In the previous section of this guide, we went in-depth about the strategic issues surrounding 3D printing in hospitals, which included the critical role played by clinical trials, organization and staffing, and regulatory/legal concerns. In this section of the guide, I will focus on the tactical issues in 3D printing in hospitals. To review, tactical issues answer the questions focusing on “how”. In other words, tactical consideration refers to how a company plans to get the job done or achieve a strategic objective. Tactical planning considers the resources available (time, money, people) along with the risks or challenges that may be encountered. Based on tactical consideration, the company determines the most efficient way to use resources to achieve strategic goals with quality results.
- Introduction: What is operational management?
- Technical Background
- Strategic Issues
- Tactical Issues in 3D Printing in hospitals
- Financial Issues
- Financial Worksheet
We will breakdown discussions on the tactical issues of 3D printing in hospitals in the following sections:
A. Talent allocation for 3D Printing in Hospitals
Currently, most medical centers rely on individuals who are 3D printing enthusiasts. These staff members are motivated and capable of learning new skills, often on their own time without additional compensation. Over time, as the demand for 3D printing increases, many centers will find themselves exhausted of manpower. Ultimately, letting hobbyists man the 3D printing center is not viable for a professional operating facility. To provide reliable 3D printing services consistently, talent allocation needs to be addressed. Typical skills necessary for staffing such a center include the following:
- Basic imaging acquisition knowledge: Imaging acquisition ranges from 3D scanning to radiological exams (CT, MRI, high-resolution ultrasound, etc). Knowing if the quality of the images acquired is adequate for 3D printing is crucial. This will require staff to understand the imaging protocol and why certain images can or cannot be used for printing
- Good CAD/3D software understanding: Training staff to use basic (and sometimes open-source) 3D printing processing software is time-consuming. Familiarity with 3D visualization software will make the learning curve much lower. The applications of 3D printing in hospitals not only include replicating human anatomy, but also include designing and modifying medical tools like surgical guides or patient-specific implants with extended functions. Therefore, CAD knowledge is necessary to maximize utilization of a 3D printing center. While most engineering and design programs now offer formal CAD (computer-aided design) education, hospital radiology staff typically do not have such a background and the learning curve could also be high.
- Understanding of 3D printing hardware (3D printer and materials): Basic maintenance is often required when working with 3D printers. Although an engineering degree is not necessary since most commercial printers are fairly user-friendly, understanding the basic mechanics and material science is necessary for workflow design and troubleshooting. As the portfolio of materials grows larger, staff members also need to know how to optimize and safely handle materials used in 3D printing. We will address this more in a later part of this guide.
- Basic medical knowledge: Having a basic understanding of the clinical case is important to produce high-quality prints, with more attention to clinically relevant aspects of the case. At a minimum, staff members should have basic knowledge of human anatomy, physiology, and pathology. This should also lead to better quality control of the final product. Typical radiology technicians or medical 3D visualization lab technologists will have these foundations already.
Within the medical community, some radiologists and radiological technicians are already equipped with these skills and have the lowest barrier to entry to staff a 3D printing center. Due to the high cost of hiring a dedicated staff member, the best choice to staff these centers is a highly trained and experienced radiological technician who is well versed in 3D software and virtual surgical planning tools.
Many larger imaging centers have dedicated imaging post-processing labs (“3D labs”), where the technologist’s main role is to use various visualization tools to create 3D images for various clinical purposes. These staff members are ideal for future 3D printing centers because of their medical knowledge, ability to communicate clinical information, and experience with existing post-processing software tools. If the volume for 3D printed models does not reach a level where a full-time technologist is needed, many of the same staff members can also be productive in other areas of the department.
B. Printer/material selection for 3D Printing in Hospitals
For comprehensive lists of printing process/printers and materials used for healthcare 3D printing, the readers can refer to Table II and Table III (embedded below). As this is an ever-changing landscape, we will continue to update this table to stay current with the community.
1. 3D Printers
Key performance characteristics in selecting printers include the following:
- Materials Selection
- Autonomous operations
- Ease of Use
- Multi-material capability
The choice of a 3D printer will depend on the end application. For example, an educational anatomical model will have less stringent requirements than a model used for surgical planning (which is considered a diagnostic tool by FDA).
Many would agree that speed is one of the most important features for hospital-based applications such as pre-surgical planning. In preoperative applications, the need for the model may be more urgent but printing usually takes hours and sometimes days. Improvement to the existing printers to meed speed demand may include varying printing process and include optimizing the printer component, printer head, laser movement.
The next important consideration is material selection for a particular 3D printer. Limitation in bio-compatible optimized 3D printable materials is real in the healthcare arena. While there is immediate economic advantage to use a printer that can use a variety of materials, there are many limitations to the subsequent print, ranging from mechanical properties, sterilization capability, resolution, and more.
The multi-material and multi-head capabilities are also of particular interest. For example, models of the heart with color-coded parts such as veins, arteries, etc. can be made faster if the sections are not made piecemeal. Models for surgical practice often require materials with different haptic properties and would be made much faster if, once again, the complete model could be made at once and not in a piecemeal fashion.
There are limited 3D printing materials that are biocompatible and can be readily sterilized. However, since the publication of our original book, there are more major materials players in the space. [Ref] The academic reference on this subject is limited beyond tissue engineering. Stay tuned for an updated guide soon.
Having options for a variety of materials with different strength, elasticity, color/transparency, flexibility in sterilization techniques will allow for agility and wider use for 3D printing centers in hospitals.
3D printer manufacturers typically produce 3D printing materials optimal for their printers. Again, purchase decisions should start with the current and potential future applications for which the printers are intended.
3. Three questions to ask before purchase:
1) End applications of the 3D printing
As we have mentioned in previous parts of this guide, 3D printing applications in hospitals have grown beyond anatomical modeling, where visual appeal and accuracy take priority. More extended applications include surgical guides which will be in direct contact with patients for a limited timeframe. Less frequent now but definitely foreseeable future of point of care 3D printed implants will also become part of offering portfolios for more and more hospitals. Depending on the short and long term planning of a 3D printing center, it would be logical to develop a purchasing plan based on both current and future expanded needs.
For anatomical modeling and medical device prototyping, purchasing decisions focus on requirements in terms of resolution, color, texture, tactile characteristics of the final prints. For surgical guides, material options of a printing system will be more critical. For implants, the requirements will be even more limited in purchasing options. Typically, these 3D printers will be more expensive and also labor intensive to manage.
As our previous part of this guide pointed out, the regulatory and legal landscape in manufacturing higher classification medical devices in hospitals is still largely unknown. Readers are also advised to read an excellent recently published Expert’s Corner blog on product liability.
2) Size of the print
This could be related to the specialty for which the setup is intended. For example, the print size capability of a system dedicated to craniofacial reconstruction will be very different from a system dedicated to spine surgery or orthopedics. A printing system shared among different specialties will require a large enough platform for everyone, and therefore, it will be more expensive.
One benefit of 3D printing is that the 3D print does not have to have a 1:1 scale to the actual body part or pathology. The engineer can magnify or shrink the resulted model at will.
3) Sterilization consideration
Ideally, more new sterilization techniques that do not require high temperature or toxic chemicals, and techniques that require less time will be more useful.
C. Software selection for 3D Printing in Hospitals
1. Cost to use – open vs. commercial software.
“Free” may not be “cheap”.
The cost of using free open-source software such as 3D slicer or Blender includes less documentation or instruction, less technical support in case of dysfunction, and less development or updates. However, since the book was last published, communities surrounding both 3D Slicer, Blender, Meshmixer, and other free software tools have grown significantly larger. New plugins are getting developed to fit specialty needs in a grassroots fashion, encouraging more to join.
Using open-source software tools is in particular a viable option for users with a small budget, technological savvy, and willing to invest time in tweaking features. Additionally, the lack of FDA clearance could also be a deterrent for wider use in the clinical setting.
That said, time is an important factor. The opportunity cost of using an immature tool is often prohibitive for busy clinicians to learn the software themselves. While this software does require institutional level annual licensing fees, tools like Materialise Inprint Mimics and D2P 3D Systems have more intuitive UI/UX, better technical support, and therefore, less steep learning curve. Additionally, both products have FDA clearance to be used for 3D printed anatomical modeling.
2. Future trend – automation and streamlined workflow→ AI/Machine Learning.
Segmentation has been and still is the most time-consuming step of DICOM to STL conversion, although there have been quite a few innovations leveraging machine learning and artificial intelligence focusing on this challenge. Interested users can check out our Directory, where we actively update new players in the space.
Not infrequently, clinicians can spend up to 10+ hours to segment a complex pathology. Others have spent less time but still often in hours of magnitude.
Automated segmentation will be a significant future development in the software area and will prove to be extremely valuable for cost-saving improvements. Lately, new printing technologies like voxel print claim the need for segmentation will be significantly reduced to eliminated. However, such technology is currently limited to Stratasys polyjet printers. The medical application of this technology is still at early stage.
Beyond the DICOM to STL conversion step, a more streamlined end-to-end digital workflow from data/image acquisition to 3D prints is what many users are hoping for. Many steps can in theory be optimized by machine learning.
Echoing this need, many larger PACS vendors are now developing DICOM to STL conversion capability with their latest software updates. Segmentation tools are also included in some of these newer versions. Several startups and existing 3D printing companies are also actively developing products that are more user-friendly to the healthcare industry, with an end-to-end solution in mind.
D. Imaging protocoling and acquisition for 3D Printing in Hospitals
High-quality imaging acquisition is extremely important to produce a high-fidelity 3D printed model. In theory, any cross-sectional imaging modality can be protocoled to produce images compatible with 3D printing. This would include traditional adult CT, MRI. New imaging technologies including better 3D scanning, high-resolution 3D US, fetal MRI, and digital rotational angiogram (DRA) are also expanding the horizon of tools that can be used for data acquisition. [Ref, Ref, Ref]
Typically, the maximum slice thickness for any cross-sectional imaging study should be less than 2 mm. However, there is an existing publication on new reconstruction algorithms that can be used to create adequate STL files from thicker slices (~ 5mm), such as in the case of fetal MRI. [Ref, Ref, Ref, Ref]
E. Quality control and inspection for 3D Printing in Hospitals
As it was discussed earlier in this paper, errors can occur during each of the six described steps, with the accumulative error even more significant.[Ref, Ref, Ref] An agreed-upon standard for various healthcare 3D printing in hospitals is still getting developed.
Establishing such a standard may be challenging as each clinical scenario may require different quality control processes. For example, a model that is used for patient education may not require high accuracy or verifiable labeling (i.e. right vs. left, mirror image, scale, and etc.) as much as a model that is used for surgical strategy intra-operatively. That said, certain calibration processes to verify the accuracy of the conversion from digital file to physical print will be necessary.
Additional quality control steps using digital files or intraoperative measurements may also take place. Many are hoping FDA could eventually provide more guidance on quality control for a variety of clinical cases and circumstances. Licensure may be necessary to ensure the quality of a 3D printing center similar to the American College of Radiology accreditation process of U.S. medical imaging centers.
Especially with centers responsible for a larger number of prints, correct patient and anatomical identifications on the print will also be important, as avoiding errors from transforming a digital file into a physical object that is supposed to simulate reality will be critical. This is where discussions on data management could be relevant, however, underappreciated subject. Stay tuned for our updates.
F. Material management for 3D Printing in Hospitals
Choosing the material to use for making a 3D printed model can seem overwhelming as there are many choices available and factors to take into consideration. (Table III, above) The first decision is based on the intended use of the final print.
Roughly, for anatomical modeling and surgical guides, polymers are used whereas metals, PEEK, ceramics, and etc, are often used for implants given their mechanical properties.
Another consideration is the environment in which the model will be used. If the model will be taken into a sterile environment like the operating room, it must be made of a material that is sterilizable such as metal, nylon, or PEEK. The exact heat and chemical nature of the sterilization process will also affect the specific choice of material.
G. Safety for 3D Printing in Hospitals
Powder materials have special material handling requirements to prevent explosions, fires, and inhalation of hazardous materials. In 2014, Powderpart Inc, a 3D printing company, experienced an explosion, fire, and injury of workers due to improper handling of metal powders. (Ref)
Airborne emission particles are potential health safety issues. A study released in 2013 by the Illinois Institute of Technology measured the emissions of Ultra-Fine Particles (UFPs) by desktop 3D printers using extrusion of thermoplastics and found levels and particle sizes similar to that reported during grilling food on gas or electric stoves at low power. (Ref) The paper recommends caution should be used when operating some commercially available 3D printers in unvented or inadequately filtered indoor environments. (Ref)
Carnegie Mellon University (CMU) has also published a 4-page document on 3D printing safety. (Ref) It warns of the emission of nanoparticles during the extrusion process and recommends that exhaust ventilation, filtration devices, and the placement of printers be considered when setting up the devices. (Ref)
Airborne aerosol emissions are another environmental safety issue to plan for. A study released in January 2016 documented Volatile Organic Compounds (VOCs) from filament extrusion process printers including styrene, a known cancer-causing agent, from ABS. Once again, proper ventilation is required. [Ref]
In other words, there is a level of safety concern, large or small, with all 3D printing process to the people working around a 3D printer and 3D printing materials. However, these are often understudied, and long term health data is not yet available.
Post-processing introduces even more areas of safety concern. The removal of support material, which is used in applications where the model has an overhang that must be supported during the printing process, may need caustic chemicals. If the material for the supports is considered hazardous waste it must also be disposed of appropriately. The mechanical polishing for the post-print finishing introduces airborne particulates into the environment.
CMU also lists four additional safety hazards to be aware of (Ref):
- Hot surfaces – Print head block and UV lamp
- High voltage – UV lamp connector, electric outlet safety certified and ground wire
- Ultraviolet radiation – UV lamp. Don’t look at the lamp and make sure the UV screen is intact.
- Moving parts – Printing assembly
The latest product safety standards address these potential hazards, so is important to ensure the equipment has been tested and certified by an established third-party certifier.
H. Storage for 3D Printing in Hospitals
The space required for material storage and any special environmental conditions need to be evaluated before purchasing materials.
Can the materials be purchased in small quantities?
Metal powders are generally only available in industrial-sized quantities. Some materials have expiration dates; so smaller quantities should be purchased to avoid waste.
Are there specific storage requirements?
For example, nylon needs to stay in an airtight container. Otherwise, it will absorb moisture, which will cause bubbles during printing. Many factors must be considered when planning for the purchasing and storage of specific 3D printing materials.
In the next section, we will focus on the financial issues in 3D printing in hospitals.
About the Author:
Jenny Chen, MD, is currently the Founder and CEO of 3DHEALS, a company focusing on education and industrial research in the space of bioprinting, regenerative medicine, healthcare applications using 3D printing. With a focus on emerging healthcare technology, Jenny invests in and mentors relevant startups, especially companies pitching through Pitch3D. She believes a more decentralized and personalized healthcare delivery system will better our future.
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