American Brachytherapy Society consensus guidelines for locally advanced carcinoma of the cervix. Part I: general principles

Intraoperative 360-deg three-dimensional transvaginal ultrasound during needle insertions for high-dose-rate transperineal interstitial gynecologic brachytherapy of vaginal tumors

Brachytherapy, a type of radiotherapy, may be used to place radioactive sources into or in close proximity to tumors, providing a method for conformally escalating dose in the tumor and the local area surrounding the malignancy. High-dose-rate interstitial brachytherapy of vaginal tumors requires precise placement of multiple needles through holes in a plastic perineal template to deliver treatment while optimizing dose and avoiding overexposure of nearby organs at risk (OARs). Despite the importance of needle placement, image guidance for adaptive, intraoperative needle visualization, allowing misdirected needles to be identified and corrected during insertion, is not standard practice. We have developed a 360-deg three-dimensional (3-D) transvaginal ultrasound (TVUS) system using a conventional probe with a template-compatible custom sonolucent vaginal cylinder and propose its use for intraoperative needle guidance during interstitial gynecologic brachytherapy. We describe the 3-D TVUS mechanism and geometric validation, present mock phantom procedure results, and report on needle localization accuracy in patients. For the six patients imaged, landmark anatomical features and all needles were clearly visible. The implementation of 360-deg 3-D TVUS through a sonolucent vaginal cylinder provides a technique for visualizing needles and OARs intraoperatively during interstitial gynecologic brachytherapy, enabling implants to be assessed and providing the potential for image guidance.

A hybrid technique of intracavitary and interstitial brachytherapy for locally advanced cervical cancer: initial outcomes of a single-institute experience

BACKGROUND

Locally advanced uterine cervical cancer (LAUCC) with lateral tumor extension may not always be covered adequately by conventional intracavitary brachytherapy (ICBT). Hybrid intracavitary and interstitial brachytherapy (HBT) seems to be an effective alternative by improving anatomy-oriented dose optimisation. The purpose of this study was to report initial clinical result for LAUCC treated by HBT.

METHODS

Between January 2012 and November 2015, 42 patients with LAUCC (T1b2-4a) were treated with primary radiation therapy including HBT. Patients with distant metastasis other than para-aortic lymph node spread were excluded from this study. A retrospective analysis was performed for toxicity evaluation and oncological outcome calculation.

RESULTS

Median follow-up was 23.2 months (range 13.2-71.4). Two-year overall survival, progression free survival, and local control rate were 81.6, 54.4, and 80.2%, respectively. Seven patients experienced local recurrence (16.6%). Of those, five were confined to the uterus and two at the parametria. Late adverse events ≥ grade 3 were seen in 3 patients.

CONCLUSIONS

HBT can generate favorable local control in tumors which cannot be adequately covered by ICBT.

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.

Radiotherapy for isolated recurrent epithelial ovarian cancer: A single institutional experience

AIM

To evaluate the efficacy and toxicity of external beam radiotherapy (RT) for isolated recurrent epithelial ovarian cancer (EOC).

METHODS

Twenty-four isolated recurrent EOC patients treated with RT at Osaka University Hospital between January 2000 and January 2017 were included in the current study. Data regarding the primary or recurrent diseases, follow-up findings, and efficacy or toxicities of RT were collected and retrospectively analyzed. Survival rates were calculated using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

Their median age was 59 years. Most patients had International Federation of Gynecology and Obstetrics stage III-IV diseases at the initial diagnosis. Histologically, serous adenocarcinoma was predominant, followed by clear cell adenocarcinoma. All patients had received at least one regimen of platinum-based chemotherapy; 8 were platinum-sensitive relapse and the others were platinum-resistant. Lymph nodes were the most common sites of recurrence, and the median tumor size was 25.5 mm. The median total dose of RT administered was 54 Gy, with a median daily dose of 2 Gy. RT was well-tolerated, and no patients experienced Grade 3/4 toxicities. The in-field overall response rate was 58.3% (14/24), the median regression rate was -40.2% (range: -100 to 0) and the median survival period after RT was 17 months. The 1-year survival and local progression-free survival rates after RT were 66.7% and 45.8%, respectively.

CONCLUSION

RT showed significant antitumor effect against isolated recurrent EOC without causing severe toxicities. Prospective studies with sufficient statistical power are warranted to further evaluate the role of RT in this patient population.

Implementation of radiation therapist cylinder insertion for vaginal vault brachytherapy

Vaginal vault brachytherapy is a common treatment for endometrial cancer. Historically, applicator insertion has been the domain of a radiation oncologist (RO). This commentary outlines a project to improve efficiency and workforce utilisation by introducing a competency framework and training module allowing entitled radiation therapists to perform single‐channel cylinder applicator insertions and treatment delivery under RO supervision for fraction one and without supervision for subsequent fractions. The rationale, relevant regulations, implementation process and barriers are explored.

A dosimetric comparison between applicators used for brachytherapy in carcinoma cervix - A single-institute prospective study

INTRODUCTION

Cervical cancer is the second most common cancer among Indian women. Radical radiotherapy with external beam radiation therapy (EBRT) and brachytherapy is the standard treatment for FIGO stage IB2 to IVA. An appropriate selection of brachytherapy applicator is needed according to the patient's anatomy. The two most commonly used applicators for intracavitary radiotherapy (ICR), Fletcher's and Henschke, have dosimetric differences which are not well studied with two-dimensional (2D)-based planning which is the most common method used for women with carcinoma cervix in India. The purpose of our study was to compare and evaluate the dosimetric differences between these two applicators, which would help in better selection of the applicator in cervical cancer patients.

MATERIALS AND METHODS

This is a single-institute prospective study. Fifty patients randomly included in the study received EBRT and ICR by Ir192 HDR remote afterloading technique with computer-based 2D planning. Fletcher's and Henschke applicators were used alternately for first two fractions.

RESULTS

The results of the study showed lower bladder and rectal doses with Fletcher's applicator and similar doses to point A for both applicators. However, point B doses are lower with Fletcher's applicator.

CONCLUSION

Our results showed a favorable dosimetry with Fletcher's applicator in ICR of carcinoma cervix. The feasibility of placement is much better for Henschke but dosimetric advantages of Fletcher's encourage use of Fletcher's applicator for patients with favorable anatomy to reduce organs at risk doses but with the disadvantage of lower dose to point B.

Radiation therapy for elderly patients with uterine cervical cancer: feasibility of curative treatment

As the average lifespan lengthens worldwide, and the older adult population increases, the number of elderly patients with uterine cervical cancer is increasing. Because intensive and invasive treatments, including surgery, are frequently unacceptable in elderly patients, cancer treatments for these patients must be carefully considered. Elderly patients have undergone radiation therapy as less-invasive curative treatment, and it has been shown to be safe and effective for local control of cervical cancer in this population, even among patients aged ≥80 years treated with curative radiation doses. Although concurrent chemoradiotherapy is the standard treatment for locally advanced cervical cancer, it is unclear whether the addition of chemotherapy to radiation therapy prolongs survival in elderly patients. Elderly patients treated with curative radiation therapy for cervical cancer might develop more therapy-related gastrointestinal and hematological toxicities and insufficiency fractures compared with younger patients. However, advanced techniques of radiation therapy (eg, intensity-modulated radiation therapy and volumetric modulated arc therapy with photons, charged-particle radiation therapy with protons and carbon ions in external-beam radiation therapy, and image-guided adaptive brachytherapy) can minimize radiation-induced toxicities and thus make curative treatment safer and more effective for elderly patients with uterine cervical cancer.

Management for locally advanced cervical cancer: new trends and controversial issues

This article reviewed new trends and controversial issues, including the intensification of chemotherapy and recent brachytherapy (BT) advances, and also reviewed recent consensuses from different societies on the management of locally advanced cervical cancer (LACC). Intensive chemotherapy during and after radiation therapy (RT) was not recommended as a standard treatment due to severe toxicities reported by several studies. The use of positron emission tomography-computed tomography (PET-CT) and magnetic resonance imaging (MRI) for pelvic RT planning has increased the clinical utilization of intensity-modulated radiation therapy (IMRT) for the evaluation of pelvic lymph node metastasis and pelvic bone marrow. Recent RT techniques for LACC patients mainly aim to minimize toxicities by sparing the normal bladder and rectum tissues and shortening the overall treatment time by administering a simultaneous integrated boost for metastatic pelvic lymph node in pelvic IMRT followed by MRI-based image guided adaptive BT.

Preliminary report of a single-channel applicator in high dose rate afterloading brachytherapy for cervical cancer

The aim of this study was to evaluate whether a patented single‐channel applicator, which was modified from the traditional tandem applicator and wrapped with an oval‐shield alloy around the source channel, has the same clinical efficacy and safety as the standard Fletcher‐type applicator in high dose rate (HDR) brachytherapy for carcinoma of the cervix. Between December 2011 and February 2017, 299 patients with pathologically confirmed International Federation of Gynecology and Obstetrics (2009) stage Ib2‐IVa cervical cancer were recruited to the trial and finished the allocated intervention. Of the first 151 patients, 71 were allocated to the Fletcher group and 80 to the single‐channel group, satisfying the criteria for a preliminary analysis. All but 3 patients were treated with concurrent cisplatin chemotherapy and external beam radiotherapy followed by HDR brachytherapy. The 2‐year overall survival, progression‐free survival, and locoregional failure‐free survival was 80.3%, 77.5%, and 78.9%, respectively, for the Fletcher group, and 86.3%, 82.5%, and 83.8%, respectively, for the single‐channel group. The seriousness of acute treatment‐related toxicities was similar in the 2 groups. The cumulative rate of late rectal complications of grade 3‐4 in the Fletcher group and the single‐channel group was 2.8% and 2.5%, respectively. The cumulative rate of grade 3 bladder complications was 2.8% for the Fletcher group and 1.3% for the single‐channel group. The preliminary results of our study show that the patented single‐channel intracavitary applicator might be able to provide protection for the rectum and bladder and seems to have the same clinical efficacy as the standard Fletcher‐type 3‐channel applicator in HDR brachytherapy for carcinoma of the cervix. This trial was registered with the Chinese Clinical Trial Registry (registration no. ChiCTR‐TRC‐12002321).

Review of strategies for MRI based reconstruction of endocavitary and interstitial applicators in brachytherapy of cervical cancer

Brachytherapy plays an essential role in the curative intent management of locally advanced cervical cancer. The introduction of the magnetic resonance (MR) as a preferred image modality and the development of new type of applicators with interstitial components have further improved its benefits. The aim of this work is to review the current status of one important aspect in the cervix cancer brachytherapy procedure, namely catheter reconstruction. MR compatible intracavitary and interstitial applicators are described. Considerations about the use of MR imaging (MRI) regarding appropriate strategies for applicator reconstruction, technical requirements, MR sequences, patient preparation and applicator commissioning are included. It is recommendable to perform the reconstruction process in the same image study employed by the physician for contouring, that is, T2 weighted (T2W) sequences. Nevertheless, a clear identification of the source path inside the catheters and the applicators is a challenge when using exclusively T2W sequences. For the intracavitary component of the implant, sometimes the catheters may be filled with some substance that produces a high intensity signal on MRI. However, this strategy is not feasible for plastic tubes or titanium needles, which, moreover, induce magnetic susceptibility artifacts. In these situations, the use of applicator libraries available in the treatment planning system (TPS) is useful, since they not only include accurate geometrical models of the intracavitary applicators, but also recent developments have made possible the implementation of the interstitial component. Another strategy to improve the reconstruction process is based on the incorporation of MR markers, such as small pellets, to be used as anchor points. Many institutions employ computed tomography (CT) as a supporting image modality. The registration of CT and MR image sets should be carefully performed, and its uncertainty previously assessed. Besides, an important research work is being carried out regarding the use of ultrasound and electromagnetic tracking technologies.

Dosimetric impact of interfractional organs at risk variation during high-dose rate interstitial brachytherapy for gynecologic malignancies

We sought to develop a framework for the identification and management of patients at risk for organs at risk (OARs) overdosing due to interfractional anatomic variation during high-dose rate interstitial brachytherapy for gynecologic malignancies. We analyzed 40 high-dose rate interstitial brachytherapy fractions from 10 patients. Planned OAR doses were compared to delivered doses, which were calculated from computed tomography scans obtained prior to each treatment fraction. Doses were converted to equivalent doses in 2 Gy fractions (EQD2) and doses to the most exposed 2 cm³ (D_2cc) were reviewed. Patients were risk-stratified by identifying dose thresholds corresponding to a 10% or lower risk of receiving an OAR dose exceeding the corresponding planning constraint. For each OAR, 30% to 62.5% of patients received total doses greater than planned, although the magnitude of these differences was <4 Gy in over 75% of cases. Using EMBRACE II guidelines, one patient who had met the planning constraint for bladder and one for small bowel were found to have received doses exceeding the recommended limits. We next calculated thresholds for estimating the risk of OAR overdosing in individual patients and developed a framework based on these thresholds to direct time- and resource-intensive imaging and replanning efforts toward patients who are most likely to derive benefit. In summary, differential OAR dosing due to interfractional anatomic variation is common but likely rarely clinically meaningful. The proposed framework could decrease toxicity and maximize clinical efficiency.

Interfraction Variation and Dosimetric Changes in Patients With Cervical Cancer Treated With Intracavitary Brachytherapy

PURPOSE

Intracavitary brachytherapy is integral in the treatment of cervical cancer. Because of interfraction variation, the current standard is replanning with every fraction. This study aimed to determine whether there was a difference in relative dosimetry if the source position and dwell time of the first fraction were applied to subsequent fractions.

MATERIALS AND METHODS

The authors performed a retrospective review of charts and films from 2007 to 2012. Eligible cases were patients with cervical cancer treated with brachytherapy with the same dose prescription to point A. Replanning was done on the first set of orthogonal plates. Source position and dwell time were subsequently applied to the remaining fractions using actual films.

RESULTS

Twenty-nine patients were included in this study. The results showed that cervical, rectal, and bladder dose between the actual plan and the hypothetical plan were not statistically different. In the hypothetical plan, the source activity and dwell time of the first plan were applied to the orthogonal films of the subsequent fractions and showed no significant difference in all dose points.

CONCLUSION

The results of this study showed proof of concept of the safety of using the source position and dwell time of the first plan for subsequent fractions. Until further studies are performed (also using three-dimensional planning software), the concept should be considered investigational because of the small sample size of the study. Until such research is performed, it is still strongly recommended that replanning be performed with every fraction whenever it is feasible.

Bleeding after interstitial brachytherapy for cervical cancer requiring embolization

Cervical cancer is the third most common cancer among women worldwide and is usually managed with chemoradiation in advanced disease. This case presents a 41-year-old female with locally advanced cervical cancer who underwent combination intracavitary/interstitial brachytherapy after chemoradiation for local disease control. At her fifth brachytherapy session, one of the interstitial needles was malpositioned and lead to vascular injury with significant blood loss. She subsequently underwent emergent embolization of a branch of the right obturator artery with immediate clinical improvement and no complications. This is the first reported case of vascular injury from an interstitial brachytherapy needle that required arterial embolization for hemostasis.

Treatment-Related Radiation Toxicity Among Cervical Cancer Patients

Objective

The purpose of this study is to identify incidence of and factors associated with severe late toxicity in women treated with radiation for cervical cancer.

Materials and Methods

All patients with cervical cancer treated with radiation as primary or adjuvant therapy from 2005 to 2017 in a single academic institution were included. Records were reviewed for demographic information, Charlson Comorbidity Index, treatment details, toxicities, and outcomes. Patients with and those without severe late gastrointestinal toxicity (SLGIT), severe late genitourinary toxicity (SLGUT), or any SLGIT or SLGUT, defined as any toxicity (AT), were compared. Overall survival and progression-free survival were also compared.

Results

Of 179 patients identified, 21.2% had AT, 17.3% had SLGIT, and 10% had SLGUT. Estimated AT rate at 3 years was 24.2%. The mean duration of follow-up was 37 months (range, 3–146 months). Most patients (84.1%) received 3-dimensional conformal therapy, and 15.9% received intensity-modulated radiation therapy. Factors associated with AT were lower body mass index (24.9 vs 28.3, P = 0.043), white race (63.2% vs 44%, P = 0.035), and active tobacco smoking during treatment (59.5% vs 40.2%, P = 0.036). Any toxicity was not associated with 3-dimensional versus intensity-modulated radiation therapy planning, low-dose versus high-dose–rate brachytherapy or time to complete radiation treatment. Higher total cumulative radiation dose to clinical target volume was associated with SLGIT. Progression-free survival and overall survival were similar among patients with AT compared to those without toxicity.

Conclusions

In patients with cervical cancer, radiation toxicity is correlated with lower body mass index, white race, and smoking. Despite technologic advances in radiotherapy planning and delivery, toxicity remains high and interventions to reduce the burden of treatment are needed.

Early Clinical Outcomes, Patterns of Failure, and Acute Haematologic Toxicity of Image-Guided Volumetric Modulated Arc Therapy (IG-VMAT) in the Definitive Treatment of Locally Advanced Carcinoma Cervix

Purpose:

To evaluate clinical outcomes and failure patterns in patients with locally advanced cervical cancer (LACC) treated definitively using image-guided volumetric-modulated arc therapy (IG-VMAT).

Methods and materials:

This retrospective review included 18 consecutively treated patients with LACC. Treatment consisted of IG-VMAT and concurrent chemotherapy followed by intracavitary radiotherapy. The primary end points were overall survival (OS) and disease-free survival (DFS). Acute haematologic toxicity was evaluated using Radiation Therapy Oncology Group (RTOG) criteria.

Results:

A total of 16 patients were either stage IIB or IIIB and the median follow-up was 30.5 months (interquartile range: 13-36.25 months). The 2-year DFS was 63.3% (95% confidence interval [CI]: 52.8%-72.4%) and 2-year OS was 72.2% (95% CI: 62.1%-80.5%). There were 7 treatment failures, predominantly in-field. Acute haematologic toxicity was low.

Conclusions:

IG-VMAT is associated with favourable outcomes for patients with LACC.

The experiences of women receiving brachytherapy for cervical cancer: A systematic literature review

OBJECTIVES

To determine women's experiences of brachytherapy for cervical cancer.

KEY FINDINGS

Nineteen studies were included for data extraction/synthesis. Twelve studies focussed on psychological issues, seven on pharmacological aspects of women's experiences. Themes of anxiety, distress, pain, informational needs and non-pharmacological interventions were found. Nine out of ten psychological studies described brachytherapy as a distressing experience causing anxiety and distress for most women. Non-pharmacological interventions were found to be effective and inexpensive adjuncts. Peri and post-operative pharmacological management was variable, but duration of procedure was an important factor.

CONCLUSION

Brachytherapy for gynaecological cancer causes varying levels of pain, anxiety and distress. To improve women's experiences there needs to be better pain management, patient information and the development of non-pharmacological interventions. Future recommendations are to develop clinical support guidelines, audit the quality of services and develop effective interventions to improve women's experiences of brachytherapy for locally advanced cervical cancer.

High dose-rate tandem and ovoid brachytherapy in cervical cancer: dosimetric predictors of adverse events

Background

Brachytherapy (BT) is a vital component of the curative treatment of locally advanced cervical cancer. The American Brachytherapy Society has published guidelines for high dose rate (HDR) BT with recommended dose limits. However, recent reports suggest lower doses may be needed to avoid toxicity. The purpose of this study is to investigate incidence and predictive factors influencing gastrointestinal (GI) and genitourinary (GU) toxicity following HDR intracavitary brachytherapy for locally advanced cervical cancer.

Methods

We retrospectively evaluated a cohort of patients with locally advanced cervical cancer who received CT-based HDR BT. Cumulative doses were calculated using the linear-quadratic model. Statistical analyses were used to investigate clinical and dosimetric predictors of GI and GU toxicity following HDR brachytherapy according to CTCAE v4.0 grading criteria.

Results

Fifty-six women with FIGO IB1 – IVA cervical cancer were included. The overall rate of any GU adverse event (Grade 1+) was 23.3% (n = 13) and severe adverse events (Grade 3+) was 7.1% (n = 4). Of those, the bladder equivalent dose in 2- Gray (Gy) fractions (EQD₂) D_2cc was ≥80 for three of the four patients. The overall rate of any GI adverse event was 26.8% (n = 15) and the rate of severe adverse events was 14.3% (n = 8). Of those, six of the eight patients had a rectal EQD₂ D_2cc ≥ 65 Gy and seven patients had a sigmoid D2cc ≥ 65 Gy. Amongst clinically meaningful factors for development of adverse events (i.e. diabetes, smoking status, ovoid size, and treatment duration), there were no statistically significant prognostic factors identified.

Conclusions

Severe adverse events are observed even with adherence to current ABS guidelines. In the era of recent multi-institutional study results, our data also supports more stringent dosimetric goals. We suggest cumulative D2cc dose limits of: less than 80 Gy for the bladder and less than 65 Gy for the rectum and sigmoid.

Integration of MRI target delineation into rapid workflow cervical cancer brachytherapy: Impact on clinical outcomes

INTRODUCTION

We evaluated the impact of MRI-based target delineation on toxicity and tumour control after implementation of a protocol to incorporate MRI while minimizing impact on overall procedural time.

METHODS

We retrospectively reviewed outcomes for a cohort of 96 consecutive patients who received intracavitary brachytherapy for cervical cancer at our institution during 2012-2016. Starting in October 2014, an outpatient MRI was obtained for patients after Smit sleeve placement and first insertion to assess concurrent chemoradiotherapy tumour response. Then, for subsequent fractions, the MRI was co-registered by the Smit sleeve to the planning CT for target volume delineation. The primary and secondary outcomes were toxicity and local control, respectively.

RESULTS

Median follow-up for the pre- (n = 50) and post-MRI-based (n = 46) planning groups was 24.6 and 14.7 months, respectively. Median treatment duration for patients before and after MRI implementation was 56 and 58 days (P = 0.052), respectively. Cumulative rectal D2 cc was less for those with MRI-based target delineation (P = 0.005). On multivariable analysis, patients with MRI-based target delineation experienced fewer severe late (CTCAE grade ≥ 3) toxicities (P = 0.025, hazard ratio = 0.25). Local control was 86% and 91% of the pre- and post-MRI groups, respectively (P = 0.959).

CONCLUSIONS

Preliminary findings using this technique, which is applicable to other institutions without in-room MRI availability, are associated with lower radiation prescription doses, lower rectal doses and favourable toxicity rates while maintaining a rapid workflow. Longer follow-up is required to confirm equivalent local control.

Direction modulated brachytherapy (DMBT) tandem applicator for cervical cancer treatment: Choosing the optimal shielding material

PURPOSE

To investigate the dose modulation capability of a novel MRI-compatible direction modulated brachytherapy (DMBT) tandem applicator design with various high-density shielding materials for brachytherapy treatment of cervical cancer. The shield materials that have been evaluated are tantalum (Ta), pure tungsten (W), gold (Au), rhenium (Re), osmium (Os), platinum (Pt), iridium (Ir), and W' tungsten alloy (95%W, 3.5%Ni, 1.5%Cu).

MATERIALS AND METHODS

The recently proposed six-channel DMBT tandem is composed of nonmagnetic tungsten alloy (W') rod with diameter of 5.4 mm and coated with 0.3-mm thick bio-safe plastic sheath. The tandem shielding material can, however, be individually replaced with various other shields to create directional radiation. Monte Carlo N-Particle (MCNP) code was used to calculate the three-dimensional (3D) dose distributions in a water phantom for an HDR 192 Ir (mHDR-v2) source inside each DMBT tandem with various shields and a plastic conventional tandem (Con.T). Then, the 3D dose distributions were imported into an in-house-coded inverse planning optimization algorithm to obtain optimal plans for 12 clinical cases chosen at random from the international RetroEMBRACE dataset involving conventional tandem and ring (Con.T&R) applicators. All plans generated by the DMBT tandem and ring (DMBT&R) with the tungsten alloy [DMBT(W')&R] were compared with the corresponding Con.T&R plans, to generate benchmark results. These benchmark results were then considered as reference plans for other shields performances. Plans were normalized to receive the same high-risk clinical target volume (CTVHR ) D90 . The D100 , D10 , and V100 for CTVHR , and D2cm3 for organs at risk (OARs) of bladder, sigmoid, and rectum were calculated and compared.

RESULTS

Transmission factor (TF), that is, the dose in the backside of the DMBT shield over that in the front opening, at a 5 cm distance, were 36.6%, 34.8%, 31.9%, 28.9%, 27.9%, 26.2%, 26.2%, and 25.5%, for Ta, W', W, Re, Au, Os, Pt, and Ir shields, respectively. On average, the CTVHR values for D100 , V100 , D10 were not significantly different across all DMBT&R shields and the Con.T&R plans (P > 0.219). For the D2cm3 , the benchmark results showed significant reductions (P < 0.03), that is, on average, -8.3% for bladder, -10.7% for rectum, and -10.1% for sigmoid, compared to the Con.T&R plans. However, the various shields showed little improvement from the tungsten alloy (W'), where on average, rectum (bladder) [sigmoid] D2cm3 were reduced by -1.32% (-0.85%) [-1.01%], -1.25% (-0.78%) [-0.91%], -1.22% (-0.75%) [-0.86%], -0.94% (-0.60%) [-0.70%], -0.84% (-0.51%) [-0.59%], and -0.38% (-0.24%) [-0.23%] for Ir, Pt, Os, Au, Re, and W shields, relative to the benchmark W' DMBT plans, respectively. These corresponding values for Ta increased by +0.28% (+0.08%) [+0.25%], respectively.

CONCLUSION

The Ir, Pt, Os, Au, Re, and W shielding materials, respectively, in descending order, lead to better OAR sparing than the DMBT(W')&R plans. However, the amount of improvement is limited and clinically insignificant. This finding suggests that the initial W' shield remains a suitable choice given the proven MR compatibility, for use in MR-guided adaptive brachytherapy of cervical cancer.

Adjuvant therapy after radical trachelectomy for stage I cervical cancer

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Radical trachelectomy is a fertility sparing option for select stage I cervical patients.

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Indications for adjuvant treatment following trachelectomy are based on standard recommendations following hysterectomy.

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Case report outlining specifics of imaged-guided brachytherapy as part of the adjuvant treatment after trachelectomy.

Magnetic Resonance-guided External Beam Radiation and Brachytherapy for a Patient with Intact Cervical Cancer

Radiation treatment verification has improved significantly over the past decades. The field has moved from film X-rays and skin marks to fiducial tracking and daily cone beam computed tomography (CBCT) for tumor localization. We now have the ability to perform daily on-board magnetic resonance imaging (MRI), which provides superior soft tissue contrast compared to computed tomography (CT). In the management of cervical cancer, the brachytherapy literature has demonstrated that MRI allows for better delineation of the high-risk clinical target volume (HR-CTV) and the use of MRI-guided brachytherapy has translated into improved treatment outcomes. Consensus contouring guidelines for intensity modulated radiation therapy (IMRT) for cervical cancer advise including the whole uterus in the target volume and adding large planning target volume (PTV) margins to account for inter-fractional uterine motion and target motion resulting from variable rectal and bladder filling. MRI-guided radiation therapy (MRgRT) systems enable the possibility to precisely delineate the target volume on a daily basis and to perform truly adaptive delivery. This advancement in technology provides the opportunity to explore how external beam treatment volumes could be safely reduced for better sparing of pelvic organs for the benefit of our patients with cervical cancer. We describe the MR-guided definitive external beam radiation therapy and brachytherapy for a 32-year-old woman with intact cervical cancer. We contoured the uterus, bladder, rectum, and gross tumor volume (GTV) on each of her 25 set-up MRIs. We demonstrate a steady reduction in the GTV and increased displacement of the uterus and GTV as the GTV decreased in size. The findings presented suggest that cervical cancer could greatly benefit from an adaptive MRgRT approach.

Feasibility of dose enhancement assessment: Preliminary results by means of Gd-infused polymer gel dosimeter and Monte Carlo study

This work reports the experimental development of an integral Gd-infused dosimeter suitable for Gd dose enhancement assessment along with Monte Carlo simulations applied to determine the dose enhancement by radioactive and X-ray sources of interest in conventional and electronic brachytherapy. In this context, capability to elaborate a stable and reliable Gd-infused dosimeter was the first goal aimed at direct and accurate measurements of dose enhancement due to Gd presence. Dose-response was characterized for standard and Gd-infused PAGAT polymer gel dosimeters by means of optical transmission/absorbance. The developed Gd-infused PAGAT dosimeters demonstrated to be stable presenting similar dose-response as standard PAGAT within a linear trend up to 13 Gy along with good post-irradiation readout stability verified at 24 and 48 h. Additionally, dose enhancement was evaluated for Gd-infused PAGAT dosimeters by means of Monte Carlo (PENELOPE) simulations considering scenarios for isotopic and X-ray generator sources. The obtained results demonstrated the feasibility of obtaining a maximum enhancement around of (14 ± 1)% for ¹⁹²Ir source and an average enhancement of (70 ± 13)% for ²⁴¹Am. However, dose enhancement up to (267 ± 18)% may be achieved if suitable filtering is added to the ²⁴¹Am source. On the other hand, optimized X-ray spectra may attain dose enhancements up to (253 ± 22) %, which constitutes a promising future alternative for replacing radioactive sources by implementing electronic brachytherapy achieving high dose levels.

Interfraction Variations in Organ Filling and Their Impact on Dosimetry in CT Image Based HDR Intracavitary Brachytherapy

Aim:

Since anatomical and geometric variations occur with every fraction, planning, and dose optimization is necessary for every fraction of high-dose rate intracavitary brachytherapy of carcinoma cervix. In this study, we have tried to quantify the differences in doses to organs at risk (OAR) for each fraction of brachytherapy.

Methods and Materials:

One hundred and seventy computed tomography datasets of cervical cancer patients receiving intracavitary brachytherapy at our institution between January and April 2015 were analyzed. The volumes of the high-risk clinical target volume and OAR contoured were recorded for every insertion. Dose-volume histograms were generated and D90 and D100CTV and D0.1, D1, and D2cc were recorded for bladder, rectum, and sigmoid for each insertion.

Results:

Sixty-one percent had a decrease in bladder volume in the second fraction, 35% had an increase in bladder volume and 4% had no change in bladder volume. There was a strong positive correlation between increase in volume and dose (D2cc), which was statistically significant, r_s = 0.441, P = 0.013. Nearly 49.4% of patients had an increase in rectal volume during the second fraction. 45.9% had decrease in rectal volume during the second fraction. There was a positive correlation between the increase in volume and dose (D2cc), which was statistically significant, r_s = 0.393, P = 0.010. About 63.5% of the patients had a decrease in sigmoid volume during the second fraction, whereas 30.6% had an increase in volume and 5.9% had no change in volume.

Conclusion:

First, this study emphasizes the importance of imaging and planning for every fraction of brachytherapy to quantify the exact doses to the target and OAR s. Second, it is important to follow a uniform bladder protocol for every fraction, and adequate bowel preparation is needed for every fraction to minimize the interfraction variations. Finally, it also opens the realm of an adaptive planning strategy in cervical cancers which are known for rapid tumor regression during radiotherapy.

Evaluating the use of external beam radiation alone in the management of cervix cancer

Aim

To determine the outcome of patients with locally advanced cervix cancer treated with curative intent using external beam radiotherapy (EBRT), without brachytherapy.

Materials and methods

A chart review was performed of all patients with cervix cancer who received EBRT alone at our centre from 2000 to 2010. Overall survival and local control were evaluated using Kaplan–Meier survival curves.

Results

In total, 22 patients were identified. The median age and follow-up were 56 years and 65 months, respectively. The stage included IB to IVB. Main histology was squamous cell carcinoma (82%). Median tumour size was 5·5 cm. Majority treated with 3D conformal techniques and nine patients (41%) were treated with intensity-modulated radiation therapy (IMRT); 14 patients received doses of ≥65 Gy. Most patients (73%) received weekly concurrent cis-platinum. The major reason for not receiving brachytherapy was locally extensive tumour (59%). The 5-year relapse-free survival and overall survival rates were 57 and 50%, respectively. Seven patients (32%) had a component of loco-regional failure, mainly within the cervix. There was a better outcome among the nine patients treated with IMRT to a median dose of 66 Gy with a loco-regional control of 78%.

Conclusions

Patients who cannot have brachytherapy may still achieve acceptable rates of loco-regional disease control if high radiation doses (>65 Gy) was delivered.

Patient's specific integration of OAR doses (D2 cc) from EBRT and 3D image-guided brachytherapy for cervical cancer

The objective of this study was to assess the recommended DVH parameter (e.g., D2 cc) addition method used for combining EBRT and HDR plans, against a reference dataset generated from an EQD2‐based DVH addition method. A revised DVH parameter addition method using EBRT DVH parameters derived from each patient's plan was proposed and also compared with the reference dataset. Thirty‐one biopsy‐proven cervical cancer patients who received EBRT and HDR brachytherapy were retrospectively analyzed. A parametrial and/or paraaortic EBRT boost were clinically performed on 13 patients. Ten IMRT and 21 3DCRT plans were determined. Two different HDR techniques for each HDR plan were analyzed. Overall D2 cc and D0.1 cc OAR doses in EQD2 were statistically analyzed for three different DVH parameter addition methods: a currently recommended method, a proposed revised method, and a reference DVH addition method. The overall D2 cc_EQD2 values for all rectum, bladder, and sigmoid for a conformal, volume optimization HDR plan generated using the current DVH parameter addition method were significantly underestimated on average −5 to −8% when compared to the values obtained from the reference DVH addition technique (P < 0.01). The revised DVH parameter addition method did not present statistical differences with the reference technique (P > 0.099). When PM boosts were considered, there was an even greater average underestimation of −8~−10% for overall OAR doses of conformal HDR plans when using the current DVH parameter addition technique as compared to the revised DVH parameter addition. No statistically significant differences were found between the 3DCRT and IMRT techniques (P > 0.3148). It is recommended that the overall D2 cc EBRT doses are obtained from each patient's EBRT plan.

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.

CyberKnife Stereotactic Radiosurgery for Primary and Metastatic Cancer in the Cervix

Standard radiation therapy for cervical cancer consists of external beam radiation therapy followed by an intracavitary brachytherapy boost. When brachytherapy cannot be performed due to unfavorable anatomy or coexisting medical conditions, stereotactic body radiotherapy with the CyberKnife is another treatment option which is less invasive and can be performed in a shorter treatment time. We performed non-invasive therapy using the CyberKnife for five cases of urogenital cancer located in the cervix. The local tumor control was excellent with minimal toxicity. Non-invasive treatment was demonstrated as feasible with the CyberKnife for contraindication of surgery or brachytherapy.

Locally advanced squamous cell cervical cancer in a patient with septate uterus

A 33-year-old premenopausal multiparous woman with the history of septate uterus was referred to the hospital with menorrhagia and inter-menstrual bleeding occurring for the last 6 months. Work-up revealed a stage IIB cervical cancer. The patient underwent curative chemo/radiotherapy. The patient’s septate uterus presented several difficulties during application. Brachytherapy was applied using standard computed tomography-compatible tandem and ovoids. The high-risk clinical target volume (HR-CTV), intermediate risk CTV, and organs at risk were contoured according to the Groupe Européen de Curiethérapie – European Society for Radiology and Oncology (GEC-ESTRO) guidelines. Treatment was performed via 3-dimensional high-dose-rate technique with ¹⁹²Ir, with brachytherapy dose of 28 Gy in 4 fractions/7 Gy each, prescribed to the HR-CTV. Treatment was well tolerated with manageable acute toxicities. To the best of our knowledge, the current case is the second case of septate uterus with locally advanced cervical carcinoma. Due to the lack of guidelines about brachytherapy applications in patients with uterine anomaly and owing to the anatomical anomaly, brachytherapy application is challenging in this patients population.

Current status of brachytherapy in cancer treatment - short overview

Cancer incidence and mortality depend on a number of factors, including age, socio-economic status and geographical location, and its prevalence is growing around the world. Most of cancer treatments include external beam radiotherapy or brachytherapy. Brachytherapy, a type of radiotherapy with energy from radionuclides inserted directly into the tumor, is increasingly used in cancer treatment. For cervical and skin cancers, it has become a standard therapy for more than 100 years as well as an important part of the treatment guidelines for other malignancies, including head and neck, skin, breast, and prostate cancers. Compared to external beam radiotherapy, brachytherapy has the potential to deliver an ablative radiation dose over a short period of time directly to the altered tissue area with the advantage of a rapid fall-off in dose, and consequently, sparing of adjacent organs. As a result, the patient is able to complete the treatment earlier, and the risks of occurrence of another cancer are lower than in conventional radiotherapy treatment. Brachytherapy has increased its use as a radical or palliative treatment, and become more advanced with the spread of pulsed-dose-rate and high-dose-rate afterloading machines; the use of new 3D/4D planning systems has additionally improved the quality of the treatment. The aim of the present study was to present short summaries of current studies on brachytherapy for the most frequently diagnosed tumors. Data presented in this manuscript should help especially young physicians or physicists to explore and introduce brachytherapy in cancer treatments.

SIM2l attenuates resistance to hypoxia and tumor growth by transcriptional suppression of HIF1A in uterine cervical squamous cell carcinoma

Despite chemoradiotherapy being one of the most important modalities in advanced cervical cancer, there is a lack of both usable biomarkers to predict treatment outcome and of knowledge about the mechanism of refractoriness to the therapy. Here we identified a transcriptional factor Single-minded homolog 2 (SIM2) as an independent predictive biomarker for uterine cervical squamous cell carcinoma (CvSCC). The retrospective study showed that high expression level of SIM2 was correlated to good survival in CvSCC patients. SIM2 knockdown in CvSCC cell lines showed resistance to hypoxia with increased expression of HIF1A and its target genes. Loss of SIM2 also caused growth promotion, resistance to ROS, and radiation in 3D culture. Furthermore, SIM2 knockdown suppressed tumor growth with increased HIF-1α expression and angiogenesis in vivo. On the other hand, SIM2 long isoform (SIM2l)-overexpressed cells had contrary results, indicating the long isoform plays a key role for maintenance of these phenotypes. These data indicated that SIM2l has a potential to be precision medicine for CvSCC patients and that anti-angiogenesis therapy might be usable for SIM2l^Low poor survivors.

3T multiparametric MRI-guided high-dose-rate combined intracavitary and interstitial adaptive brachytherapy for the treatment of cervical cancer with a novel split-ring applicator

PURPOSE

To evaluate the role of 3T-MRI-guided adaptive high-dose-rate (HDR) combined intracavitary and interstitial brachytherapy for cervical cancer using a novel intracavitary split-ring (ICSR) applicator adapter.

METHODS AND MATERIALS

We retrospectively reviewed all HDR brachytherapy cases from 2013 to 2015 using an ICSR applicator. Initial optimization was performed using 3T multiparametric MRI (mpMRI) series with an applicator in place. The mpMRI series were discretionarily acquired before subsequent fractions for possible target adaptation. When necessary, interstitial needles (ISNs) were inserted through a novel ICSR adapter or freehand. Dosimetric parameters, clinical outcomes, and toxicities were compared between groups.

RESULTS

Seventeen patients were included, with a mean followup of 32 months. An mpMRI series preceded each initial fraction and 52.9% of patients underwent ≥1 additional pretreatment mpMRI. Among these subsequent fractions, the high-risk clinical target volume was reduced in 80% vs. 41% without pretreatment mpMRI. Five patients had ISN placement (seven insertions) to improve extracervical target coverage. Mean D₉₀ (Gy) per fraction to the high-risk clinical target volume and intermediate-risk clinical target volume with and without an ISN were 7.51 ± 1.07 vs. 6.14 ± 0.52 (p = 0.028) and 6.35 ± 0.75 vs. 5.21 ± 0.49 (p = 0.007), respectively. Mean fractional D_2cc (Gy) for organs at risk was comparable. No Grades 3-4 toxicity was reported. Disease-free survival and local control for the ICSR-ISN and ICSR-alone groups were 29.8 months/80.0% and 31.2 months/83.3%, respectively.

CONCLUSIONS

The mpMRI acquisition with ICSR applicator in place immediately before HDR brachytherapy for cervical cancer guided successful adaptive treatment optimization and delivery. Our initial experience with a novel interstitial adapter for the split-ring applicator demonstrated excellent target coverage without compromising organs at risk, resulting in good local control and disease-free survival.

Direction modulated brachytherapy (DMBT) for treatment of cervical cancer: A planning study with 192 Ir, 60 Co, and 169 Yb HDR sources

PURPOSE

To evaluate plan quality of a novel MRI-compatible direction modulated brachytherapy (DMBT) tandem applicator using ¹⁹² Ir, ⁶⁰ Co, and ¹⁶⁹ Yb HDR brachytherapy sources, for various cervical cancer high-risk clinical target volumes (CTV_HR ).

MATERIALS AND METHODS

The novel DMBT tandem applicator has six peripheral grooves of 1.3-mm diameter along a 5.4-mm thick nonmagnetic tungsten alloy rod. Monte Carlo (MC) simulations were used to benchmark the dosimetric parameters of the ¹⁹² Ir, ⁶⁰ Co, and ¹⁶⁹ Yb HDR sources in a water phantom against the literature data. 45 clinical cases that were treated using conventional tandem-and-ring applicators with ¹⁹² Ir source (¹⁹² Ir-T&R) were selected consecutively from intErnational MRI-guided BRAchytherapy in CErvical cancer (EMBRACE) trial. Then, for each clinical case, 3D dose distribution of each source inside the DMBT and conventional applicators were calculated and imported onto an in-house developed inverse planning optimization code to generate optimal plans. All plans generated by the DMBT tandem-and-ring (DMBT T&R) from all three sources were compared to the respective ¹⁹² Ir-T&R plans. For consistency, all plans were normalized to the same CTV_HR D90 achieved in clinical plans. The D_2 cm3 for organs at risk (OAR) such as bladder, rectum, and sigmoid, and D90, D98, D10, V100, and V200 for CTV_HR were calculated.

RESULTS

In general, plan quality significantly improved when a conventional tandem (Con.T) is replaced with the DMBT tandem. The target coverage metrics were similar across ¹⁹² Ir-T&R and DMBT T&R plans with all three sources (P > 0.093). ⁶⁰ Co-DMBT T&R generated greater hot spots and less dose homogeneity in the target volumes compared with the ¹⁹² Ir- and ¹⁶⁹ Yb-DMBT T&R plans. Mean OAR doses in the DMBT T&R plans were significantly smaller (P < 0.0084) than the ¹⁹² Ir-T&R plans. Mean bladder D_2 cm3 was reduced by 4.07%, 4.15%, and 5.13%, for the ¹⁹² Ir-, ⁶⁰ Co-, and ¹⁶⁹ Yb-DMBT T&R plans respectively. Mean rectum (sigmoid) D_2 cm3 was reduced by 3.17% (3.63%), 2.57% (3.96%), and 4.65% (4.34%) for the ¹⁹² Ir-, ⁶⁰ Co-, and ¹⁶⁹ Yb-DMBT T&R plans respectively. The DMBT T&R plans with the ¹⁶⁹ Yb source generally resulted in the greatest OAR sparing when the CTV_HR were larger and irregular in shape, while for smaller and regularly shaped CTV_HR (<30 cm³ ), OAR sparing between the sources were comparable.

CONCLUSIONS

The DMBT tandem provides a promising alternative to the Con.T design with significant improvement in the plan quality for various target volumes. The DMBT T&R plans generated with the three sources of varying energies generated superior plans compared to the conventional T&R applicators. Plans generated with the ¹⁶⁹ Yb-DMBT T&R produced best results for larger and irregularly shaped CTV_HR in terms of OAR sparing. Thus, this study suggests that the combination of the DMBT tandem applicator with varying energy sources can work synergistically to generate improved plans for cervical cancer brachytherapy.

Preliminary results of a new workflow for MRI/CT-based image-guided brachytherapy in cervical carcinoma

PURPOSE

We propose a method of image-guided brachytherapy (IGBT) that combines MRI-based target volume delineation for the first fraction with CT datasets of subsequent fractions, using an automatic, applicator-based co-registration, and report our preliminary experience.

MATERIALS AND METHODS

The MRI of the first fraction was used for the first brachytherapy planning. For each subsequent brachytherapy fraction, after the same applicator insertion, a new CT scan with the applicator in place was obtained. The MR image set was registered to the subsequent brachytherapy treatment planning CT using the applicator for rigid body registration. To demonstrate the registration quality, we used here the Dice index as a measurement of tandem delineation overlap between CT and MRI.

RESULTS

The median Dice index was 0.879 (range 0.610-0.932), which indicated that the contours on CT and MRI fitted well. With this combination method, the median D90 of HR CTV and the calculated D2 cm³ of the bladder, rectum, and sigmoid in each fraction were 7.2 (4.0-10.4), 5.9 (2.3-7.7), 4.0 (1.9-6.7), and 3.8 (0.6-7.2) Gy, respectively.

CONCLUSION

Our described method of MRI-guided IGBT offers a practical option for the benefits of target delineation.

Pre-plan technique feasibility in multi-interstitial/endocavitary perineal gynecological brachytherapy

Purpose

To present the implementation of a magnetic resonance imaging (MRI) pre-planning technique in multi-interstitial perineal and endocavitary gynecological brachytherapy.

Material and methods

We used a new fully MRI-compatible applicator that is capable to engage titanium needles, and an intrauterine tandem, developed in our department for the treatment of gynecological cervical cancer patients. This applicator is an attempt to combine the technical advantages of the Martinez universal perineal interstitial template (MUPIT) with the improvement in dose distribution by adding an intrauterine probe with the imaging advantages of MRI-based brachytherapy, thus preserving the stability, geometry, and robustness of the implant, avoiding possible errors of free-hand needle placement. A pre-brachytherapy MRI T2 acquisition is carried out with the template in place 3-5 days before the implant. On this image set, clinical target volume (CTV) is drawn. The required needles and their depths are selected accordingly to encompass the CTV (as conformal as possible). To facilitate this task, a Java based application linked to the treatment planning system has been developed. From this procedure, each needle identification and its depth are obtained previously to the implantation. With this information, the radiation oncologist proceeds with implant and then, a post-implant MRI is carried out, in which the contouring, needles, tandem reconstruction, and optimization are established.

Results

This pre-planning procedure has been successfully applied in 10 patients. An excellent reproduction of the virtual pre-planning has been achieved.

Conclusions

We describe a virtual pre-planning technique using a multi-interstitial and endocavitary perineal template. It is based on a virtual work with MRI images. This procedure has shown to be feasible and efficient in clinical practice by facilitating the work of specialists, and reducing uncertainties of the application.

Automated calculation of point A coordinates for CT-based high-dose-rate brachytherapy of cervical cancer

Purpose

The goal is to develop a stand-alone application, which automatically and consistently computes the coordinates of the dose calculation point recommended by the American Brachytherapy Society (i.e., point A) based solely on the implanted applicator geometry for cervical cancer brachytherapy.

Material and methods

The application calculates point A coordinates from the source dwell geometries in the computed tomography (CT) scans, and outputs the 3D coordinates in the left and right directions. The algorithm was tested on 34 CT scans of 7 patients treated with high-dose-rate (HDR) brachytherapy using tandem and ovoid applicators. A single experienced user retrospectively and manually inserted point A into each CT scan, whose coordinates were used as the “gold standard” for all comparisons. The gold standard was subtracted from the automatically calculated points, a second manual placement by the same experienced user, and the clinically used point coordinates inserted by multiple planners. Coordinate differences and corresponding variances were compared using nonparametric tests.

Results

Automatically calculated, manually placed, and clinically used points agree with the gold standard to < 1 mm, 1 mm, 2 mm, respectively. When compared to the gold standard, the average and standard deviation of the 3D coordinate differences were 0.35 ± 0.14 mm from automatically calculated points, 0.38 ± 0.21 mm from the second manual placement, and 0.71 ± 0.44 mm from the clinically used point coordinates. Both the mean and standard deviations of the 3D coordinate differences were statistically significantly different from the gold standard, when point A was placed by multiple users (p < 0.05) but not when placed repeatedly by a single user or when calculated automatically. There were no statistical differences in doses, which agree to within 1-2% on average for all three groups.

Conclusions

The study demonstrates that the automated algorithm calculates point A coordinates consistently, while reducing inter-user variability. Point placement using the algorithm expedites the planning process and minimizes associated potential human errors.

Predictive and prognostic value of intravoxel incoherent motion (IVIM) MR imaging in patients with advanced cervical cancers undergoing concurrent chemo-radiotherapy

By using the intravoxel incoherent motion (IVIM) model, the diffusion-related coefficient (D) and the perfusion-related parameter (f) can be obtained simultaneously. Here, we explored the application of IVIM MR imaging in predicting long-term prognosis in patients with advanced cervical cancers treated with concurrent chemo-radiotherapy (CCRT). In this study, pelvic MR examinations including an IVIM sequence were performed on 30 women with advanced cervical cancers at three time points (within 2 weeks before, as well as 2 and 4 weeks after, the initiation of CCRT). The performance of tumour size and IVIM-derived parameters in predicting long-term prognosis was evaluated. After a median follow-up of 24 months (range, 10∼34 months), 25/30 (83.33%) patients were alive, and 21/30 (70.00%) remained free of disease. A shrinkage rate of maximum diameter (time point 1 vs. 3) ≥ 58.31% was useful in predicting a good long-term prognosis. The IVIM-derived apparent diffusion coefficient (ADC_IVIM) value at time point 2 and the ADC_IVIM and f values at time point 3 also performed well in predicting a good prognosis, with AUC of 0.767, 0.857 and 0.820, respectively. IVIM MR imaging has great potential in predicting long-term prognosis in patients with advanced cervical cancers treated with CCRT.