A design process for a 3D printed patient-specific applicator for HDR brachytherapy of the orbit

Brachytherapy and 3D printing for skin cancer: A review paper

Brachytherapy is a type of radiation therapy, in which a radiation source is placed directly or close to a tumor. It is commonly used to treat skin cancer, and enables precise irradiation treatment of affected area (planning target volume - PTV) while minimizing exposure dose to surrounding healthy tissue (organs at risk - OARs). Recently, the use of 3D printing has begun revolutionizing brachytherapy, as it allows manufacturing of custom-designed applicators for unique shape of skin topography, tumor, and surrounding tissues. Outcome of the combination of 3D printing and brachytherapy has several advantages over traditional treatment planning methods. Some of the advantages are intuitive, whereas others can be concluded from a literature overview as follows: 1) Possibility of developing patient-specific applicators that precisely match the shape of tumor area; 2) Reduction of the time required for applicator production, especially when custom-made devices are needed; 3) Reduction of manufacturing costs; 4) Treatment procedures improvement; 5) Improvement of safety measures accelerated by the development of smart materials (e.g., polymer filaments with admixture of heavy elements); 6) Possibility of nearly instant adjustment into tumor treatment (applicators can be changed as the tumor is changing its shape); and 7) Applicators designed to securely fit to treatment area to hold radioactive source always in the same place for each fraction. Consequently, tumor-provided dose is accurate and leads to effective treatment. In this review paper, we investigated the current state-of-the-art of the application of 3D printing in brachytherapy. A number of existing reports were chosen and reviewed in terms of printing technology, materials used, treatment effectiveness, and fabrication protocols. Furthermore, the development of future directions that should be considered by collaborative teams bridging different fields of science, such as medicine, physics, chemistry, and material science were summarized. With the indicated topics, we hope to stimulate the innovative progress of 3D printing technology in brachytherapy.

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.

Comparison of the decompressive effect of different surgical procedures for dysthyroid optic neuropathy using 3D printed models

PURPOSE

To compare the decompressive effect around the optic nerve canal among 3 different decompression procedures (medial, balanced, and inferomedial) using 3D printed models.

METHODS

In this experimental study, based on data obtained from 9 patients (18 sides) with dysthyroid optic neuropathy, a preoperative control model and 3 plaster decompression models were created using a 3D printer (total, 72 sides of 36 models). A pressure sensor was placed at the optic foramen, and the orbital space was filled with silicone. The surface of the silicone was pushed down directly, and changes in pressure were recorded at 2-mm increments of pushing.

RESULTS

At 10 mm of pushing, there was significantly lower pressure in the medial (19,782.2 ± 4319.9 Pa, P = 0.001), balanced (19,448.3 ± 3767.4 Pa, P = 0.003), and inferomedial (15,855.8 ± 4000.7 Pa, P < 0.001) decompression models than in the control model (25,217.8 ± 6087.5 Pa). Overall, the statistical results for each 2-mm push were similar among the models up to 10 mm of pushing (P < 0.050). At each push, inferomedial decompression caused the greatest reduction in pressure (P < 0.050), whereas there was no significant difference in pressure between the medial and balanced decompression models (P > 0.050).

CONCLUSION

All 3 commonly performed decompression procedures significantly reduced retrobulbar pressure. Because inferomedial decompression models obtained the greatest reduction in pressure on the optic nerve canal, inferomedial decompression should be considered the most reliable procedure for rescuing vision in dysthyroid optic neuropathy.

3D Printing in Eye Care

Three-dimensional printing enables precise modeling of anatomical structures and has been employed in a broad range of applications across medicine. Its earliest use in eye care included orbital models for training and surgical planning, which have subsequently enabled the design of custom-fit prostheses in oculoplastic surgery. It has evolved to include the production of surgical instruments, diagnostic tools, spectacles, and devices for delivery of drug and radiation therapy. During the COVID-19 pandemic, increased demand for personal protective equipment and supply chain shortages inspired many institutions to 3D-print their own eye protection. Cataract surgery, the most common procedure performed worldwide, may someday make use of custom-printed intraocular lenses. Perhaps its most alluring potential resides in the possibility of printing tissues at a cellular level to address unmet needs in the world of corneal and retinal diseases. Early models toward this end have shown promise for engineering tissues which, while not quite ready for transplantation, can serve as a useful model for in vitro disease and therapeutic research. As more institutions incorporate in-house or outsourced 3D printing for research models and clinical care, ethical and regulatory concerns will become a greater consideration. This report highlights the uses of 3D printing in eye care by subspecialty and clinical modality, with an aim to provide a useful entry point for anyone seeking to engage with the technology in their area of interest.

Radiation therapy for uveal melanoma: a review of treatment methods available in 2021

PURPOSE OF REVIEW

Radiation therapy has become the standard of care for the treatment of uveal melanoma. We intend to outline the current radiation therapy methods that are employed to treat uveal melanoma. We will outline their relative benefits over one another. We will also provide some background about radiation therapy in general to accustom the ophthalmologists likely reading this review.

RECENT FINDINGS

Four main options exist for radiation therapy of uveal melanoma. Because the eye is a small space, and because melanomas are relatively radioresistant, oncologists treating uveal melanoma must deliver highly focused doses in high amounts to a small space. Therapies incorporating external beams include proton beam therapy and stereotactic radiosurgery. Stereotactic radiosurgery comes in two forms, gamma knife therapy and cyberknife therapy. Radiation may also be placed directly on the eye surgically via plaque brachytherapy. All methods have been used effectively to treat uveal melanoma.

SUMMARY

Each particular radiotherapy technique employed to treat uveal melanoma has its own set of benefits and drawbacks. The ocular oncologist can choose amongst these therapies based upon his or her clinical judgment of the relative risks and benefits. Availability of the therapy and cost to the patient remain significant factors in the ocular oncologist's choice.