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Introduction: Hepatic brachytherapy using either resin or glass 90 Y microspheres is an established therapy for unresectable primary and metastatic tumors. Unlike conventional brachytherapy, microsphere brachytherapy has no software currently available for pretreatment evaluation and radiation planning. A non-MIRD radiation dose calculation approach is desired to accurately utilize spatial relationships in the liver and tumor distribution. Materials and methods: A newly developed software tool employing the technetium-99m macro aggregated albumin (99m Tc-MAA) SPECT 3-D dataset and CT scan was used to estimate the likely absorbed dose in normal liver and tumor tissue from 90 Y microsphere brachytherapy (radioembolization). Monte Carlo algorithms were utilized to maximize true 3D dose estimates for each patient's unique liver and tumor geometry. Clinical correlation was completed regarding toxicity, imaging response, and complications as an independent measure of the software's usefulness in predicting radiation effects. Comparisons were made to MIRD, Body Surface Area method, and physician prescription for 90 Y activity. Results: The software performed accurately in estimating absorbed dose in phantom testing. Patient data from 50 consecutive patients with metastatic tumors (26 colon, 24 neuroendocrine) to the liver receiving 59 radioembolization treatments were studied. The software estimate of median normal liver and tumor absorbed doses were 27.6 Gy and 41.2 Gy, respectively. Conclusions: The use of pretreatment 99m Tc-MAA SPECT co-registered to a CT scan provides useful and unique data for a newly developed non-MIRD, Monte Carlo-based radiation dosimetry software program in 90 Y microsphere brachytherapy. Software estimates of radiation dose preserving critical spatial information in the liver and tumors appeared reasonable based on clinical outcomes. Further testing and refinement of the software interface is ongoing with plans to distribute it to research organizations.

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Millimeter-wave (mmWave) communications promise Gigabit/s data rates thanks to the availability of large swaths of bandwidth between 10-100 GHz. Although cellular operators prefer the lower portions of the spectrum due to popular belief that propagation there is more favorable, the measurement campaigns to confirm this -conducted by ten organizations thus far -report conflicting results. Yet it is not clear whether the conflict can be attributed to the channel itself -measured in different environments and at different center frequencies -or to the differences in the organizations' channel sounders and sounding techniques. In this paper, we propose a methodology to measure mmWave frequency dependence, using the 26.5-40 GHz band as an example. The methodology emphasizes calibration of the equipment so that the measurement results represent the channel alone (and not the channel coupled with the channel sounder). Our results confirm that free-space propagation is indeed frequency invariant -a well understood phenomena but to our knowledge reported nowhere else at mmWave to date. More interestingly, we found that specular paths -the strongest after the line-of-sight path and so pivotal to maintaining connectivity during blockage -are the least invariant compared to weaker diffracted and diffuse paths.

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