Imaging different bone sites for medical education requires the formation of bone-equivalent materials that mimic bone density. We investigated an economic imaging composition that characterizes bone density in imaging for quality assurance and educational purposes. Four different compositions were tested to reveal the best composition in simulating bone density in X-ray imaging. Hydrated lime was discovered to be the most suitable because it is durable (stiff and does not crumble), easy to source and process, and attenuates imaging X-rays enough to resemble real bone. Hydrated lime provides a significantly better phantom than the other combinations used.
Radiologic anatomical phantoms are commercially available for quality assurance and educational purposes. However, these phantoms are considered expensive and do not demonstrate all pathological complications. Therefore, materials that can convincingly simulate bone in X-ray imaging, for educational and quality-assurance purposes, have generated great interest.
Bone is composed of organic and inorganic compounds in the form of minerals. Living bone consists of 10% - 20% water and 60% - 70% minerals, with most of the rest comprising collagen and small amounts of other substances, such as proteins and inorganic salts [
The mineral component can be approximated by hydroxyapatite (HA, Ca10(PO4)6(OH)2). Since the composition of real bone minerals is much more complex, and contains supplementary ions such as silicon and zinc, bone minerals have Ca:P ratios ranging from 1.37 - 1.87 [
The aim of this research was to mimic bone-chemical composition for X-ray imaging, by constructing an economical phantom with widely available materials, whose density closely matched that of bone. Materials closely resembling the mineral ingredients of bone, calcium (mainly), and collagen were used to construct the phantom. The resulting product of these constituents can simulate bone in different anatomical and pathological conditions, for both quality assurance and educational purposes.
Materials of a similar density to that of bone were chosen for X-ray imaging. Hydrated lime (calcium hydroxide Ca(OH)2) was used to represent calcium [
Four samples of different proportions of various components were prepared to investigate the chemical composition that best mimicked bone in X-ray imaging (see
Hydrated lime is a building substance, purchased from a building materials store and manufactured by Arabian Industries, Riyadh, Kingdom of Saudi Arabia. Agar strips, originating from China, were purchased from a grocery store. The agar was ground to a powder, the lime was filtered, and all solid materials were blended together. The mixing process of four (10 cm-wide) shakes per second for 1 minute mixed all solid materials homogeneously. These materials were mixed with Safa (branded) water (Ca-Na-HCO3-C1-SO4) [
All solid mixtures (
Sample number | Chemical composition of solid materials |
---|---|
1 | 100% lime |
2 | 70% lime, 30% gelatin |
3 | 40% lime, 30% gelatin, 30% KPO |
4 | 70% lime, 30% KPO |
Ca | Mg | Na | K | Fe | HCO3 | SO4 | NO3 | Cl | F | BrO3 |
---|---|---|---|---|---|---|---|---|---|---|
19.0 | 3.0 | 19.0 | 1.80 | 0.00 | 39.0 | 27.0 | 2.80 | 33.0 | 1.00 | <0.01 |
the ions present in the water before mixing were ignored. For example, the weight of sodium ions (Na = 19 ppm) in 1 mL of water is only 0.0190 mg, which is relatively insignificant. Mixtures were cast in molds to mirror bone dimensions. The X-ray machine used to image the samples was a Definium 6000, General Electric, 2009 with imaging parameters set as 10 mA, 50 kV, and 1.6 mAs.
The four samples, listed in
The choice of ideal sample depended on the qualitative information gathered in
Sample one was clearly the best material and met all our specifications (
Sample number | Sample characterization | |||
---|---|---|---|---|
Easy to find materials | Easy to produce | Durability | X-ray image acceptance | |
1 | Yes | Yes | Yes | Yes |
2 | Yes | Yes | No | Yes |
3 | No | No | No | No |
4 | No | Yes | No | No |
The idea of discovering a new economical material that mimics bone density in X-ray imaging started when trying to make phantoms of different bone fractures and sites for medical education and quality assurance purposes. Different materials have been discovered in the literature, however, they are not economical, durable, nor easy to produce. Among the tested materials in this study, the most economical at mimicking bone in X-ray imaging was hydrated lime. Hydrated lime is durable (stiff and does not crumble), easy to find and process, and has a good X-ray image intensity compared with that of real bone. Future work should involve X-ray imaging testing of different hydrated-lime morphologies that simulate their real-bone counterparts.
All thanks to The Creator for His blessings. I would like to thank radiographers Mr. Shuraim Alyami and Mr. Hashim Alalawi for operating the X-ray machine, acquiring the radiographs, and optimizing the images. Special thanks to Dr. Saddig Jastaniah for qualifying the resultant images. I would also like to thank Editage (http://www.editage.com/) for English language editing.
The author declares no conflicts of interest regarding the publication of this paper.
Alkhateeb, S.M. (2019) Mimicking Bone Chemical Composition Using Economical Materials for X-Ray Imaging Quality Assurance and Educational Purposes. Open Journal of Biophysics, 9, 83-87. https://doi.org/10.4236/ojbiphy.2019.92006