Accuracy and dosimetric parameters comparison of 3D-printed non-coplanar template-assisted computed tomography-guided iodine-125 seed ablative brachytherapy in pelvic lateral recurrence of gynecological carcinomas

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.

A new technique for trans-perirectal iodine-125 seed implantation in prostatic cancer guided by CT and 3D printed template: Two case reports

Low-dose-rate prostate brachytherapy with permanent iodine-125 is an important curative treatment for low-risk prostate cancer, and it has been demonstrated that brachytherapy with permanent seeds is an effective treatment. However, differences in prostate volume, spatial location, and gland deformation between images obtained in the pre-planning phase and those obtained during the implantation procedure affect accurate delivery of the pre-planned dose. Furthermore, the complicated procedure could be a burden to elderly patients, for example, the risks associated with general anesthesia. In addition, ultrasound images are not as clear as computed tomography (CT) images with regard to identifying the location of seeds. Therefore, a new method for guidance during the procedure is urgently needed. Here, we have described a new method for precise trans-perirectal insertion of radioactive iodine-125 seeds in patients with prostate cancer under the guidance of CT and a 3D-printed template. These are some of the advantages of this technique over the standard procedure for seed implantation in the prostate: It requires only local anesthesia, the pre-planning phase can be completed before the procedure, and the operation time is considerably shorter. This report describes trans-pararectal iodine-125 seed brachytherapy for prostate cancer under local anesthesia and the guidance of a 3D printed template in two elderly patients. The dose parameters determined in the preoperative planning phase were verified postoperatively and found to be consistent. Further, the procedure was completely successfully with no major complications in both cases, and the patients’ prostate-specific antigen levels were normal at the most recent follow-up conducted 50 months after the procedure. Therefore, this technique seems promising for prostate cancer brachytherapy, and its application needs to be researched and extended further in the future.

Re-Irradiation for Recurrent Cervical Cancer: A State-of-the-Art Review

The recurrence rate of cervical cancer after primary treatment can reach 60%, and a poor prognosis is reported in most cases. Treatment options for the recurrence of cervical cancer mainly depend on the prior treatment regimen and the location of recurrent lesions. Re-irradiation is still considered as a clinical challenge, owing to a high incidence of toxicity, especially in in-field recurrence within a short period of time. Recent advances in radiotherapy have preliminarily revealed encouraging outcomes of re-irradiation. Several centers have concentrasted on stereotactic body radiation therapy (SBRT) for the treatment of well-selected cases. Meanwhile, as the image-guiding techniques become more precise, a better dose profile can also be achieved in brachytherapy, including high-dose-rate interstitial brachytherapy (HDR-ISBT) and permanent radioactive seed implantation (PRSI). These treatment modalities have shown promising efficacy with a tolerable toxicity, providing further treatment options for recurrent cervical cancer. However, it is highly unlikely to draw a definite conclusion from all of those studies due to the large heterogeneity among them and the lack of large-scale prospective studies. This study mainly reviews and summarizes the progress of re-irradiation for recurrent cervical cancer in recent years, in order to provide potential treatment regimens for the management of re-irradiation.

Chinese Expert Consensus on Iodine125 Seed Implantation for Recurrent Cervical Cancer in 2021

The treatment modality for recurrent cervical cancer (rCC) is limited, and the prognosis of these patients is poor. Seed implantation could be an important component of rCC management in the context of dose boost or salvage therapy after surgery or radiotherapy, which is characterized by a minimally invasive, high local dose, and rapidly does fall, sparing normal tissue. For patients with good performance status and lateral pelvic wall recurrence with an available puncture path, seed implantation was recommended, as well as for selected central pelvic recurrence and extra-pelvic recurrence. The combination of brachytherapy treatment planning system and CT guidance was needed, and three-dimensional printing templates could greatly improve the accuracy, efficiency, and quality of seed implantation to achieve a potential ablative effect and provide an efficient treatment for rCC. However, the recommendations of seed implantation were mainly based on retrospective articles and lack high-quality evidence, and multicenter prospective randomized studies are needed. In this consensus on iodine¹²⁵ seed implantation for rCC, indication selection, technical process and requirements, dosimetry criteria, radiation protection, combined systemic therapy, and outcomes of seed implantation for rCC are discussed.

Low-activity 125I implantation into VX2 tumor rabbits and quantitative evaluation of the precise therapeutic effect

There is still controversy about quantitatively evaluating the therapeutic effect of radioactive low-activity iodine-125 seeds (¹²⁵I seeds). In the present study, a paired VX₂ tumor model in a rabbit hind leg muscle was established, which is virus-induced anaplastic squamous cell carcinoma characterized by hypervascularity, rapid growth and easy propagation in the skeletal muscle. ¹²⁵I seeds with 0.4 and 0.7 mCi activity were implanted into the left and right legs, respectively, using a radiation treatment planning system under positron emission tomography (PET)/computed tomography (CT) guidance. PET/CT scans and hematoxylin and eosin staining were observed at 72 h and 2 and 4 weeks after implantation to assess the therapeutic effect. The results showed that the average tumor length and standard uptake value (SUV) decreased over time, and both ¹²⁵I seed groups achieved therapeutic effects at 4 weeks post-implantation. Quantitative evaluation of tumor inhibition rate, SUV variation and tumor marker ratio (Bcl-2/Bax) suggested that 0.7 mCi ¹²⁵I seeds were more suitable than 0.4 mCi seeds in a clinical setting.

Stereotactic Ablative Brachytherapy: Recent Advances in Optimization of Radiobiological Cancer Therapy

Brachytherapy (BT), a type of focal anti-cancer radiotherapy, delivers a highly focused radiation dose to localized tumors, sparing surrounding normal tissues. Recent technological advances have helped to increase the accuracy of BT and, thus, improve BT-based cancer treatment. Stereotactic ablative brachytherapy (SABT) was designed to improve the ablative effect of radiation, which was achieved via improved image guidance, and calculation of ablative dose, shorter treatment duration, and better organ preservation. Recently collected data characterized SABT as having the potential to cure various early-stage cancers. The method provides higher tumor control rate levels that were previously achievable only by surgical resection. Notably, SABT is suitable for application with unresectable malignancies. However, the pathological assessment of SABT irradiated tumors is limited due to difficulties in specimen acquisition. Prostate, lung, liver, and gynecological cancers are the most commonly reported SABT-treated malignancies. This study will give an overview of SABT, focusing on the advances in SABT optimization, and provide insights on the future benefits of the combined application of SABT with cancer immunotherapies.

The accuracy and dosimetric analysis of 3D-printing non-coplanar template-assisted iodine-125 seed implantation for recurrent chest wall cancer

Purpose

To investigate the accuracy and dosimetry of 3D-printing non-coplanar template (3D-PNCT)-assisted computed tomography (CT)-guided iodine-125 seed implantation (¹²⁵I-SI) for recurrent chest wall cancer (rCWC).

Material and methods

This was a retrospective study of 19 patients with 22 rCWC treated with 3D-PNCT-assisted CT-guided ¹²⁵I-SI, from Mar 2017 to Mar 2020 in our institute.

Results

Mean needle entrance deviation was 4.50 ±2.70 mm, mean angular deviation was 3.40 ±3.10 degrees, and mean depth deviation was 5.20 ±5.20 mm. No significant difference was found for dosimetric parameters (except conformity index) between pre-plan and post-plan; D₉₀, D₁₀₀, V₁₀₀, V₁₅₀, and V₂₀₀ were 157.74 ±24.23 and 151.71 ±33.62 (p = 0.228), 85.36 ±34.09 and 70.46 ±23.48 (p = 0.067), 0.93 ±0.04 and 0.90 ±0.07 (p = 0.068), 0.64 ±0.16 and 0.64 ±0.16 (p = 0.984), and 0.35 ±0.17 and 0.37 ±0.18 (p = 0.382) for pre-plan and post-plan, respectively. Conformity index, external index, and homogeneity index were 0.57 ±0.16 and 0.52 ±0.15 (p = 0.007), 0.73 ±0.55 and 0.79 ±0.53 (p = 0.096), and 0.31 ±0.15 and 0.30 ±0.14 (p = 0.504) for pre-plan and post-plan, respectively. Median follow-up time was 8 months (range, 3-30 months). Complete response was observed in 4/22 (18.1%), partial response in 13/22 (59.1%), stable disease in 4/22 (18.1%), and progression disease in 1/22 (4.5%) of the cancers. Among patients with pain before ¹²⁵I-SI, pain relief rate was 87.5% (7/8). No peri-operative complications of more than grade 2 were observed.

Conclusions

3D-PNCT-assisted CT-guided ¹²⁵I-SI may be safe and feasible as palliative therapy for non-surgical candidates and painful patients with rCWC.