Browsing by Subject "Nanodetector"
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Item Open Access Chest Phantom Development for Chest X-ray Radiation Protection Surveys, Internal Beta Dosimetry of an Iodine-131 Labelled Elastin-Like Polypeptide, and I-131 Beta Detection Using a Scintillating Nanoparticle Detector(2018) Hyatt, Steven PhilipProject 1: Chest Phantom Development for Chest X-ray Radiation Protection Surveys
Purpose: Develop an acrylic phantom to accurately represent an average adult’s chest for use in radiographic chest unit radiation protection surveys.
Materials and Methods: 6 sheets of 3.81 cm thick acrylic were cut and assembled to form a 30.5 x 30.5 x 20.3 cm hollow box phantom. The acrylic served as tissue equivalent material and the hollow center simulated lungs in a human patient. Six sheets of 1 mm thick aluminum were cut to line the inner walls of the acrylic phantom to potentially boost scatter radiation. Three phantoms underwent posterior-anterior (PA) and lateral chest protocol radiographic scans: the acrylic phantom (with and without the aluminum lining), a 3 gallon water bottle filled with water, and an adult male anthropomorphic phantom. The phantoms were set up as though they were adult patients and scanned with automatic exposure control. Scatter radiation was measured with ion chamber survey meters at 4 points within the room for each phantom and protocol. The scatter data from the acrylic phantom and water bottle were compared to the anthropomorphic phantom to determine which one more accurately represented an adult patient.
Results: For the PA protocol, the average percent difference in measurements between the acrylic phantom and anthropomorphic phantom was 33.3±28.8% with the aluminum lining and 33.0±21.2% without the lining. The percent difference between the water bottle and anthropomorphic phantom was 66.5±42.0%. For the lateral protocol, the average percent difference in measurements between the acrylic phantom and anthropomorphic phantom was 157.6±5.6% with the aluminum lining and 143.0±17.6% without the lining. The percent difference between the water bottle and anthropomorphic phantom was 78.3±22.8%.
Conclusions: The acrylic phantom provided a more accurate comparison to the anthropomorphic phantom than the water bottle for the PA protocol. For the lateral protocol, neither the acrylic phantom nor water bottle provided an adequate comparison to the anthropomorphic phantom.
Project 2: Internal Beta Dosimetry of an Iodine-131 Labelled Elastin-Like Polypeptide
Purpose: Develop a model and simulation to better understand the dosimetry of an I-131 labeled elastin-like polypeptide (ELP) brachytherapy technique.
Materials and Methods: To develop the model, an average scenario based on mouse trials was explored. A 125 mg tumor was approximated as a sphere, with the I-131 ELP injected into its center. The ELP solidifies into a spherical depot – approximately 1/3 the volume of the tumor – and becomes a permanent brachytherapy source. The injected activity of I-131 was 1.25 mCi. I-131 primarily emits β radiation with an average energy of 182 keV, therefore it was determined that all such emissions were confined within the bounds of the tumor. Gamma emissions associated with I-131 were ignored as they were determined to have enough energy to escape the bounds of the tumor without any interaction. This model was implemented into a simulation using the Monte Carlo program FLUKA. From this simulation, the absorbed dose to the tumor and ELP depot, along with the dose profile, was calculated.
Results: The tumor received an absorbed dose of 72.3 Gy while the ELP received 1.14×10^3 Gy. From the dose profile, it was determined that 99% of the absorbed dose to the tumor was highly localized to a 0.3 mm region surrounding the ELP depot.
Conclusions: The model and simulation provided a better understanding of the dosimetry underlying the novel ELP brachytherapy technique. Results obtained demonstrated that the ELP method delivers doses that are comparable to current conventional brachytherapy techniques.
Project 3: I-131 Beta Detection Using a Scintillating Nanoparticle Detector
Purpose: Determine if a scintillating nanocrystal fiber optic detector (nano-FOD) could detect β emissions from I-131.
Materials and Methods: The nano-FOD’s β response was tested using a source vial containing 101 mCi of I-131 in 2 mL of stabilizing solution. A glass vial containing the I-131 was placed inside a lead pig for shielding. A 1 mm diameter hole was drilled through the tops of the vial and pig to allow insertion of the nano-FOD. Measurements were taken every day over a 17 day period by repeatedly submerging the nano-FOD in the I-131 solution and recording the voltage signal it produced. The activity at the time of measurement was calculated based on the time and date of data acquisition. The net signal and signal-to-noise ratio (SNR) were then calculated and plotted as functions of I-131 concentration.
Results: The nano-FOD produced a measurable response when exposed to the β emissions of I-131. The net signal and SNR both demonstrated a linear correlation with the concentration of I-131.
Conclusions: The nano-FOD was demonstrated to be capable of β detection with a linear correlation to activity. If the signals measured can be calibrated to radiation exposure, then the nano-FOD has promising applications as a novel β detector.
Item Open Access Validation of Isodose Curves for AIRO Mobile CT, P-32 Pure-Beta and I-131 Mixed Beta/Gamma Detection Utilizing Nano-Fiber Optic Detector(2019) Smiley, Brianna RochelleProject 1: Validation of Isodose Curves for AIRO Mobile CT
Purpose: Validate isodose curves provided by the manufacturer for the Airo Mobile CT to determine if, indeed, it is safe for those who are operating the machine.
Materials and Methods: To determine the maximum number of scans per year allowed, hospitals rely on the data provided by the manufacturer. It is not common practice to verify the data provided for CT scanners. To validate the information provided by the manufacturer, the same CT settings were utilized for testing. The manufacturer settings were 120 kV, 100 mA and 1.92 sec and a 32 cm body CTDI phantom was used to generate scatter patterns. Replicating these conditions, two ion chambers were used to collect measurements of scattered radiation at different distances around the MobileCT gantry.
Results: Following the manufacturer settings, the average percent difference between the manufacturer data and the data collected in this experiment was 24.16 ± 15%.
Conclusions: The results provided information that confirmed the validity of the data provided by the manufacturer. Through this verification, it was shown that the scattered air kerma determined through experimentation was comparable to the data provided by the manufacturer.
Project 2: P-32 pure-beta detection utilizing nano-fiber optic detector
Purpose: Determine if the nano-fiber optic detector is capable of detecting pure β emissions by placing it in contact with P-32 in liquid solution.
Materials and Methods: The P-32 was placed into a vial with 2 mL of stabilizing solution. The vial was placed in a lead pig that was modified with a 1 mm opening on the lid for the nano-FOD to be inserted through. Measurements of the nano-FOD’s response to pure beta emissions were collected by submerging the nano-FOD into a vial containing 76.2 mCi of liquid P-32 and evaluating the voltage output that was produced. For P-32, this was done over a 45-day period to determine if the nano-FOD was able to accurately measure activity over time. From the data collected, the net signal and signal-to-noise ratio (SNR) were calculated and compared to the P-32 concentration, which showed a linear correlation when plotted.
Results: The nano-FOD was able to demonstrate a noticeable response when inserted into the P-32 solution. The data from the net signal allowed for the determination of the experimental half-life which was 13.46 ± 0.87 days. When compared to the published half-life of P-32, which is 14.29 days, the percent difference between the experimental and published half-life was 5.8%.
Conclusions: The results from this data collection provide confirmation that the nano-FOD device can be utilized as a real-time β detector. Using Monte Carlo simulations, the signals measured with the nano-FOD have been calibrated to radiation exposure, proving the nano-FODs ability to be utilized as a novel β detector.
Project 3: I-131 mixed-beta and gamma detection utilizing nano-fiber optic detector
Purpose: Determine if the nano-fiber optic detector is capable of accurately detecting mixed β and γ radiation by placing it in contact with I-131.
Materials and Methods: The I-131 was placed into a vial with 2 mL of stabilizing solution. The vial was placed in a lead pig that was modified with two openings on the lid for each of the nano-FODs to be inserted through. The first opening was used to insert directly into the I-131 solution to be exposed to both the β and γ emissions. The second opening led the nano-FOD into a Lucite sheath that blocks all β emissions, so that only the γ component was detected by the nano-FOD. Measurements of the nano-FOD’s response to mixed β and γ emissions were collected by submerging the nano-FOD into the vial containing 105 mCi of liquid I-131 and evaluating the voltage output that was produced. For I-131, this was done over a 20-day period to determine if the nano-FOD was able to measure activity over time for both the mixed signal and the gamma signal.
Results: The signal produced by the nano-FOD from being exposed to the mixed beta and gamma emissions of I-131 shows the nano-FODs capability of detecting radiation in mixed fields. The net signal over time provided an experimental half-life comparable to that of the published half-life of I-131.
Conclusions: The nano-FOD is capable of functioning in a mixed field. The post-processing data analysis for this nano-FOD needs modification and will provide insight into the future of utilizing the nano-FOD in mixed fields.