The Role of 3D Printing in Medical Applications: A State of the Art. J Healthc Eng. 2019;2019:5340616. [PMID: 31019667 PMCID: PMC6451800 DOI: 10.1155/2019/5340616]

Evaluation of the Dimensional Accuracy of 3D-Printed Anatomical Mandibular Models Using FFF, SLA, SLS, MJ, and BJ Printing Technology

With the rapid progression of additive manufacturing and the emergence of new 3D printing technologies, accuracy assessment is mostly being performed on isosymmetric-shaped test bodies. However, the accuracy of anatomic models can vary. The dimensional accuracy of root mean square values in terms of trueness and precision of 50 mandibular replicas, printed with five common printing technologies, were evaluated. The highest trueness was found for the selective laser sintering printer (0.11 ± 0.016 mm), followed by a binder jetting printer (0.14 ± 0.02 mm), and a fused filament fabrication printer (0.16 ± 0.009 mm). However, highest precision was identified for the fused filament fabrication printer (0.05 ± 0.005 mm) whereas other printers had marginally lower values. Despite the statistically significance (p < 0.001), these differences can be considered clinically insignificant. These findings demonstrate that all 3D printing technologies create models with satisfactory dimensional accuracy for surgical use. Since satisfactory results in terms of accuracy can be reached with most technologies, the choice should be more strongly based on the printing materials, the intended use, and the overall budget. The simplest printing technology (fused filament fabrication) always scored high and thus is a reliable choice for most purposes.

Cinematic rendering for three-dimensional reconstructions of the chest wall: a new reality

Computed tomography with multiple detectors and the advancement of processors improved rendered images and three-dimensional reconstructions in clinical practice. Traditional axial slices form non-intuitive images because they are seen in only one plane. The three-dimensional reconstructions can show structures details and diseases with complex anatomy in different perspectives. Cinematic rendering is a newly three-dimensional reconstruction technique, already approved for clinical use, which can produce realistic images from traditional computed tomography data. The algorithm used is based on light trajectory methods and the global lighting model, which simulate thousands of images from all possible directions. Thus, the technique shapes the physical propagation of light and generates a realistic three-dimensional image with depth, shadows and more anatomic details. It is a multidimensional rendering acquired through complex lighting effects. The aim of this article was to show the advance of three-dimensional technology with the cinematic rendering in images exams of the thoracic wall.

Polymers for Extrusion-Based 3D Printing of Pharmaceuticals: A Holistic Materials-Process Perspective

Three dimensional (3D) printing as an advanced manufacturing technology is progressing to be established in the pharmaceutical industry to overcome the traditional manufacturing regime of 'one size fits for all'. Using 3D printing, it is possible to design and develop complex dosage forms that can be suitable for tuning drug release. Polymers are the key materials that are necessary for 3D printing. Among all 3D printing processes, extrusion-based (both fused deposition modeling (FDM) and pressure-assisted microsyringe (PAM)) 3D printing is well researched for pharmaceutical manufacturing. It is important to understand which polymers are suitable for extrusion-based 3D printing of pharmaceuticals and how their properties, as well as the behavior of polymer-active pharmaceutical ingredient (API) combinations, impact the printing process. Especially, understanding the rheology of the polymer and API-polymer mixtures is necessary for successful 3D printing of dosage forms or printed structures. This review has summarized a holistic materials-process perspective for polymers on extrusion-based 3D printing. The main focus herein will be both FDM and PAM 3D printing processes. It elaborates the discussion on the comparison of 3D printing with the traditional direct compression process, the necessity of rheology, and the characterization techniques required for the printed structure, drug, and excipients. The current technological challenges, regulatory aspects, and the direction toward which the technology is moving, especially for personalized pharmaceuticals and multi-drug printing, are also briefly discussed.

Three-Dimensionally-Precise Breast Conformal Device for IMRT in Breast Cancer Patients Treated With Breast-Conserving Surgery-A Pilot Randomized Controlled Trial

OBJECTIVE

To examine the accuracy and efficiency of breast radiotherapy after breast-conserving surgery of a novel 3-dimensional (3D) printing tissue compensator technology, the 3D-precise breast conformer, compared with a usual compensator and an unstructured compensator.

METHODS

This novel device is patented in China (patent No.: ZL2015 2 0259472.9). Thirty patients with breast cancer after breast-conserving surgery were randomly divided into 2 control groups (no compensator, NST group, and usual compensator, ST group) and 1 study group (3D-precise breast conformer, 3D-BCT group) (n = 10/group). Before radiotherapy, all patients were scanned in the same CT positioning conditions to prepare the treatment plans.

RESULTS

The 3D-BCT showed the best homogeneity index (HI) (0.08 ± 0.03) and conformity index (CI) (0.95 ± 0.03), while the NST group showed the worst HI (0.34 ± 0.07) and CI (0.78 ± 0.06), with the ST group between the 2 (HI: 0.15 ± 0.05; CI: 0.87 ± 0.04) (all P < 0.01). The common tissue compensation membrane could lead to 95-100% of the prescription dose covering 85-95% of the target volume, and the uniformity and conformability of the target dose were improved overall compared with the NST group. In the 3D-BCT group, 100% of the prescription dose covered the target volume of 95-100%.

CONCLUSION

The 3D-precision breast conformal device had the highest individualization, uniformity, and conformity. The V95, V98, CI, and HI of PTV were optimal in the 3D-BCT group, and an ideal isodose curve distribution of the breast and clavicle upper and lower target areas was achieved. This device could improve the surface dose and the efficacy of radiotherapy after breast-conserving surgery.

Effect of Shot Peening on the Mechanical Properties and Cytotoxicity Behaviour of Titanium Implants Produced by 3D Printing Technology

Structural discontinuities characterize the implants produced directly from metal powders in 3D printing technology. Mainly, the surface defects should be subjected to procedures associated with surface layer modification (likewise shot peening) resulting in the increase of the implant service life maintaining optimal biocompatibility. Therefore, the purpose of the present study was to investigate the effect of type of shot used for the peening process on the Ti-6Al-4V implants functional properties as well as the biological properties. The components were produced by DMLS (direct metal laser sintering) additive technology. The surfaces of titanium specimens have been subjected to the shot peening process by means of three different shots, i.e., CrNi steel shot, crushed nut shells, and ceramic balls shot. Then, the specimens have been subjected to profilometric analysis, microhardness tests, and static strength testing as well as to the assessment of biocompatibility in respect of cytotoxicity using human BJ fibroblasts. The shot peening process causes the strengthening of surface layer and the increase of strength parameters. Furthermore, the test results indicate good biocompatibility of surfaces being tested, and the effect of shot peening process on the titanium alloy cytotoxicity is acceptable. At the same time, most favourable behaviour in respect of cytotoxicity has been found in the case of surfaces modified by means of ceramic balls > nut shells > CrNi steel shot correspondingly.

Regenerative Medicine: "Are We There Yet?"

Translation of regenerative therapies to the patient-bench-to-bedside-is one of the global multidisciplinary challenges of our time. New cell-based therapies are reaching the clinic through staged trials leading eventually to routine adoption. The roots of stem cell therapy lie in surgical practice and transplantation medicine with multiple multidisciplinary challenges emerging to support the new therapies. Control of stem cell behavior in line with regulatory confidence is an example of these challenges. One successful journey from bench-to-bedside is the generation of cartilage through autologous cell-based approaches for use in the repair of the knee joint. An analysis of this journey in Europe reveals success and failure; new initiatives include adopting more quantitative modelling and "organ on a chip" approaches to be used in clinical translation reducing experimental time and redressing the lack of preclinical models. The current state and challenges for the field are outlined with the question posed, "are we there yet?"