Technical details and clinical outcomes after high-dose-rate intracavitary brachytherapy for squamous cell carcinoma of external auditory canal and external beam radiotherapy for nodal coverage: A case report.

Purpose: To report technical details and 15-month outcomes of a patient with node-positive external auditory canal (EAC) squamous cell carcinoma (SCC) treated with definitive intracavitary high-dose-rate (HDR) brachytherapy to primary tumor, and external beam radiotherapy (EBRT) to draining lymphatics. Material and methods: A 21-year-old male was diagnosed with SCC of the right EAC. The patient underwent definitive HDR intracavitary brachytherapy, 340 cGy/fraction for 14 twice-daily fractions, followed by EBRT using intensity-modulated radiation therapy (IMRT) to cover the grossly enlarged pre-auricular node, ipsilateral intra-parotid, and cervical lymph node levels II and III. Results: The approved brachytherapy plan had an average high-risk clinical tumor volume (CTV-HR) D90 of 341 cGy with a total dose of 47.7 Gy (BED, 80.3 Gy, EQD2, 66.6 Gy). For the approved IMRT plan, the prescription to the involved right pre-auricular node was 66 Gy in 33 fractions, and more than 95% of the target received at least 62.7 Gy. High-risk nodal regions were simultaneously prescribed: 59.4 Gy in 1.8 Gy fractions, and more than 95% received at least 56.4 Gy. Organs at risk (OARs) were kept below their dose constraints.The patient tolerated both the procedures with no grade ≥ 2 treatment-related adverse events. Grade 1 dermatitis in the right pre-auricular and cervical areas during the course of EBRT was experienced. Fifteen months post-RT, the patient has no evidence of disease, and was noted to have EAC stenosis, which translated to moderate conductive hearing loss of the right ear. Thyroid function was normal at 15 months after EBRT. Conclusions: This case report illustrates that the delivered definitive radiotherapy is technically feasible, effective, and well-tolerated in patients with SCC of EAC.

Clinical outcomes of single application multi-fractionated CT-guided interstitial high-dose-rate brachytherapy for locally advanced cervical cancer: A multi-institution initial experience.

Purpose: The aim of the study was to evaluate the safety and clinical outcomes of single application multi-fractionated computed tomography (CT)-guided interstitial high-dose-rate brachytherapy given in four fractions in locally advanced cervical cancer. Material and methods: Patients with locally advanced cervical cancer stage IIB-IVA treated definitively with external radiation ± weekly cisplatin, followed by single application multi-fractionated CT-guided interstitial high-dose-rate brachytherapy in four fractions were included. Dosimetry data, clinical response, and toxicity records were reviewed. Results: Between January 2018 and December 2022, twenty-two patients were included. Clinical stage distribution was as follows: IIB - 13.6%, IIIB - 27.3%, IIIC - 22.7%, and IVA - 36.4%. Mean high-risk clinical target volume (HR-CTV) was 66.19 ±32.69 cm3, and HR-CTV D90 dose was 86.8 ±1.7 Gy. 2 cc doses to bladder, rectum, and sigmoid were 84.6 ±2.8 Gy, 71.5 ±2.4 Gy, and 65.6 ±4.0 Gy, respectively. Mean overall treatment time was 66 ±21 days. With a median follow-up of 11.5 months (range, 5-44 months), median survival and local control were not achieved. One-year local control rate, one-year progression-free survival, and one-year overall survival were 82%, 66%, and 78%, respectively. Univariate analysis showed overall treatment time to be the only variable associated with all oncologic outcomes. For acute toxicity, grade 3 toxicity in four patients and grade 4 toxicity of infection in one patient were observed. For late toxicity, grade 3 gastrointestinal toxicity was noted in two patients. Conclusions: Initial results suggest that single application multi-fractionated CT-guided interstitial brachytherapy given in four fractions in locally advanced cervical cancer seems to be feasible and safe, but additional evidence is needed to generate more validated conclusions.

Phase 1/2 trial evaluating the effectiveness and safety of dose-adapted Hypofractionated pelvic radiotherapy for Advanced Cervical cancers INeligible for ChemoTherapy (HYACINCT).

BACKGROUND: The standard treatment for locally advanced cervical cancer (LACC) is concurrent chemoradiation (CRT) followed by brachytherapy (BRT). The addition of chemotherapy (ChT) to radiotherapy (RT) is associated with a 7.5% improvement in overall survival but with more grade 3-4 acute toxicities (16.4% vs 4.9%, CRT vs RT alone). The risk-benefit ratio could be less favorable in advanced disease with renal dysfunction secondary to tumor-related hydronephrosis; borderline cardiac function; and frail patients. RT alone followed by BRT achieves long-term locoregional control <62%. Hypofractionated RT (HF-RT) using older techniques result in comparable disease control and low late toxicity rates (4-8%). Dose-adapted HF-RT using intensity-modulated RT with nodal simultaneous integrated boost (nSIB) could improve tumor control and toxicity, when ChT is contraindicated. METHODS: The HYACINCT study is a two-phase study to determine the effectiveness and safety of HF-RT with nSIB in LACC when ChT is contraindicated. Phase 1 is a dose-escalation study using standard 3 + 3 design, to determine the maximum tolerated dose (MTD) for nSIB in combination with pelvic HF-RT (2.67 Gy x 15 fractions). Phase 2 is a single-arm clinical trial using Simon's two-stage design, to assess the efficacy of HF-RT with nSIB in terms of tumor response. Adult women with biopsy-proven, untreated LACC, with contraindication to ChT will be included in this trial. DISCUSSION: For the phase 1, the primary endpoint is dose-limiting toxicity (DLT), or any grade ?3 acute or sub-acute toxicity. The dose level at which incidence of DLT is ?33% is defined as the maximum tolerance dose (MTD). For the phase 2, the primary endpoint is complete response at 3 months post-treatment. Secondary outcomes are progression-free and overall survival, acute and late toxicity, and patient-reported outcomes (EPIC, EORTCQLQ C30 + CX24, PGIC, PCIS). Trial registration: NCT05210270.

Orbital mold brachytherapy for recurrent orbital mesenchymal chondrosarcoma: a case report.

PURPOSE: The aim of this case report is to present a case of orbital mesenchymal chondrosarcoma sarcoma with multiple recurrences, and to report technical details of a contemporary approach for orbital brachytherapy that can be used in low-resource settings. MATERIAL AND METHODS: A 46-year-old female diagnosed with recurrent orbital mesenchymal chondrosarcoma of the left orbit presented with her third local recurrence. The patient proceeded with conservative surgery with planned adjuvant high-dose-rate brachytherapy 2 weeks post-surgery. Brachytherapy mold applicator was fabricated using thermoplastic mask, ProGuide catheter needles, catheter fixation buttons, and a strip of gauze. Ideal catheter placement was done with CT simulation planning. RESULTS: High-risk clinical target volume (HR-CTV) corresponded to gross tumor residual, and intermediate-risk clinical target volume (IR-CTV) corresponded to the whole orbit. Flexitron iridium-192 high-dose-rate (HDR) brachytherapy plan was generated using Oncentra brachytherapy planning system. The treatment plan had HR-CTV total dose of 55.6 Gy and equivalent dose in 2 Gray fractions (EQD2) of 96 Gy. IR-CTV total dose was 45.5 Gy and EQD2 of 70 Gy. The plan was evaluated using dose-volume histogram and dosimetric parameters, which showed adequate irradiation of tumor volume and at-risk areas. The patient underwent orbital brachytherapy without any adverse events, except for mild skin erythema. One-year post-treatment showed no local recurrence and no soft tissue necrosis or swelling. CONCLUSIONS: In the previously irradiated orbital sarcoma patient, adjuvant brachytherapy is an effective and safe modality for the delivery of sufficient radiation dose to the target, as presented in the current case report. The materials used in the brachytherapy applicator are easily available in majority of radiation therapy centers and can be manufactured even in low-resource settings.

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.

A novel applicator design for intracavitary brachytherapy of the nasopharynx: Simulated reconstruction, image-guided adaptive brachytherapy planning, and dosimetry.

PURPOSE: In nasopharyngeal cancer, brachytherapy is given as boost in primary treatment or as salvage for recurrent or persistent disease. The Rotterdam nasopharyngeal applicator (RNA) allows for suboptimal reduction of soft palate radiation dose, based on image-guided brachytherapy plans. Building on the RNA, we propose a novel design, the Benavides nasopharyngeal applicator (BNA). METHODS AND MATERIALS: The virtual BNA was reconstructed on two cases (one T1, one T2) previously treated with intracavitary brachytherapy using the RNA. Dose was prescribed to the high-risk clinical target volumes (CTVs) and optimization was such that high-risk CTV D90 ≥ 100% of prescribed dose (PD), intermediate-risk-CTV D90 ≥ 75% PD, and soft palate D2cc ≤ 120% PD. The optimized RNA and BNA image-guided brachytherapy plans were compared in terms of CTV coverage and organs-at-risk sparing. RESULTS: Optimization objectives were more easily met with the BNA. For the T1 case, all three planning objectives were easily achieved in both the RNA and BNA, but with 18-19% lower soft palate doses with the BNA. For the T2 case, the CTV planning objectives were achieved in both the RNA and BNA, but the soft palate constraint was only achieved with the BNA, with 38-41% lower soft palate doses. CONCLUSIONS: Compared to the RNA, the BNA permits easier optimization and improves therapeutic ratio by a significant reduction of soft palate doses, based on simulation using a proposed system for CTV/organs-at-risk delineation, prescription, and optimization for image-guided adaptive brachytherapy. Clinical piloting using a prototype is necessary to evaluate its feasibility and utility.

Radiation Planning Assistant - A Streamlined, Fully Automated Radiotherapy Treatment Planning System.

The Radiation Planning Assistant (RPA) is a system developed for the fully automated creation of radiotherapy treatment plans, including volume-modulated arc therapy (VMAT) plans for patients with head/neck cancer and 4-field box plans for patients with cervical cancer. It is a combination of specially developed in-house software that uses an application programming interface to communicate with a commercial radiotherapy treatment planning system. It also interfaces with a commercial secondary dose verification software. The necessary inputs to the system are a Treatment Plan Order, approved by the radiation oncologist, and a simulation computed tomography (CT) image, approved by the radiographer. The RPA then generates a complete radiotherapy treatment plan. For the cervical cancer treatment plans, no additional user intervention is necessary until the plan is complete. For head/neck treatment plans, after the normal tissue and some of the target structures are automatically delineated on the CT image, the radiation oncologist must review the contours, making edits if necessary. They also delineate the gross tumor volume. The RPA then completes the treatment planning process, creating a VMAT plan. Finally, the completed plan must be reviewed by qualified clinical staff.

Model for Estimating Power and Downtime Effects on Teletherapy Units in Low-Resource Settings.

PURPOSE: More than 6,500 megavoltage teletherapy units are needed worldwide, many in low-resource settings. Cobalt-60 units or linear accelerators (linacs) can fill this need. We have evaluated machine performance on the basis of patient throughput to provide insight into machine viability under various conditions in such a way that conclusions can be generalized to a vast array of clinical scenarios. MATERIALS AND METHODS: Data from patient treatment plans, peer-reviewed studies, and international organizations were combined to assess the relative patient throughput of linacs and cobalt-60 units that deliver radiotherapy with standard techniques under various power and maintenance support conditions. Data concerning the frequency and duration of power outages and downtime characteristics of the machines were used to model teletherapy operation in low-resource settings. RESULTS: Modeled average daily throughput was decreased for linacs because of lack of power infrastructure and for cobalt-60 units because of limited and decaying source strength. For conformal radiotherapy delivered with multileaf collimators, average daily patient throughput over 8 years of operation was equal for cobalt-60 units and linacs when an average of 1.83 hours of power outage occurred per 10-hour working day. Relative to conformal treatments delivered with multileaf collimators on the respective machines, the use of advanced techniques on linacs decreased throughput between 20% and 32% and, for cobalt machines, the need to manually place blocks reduced throughput up to 37%. CONCLUSION: Our patient throughput data indicate that cobalt-60 units are generally best suited for implementation when machine operation might be 70% or less of total operable time because of power outages or mechanical repair. However, each implementation scenario is unique and requires consideration of all variables affecting implementation.