The dosimetry evaluation of 3D printing non-coplanar template-assisted CT-guided 125I seed stereotactic ablation brachytherapy for pelvic recurrent rectal cancer after external beam radiotherapy

Experts consensus on 3D-printing template-assisted CT-guided radioactive iodine-125 seed implantation for recurrent soft tissue carcinoma in China

Permanent radioactive iodine-125 seed implantation (RISI), known as radioactive seed implantation, is a minimally invasive internal radiation technique. This method involves implanting 125I seeds (4.5 × 0.8 mm, encapsulated in a nickel-titanium alloy) into tumors under image guidance. The radionuclide continuously releases low energy γ-rays, effectively killing tumor cells. RISI delivers high local doses with minimal damage to surrounding normal tissues. It is performed through image-guided percutaneous puncture, accompanied by high precision, minimal trauma, and rapid recovery. In Western countries, RISI is primarily utilized for early-stage prostate cancer. In 2002, Professor Junjie Wang introduced computed tomography (CT)-guided technology for RISI, expanding its indications to head and neck, thoracic, abdominal, pelvic, and spinal tumors. In 2014, he proposed the concept of image-guided interventional brachytherapy, advancing minimally invasive brachytherapy. In 2015, he integrated three-dimensional 3D-printing template (3D-PT) with CT-guided technology, significantly enhancing the precision, quality, and efficiency of RISI, and introduced the concept of stereotactic brachytherapy. Over nearly 20 years, RISI has developed into a standardized procedure, involving preoperative planning, intraoperative optimization, and postoperative verification, highlighting its role in comprehensive cancer treatment. The main treatments for soft tissue sarcoma (STS) include surgery or surgery combined with radiotherapy and chemotherapy. However, STS is prone to local recurrence, and effective treatments are lacking after recurrence. Experts have conducted extensive trials on RISI for the treatment of recurrent STS (r-STS), accumulating significant clinical experience. This study aimed to establish standards and consensus on 3D-PT-assisted CT-guided RISI for the treatment of r-STS.

3D‑printed template‑guided iodine‑125 seed implantation to treat complete occlusion of the superior vena cava in pulmonary sarcomatoid carcinoma: A case report

Pulmonary sarcomatoid carcinoma (PSC), which is a type of non-small-cell lung carcinoma (NSCLC), is characterized by a high degree of malignancy, poor differentiation and a high incidence of pulmonary malignancy. In addition, PSC has a stronger invasive ability than other types of NSCLC and is not sensitive to radiation or chemotherapy. Furthermore, 90% of PSC cases exhibit vascular invasion; therefore, there is a risk of multiple metastases to the lung, bone, adrenal glands and brain, and consequently a poor prognosis, in the early stage. Targeted therapy and immunotherapy currently offer a new treatment direction; however, there have not been any significant advances in localized treatment in recent years. Thus, there is an urgent need for new localized treatment strategies. The present study describes the case of a 65-year-old man with recurrence of PSC after multi-line treatment with chemotherapy, radiotherapy, gamma knife and argon-helium knife treatment. In addition, the patient developed superior vena cava syndrome, and exhibited severe compression of the superior vena cava, chest discomfort, dyspnea and severe facial edema after chemotherapy, local gamma knife therapy (35 Gy, delivered through 14 2.5-Gy doses), argon-helium knife therapy and radiation therapy (28 Gy, delivered through seven 4-Gy doses). Partial remission was achieved after local implantation of iodine-125 (I125) seed under the guidance of a 3D-printed template, with progression-free survival observed up to 8 months afterwards. In conclusion, in patients with PSC who develop superior vena cava blockage after numerous treatment regimens, salvage I125 brachytherapy with a 3D-printed template may be suitable, and may improve local control and symptoms.

Treatment of recurrent tracheal adenoid cystic carcinoma with a covered airway stent loaded with Iodine-125 seeds: a 5-year follow-up case report

Background

The treatment of recurrent tracheal adenoid cystic carcinoma (TACC), a rare pulmonary malignant tumor, typically involves bronchoscopic interventional therapy for patients ineligible for surgery or external radiotherapy. This report describes an innovative treatment approach for TACC, initially managed with interventional bronchoscopy and subsequently with a Y-shaped airway stent loaded with 125I seeds, following recurrence after 2 years.

Case presentation

A 50-year-old man presented with intermittent coughing for 2 months and was admitted to the hospital after the discovery of TACC a month earlier. Preoperative bronchial artery embolization was performed to reduce the risk of bleeding, followed by bronchoscopic tumor resection in January 2017 using an electric loop at the base, complemented by argon plasma coagulation (APC) and cryotherapy. Although short-term outcomes were favorable, the long-term prognosis remained suboptimal. Due to tumor recurrence, airway tumor resection and implantation of the 125I seed stent were performed under bronchoscope guidance in early 2019. The stent was removed 5 months later. The patient tolerated the procedure well and exhibited no signs of relapse or progression during the 5-year postoperative follow-up period. This case illustrates the successful application of a stent loaded with 125I seeds for treating unresectable TACC.

Conclusions

Treatment of TACC with a covered airway stent loaded with 125I seeds may be a safe, effective, and scalable method.

3D-printed brachytherapy in patients with cervical cancer: improving efficacy and safety outcomes

OBJECTIVE

This study aims to evaluate the efficacy and safety of 3D printing technology in brachytherapy for cervical cancer, comparing its outcomes with conventional free hand implantation brachytherapy.

METHODS

A total of 50 cervical cancer patients treated at the First Affiliated Hospital of Gannan Medical College from January 2019 to July 2023 were included in this study. Patients were divided into two groups: 25 patients received intensity-modulated radiotherapy (IMRT) combined with 3D-printed brachytherapy, and 25 patients underwent IMRT combined with free hand brachytherapy implantation. Key indicators analyzed included short-term therapeutic effects, survival outcomes, operation times, the number of CT scans, the number of needles inserted, dosimetric parameters, and complications.

RESULTS

The use of 3D-printed brachytherapy significantly improved the safety of radiation therapy operations, especially for large tumors (≥ 30 mm), by providing more precise dose distribution and reducing the radiation doses received by critical organs such as the bladder and rectum. Compared to the artificial implant group (88% prevalence), the 3D-printed brachytherapy group showed a significantly lower incidence of radiation enteritis (29.2% prevalence, p < 0.001). There were no significant differences in other complications between the two groups. For instance, the incidence of radiation cystitis was relatively high in the 3D-printed brachytherapy group (79.2% prevalence) compared to the artificial implant group (64% prevalence, p = 0.240). The median follow-up period in this study was 22.5 months [IQR 18-29]. Among the 49 patients included, 43 had cervical squamous carcinoma and 6 had cervical adenocarcinoma. Short-term therapeutic response rates were comparable, with no significant difference in overall survival observed between the two groups.

CONCLUSION

3D-printed brachytherapy offers a more effective and safer therapeutic option for patients with cervical cancer, particularly for those with large tumors or complex anatomical structures.

Clinical efficacy of iodine-125 (125I) seed implantation in patients with iodine-refractory differentiated thyroid cancer

Patients with radioactive iodine refractory differentiated thyroid cancer (RAIR-DTC) are resistant to radioactive iodine-131(131I) treatment, and the clinical treatment for these patients is complex. The implantation of iodine-125 (125I) seeds in the lesion has been successfully applied to treat malignant tumors, but there are few reports on using 125I particles in the treatment of RAIR-DTC. This retrospective study collected data of 92 patients with RAIR-DTC. Patients treated with sorafenib were included in a control group (50 cases with 72 lesions) and patients treated with 125I implantation were included in an observation group (42 cases with 68 lesions). The results showed that compared with those in the control group, the lesion volume was lower and the VVR was higher in the observation group (P<0.05). The Tg and Tg-Ab levels 6 months after treatment were lower than those before treatment in both groups, and the post-treatment Tg and Tg-Ab levels of the observation group were lower than those of the control group (P<0.05). The efficacy, disease control rate, and objective remission rate were not significantly different between the observation group and the control group (P>0.05). Overall survival of patients in the observation group was longer than that in the control group, χ2 = 4.430, P = 0.035. The incidence of total adverse reactions in the observation group was lower than that in the control group (P<0.05). In conclusion, 125I seed implantation is effective in RAIR-DTC treatment as it can prolong the overall survival of patients while maintaining a safe profile.

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.

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.

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.

PD-1 Inhibitor Maintenance Therapy Combined Iodine-125 Seed Implantation Successfully Salvage Recurrent Cervical Cancer after CCRT: A Case Report

Cervical cancer is the fourth most common cancer in females worldwide. Patients with stage III and IV cervical cancer based on the Federation of Gynecology and Obstetrics (FIGO) classification have higher recurrence rates. Because of organs at risk (OAR) protection and the low indication rate of salvage surgery, the choice of treatment is always challenging. Systemic chemotherapy is palliative and can be performed in conjunction with surgery or radiotherapy; however, it has no significant benefit to survival. Brachytherapy and stereotactic body radiotherapy (SBRT) are characterized by extremely high radiation doses applied to tumor cells while sparing the normal tissues. Several studies have investigated the efficacy of these technologies in recurrent cervical cancer and showed promising results. The immune checkpoint inhibitors approach was also investigated and showed promising results too. Herein, we report a case of a patient with cervical cancer that recurred five months after adjuvant chemotherapy and concurrent chemoradiotherapy. The disease prognosis after interstitial implantation brachytherapy (IIB) was determined. Then, the patient underwent radioactive 125I-seed implantation combined with PD-1 inhibitor treatment. The patient exhibited a partial response after seed implantation, and up to now, the duration of this partial response was 24 months.

Analysis on the accuracy of CT-guided radioactive I-125 seed implantation with 3D printing template assistance in the treatment of thoracic malignant tumors

This article analyzes the accuracy of needle track and dose of a 3-dimensional printing template (3DPT) in the treatment of thoracic tumor with radioactive I-125 seed implantation (RISI). A total of 28 patients were included. The technical process included: (i) preoperative CT positioning, (ii) preoperative planning design, (iii) 3DPT design and printing, (iv) 3DPT alignment, (v) puncture and seed implantation. The errors of needle position and dosimetric parameters were analyzed. A total of 318 needles were used. The mean errors in needle depth, needle insertion point, needle tip and needle angle were 0.52 ± 0.48 cm, 3.4 ± 1.7 mm, 4.4 ± 2.9 mm and 2.8 ± 1.7°, respectively. The differences between actual needle insertion angle and needle depth and those designed in the preoperative were statistically significant (p < 0.05). The mean values of all the errors of the chest wall cases were smaller than those of the lungs, and the differences were statistically significant (p < 0.05). There was no significant difference between the D90 calculated in the postoperative plan and those designed in the preoperative and intraoperative plans (p > 0.05). Some dosimetric parameters of preoperative plans such as V100, V200, CI and HI were not consistent with that of preoperative plans, and the difference was statistically significant (p < 0.05). However, there were no statistical difference in the dosimetric parameters between the postoperative plans and intraoperative plans (p > 0.05). We conclude that for thoracic tumors, even under the guidance of 3DPT, there will be errors. The plan should be optimized in real time during the operation.

Advances in 3D-Printed Surface-Modified Ca-Si Bioceramic Structures and Their Potential for Bone Tumor Therapy

Bioceramics such as calcium silicate (Ca-Si), have gained a lot of interest in the biomedical field due to their strength, osteogenesis capability, mechanical stability, and biocompatibility. As such, these materials are excellent candidates to promote bone and tissue regeneration along with treating bone cancer. Bioceramic scaffolds, functionalized with appropriate materials, can achieve desirable photothermal effects, opening up a bifunctional approach to osteosarcoma treatments-simultaneously killing cancerous cells while expediting healthy bone tissue regeneration. At the same time, they can also be used as vehicles and cargo structures to deliver anticancer drugs and molecules in a targeted manner to tumorous tissue. However, the traditional synthesis routes for these bioceramic scaffolds limit the macro-, micro-, and nanostructures necessary for maximal benefits for photothermal therapy and drug delivery. Therefore, a different approach to formulate bioceramic scaffolds has emerged in the form of 3D printing, which offers a sustainable, highly reproducible, and scalable method for the production of valuable biomedical materials. Here, calcium silicate (Ca-Si) is reviewed as a novel 3D printing base material, functionalized with highly photothermal materials for osteosarcoma therapy and drug delivery platforms. Consequently, this review aims to detail advances made towards functionalizing 3D-printed Ca-Si and similar bioceramic scaffold structures as well as their resulting applications for various aspects of tumor therapy, with a focus on the external surface and internal dispersion functionalization of the scaffolds.