Social and Professional Impact of Learning Communities Within the Alliances for Graduate Education and the Professoriate Program at Michigan State University.

At Michigan State University (MSU), the AGEP learning community features the participation of over 70% of the African-American, Latinx, and Native-American under-represented minorities (URM), also referred to as Black, Indigenous, and People of Color (BIPOC) doctoral students in fields sponsored by the National Science Foundation (NSF). Monthly learning community (LC) meetings allow AGEP participants to create dialogues across disciplines through informal oral presentations about current research. The learning communities also offer opportunities to share key information regarding graduate school success and experience; thus providing a social network that extends beyond the academic setting. At MSU, AGEP also provides an interdisciplinary and multigenerational environment that includes graduate students, faculty members, post-docs and prospective graduate students. Using monthly surveys over a 4-year period, we evaluated the impact of this AGEP initiative focusing on the utility of the program, perceptions of departmental climate, career plans and institutional support. Findings indicate that AGEP participants consider their experiences in the program as vital elements in the development of their professional identity, psychological safety, and career readiness. Experiences that were identified included networking across departments, focus on career placement, involvement in minority recruitment and professional development opportunities. Additionally, AGEP community participants resonated with the "sense of community" that is at the core of the MSU AGEP program legacy. In this article, we proposed a variation of Tomlinson's Graduate Student Capital model to describe the AGEP participants' perceptions and experiences in MSU AGEP. Within this 4-year period, we report over 70% graduation rate (completing with advanced degrees). More than half of Ph.D. students and almost 30% of master's degree students decided to pursue academia as their careers. In addition, we found a high satisfaction rate of AGEP among the participants. Our analysis on graduate student capital helped us identify motivating capital development by years spent at MSU and as an AGEP member. These findings may provide some insight into which capitals may be deemed important for students relative to their experiences at MSU and in AGEP and how their priorities change as they transition toward graduation.

Comparison of Rapid to Standard Volumetric Modulated Arc Therapy for Palliative Radiotherapy in Lung Cancer Patients.

Patients with incurable lung cancer often present with debilitating symptoms that require urgent palliative radiotherapy. Volumetric modulated arc therapy (VMAT) provides several dosimetric advantages compared to basic non-conformal techniques, but involves complex planning resulting in a slower turn-around time for treatment. A simplified planning technique known as 'rapid VMAT' was developed with an aim to deliver palliative treatment to patients within 48 hours. The purpose of this study was to prospectively compare the dosimetric quality of rapid VMAT plans to standard VMAT plans. Fourteen consecutive rapid VMAT cases were re-planned de novo as per standard VMAT planning guidelines. Planning target volume (PTV) and organs at risk (OARs) were then compared. PTV coverage and dose to OARs including the spinal canal, lung, heart, and esophagus were similar between rapid and standard VMAT. Each plan was ready for treatment within 48 hours of the CT simulation. This study describes an expedited process for which palliative radiotherapy can be delivered to lung tumors with a similar robust quality that is provided for curative intent VMAT radiotherapy plans.

Internal and external generalizability of temporal dose-response relationships for xerostomia following IMRT for head and neck cancer.

BACKGROUND AND PURPOSE: To study internal and external generalizability of temporal dose-response relationships for xerostomia after intensity-modulated radiotherapy (IMRT) for head and neck cancer, and to investigate potential amendments of the QUANTEC guidelines. MATERIAL AND METHODS: Objective xerostomia was assessed in 121 patients (nCohort1=55; nCohort2=66) treated to 70Gy@2Gy in 2006-2015. Univariate and multivariate analyses (UVA, MVA with 1000 bootstrap populations) were conducted in Cohort1, and generalizability of the best-performing MVA model was investigated in Cohort2 (performance: AUC, p-values, and Hosmer-Lemeshow p-values (pHL)). Ultimately and for clinical guidance, minimum mean dose thresholds to the contralateral and the ipsilateral parotid glands (Dmeancontra, Dmeanipsi) were estimated from the generated dose-response curves. RESULTS: The observed xerostomia rate was 38%/47% (3months) and 19%/23% (11-12months) in Cohort1/Cohort2. Risk of xerostomia at 3months increased for higher Dmeancontra and Dmeanipsi (Cohort1: 0.17·Dmeancontra+0.11·Dmeanipsi-8.13; AUC=0.90±0.05; p=0.0002±0.002; pHL=0.22±0.23; Cohort2: AUC=0.81; p<0.0001; pHL=0.27). The identified minimum Dmeancontra thresholds were lower than in the QUANTEC guidelines (Cohort1/Cohort2: Dmeancontra=12/19Gy; Dmeancontra, Dmeanipsi=16, 25/20, 26Gy). CONCLUSIONS: Increased Dmeancontra and Dmeanipsi explain short-term xerostomia following IMRT. Our results also suggest decreasing Dmeancontra to below 20Gy, while keeping Dmeanipsi to around 25Gy. Long-term xerostomia was less frequent, and no dose-response relationship was established for this follow-up time.

Pion effects in flattening filter-free radiation beams.

Flattening filter-free radiation beams have higher dose rates that significantly increase the ion recombination rate in an ion chamber's volume and lower the signal read by the chamber-electrometer pair. The ion collection efficiency correction (P(ion)) accounts for the loss of signal and subsequently changes dosimetric quantities when applied. We seek to characterize the changes to the percent depth dose, tissue maximum ratio, relative dose factor, absolute dose calibration, off-axis ratio, and the field width. We measured P(ion) with the two-voltage technique and represented P(ion) as a linear function of the signal strength. This linear fit allows us to correct measurement sets when we have only gathered the high voltage signal and to correct derived quantities. The changes to dosimetric quantities can be up to 1.5%. Charge recombination significantly affects percent depth dose, tissue maximum ratio, and off-axis ratio, but has minimal impact on the relative dose factor, absolute dose calibration, and field width.

CT, MR, and ultrasound image artifacts from prostate brachytherapy seed implants: the impact of seed size.

PURPOSE: To investigate the effects of brachytherapy seed size on the quality of x-ray computed tomography (CT), ultrasound (US), and magnetic resonance (MR) images and seed localization through comparison of the 6711 and 9011 (125)I sources. METHODS: For CT images, an acrylic phantom mimicking a clinical implantation plan and embedded with low contrast regions of interest (ROIs) was designed for both the 0.774 mm diameter 6711 (standard) and the 0.508 mm diameter 9011 (thin) seed models (Oncura, Inc., and GE Healthcare, Arlington Heights, IL). Image quality metrics were assessed using the standard deviation of ROIs between the seeds and the contrast to noise ratio (CNR) within the low contrast ROIs. For US images, water phantoms with both single and multiseed arrangements were constructed for both seed sizes. For MR images, both seeds were implanted into a porcine gel and imaged with pelvic imaging protocols. The standard deviation of ROIs and CNR values were used as metrics of artifact quantification. Seed localization within the CT images was assessed using the automated seed finder in a commercial brachytherapy treatment planning system. The number of erroneous seed placements and the average and maximum error in seed placements were recorded as metrics of the localization accuracy. RESULTS: With the thin seeds, CT image noise was reduced from 48.5 ± 0.2 to 32.0 ± 0.2 HU and CNR improved by a median value of 74% when compared with the standard seeds. Ultrasound image noise was measured at 50.3 ± 17.1 dB for the thin seed images and 50.0 ± 19.8 dB for the standard seed images, and artifacts directly behind the seeds were smaller and less prominent with the thin seed model. For MR images, CNR of the standard seeds reduced on average 17% when using the thin seeds for all different imaging sequences and seed orientations, but these differences are not appreciable. Automated seed localization required an average (±SD) of 7.0 ± 3.5 manual corrections in seed positions for the thin seed scans and 3.0 ± 1.2 manual corrections in seed positions for the standard seed scans. The average error in seed placement was 1.2 mm for both seed types and the maximum error in seed placement was 2.1 mm for the thin seed scans and 1.8 mm for the standard seed scans. CONCLUSIONS: The 9011 thin seeds yielded significantly improved image quality for CT and US images but no significant differences in MR image quality.

Characterization, prediction, and correction of geometric distortion in 3 T MR images.

The work presented herein describes our methods and results for predicting, measuring and correcting geometric distortions in a 3 T clinical magnetic resonance (MR) scanner for the purpose of image guidance in radiation treatment planning. Geometric inaccuracies due to both inhomogeneities in the background field and nonlinearities in the applied gradients were easily visualized on the MR images of a regularly structured three-dimensional (3D) grid phantom. From a computed tomography scan, the locations of just under 10 000 control points within the phantom were accurately determined in three dimensions using a MATLAB-based computer program. MR distortion was then determined by measuring the corresponding locations of the control points when the phantom was imaged using the MR scanner. Using a reversed gradient method, distortions due to gradient nonlinearities were separated from distortions due to inhomogeneities in the background B0 field. Because the various sources of machine-related distortions can be individually characterized, distortions present in other imaging sequences (for which 3D distortion cannot accurately be measured using phantom methods) can be predicted negating the need for individual distortion calculation for a variety of other imaging sequences. Distortions were found to be primarily caused by gradient nonlinearities and maximum image distortions were reported to be less than those previously found by other researchers at 1.5 T. Finally, the image slices were corrected for distortion in order to provide geometrically accurate phantom images.

A randomized, double-blind, double-dummy, controlled dose comparison of thalidomide for treatment of erythema nodosum leprosum.

In a randomized, double-blind, double-dummy controlled study, 22 men with erythema nodosum leprosum (ENL) received six capsules containing either 100 mg (group A, n = 12) or 300 mg (group B, n = 10) of thalidomide daily for one week. A six-week, four capsules per day taper followed, in which group A received 50 mg/day of thalidomide in weeks 2 and 3, then dummy capsules in weeks 4 through 7, while group B had gradual decrements every two weeks. Both regimens caused comparable improvement in 19 patients at day 7 (group A [12 of 12] versus group B [7 of 10]; P = 0.08), but slower tapering in group B showed less re-emergence of ENL through week 7 (P = 0.02, versus group A). Most patients developed new lesions soon after stopping treatment. Slower tapering from a higher initial thalidomide dose may improve clinical ENL responses, but high recurrence rates after discontinuation indicates further assessment is needed to identify better tapering regimens.

Application of magnetization transfer at 3.0 T in three-dimensional time-of-flight magnetic resonance angiography of the intracranial arteries.

PURPOSE: To apply magnetization transfer (MT) at 3.0 T in three-dimensional time-of-flight magnetic resonance angiography of the intracranial arteries. MATERIALS AND METHODS: This study was performed on phantoms and seven volunteers to determine the effects of MT at 3.0 T. By using a modulated MT approach and an altered phase encode order, the specific absorption rate (SAR) was kept below 3 W/kg over any 8-second time period. RESULTS: For a 20-degree flip angle and 36 msec repetition time, the background suppression at 3.0 T was improved with MT by 52 +/- 5% for white matter and 40 +/- 8% for grey matter, making the distal intracranial vasculature significantly more discernible. CONCLUSIONS: MT at 3.0 T can significantly improve background suppression in 3D time-of-flight magnetic resonance angiography (MRA) of the intracranial arteries without exceeding SAR guidelines.