Needle use and dosimetric evaluation in cervical cancer brachytherapy using the Utrecht applicator

The Kelowna template for combined intracavitary and interstitial brachytherapy for gynecologic malignancies: Design, application, treatment planning, dosimetric and treatment outcomes

PURPOSE

We report the feasibility, experience, and early outcomes of the combined intracavitary and interstitial dedicated applicator using the Kelowna GYN template (Varian, Palo Alto, CA).

METHODS AND MATERIALS

The Kelowna GYN template is CT compatible and used for the treatment of gynecologic cancers. In cases with patients that have an intact uterus, a modified applicator system using the Kelowna GYN template and a 3D printed adapter piece allows for compatibility with an intrautaerine tandem.

RESULTS

We reviewed the treatment course of 23 patients comprising of 86 fractions of HDR treatment. Median D90 for cervical tumors (n = 7) was 82.4 Gy (range 77.7-92.6); for postoperative cervical tumors (n = 2) was 73.9 Gy (range 72.0-5.8); for vaginal tumors (n = 4) was 85.8 Gy (range 79.8-88.1); for recurrent endometrial (n = 10) was 86.9 Gy (range 74.8-103.2). Median EQD2 D2cc for bladder was 72.4 Gy (range 47.7-99.4), for rectum was 61.2 Gy (range 52.4-80.6), and for sigmoid colon of 50.5 Gy (44.3-66.9). At a median follow-up of 12 months, 2 patients had a local recurrence. Two patients had distant recurrence: one with carcinomatosis at 6 months, and one with pulmonary metastases at 3 months. No patients had late grade three toxicities.

CONCLUSIONS

Our single institutional experience supports the use of the Kelowna template as a robust system as a combined IC-IS applicator resulting in versatile and reproducible implants for a variety of gynecologic malignancies.

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.

Non-anesthetist-administered moderate sedation with midazolam and fentanyl for outpatient MRI-aided hybrid intracavitary and interstitial brachytherapy in cervix cancer: a single-institution experience

Purpose

The aim of the study was to determine the feasibility of interstitial brachytherapy under non-anesthetist-administered moderate sedation, to identify factors influencing the insertion, and the total procedural time.

Material and methods

A total of 47 insertions with hybrid intracavitary and interstitial applicators were performed in 23 patients from March 2017 to March 2020. Moderate sedation was achieved with intravenous midazolam and fentanyl administered by non-anesthetist. Insertion time and procedural time was recorded. Univariate and multivariate analysis were performed to evaluate the impact of different factors on insertion and procedural time.

Results

A total of 238 needles (range, 2-8 per insertion) were implanted, with an average insertion depth of 30 mm (range, 20-40 mm). The mean doses for midazolam and fentanyl were 3 mg (standard deviation [SD] = 1) and 53.3 mcg (SD = 23.9) per insertion, respectively. The median insertion time was 30 minutes (interquartile range [IQR] = 22-40), and the median total procedural time was 4.3 hours (IQR = 3.6-5.2). First time insertion, insertions performed before 2019, and higher midazolam dose were associated with significantly longer insertion time, whereas longer insertion time, MRI-based planning, and insertions performed before 2019 were associated with significantly longer total procedural time.

Conclusions

Outpatient interstitial brachytherapy with non-anesthetist-administered sedation is achievable and well-tolerated. This method may significantly lessen the burden on hospital resources and has the potential to be cost-effective.

Computed Tomography-Guided Optimization of Needle Insertion for Combined Intracavitary/Interstitial Brachytherapy With Utrecht Applicator in Locally Advanced Cervical Cancer

PURPOSE

There are no international guidelines for optimal needle insertion during interstitial intracavitary brachytherapy (IS-ICBT) for cervical cancer. We aimed to investigate the clinical feasibility and added value of computed tomography (CT) guidance to optimize needle insertion in IS-ICBT using the Utrecht applicator and to evaluate needle shifts.

METHODS AND MATERIALS

We enrolled 24 patients who were treated with interstitial-brachytherapy. Two CT scans each were performed for every patient: (1) after applicator insertion without needles (CT_preneedle) and (2) after needle insertion (CT_postneedle). In addition to magnetic resonance imaging after external-beam radiation therapy, CT_preneedle was used to determine optimal needle locations and insertion lengths based on applicator and organs at risk positioning on the day of treatment; CT_postneedle was used for IS-ICBT planning. The needle-channel axis was used as a reference to determine needle-shift evolution.

RESULTS

A total of 266 interstitial needles were inserted in 76 of 93 BT fractions with high intra- and interpatient variations in the number of inserted needles. Based on CT_preneedle findings, needle insertion was avoided in 9, 4, 2, and 2 patients at the first, second, third, and fourth fractions, respectively. The unloaded needle frequency was 4%. Average needle contribution to total dwell time was 37.2% ± 19.2%. Shifting was observed in 68% of the needles (mean shift 2.0 ± 2.3 mm), mostly in the posterior direction, and in needles with a larger insertion length. Needle reinsertion was not needed in any patient. No complication due to needle insertion was observed, except for minor vaginal bleeding in 1 patient after needle removal.

CONCLUSIONS

The adaptive CT-guided IS-ICBT application was feasible and resulted in fewer unloaded needle insertions or complications and more efficient use with higher needle contribution to the treatment. Needle shift was frequent but did not require needle reinsertion with the proposed method.

Three-dimensional image-guided combined intracavitary and interstitial high-dose-rate brachytherapy in cervical cancer: A systematic review

PURPOSE

To evaluate the local control and toxicities of three-dimensional image-guided combined intracavitary and interstitial (IC/IS) high-dose-rate brachytherapy (BT) in cervical cancer through a systematic review.

METHODS AND MATERIALS

A systematic review of relevant studies was performed through the PubMed, Web of Science, and Cochrane Library databases through May 10, 2020. Articles reporting on IC/IS technology, volumetric doses to high-risk clinical target volume (HR-CTV) and organs at risk (OARs), tumor control and/or treatment-related side effects were identified. The key information, including the type of applicator, implantation technology, characteristics of implantation, volumetric doses, tumor control, and/or treatment-related side effects, was extracted. A probit model analysis between HR-CTV D90 and tumor local control was performed.

RESULTS

Twelve studies encompassing 520 patients were included in the probit model between HR-CTV D90 and the local control rate. The probit model showed a significant relationship between the HR-CTV D90 value and the local control probability, p = 0.003. The prescribed dose of 85 Gy_EQD2,10 would in theory warrant an 87.4% (95% confidence interval 82.5%-90.5%) local control rate.

CONCLUSION

IC/IS BT is an appropriate method to achieve a high therapeutic ratio for tumors with large volumes or poor responses after external irradiation in cervical cancer. The probit model showed that the dose escalation of HR-CTV D90 was helpful to improve the local tumor control rate.

Bibliometric analysis of the 100 most cited articles on cervical cancer radiotherapy

PURPOSE

To identify the 100 most cited research articles on cervical cancer radiotherapy.

METHODS

The Web of Science and Scopus databases were searched to identify the 100 most cited articles on cervical cancer radiotherapy as of September 29, 2019. Articles were ranked based on the total citations received from 2 databases. One hundred articles about radiotherapy for cervical cancer were identified. The following important information was extracted: author, journal, year and month of publication, country or region, and radiotherapy technologies.

RESULTS

The 100 most cited articles on cervical cancer radiotherapy were published between 1964 and 2016, and the total citations from 2 databases ranged from 3478 to 211, including a total of 49,262 citations as of September 29, 2019. The index of citations per year ranged from 170.4 to 13.1. These articles were from 16 countries or regions, with most publications being from the United States (n = 38), followed by Austria (n = 15), Canada (n = 8), France (n = 8) and the United Kingdom (n = 7). The International Journal of Radiation Oncology, Biology, Physics produced the most articles (n = 42), followed by Radiotherapy and Oncology (n = 13), Cancer (n = 8) and Journal of Clinical Oncology (n = 7). These articles were categorized as original studies (n = 86), recommendations (n = 5), guidelines (n = 5) and reviews (n = 4). Of the 100 most cited articles, intracavitary brachytherapy (n = 50) and 3-dimensional conformal radiotherapy (n = 34) were the most commonly used treatment techniques.

CONCLUSION

To the best of our knowledge, this is the first report and analysis of the most cited articles on cervical cancer radiotherapy. This bibliographic study presents the history of technological development in external radiation therapy and brachytherapy. Brachytherapy is an indispensable part of radiotherapy for cervical cancer. The International Journal of Radiation Oncology Biology Physics is the journal with the most publications related to cervical cancer radiotherapy.

Prediction of optimal needle configuration in the first fraction of cervix brachytherapy

Background and purpose

Applying needles in the first brachytherapy (BT) fraction for patients with locally advanced cervical cancer allows for more dose conformality and OAR sparing, but is more challenging than in subsequent fractions, as pre-implant imaging with applicator in situ is lacking. We investigate whether a needle simulation, a fixed needle configuration or a multidisciplinary discussion-based configuration can predict more accurately which applicator needle positions are best suited for use in the first BT fraction.

Materials and methods

For 20 patients we retrospectively determined the "reference" needle configuration (RC) for the first BT fraction using magnetic resonance imaging (MRI) scans with applicator in situ. We simulated a pre-MRI needle configuration (PC) using the MRI made in the fourth week of external beam radiotherapy (EBRT) without applicator in situ. We generated a fixed needle configuration (FC) from the most common RC needles. Using Dice's similarity coefficient (DSC) we compared each of these needle configurations, including the clinically applied "multidisciplinary consensus" needle configuration (MC), with RC. We considered two scenarios: allowing up to ten needles (scenario 1), and limiting the needle number (scenario 2). The analysis was repeated omitting two mid-ventral needles previously determined as non-essential to treatment planning.

Results

For both scenarios, the median DSC for PC and FC was higher than for MC (scenario1:DSC_PC = 0,78; DSC_FC = 0,75; DSC_MC = 0,57; scenario 2:DSC_PC = 0,74; DSC_FC = 0,73; DSC_MC = 0,59), while omitting mid-ventral needles resulted in no statistically significant differences in DSC.

Conclusions

The PC or FC method are at least as accurate as the MC, with the FC preferred for efficiency.