Applying corrections for count rate effects, attenuation, and scatter will be essential for the PEM Flex Solo II to be able to produce quantitatively accurate images.

The detectability performance of this PEM system demonstrated its ability to resolve small objects with low activity concentration ratios which may assist in the identification of early stage breast cancer. The results of this investigation can be used to correlate lesion detectability with tumor size, ACR, count rate, and breast thickness.

Purpose: To evaluate aluminum‐oxide (Al2O3:normalC) optically stimulated luminescence (OSL) dosimeters as a potential alternative to thermoluminescent dosimeters (TLDs) for remote dosimetry services provided by the Radiological Physics Center (RPC) at the University of Texas M. D. Anderson Cancer Center. Method and Materials: OSL dosimeters were placed equidistant (< 1 cm) from the center of a 20 cm × 20 cm Solid Water™ (SW) phantom which provided backscatter and build‐up. OSL dosimeters were also irradiated in an acrylic mini‐phantom based on the RPC's mailable TLD system mini‐phantom. For modality‐dependence measurements, dosimeters were irradiated to doses of either 100 or 300 cGy with 6 or 15 MV photons or 8 or 15 MeV electrons. All other irradiations were performed with a Co‐60 unit. A Landauer microStar™ reader was used to measure the dosimeter responses. Results: The calculated percent standard deviation of the reproducibility readings was less than 1.4% for doses of 50 cGy and 300 cGy, and less than 0.9% for a dose of 1000 cGy. The measured dose response was linear at doses less than 600 cGy, and independent of modality. Field‐size output factors measured with OSL dosimeters agreed with those measured with an ion chamber within 1.5%. Heat, cold and humidity had no effect on the dosimeters, but exposure to light significantly decreased their response. Measurements of fading demonstrated that a 4% loss of signal occurs over the first ten days after irradiation, after which the response changes less than 1% up to 90 days. The dosimeters lost 0.2% of signal with each successive reading. Conclusion: The precision of OSL dosimeters is comparable to that provided by TLDs used for remote dosimetry and warrants further investigation. Conflict of Interest: This work was supported in part by Landauer Corporation and by PHS grant CA10953 from the NCI, DHHS.

In order to ensure a reliable and repeatable additive manufacturing process, the material delivery rate in the directed energy deposition (DED) process requires in situ monitoring and control. This paper demonstrates acoustic emission (AE) sensing as a method of monitoring the flow of powder feedstock in a powder fed DED process. With minimal calibration, this signal closely correlates to the actual mass flow rate. This article describes the fabricated mass flow monitoring system, documents various conditions in which the actual flow rate deviates from its set value, and details situations that highlight the system’s utility. While AE mass flow monitoring is not free of concerns, its features make it an attractive measurement technique in the powder-fed DED process. The work presented here highlights the results obtained and illustrates that accurate monitoring of powder flow in real-time regardless of environmental conditions within the build chamber is possible.

No abstract

The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner.

No abstract

No abstract