HRCTV. The external iliac node (ELN), internal iliac node (ILN) and obturator (OBT) were contoured and the median EQD2 of the lymph nodes was calculated.

Results

The median bilateral EQD2 values of ELN were 1.55 Gy (TR), 1.75 Gy (TO), 1.9 Gy (TO + FH), of ILN these were 2.57 Gy (TR), 3.27 Gy (TO), 3.04 Gy (TO + FH), and of OBT these were 3.69 Gy (TR), 4.46 Gy (TO), 4.69 Gy (TO + FH), respectively. The total median EQD2 values of TR, TO and TO + FH were 52.71 Gy, 53.03 Gy, and 53.88-62.73 Gy, respectively.

Conclusion

Our study calculated the median EQD2 to the pelvic lymph nodes using three types of applicators in brachytherapy. This could serve as reference to decide on the EBRT boost dose while treating patients with enlarged pelvic lymph nodes.

MRI-Directed Brachytherapy for Cancer of the Uterine Cervix: A Case Report, Review, and Perspective on the Importance of Widespread Use of This Technological Advance in the United States

Cervical cancer remains a major health challenge in the United States (US), especially among the low socioeconomic and African American populations. The demographics of Mississippi constitute a relatively high percentage of this high-risk population. External beam radiation therapy (EBRT) combined with concurrent chemotherapy and followed by brachytherapy is the gold standard of treatment for stage IB3 through IVA cervical cancer. Arguably, brachytherapy is the most important component of this treatment process. Patterns of Care studies (PCS) and other more recent studies have shown that brachytherapy cannot be omitted or replaced by conventional or image-guided EBRT. The last decade has witnessed the expanding use of image-guided brachytherapy (IGBT). Studies have established the superiority of IGBT over point-based brachytherapy. MRI is associated with superior soft tissue definition compared with CT and is emerging as the new standard of care. The Gynaecological Groupe Européen de Curiethérapie and the European Society for Radiotherapy and Oncology [(GYN) GEC-ESTRO] have recommended that the dose be prescribed to the high-risk clinical target volume (HR-CTV). This volume includes residual tumor present at the time of brachytherapy, the cervix, and any gray areas seen on the scan. The (GYN) GEC-ESTRO has shown that a dose of >8500 cGy delivered in <50 days results in an approximate 10% increase in pelvic control (PC), disease-specific survival, and overall survival (OS) compared to historical controls. The normal tissue toxicity is comparable or better than historical controls as well. This dose, while maintaining normal tissue constraints, may only be achievable with a hybrid intracavitary/interstitial (IC/IS) needle device guided by MRI-based targeting. 

The University of Mississippi Medical Center (UMMC) has initiated an MRI-based cervical brachytherapy program and has treated 18 patients to date; our experience confirms the above findings. In this report, we propose that MRI guidance is necessary and a hybrid IC/IS needle device is required to achieve adequate dose coverages.

Dose rate in the highest irradiation area of the rectum correlates with late rectal complications in patients treated with high-dose-rate computed tomography-based image-guided brachytherapy for cervical cancer

The purpose of this study was to evaluate the effect of dose rate to the rectum on late rectal complications in patients treated with computed tomography (CT)-based image-guided brachytherapy (IGBT) for cervical cancer. The subjects were 142 patients with cervical cancer who underwent Ir-192 high-dose-rate (HDR)-IGBT between March 2012 and January 2018. The dose rate to the rectum was calculated using in-house software. The minimum, mean and maximum effective dose rate (EDR) was calculated for voxels of the rectal volume covered by cumulative doses >D0.1cc, >D2cc, and > D5cc. The average EDR of three to four brachytherapy sessions was calculated (EDR for patients; EDRp). The total dose of the rectum was calculated as the biologically equivalent dose in 2-Gy fractions (EQD2). The associations between EDRp for D0.1cc, D2cc, and D5cc and the respective rectal EQD2 values with late rectal complications were then analyzed. The median follow-up period was 40 months. Patients with rectal complications of ≥Grade 1 received a significantly higher mean EDRp for D0.1cc-5cc and had a greater EQD2 for D0.1cc-5cc. Multivariate analysis was performed using the mean EDRp for D2cc, EQD2 for D2cc, heavy smoking and BMI. Of these four variables, mean EDRp for D2cc (HR = 3.38, p = 0.004) and EQD2 for D2cc (HR = 2.59, p = 0.045) emerged as independent predictors for late rectal complications. In conclusion, mean EDRp and EQD2 were associated with late rectal complications in patients treated with HDR CT-based IGBT for cervical cancer.

Dosimetric feasibility of computed tomography-based image-guided brachytherapy in locally advanced cervical cancer: a Japanese prospective multi-institutional study

The aim of this study was to assess the feasibility of planning dose-volume histogram (DVH) parameters in computed tomography-based 3D image-guided brachytherapy for locally advanced cervical cancer. In a prospective multi-institutional study, 60 patients with stage IIA2-IVA cervical cancer from eight institutions were treated with external beam radiotherapy using central shielding and intracavitary or hybrid (combined intracavitary/interstitial) brachytherapy (HBT). The dose constraints were set as a cumulative linear quadratic equivalent dose (EQD2) of at least 60 Gy for high-risk clinical target volume (HR-CTV) D90, D2cc ≤ 75 Gy for rectum, D2cc ≤ 90 Gy for bladder and D2cc ≤ 75 Gy for sigmoid. The median HR-CTV D90 was 70.0 Gy (range, 62.8-83.7 Gy) in EQD2. The median D2cc of rectum, bladder and sigmoid was 57.1 Gy (range, 39.8-72.1 Gy), 68.9 Gy (range, 46.5-84.9 Gy) and 57.2 Gy (range, 39.2-71.2 Gy) in EQD2, respectively. In 76 of 233 sessions (33%), 23 patients underwent HBT, and the median number of interstitial needles was 2 (range, 1-5). HBT for a bulky HR-CTV (≥40 cm3) significantly improved the HR-CTV D90 compared with intracavitary brachytherapy alone (P = 0.010). All patients fulfilled the dose constrains for target and at risk organs by undergoing HBT in one-third of sessions. We conclude that the planning DVH parameters used in our protocol are clinically feasible.