Brachytherapy Applications Research Articles

A new way to visualize prostate brachytherapy needles using ultrasound color Doppler and needle surface modifications

Suboptimal ultrasound conspicuity of the brachytherapy applicator can lead to inaccurate image reconstructions of the applicator resulting in decreased tumor control or increased normal tissue dose. This feasibility study aims to improve ultrasound conspicuity of high-dose rate (HDR) brachytherapy needles by modifying the surface of the needles to produce a color Doppler twinkling signature. Surface modifications of standard 17-gauge titanium HDR brachytherapy needles included laser-scribing, application of polymethyl methacrylate (PMMA), and coating with a commercially available echogenic coating. Laser-scribing was performed with variable widths (0.1-1 mm) and depths (10-100 μm). The echogenic coating was applied with 3 different thicknesses (27, 40, and 64 μm). Unmodified and modified needles were imaged under B-mode and color Doppler ultrasound in phantom and cadaver, and the signal strength was recorded. Laser-scribed, PMMA-coated, and echogenic-coated brachytherapy needles produced a twinkling signature along the needle shaft on color Doppler ultrasound. Twinkling was observed with laser-scribe depths >20 μm and widths >0.1 mm and from echogenic coatings 40 μm and 64 μm thick. Twinkling was not observed with unmodified needles. The twinkling signature had a spectral composition with a uniform magnitude between the velocities of 2 to 16 cm/s. Color Doppler ultrasound of surface-modified brachytherapy applicators may improve applicator conspicuity aiding applicator placement and digitization. HDR brachytherapy needles may be modified to produce the twinkling signature via laser-scribing, PMMA rings, or applying an echogenic coating.

Feasibility of quantitative diffusion-weighted imaging during intra-procedural MRI-guided brachytherapy of locally advanced cervical and vaginal cancers

PurposeTo determine the feasibility of quantitative apparent diffusion coefficient (ADC) acquisition during magnetic resonance imaging-guided brachytherapy (MRgBT) using reduced field-of-view (rFOV) diffusion-weighted imaging (DWI). Methods and MaterialsT2-weighted (T2w) MR and full-FOV single-shot echo planar (ssEPI) DWI were acquired in 7 patients with cervical or vaginal malignancy at baseline and prior to brachytherapy, while rFOV-DWI was acquired during MRgBT following brachytherapy applicator placement. The gross target volume (GTV) was contoured on the T2w images and registered to the ADC map. Voxels at the GTV's maximum Maurer distance comprised a central sub-volume (GTVcenter). Contour ADC mean and standard deviation were compared between timepoints using repeated measures ANOVA. ResultsssEPI-DWI mean ADC increased between baseline and prebrachytherapy from 1.03 ± 0.18 10−3 mm2/s to 1.34 ± 0.28 10−3 mm2/s for the GTV (p = 0.06) and from 0.84 ± 0.13 10−3 mm2/s to 1.26 ± 0.25 10−3 mm2/s at the level of the GTVcenter (p = 0.03), consistent with early treatment response. rFOV-DWI during MRgBT demonstrated mean ADC values of 1.28 ± 0.14 10−3 mm2/s and 1.28 ± 0.19 10−3 mm2/s for the GTV and GTVcenter, respectively (p = 0.02 and p = 0.03 relative to baseline). No significant differences were observed between ssEPI-DWI and rFOV-DWI ADC measurements. ConclusionsQuantitative ADC measurement in the setting of MRI guided brachytherapy implant placement for cervical and vaginal cancers is feasible using rFOV-DWI, with comparable mean ADC comparable to prebrachytherapy ssEPI-DWI, and may enable MRI-guided radiotherapy targeting of low ADC, radiation resistant sub-volumes of tumor.

The Use of 3D Printing Technology in Gynaecological Brachytherapy-A Narrative Review.

Radiation therapy, including image-guided adaptive brachytherapy based on magnetic resonance imaging, is the standard of care in locally advanced cervical and vaginal cancer and part of the treatment in other primary and recurrent gynaecological tumours. Tumour control probability increases with dose and brachytherapy is the optimal technique to increase the dose to the target volume while maintaining dose constraints to organs at risk. The use of interstitial needles is now one of the quality indicators for cervical cancer brachytherapy and needles should optimally be used in ≥60% of patients. Commercially available applicators sometimes cannot be used because of anatomical barriers or do not allow adequate target volume coverage due to tumour size or topography. Over the last five to ten years, 3D printing has been increasingly used for manufacturing of customised applicators in brachytherapy, with gynaecological tumours being the most common indication. We present the rationale, techniques and current clinical evidence for the use of 3D-printed applicators in gynaecological brachytherapy.

Dosimetry and safety of single-channel applicators for intracavitary brachytherapy in cervical cancer

High-dose-rate intracavitary brachytherapy plays a crucial role in achieving local control in the treatment of unresectable uterine cervical cancer. In this treatment approach, the single-channel applicator (SCA) offers a simpler structure for implantation compared to the fletcher applicator set (FAS), easing the treatment planning. To evaluate the dosimetry and safety of the SCA for intracavitary brachytherapy in cervical cancer, the present study aims to assess its dose distribution in relation to the FAS. In this study, we compared the physical and dosimetric characteristics of the inferential reference points (A, cervix; B, bladder; and R, rectum) of the SCA to those obtained with tandem and FAS dosing. Dosimetric characteristics and dose distributions in a Chinese female anthropomorphic phantom were evaluated using RGD-3B thermoluminescent dosimetry. The SCA generated an oblate, pear-shaped dose distribution curve, resulting in a reduced high-dose area along the bladder-rectum axis. Compared to the tandem, the SCA resulted in dose reductions of 21% and 17% at the bladder and rectum, respectively. When compared to the FAS, the dosing with the SCA at the bladder and rectum did not show significant differences concerning the occurrence of severe toxic effects. The SCA demonstrated a dose distribution curve similar to the standard FAS but not the tandem. The results of the present study indicate that both SCA and FAS showed equally acute toxicity and resulted in late injuries to the rectum and bladder. Nevertheless, the SCA’s simpler structure, which allows for more convenient placement and planning, warrants further clinical investigations to assess its efficacy and practical application.

A comparative study of the effectiveness of multiagent platinum based concurrent plus adjuvant versus conventional single agent platinum based concurrent chemotherapy in carcinoma cervix.

85 Background: Cervical cancer is the 4th most common cancer in females worldwide. Combination of external beam radiotherapy (EBRT) and intracavitary brachytherapy (BT) with concurrent chemotherapy is the current standard of care for locally advanced cervical cancer. Even though the trials used separate combinations, the common end point suggested that platinum is single most effective chemotherapy agent. Since the latest data on platinum based polychemotherapy globally indicates its overall benefit, further trials are required to determine what regimens would be ideal for treatment of cervical cancer with maximum benefits and least toxicities. Objectives: 1. To compare the response to doublet polychemotherapy with conventional chemotherapy in carcinoma cervix treated with chemoradiation. 2. To compare toxicity profile of doublet polychemotherapy with conventional chemotherapy. Methods: 66 patients of carcinoma cervix were enrolled in this study and were randomized to two arms. Arm A (n=34) was the experimental arm and the patients received concurrent weekly cycles of cisplatin(40mg/m2) plus gemcitabine (125mg/m2) along with EBRT followed by HDR brachytherapy, after 2-3 weeks of which they received 2 adjuvant cycles (21 days each) of gemcitabine (1000mg/m2 on Day1 and Day 8) and cisplatin (50mg/m2 on Day 1). Arm B(n=32) was the control arm and the patients received standard treatment which is concurrent weekly cycles single agent cisplatin(40mg/m2) with EBRT followed by HDR brachytherapy. EBRT doses ranged from 45Gy to 50.4 Gy at 1.8 to 2 Gy per fraction .BT application was either ICBT or ISBT depending on tumour response to EBRT, assessed by MRI. Patients were followed up for response assessment and late toxicities within 6 months of completion of treatment by clinical examination and MRI which was reported using RECIST 1.1 criteria. Results: On 6 month follow up MRI, number of patients achieving CR was 10% higher in the experimental arm (Arm A, n=33;97.06%) than the control arm (Arm B, n=28;87.5%).PR was seen in 2 patients, both from Arm B. Of the 3 patients presenting with PD at follow up 1 belonged to Arm A and 2 to Arm B (2.94% vs 6.25%). On pre-brachytherapy MRIs, the size reduction was better in Arm A and this reduction allowed a majority of patients in said arm to undergo ICBT instead of ISBT. The number of patients achieving >50% reduction post EBRT was 40% higher in Arm A. Acute GI and Hematological toxicities were seen in both arms but were higher in Arm A. as was Grade 3 neutropenia. Late toxicities were similar in both arms. Conclusions: The study concluded that the use of multiagent platinum-based chemotherapy in concurrent plus adjuvant setting can be advantageous. Improved tumour reduction can be achieved & disease can be made more amenable for ICBT. The accompanying toxicities were transient and clinically manageable.

Impact of uterine deformation induced by applicator on brachytherapy dosimetric value: an uterine-mimicking-phantom study

Brachytherapy (BT) is subjected to uncertainties from imaging, treatment planning, and anatomical variations. It is necessary to identify the uncertainties, their magnitude, and their impact on the overall uncertainty of dose delivery. The aim of the present phantom-based study is to investigate the deformation of the uterus anatomy induced by BT applicator insertion and the relationship between dose and location of the inserted applicator. A novel flexible phantom was designed based on female pelvic anatomy by the 3D printing process to simulate the deformation and movement of the uterine during the BT process. The applicator was inserted into the uterus and in order to simulate the uterus motion, the phantom was moved in four directions, right, left, down, and up. The CT and ultrasound images were obtained. A two-stage registration algorithm was designed to register the ultrasound and CT images in order to calculate the applicator displacements map. This map was used to calculate delivered dose error to uterus and rectum and to correct the planned dose values in treatment planning procedure. The results showed that in a planned D90 (dose) of 9.4 Gy for the uterus and maximum dose of 1.8 Gy to the rectum, movement of applicator leads to a big deviation in final delivered doses. After the applicator moved to the right and left directions, the D90 delivered to the uterus was 6.2 Gy and 5.6 Gy, respectively. Moreover, by moving downwards and upwards, the uterus received 0.4 and 1.2 Gy lower than 9.4 Gy. Similarly, the maximum dose to the rectum in right, left, down, and up directions after applicator movement were 3.4 Gy, 3.3 Gy, 3.7 Gy and 3.2 Gy, respectively which highlighted the higher delivered dose to the rectum. The results of the study demonstrate that applicator displacement can lead to uterine underdosing and also increase the risk of rectum irradiation. Ultimately, image-guided brachytherapy and using image registration can increase the accuracy of treatment and reduce the errors of delivered dose to target volume and organs at risk, especially in uterus cancer.

A quick guide on implementing and quality assuring 3D printing in radiation oncology.

As three-dimensional (3D) printing becomes increasingly common in radiation oncology, proper implementation, usage, and ongoing quality assurance (QA) are essential. While there have been many reports on various clinical investigations and several review articles, there is a lack of literature on the general considerations of implementing 3D printing in radiation oncology departments, including comprehensive process establishment and proper ongoing QA. This review aims to guide radiation oncology departments in effectively using 3D printing technology for routine clinical applications and future developments. We attempt to provide recommendations on 3D printing equipment, software, workflow, and QA, based on existing literature and our experience. Specifically, we focus on three main applications: patient-specific bolus, high-dose-rate (HDR) surface brachytherapy applicators, and phantoms. Additionally, cost considerations are briefly discussed. This review focuses on point-of-care (POC) printing in house, and briefly touches on outsourcing printing via mail-order services.

Organ sparing treatment for penile cancer using a 3D-printed high-dose-rate brachytherapy applicator

PURPOSEWe present a case study of the treatment of localized squamous cell carcinoma on the glans penis with a custom-fabricated high-dose-rate (HDR) brachytherapy applicator. METHODS AND MATERIALSA cylindrically shaped applicator was fabricated with eight embedded channels suitable for standard plastic brachytherapy catheters. An additional custom silicone bolus/sleeve was designed to be used with the 3D-printed applicator to provide an additional offset from the source to skin to reduce the surface dose and for patient comfort. RESULTSThe patient (recurrent cT1a penile cancer) underwent CT simulation, and the brachytherapy plan was created with a nominal prescription dose of 40 Gy in 10 fractions given bidaily to the surface, and 35 Gy at 5 mm depth. Dose coverage to the clinical target volume was 94% (D90). Most fractions were treated with only 5-10 min of setup time. Follow up visits up to 1 year showed no evidence of disease with no significant changes in urinary and sexual function and limited cosmetic detriment to the patient. CONCLUSIONSPatient-specific organ-sparing HDR plesiotherapy using 3D printing technology can provide reliable and reproducible patient setup and may be effective in achieving disease control for superficial penile cancer, although preserving patient quality of life.

Analysis of applicator displacement in accelerated partial breast irradiation using a strut-based design brachytherapy applicator

PURPOSEThis study aimed to identify factors associated with strut-adjusted volume implant (SAVI) displacement in accelerated partial breast irradiation (APBI) using a SAVI device. METHODS AND MATERIALSWe retrospectively analyzed computed tomography scans taken at the time of treatment planning and immediately before treatment in 61 patients (median age; 55 years, range; 40–85) treated with SAVI and determined the amount of SAVI displacement that occurred between the time from planning to the treatment. The displacement was calculated for the CT axis and SAVI axis, which is related to the SAVI structure. To investigate the cause of the displacement, multivariate analysis was performed on the calculated standard deviation and the insertion angle of SAVI with respect to the sternum in each cross-section, breast density, amount of air around the SAVI, and SAVI length inside the patient to obtain the β coefficient (p-value). RESULTSOn the CT coordinate system, positive correlations were observed between the SAVI insertion angle and air volume in the lateral (β coefficient:0.255–0.483) and rotational directions (β coefficient:0.341). On the SAVI coordinate system, positive correlations were observed between the SAVI insertion angle and air volume in all lateral (β coefficient:0.270–0.354) and rotational directions (β coefficient:0.294). A negative correlation was observed between the SAVI length inside the patient and the rotational direction (β coefficient: −0.262). CONCLUSIONSAVI insertion angle, the amount of the air outside SAVI and SAVI insertion length are factors which affect the displacement of the applicator. From the results, the applicator displacement and rotation must be <3 mm and 10o in order to meet all the dose criteria. Thus, we should be aware of these factors during insertion of the device to avoid the problem in treatment delivery for the APBI.

Long-term outcomes of intraoperatively-placed applicator brachytherapy for rapid completion of breast conserving treatment: An analysis of a prospective registry data.

To evaluate the long-term outcome of accelerated partial breast irradiation utilizing intraoperatively placed applicator-based brachytherapy (ABB) in early-stage breast cancer. From our prospective registry, 223 patients with pTis-T2, pN0/pN1mic breast cancer were treated with ABB. The median treatment duration including surgery and ABB was 7days. The prescribed doses were 32Gy/8 fx BID (n=25), 34Gy/10 fx BID (n=99), and 21Gy/3 fx QD (n=99). Endocrine therapy (ET) adherence was defined as completion of planned ET or≥80% of the follow-up (FU) period. Cumulative incidence of ipsilateral breast tumor recurrence (IBTR) was estimated and influencing factors for IBTR-free survival rate (IBTRFS) were analyzed. 218/223 patients had hormone receptor-positive tumors, including 38 (17.0%) with Tis and 185 (83.0%) with invasive cancer. After a median FU of 63months, 19 (8.5%) patients had recurrence [17 (7.6%) with an IBTR]. Rates of 5-year IBTRFS and DFS were 92.2% and 91.1%, respectively. The 5-year IBTRFS rates were significantly higher for post-menopausal women (93.6% vs. 66.4%, p=0.04), BMI<30kg/m2 (97.4% vs. 88.1%, p=0.02), and ET-adherence (97.5% vs. 88.6%, p=0.02). IBTRFS did not differ with dose regimens. Postmenopausal status, BMI<30kg/m2, and ET- adherence predicted favorable IBTRFS. Our results highlight the importance of careful patient selection for ABB and encouragement of ET compliance.

A 3D-Printable, Low-Cost Obturator for Less Invasive Gynecologic Brachytherapy.

The purpose of this report is to design, develop, and evaluate a cost-effective applicator for interstitial brachytherapy (ISBT) to minimize patient morbidity and facilitate access to curative radiation treatment for gynecologic cancers, especially in low-resource settings. A computer-aided design and prototype were developed of a proposed applicator that incorporates 44 slotted channels to gently guide needles, with or without a tandem, through the vaginal canal, effectively eliminating the need for transcutaneous needle insertions typically employed during ISBT of advanced gynecologic cancer and thus reducing the risk of vaginal laceration and bladder or rectal injury. The tested prototype was developed using AutoCAD software (Autodesk,San Francisco, CA) and 3D printed in Accura Xtreme Gray material using stereolithography. Small-scale iterative tests using a gelatin phantom were conducted on this prototype to confirm the efficacy of the applicator through inter-operator usability, needle stability, and needle arrangement. A promising prototype was developed aimed at addressing key issues with traditional perineum-based templates to facilitate ISBT, including being able to cover bulky tumors with parametrial extension reliably, decrease the risk of tissue or organ injury, and treat women with a prior hysterectomy. Results of preclinical testing demonstrated that the applicator met its purpose, suggesting that it may facilitate ISBT without the morbidity typically associated with the procedure, especially by addressing concerns associated with implementing the procedure in low-resource settings. The applicator shows substantial promise in the treatment of advanced gynecologic cancer. While further testing remains necessary to confirm its translatability to the clinical setting, the applicator appears capable of meeting its design objectives, representing its potential for improving upon current methods.

Three-Fraction Accelerated Partial Breast Irradiation (APBI) Delivered With Interstitial Brachytherapy Is Safe: First Results From the Tri-fraction Radiation Therapy Used to Minimize Patient Hospital Trips (TRIUMPH-T) Trial

Shorter courses of breast radiotherapy are offered as an alternative to 4 weeks of whole-breast irradiation after lumpectomy, including brachytherapy. A prospective phase 2multi-institution clinical trial to study 3-fraction accelerated partial breast irradiation delivered by brachytherapy was conducted. The trial treated selected breast cancers after breast-conserving surgery with brachytherapy applicators that delivered 22.5 Gy in 3 fractions of 7.5 Gy. The planning treatment volume was 1 to 2 cm beyond the surgical cavity. Eligible women were age ≥45 years with unicentric invasive or in situ tumors ≤3 cm excised with negative margins and with positive estrogen or progesterone receptors and no metastases to axillary nodes. Strict dosimetric parameters were required to be met and follow up information was collected from the participating sites. Two hundred patients were prospectively enrolled; however, a total of 185 patients who were enrolled were followed for a median of 3.63 years. Three-fraction brachytherapy was associated with low chronic toxicity. There was excellent or good cosmesis in 94% of patients. There were no grade 4 toxicities. Grade 3 fibrosis at the treatment site was present in 1.7% and 32% percent had grades 1 or 2 fibrosis at the treatment site. There was 1 rib fracture. Other late toxicities included 7.4% grade 1 hyperpigmentation, 2% grade 1 telangiectasias, 1.7% symptomatic seromas, 1.7% abscessed cavities, and 1.1% symptomatic fat necrosis. There were 2 (1.1%) ipsilateral local recurrences, 2 (1.1%) nodal recurrences and no distant recurrences. Other incidents included one contralateral breast cancer and 2 second malignancies (lung). Ultra-short breast brachytherapy is feasible and has excellent toxicity and could be an alternative to standard 5-day, 10 fraction accelerated partial breast irradiation in eligible patients. Patients from this prospective trial will continue to be followed to evaluate long-term outcomes.

Dosimetric Study to Estimate Deviations in Delivered Radiation Dose due to Occluded Air Spaces in Vaginal Vault Brachytherapy Applications.

To develop a dosimetric tool to estimate the dose delivered in the presence of air pockets with EBT3 film while simulating the conditions of vaginal vault brachytherapy (VVBT) with 3.0 diameter cylindrical applicator at a prescription dose distance of 5mm from the surface of it. Six acrylic plates (10 cm x 10 cm, 0.5 cm thick) with four different types of slots were designed and produced locally. They can hold a cylindrical vaginal brachytherapy applicator in the centre, air equivalent material from the applicator's surface [(sizes 4.5 mm (A), 3.0 mm (B), and 2.0 mm (C)], EBT3 film at the prescribed dose distance, and holder rods. Plates were layered together with acrylic rods and assembled in a holding box in a water phantom. Three treatment plans done in TPS with prescription doses of 2 Gy, 3 Gy, and 4 Gy at 5.0 mm with a treatment length of 6 cm, and were executed in Co-60-based HDR brachytherapy unit (M/s SagiNova, Germany) with & without the placement of air equivalent material, and the dose received at slot locations A, B, & C were noted. The mean percentage deviation of measured dose without and with presence of air pocket at A, B and C was 13.9%, 11.0% and 6.4% respectively for all dose prescriptions. As the air pocket size expanded radially from 2.0 mm to 4.5 mm, the increase in dosage ranged from 6.4% to 13.9% which was due to the fact that the film was held at dosage prescription distance and the lack of attenuation of photons radially through air pocket. The present study can be carried out with a 3D printed phantom that simulates VVBT application having air pockets of different dimensions at different locations and also can be analyzed with Monte Carlo simulations.

PO-2164 Measurement of the force braking down the source in its movement through brachytherapy applicator

PO-2164 Measurement of the force braking down the source in its movement through brachytherapy applicator

PO-2151 clinical outcomes of using 3D-printed applicators for HDR brachytherapy in gynecological malignancy

PO-2151 clinical outcomes of using 3D-printed applicators for HDR brachytherapy in gynecological malignancy

PO-2134 Planning study using various applicators for vaginal cuff brachytherapy; Three ovoids technique

PO-2134 Planning study using various applicators for vaginal cuff brachytherapy; Three ovoids technique

PO-2177 Study of dwell positions discrepancies from TPS in brachytherapy RING applicators

PO-2177 Study of dwell positions discrepancies from TPS in brachytherapy RING applicators

PO-2168 3D - print technology of individually adapted vaginal and rectal applicators for brachytherapy

PO-2168 3D - print technology of individually adapted vaginal and rectal applicators for brachytherapy

MO-0297 Fast catheter trajectory planning for patient-tailored cervical cancer brachytherapy applicators

MO-0297 Fast catheter trajectory planning for patient-tailored cervical cancer brachytherapy applicators

OC-0129 Impact of brachytherapy applicator on morbidity and local control in cervix cancer: EMBRACE study

OC-0129 Impact of brachytherapy applicator on morbidity and local control in cervix cancer: EMBRACE study