A heart needs to function properly. pumping blood and getting rid of CO2 in that blood. Modern technology provides solutions for the doctors, sometimes with the help of 3D printing. Cardiac phantoms would be one example, since they can be used for mimicking anatomical imaging tasks.
The use of 3D printing for making cardiac phantoms was recently described in the study called ‘Optimisation of CT protocols for cardiac imaging using three-dimensional printing technology,’ by Kamarul Amin Abdullah of the University of Sydney.
It covers making a cardiac insert phantom, placing it inside the “Lungman” multi-functional chest phantom and performing a CT scan. The last step covers the use of algorithms for dose optimization.
Phantoms are the solution to optimize and refine imagery, especially for CT scans. and evaluate the needed dose of radiation. The latter is more important than it sounds, since various studies show that radiation doses from CT scans have been steadily on the rise during recent years in both Australia and the US.
Since the CT scan technology is more widely available today than ever before, the level of radiation exposure continues to be a cause for concern. There are various solutions to reduce cancer risk during exposure, including tube current reduction, low tube voltage, other protocols, ECG-gating and Bismuth shielding, as well as others, including iterative reconstruction (IR) algorithms.
The usage of phantom-based dose optimization methodology proves to be advantageous, especially for imaging of coronary issues, since basing studies only on real patients has its own limits.
The Catphan phantoms, as well as the ones of American College of Radiology ones, are commonly used for such purposes. But coronary problems require even more accurate solutions.
The Catphan 500 phantom and its modules that are used for various purposes
The studies state that the Lungman anthropomorphic chest phantom comes with a cardiac insert. But the heart-mimicking solution is quite limited in the features. As an example, there is only homogenous material.
The researchers state that it would be more accurate to replace the cardiac insert with a better phantom that would provide CCTA image appearances more similar to a real human heart.
The study also covers the benefits of 3D printing in phantom development. But a 3D printed heart insert for the Lungman phantom has not been made before.
The researchers write: “Consequently, evidence to demonstrate the application of this 3D-printed cardiac insert phantom for CCTA dose optimization is lacking.”
The picture on the left shows the Lungman chest phantom, while the right one shows the heart and lung structures located within the phantom.
Below is the list of some of the goals of the study:
3D printing a cardiac insert phantom using volumetric CT image datasets
Evaluate a 3D printed phantom for an IR algorithm
Finding out optimal IR algorithm strengths for low-tube voltage CCTA protocols
3D printing has been used in the medical sector for various purposes for years: from student training and improving patient care to pre-surgery planning. There are even developments in the field of bioprinted organs. But the number of studies dedicated to 3D printing for making cardiac phantoms is rather small. But the authors of this research managed to 3D print a cardiac insert for the Lungman chest phantom with the similar specifications: We have seen 3D printing in a wide range of medical models, from those fabricated to train medical students to those meant to streamline patient care, and models created for pre-surgical planning. Not a lot of research has been involved in creating cardiac phantoms, though. For this study, they were able to 3D print an insert with the same specifications as the first Lungman cardiac insert:
“The new 3D printed cardiac insert was positioned into the Lungman phantom and scanned using standard CCTA protocols. The resultant images were compared to the patient and Catphan® 500 phantom images. HU values of the attenuating materials within the new 3D-printed cardiac insert phantom were comparable to tissues in the patient image datasets and materials in the Catphan® 500 phantom.”
The Creatbot DM Plus 3D printer was used to make the phantom. Other accurate 3D printers by the same company can be used as well, for example, the Creatbot F160. The insert was afterwards filled with contrast media and oil.
The results were compared to the datasets of real patients and the results of the Catphan 500.
It was found that using an IR algorithm (actually, all types of them) allows for lower exposure without significant difference with accuracy between the FBR and IR algorithms.
The end result is that the team discovered that 3D printing can be used for studies on dose optimization.
“Evidence provided should also provide new horizons to researchers for novel 3D-printed phantoms and facilitate a better CT optimisation process regarding their clinical implementation,” concluded the researchers.
3D printed cardiac insert; (c) Placing the Catphan 500 phantom on the scanner table; (d) Positioning the Lungman chest phantom with the 3D printed cardiac insert phantom (inside of it) on the scanner table
