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Photodynamic Therapy Calibration Device for The Treatment of Abscesses

Clinical Use Scenario

The clinical scenario in which our device will be used as explained by Dr. Baran, our customer, is as follows. In order to maximize the treatment efficiency of the PDT abscess treatment system, it’s necessary to obtain a measurement of the reflectance and absorbance properties of the patient’s specific abscess so that the appropriate light dose can be delivered to kill the most pathogens within the abscess. Within the operating room, a surgeon performs the incision necessary for abscess-treatment procedure and places a drainage catheter into the abscess to drain all fluid. Then, the probe is inserted through the drainage catheter to measure the optical properties of the abscess and deliver the appropriate light dose for treatment. Before the probe can measure the optical properties of the abscess, it needs to be calibrated by our device. As the probe directly interfaces with our device prior to entering the human body, it’s critical for patient safety that the probe remains sterile during its interaction with our device. 

Most times, someone other than the surgeon takes the calibration measurement – usually the resident. The resident who is fully sterile, places the probe into the inlet of our device and the technician who stands next to the non-sterile PDT system devices initiates the calibration measurement. Because the PDT system technology is considered a non-sterile field, having the resident take measurements very close to the actual PDT device system poses a risk of breaching the sterile field. As such, our device is separate from the system, and can be handheld by the resident, allowing it to stay in the sterile field.

Needs, Wants, & Metrics

Because our primary customer for this project is Dr. Baran, as we are building a calibration device to supplement his abscess-treating PDT system, we had a conversation with him directly to ascertain what would be the needs and wants of our device. We then turned those qualitative metrics into quantifiable deliverables we wanted our device to have. From our discussion, we ascertained that our device has very specific needs and wants:

  • It needs to be sterile/sterilizable because it will come in contact with the PDT probe that will be entering a patient’s body
  • It needs to firmly mount the probe in place so that there’s no human error with regards to the angle and distance at which the light source and receptors obtain the calibration measurement
  • It needs to be opaque enough to block out all room light so that there is no interference for the calibration measurement

We then took these metrics and tabularly ranked them in order of importance.

Design Metrics

Metrics  Design Specifications 
X Opacity (%) ~100% 
The device is sterile such that X% of pathogens have been killed prior to the device’s exposure to the probe  ~100%
The probe stays within an angle of X degrees with reference to the reflectance standard.  30 degrees
The probe is a distance of X from the reflectance spectra X = 5 mm – 15 mm 
Must be able to withstand a temperature of X degrees. 132 °C

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