Manufacturing and evaluation of multi-channel cylinder applicator with 3D printing technology

Design approach and benefits of the 3D-printed vaginal individualized applicator (VIA)

PURPOSE

Interstitial gynecologic brachytherapy necessitates precise needle placement, requiring time and expertise. We aimed to simplify interstitial procedures and facilitate optimal needle distribution with individualized vaginal templates to guide interstitial needles.

MATERIALS/METHODS

We developed the 3D-printed vaginal individualized applicator (VIA), a cylindrical template containing individualized internal channels that guide interstitial needles to cover the tumor extent. Eight patients underwent VIA only interstitial implants (VIA only), and five intact cervical cases were treated using tandem and customized VIA (VIA + T). Procedure length, number of needles utilized and dosimetric measures were evaluated.

RESULTS

VIA was successfully designed and used clinically for 24 procedures (8 VIA only, 16 VIA + T). Average procedure needle insertion time reduced from 80.9 min for traditional interstitial to 42.9 min for VIA only, approximately 47% shorter with a similar mean high risk CTV volume (28.3 cc VIA only vs. 32.4 cc) and excellent dosimetry with average CTV V100% (94.3% and 94.4%). VIA + T was particularly useful in patients with small vaginal canals and large tumor size. For the five VIA + T patients average tumor size was 68.0cc (range 26.6-143.5 cc). VIA + T procedures were approximately 20% shorter than hybrid procedures with other applicators with mean length of 20.1 min and an average of 6.8 needles (range 3-12).

CONCLUSION

Our novel 3D-printed VIA facilitates gynecologic interstitial brachytherapy by simplifying needle placement, reducing procedure time, and maintaining excellent dosimetry. VIA can be customized for various clinical scenarios, particularly beneficial for large tumors or small vaginal canals.

Intensity-modulated vaginal brachytherapy applicator and single- and multi-channel applicators in vaginal cuff brachytherapy

Purpose

To compare the dosimetric performance of vaginal intensity-modulated brachytherapy (IM-BRT) applicator and single- (SC-BRT) and multi-channel brachytherapy (MC-BRT) applicators for vaginal cuff brachytherapy (VC-BRT).

Material and methods

Fifteen patients with uterine-confined endometrium cancer who received adjuvant VC-BRT were included in this study. IM-BRT, SC-BRT, and MC-BRT treatment plans were created for two different clinical target volume (CTV) definitions: 1. Standard CTV, called CTVs; and 2. Virtually defined CTV, called CTVv, with asymmetrical tumor extension > 5 mm in thickness. Plan comparison was performed using dose-volume histogram (DVH) and treatment planning parameters.

Results

According to DVH analysis, D98 for CTVv and D2 for both CTVs and CTVv showed statistically significant differences between IM-BRT and SC-BRT plans, but there was no significant difference between IM-BRT and MC-BRT plans in terms of D98 and D2 for both CTVs and CTVv. Additionally, for CTVv plans, IM-BRT was found to be significantly superior to SC-BRT for the rectum (D2cc, V5Gy, and V7Gy), bladder (D2cc and V7Gy), and small bowel (D2cc, V5Gy, and V7Gy). On the other hand, DVH parameters of the sigmoid showed large difference between IM-BRT and SC-BRT plans, but it was not statistically significant. Similarly, the use of IM-BRT applicator demonstrated a noticeable dose reduction in all defined OARs when compared with MC-BRT applicator, but statistically significant for the rectum V7Gy (p = 0.03) only.

Conclusions

While the IM-BRT applicator is still in pre-clinical phase, our investigation demonstrated the proof-of-concept in real patient treatment plans with promising dosimetric results compared with SC-BRT and MC-BRT plans in selected patient group.

Evaluating dose distributions of high dose rate 60Co brachytherapy in an asymmetric tumor: A comparison of different designs of vaginal cylindrical applicators

The aim of this study is to evaluate organ-at-risk (OAR) doses obtained from different designs of intracavitary cylinder applicators during high-dose-rate (HDR) brachytherapy of an asymmetric vaginal tumor. Dose distributions around five cylinder applicators were obtained using the Geant4 toolkit. Three of these applicators are commercially available: single-channel, multi-channel, and shielded. Additionally, two proposed sub-configurations were evaluated: (I) a combination of the multichannel applicator with a central shield and (II) a dynamically modulated cylinder (DMC). The dose distributions of the proposed applicators were compared to those of the single-channel cylinder applicator. The results showed that using a cylindrical applicator with a higher degree of freedom in plan optimization can improve OAR, sparing up to 60% for the rectum and 20% for the bladder. In conclusion, this work suggests using a new design of a cylindrical applicator to enhance the therapeutic ratio of brachytherapy for asymmetric and irregularly shaped vaginal tumors.

Personalized Brachytherapy for a Herlyn-Werner-Wunderlich Syndrome Patient with Endometrial Cancer: A Case Report

Purpose

Endometrial carcinoma (EC) is a common gynecological malignancy. Vaginal cuff brachytherapy (VBT) is an adjuvant treatment for EC. Since a single-channel cylinder sometimes delivers inadequate dose coverage to the vaginal apex, three-dimensional (3D) printing technology can be used to achieve satisfactory dose distribution. Here, we report the first case of an EC patient with Herlyn-Werner-Wunderlich syndrome (HWWS) treated with VBT using 3D-printed applicators.

Case Presentation

Here, we present a case study of an endometrial cancer patient with HWWS who underwent surgery. During adjuvant radiotherapy, 3D-printed applicators were used in VBT. To accomplish the reconstruction of the source pathways on magnetic resonance imaging, catheters with copper sulfate were placed in two 3D-printed applicators. The early tolerance of this treatment was positive. During the 6-month follow-up, locoregional recurrence was not detected.

Conclusion

Our findings strongly indicate that VBT with 3D-printed applicators may be a reasonable treatment option for EC with HWWS.

3D printing in brachytherapy: A systematic review of gynecological applications

PURPOSE

To provide a systematic review of the applications of 3D printing in gynecological brachytherapy.

METHODS

Peer-reviewed articles relating to additive manufacturing (3D printing) from the 34 million plus biomedical citations in National Center for Biotechnology Information (NCBI/PubMed), and 53 million records in Web of Science (Clarivate) were queried for 3D printing applications. The results were narrowed sequentially to, (1) all literature in 3D printing with final publications prior to July 2022 (in English, and excluding books, proceedings, and reviews), and then to applications in, (2) radiotherapy, (3) brachytherapy, (4) gynecological brachytherapy. Brachytherapy applications were reviewed and grouped by disease site, with gynecological applications additionally grouped by study type, methodology, delivery modality, and device type.

RESULTS

From 47,541 3D printing citations, 96 publications met the inclusion criteria for brachytherapy, with gynecological clinical applications compromising the highest percentage (32%), followed by skin and surface (19%), and head and neck (9%). The distribution of delivery modalities was 58% for HDR (Ir-192), 35% for LDR (I-125), and 7% for other modalities. In gynecological brachytherapy, studies included design of patient specific applicators and templates, novel applicator designs, applicator additions, quality assurance and dosimetry devices, anthropomorphic gynecological applicators, and in-human clinical trials. Plots of year-to-year growth demonstrate a rapid nonlinear trend since 2014 due to the improving accessibility of low-cost 3D printers. Based on these publications, considerations for clinical use are provided.

CONCLUSIONS

3D printing has emerged as an important clinical technology enabling customized applicator and template designs, representing a major advancement in the methodology for implantation and delivery in gynecological brachytherapy.

Individualized medicine using 3D printing technology in gynecology: a scoping review

OBJECTIVE

Developments in 3-dimensional (3D) printing technology has made it possible to produce high quality, affordable 3D printed models for use in medicine. As a result, there is a growing assessment of this approach being published in the medical literature. The objective of this study was to outline the clinical applications of individualized 3D printing in gynecology through a scoping review.

DATA SOURCES

Four medical databases (Medline, Embase, Cochrane CENTRAL, Scopus) and grey literature were searched for publications meeting eligibility criteria up to 31 May 2021.

STUDY ELIGIBILITY CRITERIA

Publications were included if they were published in English, had a gynecologic context, and involved production of patient specific 3D printed product(s).

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies were manually screened and assessed for eligibility by two independent reviewers and data were extracted using pre-established criteria using Covidence software.

RESULTS

Overall, 32 studies (15 abstracts,17 full text articles) were included in the scoping review. Most studies were either case reports (12/32,38%) or case series (15/32,47%). Gynecologic sub-specialties in which the 3D printed models were intended for use included: gynecologic oncology (21/32,66%), benign gynecology (6/32,19%), pediatrics (2/32,6%), urogynecology (2/32,6%) and reproductive endocrinology and infertility (1/32,3%). Twenty studies (63%) printed 5 or less models, 6/32 studies (19%) printed greater than 5 (up to 50 models). Types of 3D models printed included: anatomical models (11/32,34%), medical devices, (2/32,6%) and template/guide/cylindrical applicators for brachytherapy (19/32,59%).

CONCLUSIONS

Our scoping review has outlined novel clinical applications for individualized 3D printed models in gynecology. To date, they have mainly been used for production of patient specific 3D printed brachytherapy guides/applicators in patients with gynecologic cancer. However, individualized 3D printing shows great promise for utility in surgical planning, surgical education, and production of patient specific devices, across gynecologic subspecialties. Evidence supporting the clinical value of individualized 3D printing in gynecology is limited by studies with small sample size and non-standardized reporting, which should be the focus of future studies.

Characteristics of preplan-based three-dimensional individual template-guided brachytherapy compared to freehand implantation

Image-guided adaptive intracavitary/interstitial brachytherapy (IC/IS IGABT) has exhibited superior dosimetry advantage and local control for locally advanced cervical cancer (LACC). Our group designed a type of cylindrical three-dimensional (3D) printed vaginal template combining an intracavitary applicator with straight and oblique interstitial needles according to the preplan on computed tomography images. This work aimed to research the consistency of the preplan with the treatment plan at every fraction to verify the practical guiding significance of the preplan. We also investigated the difference between 3D-printed template-guided implantation compared with freehand implantation for LACC. Twenty-six patients were treated with 3D-printed individual templates (3D template group), and 20 patients were treated by using freehand insertion (freehand group). Patients in the 3D template group would take a preplan one week before treatment to design and print the individual template, while the freehand group did not. All patients accepted volumetric rotational intensity-modulated radiotherapy at a dose of 49.4 Gy in 26 fractions and subsequent brachytherapy at a dose of 26 Gy in four fractions. All analyses were performed by utilizing SPSS 26. The insertion depth was decreased in fractions 1 and 4 compared with the preplan. None of the dose volume histogram parameters of fractions 1-3, nor the D_2cc of bladder and bowel at fraction 4 were barely changed compared with the preplan. The D₉₀ and D₉₈ of the high-risk clinical target volume in the 3D template group were statistically higher than those in the freehand group (p < 0.01). The D_2cc of the rectum, bladder, bowel, and sigmoid in the 3D template group were all lower than those in the freehand group (p < 0.01). The preplan in this research is consistent with treatment plans, which is important to ensure the feasibility of applying a 3D-printed template in brachytherapy. The 3D-printed individual guidance template was an effective method in brachytherapy for locally advanced cervical cancer.

The value of brachytherapy in the age of advanced external beam radiotherapy: a review of the literature in terms of dosimetry

Brachytherapy (BT) has long been used for successful treatment of various tumour entities, including prostate, breast and gynaecological cancer. However, particularly due to advances in modern external beam techniques such as intensity-modulated radiotherapy (IMRT), volume modulated arc therapy (VMAT) and stereotactic body radiotherapy (SBRT), there are concerns about its future. Based on a comprehensive literature review, this article aims to summarize the role of BT in cancer treatment and highlight its particular dosimetric advantages. The authors conclude that image-guided BT supported by inverse dose planning will successfully compete with high-tech EBRT in the future and continue to serve as a valuable modality for cancer treatment.