Phantom structure

Phantom structures are artificial structures designed to emulate properties of the human body in matters such as, including, but not limited to, light scattering and optics, electrical conductivity, and sound wave reception. Phantoms have been used experimentally in lieu of, or as a supplement to, human subjects to maintain consistency, verify reliability of technologies, or reduce experimental expense.[1] They also have been employed as material for training technicians to perform imaging.[2]

Optical phantoms
Main article: Imaging phantom

Optical tissue phantoms, or imaging phantoms, are reported to be used largely for three main purposes: to calibrate optical devices, record baseline reference measurements, and for imaging the human body.[3] Optical tissue phantoms may have irregular shape of body parts.[4]

Composite Materials

Optical phantoms can be made from a number of materials. These are including but not limited to: 

  • homogenized milk[3]
  • non-dairy creamer[3]
  • wax[3]
  • blood and yeast suspension[3]
  • water-soluble dye (India ink)[3]
  • intralipid[3]
  • latex microspheres[3]
  • solid epoxy[4][3]
  • liquid rubber[4]
  • silicone[3]
  • polyester[3]
  • polyurethane[3]

Computational phantoms
Main article: Computational human phantom

Computational human phantoms have many uses, including but not limited to, biomedical imaging computational modeling and simulations, radiation dosimetry, and treatment planning.[5]

Physiological models

Phantom head

While using research oriented and Commercial Off The Shelf (COTS) EEG technologies built for monitoring brain activity, scientists established the need for a benchmark reading of neural electrical activity.[1] EEG readings’ strong dependency on mechanical contact makes the technology sensitive to movement.[6] This and a high responsivity to environmental conditions may lead to signal noise. Without a baseline, it is hard to interpret whether abnormal clinical data is a result of faulty technology, patient inconsistency or noncompliance, ambient noise, or an unexplained scientific principle.[1]

A phantom head was described by researchers in 2015. This head was developed at the U.S. Army Research Laboratory.[1] Reported intent for the engineering of this phantom head was to “accurately recreate real and imaginary scalp impedance, contain internal emitters to create dipoles, and be easily replicable across various labs and research groups.” [7]

The scientists used an inverse 3D printed mold that was reproduced an anonymized MRI image. The head consisted of ballistics gel with a composition that included salt in order to conduct electricity like human tissue.[8] Ballistics gelatin was chosen because it conducts electricity,[8] while also possessing mechanical properties similar to living tissue.[9][10] Multiple electric wires within the Army’s phantom head carried electric current. A CT scan was used to verify proper electrode placement.[8] The limitations of this phantom was that the material was not sufficiently durable.[1][8] The refrigerated gel degraded relatively quickly, by approximately .3% each day.[8]

Other reported models had been made of saline filled spheres.[11]

Phantom pancreas

In 2013, a patent submission for a prostate phantom was reported. The prostate was composed of three separate phantom layers of prostate, perineal gland, and skin tissue and developed for the study of prostate cancer brachytherapy. The scientists claimed that the phantom emulates the imaging and mechanical properties of the prostate and surrounding tissues.[12]

Phantom ear

In 2002, researchers proposed an ear phantom for experimental studies on sound absorbance rates of cellular emissions.[13]

Phantom skin

Several designs of phantom skin have been developed for various uses including, but not limited to, studying skin lesion therapy, applications of narrowband and ultra-band microwaves (like breast cancer detection),[14] and imaging fingernails and underlying tissues.[15]

Phantom breast

Ultrasound tissue elastography is a method to determine tissue health, as pathologies have been noted to increase the elasticity of tissue. In 2015, a tissue-like agar-based phantom had been reported to be useful in compression elastographical diagnosis of breast cancer. The scientists replicated the clinical appearance of conditions such as fibroadenoma and invasive ductal carcinoma in the phantom breast and compared elastographic and sonographic images.[2]

Additionally, a recipe for the formation of a semi-compressible phantom breast with liquid rubber has been reported.[4]

gollark: > By using potatOS, agreeing to be bound by these terms, misusing potatOS, installing potatOS, reading about potatOS, knowing about these terms, knowing anyone who is bound by these terms, disusing potatOS, reading these terms, or thinking of anything related to these terms, you agree to be bound by these terms both until the last stars in the universe burn out and the last black holes evaporate and retroactively, arbitrarily far into the past.
gollark: So I don't want to actually have to manage one or several.
gollark: I mean, the majority of what children do seems to be annoying.
gollark: Exactly. You are ALL bound by the privacy policy, but only the potatOS one, not the endOS one.
gollark: Also, just a note, you're bound by the potatOS privacy policy.

References
  1. "'Phantom head' may one day take guesswork out of EEG monitoring". www.army.mil. Retrieved 2018-08-22.
  2. Manickam K, Reddy MR, Seshadri S, Raghavan B (October 2015). "Development of a training phantom for compression breast elastography-comparison of various elastography systems and numerical simulations". Journal of Medical Imaging. 2 (4): 047002. doi:10.1117/1.JMI.2.4.047002. PMC 4682573. PMID 26697511.
  3. "Project: Optical Phantoms". omlc.org. Retrieved 2018-08-22.
  4. "Photon Migration Imaging Lab". www.nmr.mgh.harvard.edu. Retrieved 2018-08-22.
  5. "6th International Workshop on Computational Human Phantoms | August 27 – 30, 2017 in historic Annapolis, MD, USA". www.cpworkshop.org. Retrieved 2018-08-22.
  6. Slipher GA, Hairston WD, Bradford JC, Bain ED, Mrozek RA (2018-02-06). "Carbon nanofiber-filled conductive silicone elastomers as soft, dry bioelectronic interfaces". PLOS ONE. 13 (2): e0189415. Bibcode:2018PLoSO..1389415S. doi:10.1371/journal.pone.0189415. PMC 5800568. PMID 29408942.
  7. Hairston WD, A Slipher G, B Yu A (2016-09-24). "Ballistic gelatin as a putative substrate for EEG phantom devices". arXiv:1609.07691. Bibcode:2016arXiv160907691H. Cite journal requires |journal= (help)
  8. "Summer student's EEG research continues to develop at ARL | U.S. Army Research Laboratory". www.arl.army.mil. Retrieved 2018-08-22.
  9. Richler, D; Rittel, D (2014-06-01). "On the Testing of the Dynamic Mechanical Properties of Soft Gelatins". Experimental Mechanics. 54 (5): 805–815. doi:10.1007/s11340-014-9848-4.
  10. Farrer AI, Odéen H, de Bever J, Coats B, Parker DL, Payne A, Christensen DA (2015-06-16). "Characterization and evaluation of tissue-mimicking gelatin phantoms for use with MRgFUS". Journal of Therapeutic Ultrasound. 3: 9. doi:10.1186/s40349-015-0030-y. PMC 4490606. PMID 26146557.
  11. Collier, T. J.; Kynor, D. B.; Bieszczad, J.; Audette, W. E.; Kobylarz, E. J.; Diamond, S. G. (2012). "Creation of a Human Head Phantom for Testing of Electroencephalography Equipment and Techniques - IEEE Journals & Magazine". IEEE Transactions on Bio-Medical Engineering. 59 (9): 2628–34. doi:10.1109/TBME.2012.2207434. PMID 22911537.
  12. "U.S. Patent No. US 8,480.407 B2" (issued Jul.9, 2013)
  13. Gandhi OP, Kang G (2002). "Some present problems and a proposed experimental phantom for SAR compliance testing of cellular telephones at 835 and 1900 MHz". Physics in Medicine and Biology. 47 (9): 1501–18. Bibcode:2002PMB....47.1501G. doi:10.1088/0031-9155/47/9/306. ISSN 0031-9155. PMID 12043816.
  14. Lazebnik M, Madsen EL, Frank GR, Hagness SC (September 2005). "Tissue-mimicking phantom materials for narrowband and ultrawideband microwave applications". Physics in Medicine and Biology. 50 (18): 4245–58. Bibcode:2005PMB....50.4245L. doi:10.1088/0031-9155/50/18/001. PMID 16148391.
  15. Tuchin VV, Bashkatov AN, Genina EA, Kochubey V, Lychagov V, Portnov SA, Trunina NA, Miller DR, Cho S (2011-02-10). "Finger tissue model and blood perfused skin tissue phantom". Dynamics and Fluctuations in Biomedical Photonics VIII. SPIE. 7898: 78980Z. Bibcode:2011SPIE.7898E..0ZT. doi:10.1117/12.881604.
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