Ultrasound-guided tandem placement for low-dose-rate brachytherapy in advanced cervical cancer minimizes risk of intraoperative uterine perforation

Brachytherapy: common pitfalls

Gynecologic radiation oncology is a demanding area of oncology requiring expertise in external beam and brachytherapy. Both physicians and physicists are called on to use their full complement of skills to employ state-of-the-art treatments to benefit patients. A wide variety of unusual presentations are frequent in gynecology, and hence, it is necessary to have a number of techniques available to offer the optimal treatments. The heterogeneity of treatments and the rarity of certain gynecological presentations lead to complexity and potential error. We reviewed previous gynecological high dose rate brachytherapy treatment images and plans for patients from the past decade and identified examples of common problems to share with the community. The strategies to prevent or recover from these pitfalls are also presented. With increasing number of applicator choices, it is critical for clinics to follow rigorous commissioning steps to ensure treatment process safety as described. The clinics should consider implementing a thorough on-boarding program and regular hands-on practice as a continuous quality improvement measure. The use of checklists can be invaluable and result in fewer human errors. Gynecological chart rounds that focus on brachytherapy are also encouraged. Lastly, an incident learning system to document small deviations that occur in the process, and a rigorous root cause analysis process could help prevent potential future incidents.

Self-supervised learning for accelerated 3D high-resolution ultrasound imaging

PURPOSE

Ultrasound (US) imaging has been widely used in diagnosis, image-guided intervention, and therapy, where high-quality three-dimensional (3D) images are highly desired from sparsely acquired two-dimensional (2D) images. This study aims to develop a deep learning-based algorithm to reconstruct high-resolution (HR) 3D US images only reliant on the acquired sparsely distributed 2D images.

METHODS

We propose a self-supervised learning framework using cycle-consistent generative adversarial network (cycleGAN), where two independent cycleGAN models are trained with paired original US images and two sets of low-resolution (LR) US images, respectively. The two sets of LR US images are obtained through down-sampling the original US images along the two axes, respectively. In US imaging, in-plane spatial resolution is generally much higher than through-plane resolution. By learning the mapping from down-sampled in-plane LR images to original HR US images, cycleGAN can generate through-plane HR images from original sparely distributed 2D images. Finally, HR 3D US images are reconstructed by combining the generated 2D images from the two cycleGAN models.

RESULTS

The proposed method was assessed on two different datasets. One is automatic breast ultrasound (ABUS) images from 70 breast cancer patients, the other is collected from 45 prostate cancer patients. By applying a spatial resolution enhancement factor of 3 to the breast cases, our proposed method achieved the mean absolute error (MAE) value of 0.90 ± 0.15, the peak signal-to-noise ratio (PSNR) value of 37.88 ± 0.88 dB, and the visual information fidelity (VIF) value of 0.69 ± 0.01, which significantly outperforms bicubic interpolation. Similar performances have been achieved using the enhancement factor of 5 in these breast cases and using the enhancement factors of 5 and 10 in the prostate cases.

CONCLUSIONS

We have proposed and investigated a new deep learning-based algorithm for reconstructing HR 3D US images from sparely acquired 2D images. Significant improvement on through-plane resolution has been achieved by only using the acquired 2D images without any external atlas images. Its self-supervision capability could accelerate HR US imaging.

A new development in ultrasound-compatible gynecologic brachytherapy simulators

PURPOSE

Gynecologic brachytherapy is an essential component in the curative treatment of cervical cancer. With the decline in brachytherapy utilization, gynecologic brachytherapy simulators are being used to provide a mechanism to enhance proficiency-based resident training. However, most models that have been used lack procedural fidelity as they are either repurposed from OB/GYN basic models or from physics phantoms. Therefore, we set out to develop a high-fidelity, ultrasound- and CT-compatible gynecologic brachytherapy training simulator.

METHODS AND MATERIALS

Based on prior experience with gynecologic training simulators on the market, we developed a wish list for an ultrasound-compatible brachytherapy training model. A custom simulator was developed based on an existing pelvic ultrasound trainer. Features included a cervical os and endometrial canal as well as a palpable and hypoechoic cervical tumor.

RESULTS

The model took about 3 months from the initial meeting with the developer to completion. The properties of the material were equivalent to water for ultrasound, CT, and also MRI and the model did not show signs of degradation after multiple tandem insertions.

CONCLUSIONS

A high-fidelity ultrasound-compatible simulator was effectively developed and utilized to improve resident training to perform brachytherapy implants with a derivative benefit in the long term of improving survival for women with advanced gynecologic malignancies through having access to more proficient brachytherapists. Future directions include enhancing the model to allow for repetitive needle insertion and suturing for interstitial training as well as creating variations in anatomy (e.g., retroverted uterus, bulky tumors, etc.) for more advanced technical training.

Radiation Dose in the Uterine Perforation by Tandem in 3-Dimensional Cervical Cancer Brachytherapy

Cervical cancer patients may sometimes experience different types of uterine perforation by a tandem during brachytherapy. The purpose of this study was to address possibly different management strategies regarding different tandem positions from a dosimetry aspect by evaluating radiation doses delivered to organs-at-risk (OAR) in order to help medical professionals handle different types of uterine perforation. Images and dosimetry data in cervical cancer brachytherapy with uterine perforation were reviewed. Uterine perforation was classified into anterior and posterior perforation according to their tandem positions. Radiation doses received by OAR, including D_2cc and D_1cc of the bladder, rectum, and sigmoid colon, were statistically compared with nonperforation. The doses of high-risk clinical target volume (HR-CTV) of cervical tumor and bilateral point A were also compared in order to assure that the plans had not compromised the treatment efficacy. A total of 21 applications were assessed, including 5 with anterior perforation, 4 with posterior perforation, and 12 without perforation. In anterior perforation, the bladder was the only organ that received a significantly increased dose about 30% at D_2cc and D_1cc. However, in posterior perforation, multiple OAR received significantly excessive doses: approximately 30% for the bladder, 37% for the rectum, and 100% for the sigmoid colon. The OAR dose assessment was based on a statistically equivalent cervical tumor dose. Different management strategies are possible for anterior vs posterior perforation during brachytherapy due to different detrimental extents on OAR dosimetry. The bladder warrants more attention in anterior perforation, without compromising target coverage in treatment planning. On the other hand, repositioning may be considered in posterior perforation due to relatively massive OAR detriments. This concept is a new one and is given for the first time.

Off-line magnetic resonance imaging navigation of cervix cancer brachytherapy in patients with risk factors for uterine perforation

Purpose

There are no reports on pre-insertion identification of cervix cancer patients at risk for uterine perforation during brachytherapy (BT). Our aim was to assess the incidence of risk factors in our patient cohort, and assess feasibility of a novel technique of magnetic resonance imaging (MRI)-guided navigation for applicator insertion (NAI) in high-risk cases.

Material and methods

All patients with locally advanced cervical cancer, treated with image guided adaptive BT at our department between October 2013 and June 2017 were considered for analysis. Tumor characteristics on initial MRI (MRI_initial), pre-BT MRI (MRI_pre-BT), and BT MRI (MRI_BT) were assessed. Frequency of risk factors (age above 60 years, retroverted/retroflected uterus, tumor necrosis, non-visible cervical orifice, distorted cervical canal) was recorded. Patients with two or more factors underwent MRI guided NAI. Time needed for NAI was estimated and procedure feasibility score assigned using a three-tiered scoring system.

Results

Twenty-seven patients (98 insertions) were included. Mean tumor volume was 70.2 (± 47.9), 17.8 (± 18.9), and 10.3 (± 9.1) cm³ on MRI_initial, MRI_pre-BT, and MRI_BT1, respectively (p < 0.05). In 16 (59%) cases, ≥ 1 perforation risk factor was found on MRI_pre-BT: distorted canal in 12 (44%), necrosis in 9 (33%), retroverted/retroflected uterus in 8 (30%) cases. Nine (33%) patients had ≥ 2 risk factors and underwent MRI guided NAI. Additional time to perform NAI was estimated at 105 minutes, and feasibility score was 1 in all cases. There were no cases of uterine perforation.

Conclusions

Using pre-insertion MRI, we found ≥ 2 risk factors for uterine perforation in 1/3 of patients. Off-line MRI navigation was feasible and enabled non-complicated insertion in all cases. Further studies with larger sample size are warranted to assess its clinical efficacy.

Intraoperative sonographic guidance for intracavitary brachytherapy of cervical cancer

BACKGROUND

To describe the role and benefits of intraoperative sonographic (US) guidance in intracavitary brachytherapy of cervical cancer.

METHODS

The data of 142 patients who received tandem-based intracavitary brachytherapy for cervical cancer between January 2010 and June 2015 were retrospectively reviewed. US guidance was carried out for tandem selection and appropriate application. The complications and applicator conformity were assessed with planning CT.

RESULTS

Intracavitary brachytherapy was performed under US guidance for 412 insertions in 113 consecutive patients with cervical cancer. Before we started to use US guidance, applications were done in 29 patients: uterine perforation occurred in two patients (6.9%), the tandem length was short in two patients (6.9%), the tandem length was long in four patients (13.8%), and tandem was in myometrium in three patients (10.3%). We then decided to use US guidance routinely. With US guidance, only 1 of 113 patients had uterine perforation (0.9%), tandem length was short in only one patient (0.9%), and tandem was in myometrium in one patient (0.9%).

CONCLUSIONS

Real-time US provided safe and effective guidance for intracavitary brachytherapy of cervical cancer resulting in decreased rates of perforations and misplacement of applicators. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 46:8-13, 2018.

Routine use of ultrasound guided tandem placement in intracavitary brachytherapy for the treatment of cervical cancer - a South Indian institutional experience

PURPOSE

Intracavitary brachytherapy necessitates the insertion of a tandem applicator through the cervical os into the uterine cavity. Blind insertion of the tandem may result in suboptimal tandem placement. This decreases the control of the tumor locally and may result in uterine perforation. Although routine real time ultrasound guided tandem placement has shown better results, it is seldom practised. The aim of this work is to evaluate the role of routine real-time intraoperative trans-abdominal ultrasound guided tandem placement in intracavitary brachytherapy for the treatment of cervical cancer.

MATERIAL AND METHODS

This is a prospective single institutional study conducted from April 2013 to May 2015. A total of 96 patients of locally advanced cervical cancer were treated with routine ultrasound guided brachytherapy amounting to a total of 282 intracavitary applications.

RESULTS

In 78 of the study patients, the cervical os could be easily identified visually, which was then confirmed with ultrasound guidance. In another 12 patients, though the os could be identified visually, uterine sounding was only possible under ultrasound guidance. In another 4 patients, the cervical os could not be identified visually as the cervix was flushed with vagina and ultrasound guidance was necessary for accurate os identification. In 2 of the study patients, intraoperative ultrasound helped in identifying the patients suitable for interstitial brachytherapy rather than intracavitary brachytherapy. Out of the 96 study patients, the length of the uterine canal changed in 15 patients during the subsequent brachytherapy application.

CONCLUSIONS

This procedure is strongly advocated for proper placement of the tandem applicator and to avoid perforations. It is an accurate, fast, easily available, and cost-effective method. Hence, it can be incorporated in intracavitary applications for cervical cancers even in the developing countries where cost, accessibility, and time are important issues.

Uterine perforation and its dosimetric implications in cervical cancer high-dose-rate brachytherapy

Purpose

To retrospectively assess the incidence of sub-serosal and uterine perforation of intra-uterine tandem in intracavitary high-dose-rate (HDR) brachytherapy for cervical cancer, and to evaluate its dosimetric implications on computed tomography (CT)-based treatment planning.

Material and methods

Computed tomography images and brachytherapy plans of cervical cancer patients treated from February 2006 to December 2012 were reviewed for sub-optimal implants (sub-serosal and uterine perforation), and their correlation with cancer FIGO stage and patients’ age. For each patient, the plans showing sub-optimal insertion of intra-uterine tandem were analyzed and compared to plans with adequate insertion. The difference in dose coverage of clinical-target-volume (CTV) and variation of the dose delivered to organs-at-risk (OARs) rectum and bladder were evaluated.

Results

A total of 231 brachytherapy plans for 82 patients were reviewed. We identified 12 (14.6%) patients and 14 (6%) applications with uterine perforation, and 12 (14.6%) patients and 20 (8.6%) applications with sub-serosal insertion of tandem. Data analysis showed that advanced stage correlates with higher incidence of sub-optimal implants (p = 0.005) but not the age (p = 0.18). Dose-volume-histograms (DVHs) analysis showed large variations for CTV dose coverage: D₉₀ significantly decreased with average of –115.7% ± 134.9% for uterine perforation and –65.2% ± 82.8% for sub-serosal insertion (p = 0.025). The rectum and bladder dose assessed by D_2cc increased up to 70.3% and 43.8%, respectively, when sub-optimal insertion of uterine tandem occurred.

Conclusions

We report a low incidence of uterine perforation and sub-serosal insertion of uterine tandem in intracavitary HDR brachytherapy for cervical cancer. However, the effects on treatment plan dosimetry can be considerably detrimental. Therefore, we recommend image-guided insertion, at least for the challenging cases.

Construction of multifunctional organic–inorganic hybrid Bi2S3–PLGA capsules for highly efficient ultrasound-guided radiosensitization of brachytherapy

A novel multifunctional Bi₂S₃–PLGA capsule has been designed and synthesized for significantly enhancing the therapeutic efficiency of cancer brachytherapy.

A review of recent developments in image-guided radiation therapy in cervix cancer

Brachytherapy is an essential part of radiotherapy treatment for cervical cancer. Over the decades, it has evolved from manual loading of radium and caesium to remote after-loaders and from low-dose and medium-dose rates to high-dose rates. Over the past 10 years, 3D image-based Brachytherapy has evolved and established itself as the gold standard, improving local control and overall survival, and significantly reducing toxicity. In this article, we review some of the available literature on gynaecologic brachytherapy, more specifically on topics such as dose rates, high-dose-rate/pulsed-dose-rate (HDR/PDR) brachytherapy and image-based brachytherapy (IBBT), and present some of the evidence that establishes IBBT.

Intraoperative Ultrasound Guidance During Intracavitary Brachytherapy Applicator Placement in Cervical Cancer: The University of Alabama at Birmingham Experience

Objective

The objective of this study was to evaluate the University of Alabama at Birmingham experience with routine intraoperative ultrasound (IUS)–guided tandem placement for cervical cancer.

Methods

Between 1999 and 2008, 243 cervical cancer patients underwent IUS-guided tandem placement. One hundred thirty-nine patients received low-dose-rate brachytherapy, and 104 received high-dose-rate brachytherapy. Three hundred fifty-six IUS-guided procedures were performed. Clinical and imaging data were retrospectively analyzed to evaluate complications requiring reinsertion of tandem placement in the context of IUS.

Results

All 243 cervical cancer patients completed intracavitary brachytherapy. Five (1.4%) of 356 IUS-guided applicator placements resulted in uterine perforation. All of these patients underwent successful tandem insertion on the second attempt, and no significant clinical sequelae occurred. Intraoperative ultrasound enabled direct uterine visualization and facilitated real-time feedback for selection of a suitable tandem length and curvature; no suboptimal placements requiring return to the operating room occurred (excluding perforation).

Conclusions

In this large series, IUS guidance substantially increased the rate of successful applicator placement and diminished the rate of uterine perforation relative to historical controls. We strongly recommend the use of IUS guidance during operative intrauterine tandem placement for cervical cancer.

The Role of Transabdominal Sonography in Facilitating Successful Brachytherapy Outcomes in Cervical Cancer

Radiation is a standard of care in the treatment of locally advanced cervical cancer. Radiation consists of external beam radiation and brachytherapy to optimize local control and cure. High-dose-rate (HDR) brachytherapy is most commonly used in the United States. Advantages of HDR are outpatient treatment, elimination of exposure to medical staff, patient convenience, and the ability to modify the treatment because multiple fractions are used. Accurate placement of the tandem in the uterus is critical to maximize tumor control and minimize complications. Transabdominal sonography offers real-time imaging of the tandem placement, which allows the radiation oncologist to adjust the tandem position, thus ensuring correct dosimetry and treatment. This article discusses the etiology, diagnosis, and treatment of cervical cancer. This article further explains the importance of the brachytherapy technique, the role of transabdominal sonography, and how both can lead to a successful outcome for the patient.