Heated X-ray Examination Table Team Leader: Tyler Vovos BWIG: Joel Gaston BSAC: Joey Labuz Communicator: Paul Schildgen Client: Lanee MacLean Advisor: Mitch Tyler

Overview Background Information Problem Statement Design Specifications Proposed Design Heating Material Options Design Matrix Future Work

Background Information Diagnostic use of X-ray Density of body structures Skeletal pathologies, some soft tissue applications Anatomy vs. physiology Duration of procedure Current exam table Hard laminate surface Dimensions 2.2 x .75 m In medicine X-rays are primarily use to image the anatomy of the body. One of the most common uses of x-ray is in the diagnosis of skeletal pathologies. The duration of a procedure can vary from minutes to around an hour, during which time it is usually necessary for the patient to remain still. The exam table we are working with is shown. Note the hard laminate surface where a patient would lie. http://www.advanceimaging.net/

Problem Statement Current X-ray examination tables are uncomfortable Hard Cold Discomfort may cause patient movement Long examination duration Not available commercially A common patient complaint is that x-ray tables are too hard and too cold. It is our goal to find a solution to this probem.

Design Specifications Materials/design must be radiolucent No anatomical distortion Must incorporate patient or technician control Must not obstruct the technician’s workspace Patient safety Limited budget Our device must be almost completely radiolucent. We have to consider how specific materials, temperatures, and designs will cause x-ray attenuation or introduce contrast into the image. Also, it is important that our device does not alter the normal anatomy of the patient (hard/soft spots). Because the device is intended to provide the patient with a comfortable temperature, they must have control. Finally, we have the extra challenge of designing and creating a prototype with a limited budget.

Proposed Design Thermistor Microcontroller Upper Layer of Electrically Insulating Material and/or Padding Lower Layer of Electrically Insulating Material Heating Element Voltage Source Conducting material Microcontroller Thermistor 6

EEONFELT (Polyaniline Dipped Nylon) Pros: Even heating Adjustable resistivity (20 Ω/square to 106 Ω/square) Very flexible Cons: Unknown degradation Limited commercial availability http://www.eeonyx.com 7

Carbon Fiber Pros: Commercially Available Thickness: < 0.4mm Non-degradable Safe, even distribution of heat Cons: Non-uniform Maximum Temperature: 27.8° Limited flexibility http://www.warmup.com/carbon-technical-heating.phtml 8

Kapton 200RS100 Film (Polyimide) Pros: Commercially available Stable up to 350 °C Even heating Uniform Thin (~0.5 mm) Flexible Cons: Unknown degradation Dupont.com 9

Indium Tin Oxide Film Pros: Commercially available Adjustable resistivity Thin ITO layer (~100 nm) Uniform ITO deposition Cons: Degrades under repeated bending http://www.visionteksystems.co.uk/ 10

Materials Matrix Weight Kapton ITO Film Carbon Fiber EEONFELT Uniformity 30 27 12 Heating 20 TEST Radiolucency 15 Degradation Flexibility 10 9 8 Cost 7 TOTAL 100 49+ 42+ 39+ 48+ 11

Future Work Purchase all necessary materials Testing protocol: Resistivity using multi-meter Heating using infrared thermometer Radiolucency using exponential attenuation law Degradation using stress/strain analysis, and long X- ray exposure Scale up using: Ohm’s law Thermodynamic principles Exponential Attenuation Law

References Bird, B., Lightfoot, E., Stewart, W., Transport Phenomena. New York: Wiley and Sons. 2007. Links, J. M., Links, J., Prince, J., Medical Imaging Signals and Systems. Prentice Hall, 2005. http://www.advanceimaging.net/ http://www.mcmaster.com/ http://physics.nist.gov/ Personal Interview with Dr. Frank Ranallo Personal Interview with Dr. John Vetter Personal Interview with Dr. Wally Block Personal Interview with Dr. Wally Peppler Personal Interview with Prof. John Yin Testing with Lanee MacLean

Questions?

Material Heating Governed by Fourier’s law of conduction and Newton’s law of cooling Fourier Newton h = heat transfer coefficient ~6 (w/m2K) k = thermal conductivity ~0.4 (w/mK) Foam Pad TA Q Q Q Q T1 y T0 Heating Element 15

X Ray Attenuation Mass Attenuation Coefficient (µ/ρ) Dependent on Photon Energy (12.4-124 keV for Diagnostic X-rays). Testing at ~80 KeV would maximize attenuation effects. Require substantially less than 10% attenuation of beam, ideally < 1 % (99 % transmission). http://physics.nist.gov/PhysRefData/XrayMassCoef/cover.html I = End intensity IO = Incident intensity µ = Mass attenuation coefficient p = Material density x = Material thickness 16

X Ray Intensity vs. Energy Spectrum Testing Region (~ 30 to 40 Kev) Max. Photon Energy (80 KeV) Original Beam http://physics.nist.gov/PhysRefData/XrayMassCoef/cover.html Transmitted Beam (Actual Image) 30 Kev 40 Kev Energy (KeV) 17 17