Evolution and Evaluation of a Structured Applied Physics Course for Radiation Oncology and Radiation Physics Trainees.

We sought to supplement medical physics textbook knowledge and clinical learning with case-based discussions. To our knowledge, this is the first report on a structured combined applied physics curriculum for radiation oncology (RO) and medical physics (MP) trainees. We reviewed our yearly applied physics course given from the years 2016-2021 inclusive. The number of applied physics trainees ranged from 7 to 14 per year (2-9 RO and 3-6 MP residents per year). Each session was taught by a pair of (RO and MP) faculty members. Twenty-nine case-based sessions were given yearly (2016 to 2019). Because of the COVID-19 pandemic restrictions, the course was shortened to 8 case-based sessions in 2020 and 2021. For the years 2016-2021, the mean and median teaching evaluation scores were 4.65 and 5, respectively (range 2-5), where 1 represents worse teaching quality and 5, the best teaching quality. For the year 2021, 2 questions relating to the video virtual format (implemented due to the covid-19 pandemic), revealed consistent high scores with the mean and median responses of 4.14 and 5, respectively (range 1-5). The results from the teaching evaluation scores indicate that the trainees highly valued the teaching sessions and teachers. Our experience indicates that a case-based applied physics course was delivered successfully with continued high teaching evaluation scores. A video virtual platform for an applied physics course could be useful, especially for small programs without a structured applied physics curriculum.

Asymmetric alloy formation at the Fe-on-Ti and Ti-on-Fe interfaces.

The Fe-on-Ti and Ti-on-Fe interfaces were studied experimentally by Mössbauer spectroscopy (MS), transmission electron microscopy (TEM) and x-ray reflectometry (XRR) on Ti/Fe/Ti trilayers grown on Si(1 1 1) substrates by vacuum evaporation. The nanoscale structure and composition were explored in cross sections using TEM, the layer structure and the interface widths by specular x-ray reflectometry. MS was applied to identify the interface alloy phases and to determine the pure and alloyed Fe layer fractions. The experimental results were compared with molecular dynamics (MD) simulations of layer growth on Fe or Ti underlayers of different orientations. The concentration distributions provided by MD simulations show an asymmetry at the interfaces in the layer growth direction. The transition is atomically sharp at the Ti-on-Fe interface for the (0 0 1) and (1 1 0) crystallographic orientations of the Fe underlayer, while it spreads over a few atomic layers for Fe(1 1 1) underlayer and for all studied Ti underlayer orientations at the Fe-on-Ti interface. MS and XRR data on Ti/Fe/Ti trilayers confirm the asymmetry between the bottom and top Fe interface, but the inferred interface widths considerable exceed those deduced from the MD simulations.

Treatment of Refractory Gastrointestinal Bleeding in Patients With Portal Hypertension: A Case Series and Treatment Algorithm.

In patients with portal hypertension, ectopic varices can develop at any site along the gastrointestinal tract outside the classically described gastroesophageal location. Like esophageal variceal hemorrhage, bleeding from ectopic varices can be life-threatening. Diagnosis and treatment of ectopic varices can be challenging; to date, no effective treatment algorithm has been described. A systematic teamwork approach to diagnosing and treatment of ectopic varices is required to successfully manage hemorrhage from ectopic varices.

Liver transplantation in an adult with adenomatosis and congenital absence of the portal vein: a case report.

Congenital absence of the portal vein (CAPV) is a rare congenital anomaly in which the superior mesenteric veins (SMV) and splenic veins converge and bypass the liver, effectively draining directly into the systemic venous circulation via the inferior vena cava (IVC), or alternatively the renal or iliac vein, creating a native portosystemic shunt. Portosystemic shunting results in clinical manifestations of hepatic encephalopathy as well as a predisposition to focal nodular hyperplasia and tumors, including adenomas, hepatoblastoma, and hepatocellular carcinoma (HCC), by the disruption of enterohepatic blood flow. Historically, CAPV has been thought to be a rare condition found mainly at autopsy, however, in recent years due to advances in radiological techniques, CAPV detection has increased. Herein we describe a patient with known CAPV who initially underwent hepatic resection for HCC. During surveillance, additional masses were discovered and were identified as recurrent HCC. Unfortunately, this patient was not a candidate for further resection or locoregional therapy. We demonstrate that transplantation is a challenging but technically viable option for treatment of HCC complicating adenomatosis-associated CAPV.

Predictors of recurrence after radiotherapy for non-melanoma skin cancer.

Predictive factors of recurrence were examined in 448 non-melanoma skin cancers (72% basal cell carcinoma, 28% squamous cell carcinoma) treated with radiotherapy. The overall recurrence rate was 15.8% at a median follow-up of 18.4 months. In multivariate analysis, significant factors for recurrence were age (p = 0.0197), tumour size 2 cm or greater (p = 0.0095), immunosuppression (p = 0.0082), and treatment modality (p = 0.0009).

Phosphorus concentration and loading reductions following changes in fertilizer application and formulation on managed turf.

Excess phosphorus, particularly in surface waters can lead to severe eutrophication. Identifying source areas, quantifying contributions, and evaluating management practices are required to address current and future water quality concerns. A before-after study was conducted from 2003-2010 on a sub-watershed of Northland Country Club Golf Course in Duluth, MN to demonstrate the impacts of two different phosphorus management approaches (Period 1: traditional application and timing using commercially available synthetic blends; Period 2: reduced rate, low dose applications, and organic formulations). Outflow median dissolved reactive phosphorus (DRP) and total phosphorus (TP) stream concentrations were significantly less in Period 2 compared to Period 1. There was no statistical difference in the mean TP loading in Period 1 (0.25 kg ha(-1) year(-1)) compared to Period 2 (0.20 kg ha(-1) year(-1)) or between the DRP loading in Period 1 (0.15 kg ha(-1) year(-1)) compared to Period 2 (0.09 kg ha(-1) year(-1)). However, by switching to organic phosphorus formulations and reducing application rates by greater than 75%, substantial reduction in DRP and TP concentrations was achieved. Based on these findings it is recommended that turf managers (parks and recreation to golf courses) explore the feasibility of altering their fertility management related to phosphorus by including organic formulations, low dose applications, and overall rate reductions. Additionally, it is recommended that the fertilizer industry develop and make more readily available commercial blends with lesser to zero amounts of phosphorus.

Poster - Thur Eve - 75: Towards MR only simulation: MR based digitally reconstructed radiograph of head and neck.

PURPOSE: To develop a practical method to obtain bony structures from Magnetic Resonance (MR) images and to create MR- based digitally reconstructed radiographs (DRR) for MR only simulation. METHODS AND MATERIALS: Using T1-weighted MR images, air regions including the sinuses and the airway in the head and neck were manually contoured. The bone and soft tissue masks were automatically generated based on the statistical data calculated from the air contour and MR intensities. "CT like" MR images were generated by mapping the MR intensities of the voxels within these masks into the CT number ranges of these tissues. The MR-based DRRs created from "CT like" MR images were quantitatively evaluated using the co-registered MR and CT images of 10 stereotactic radiosurgery CNS patients. Ten anatomical control points, set on the contours of the skull segmented using a threshold of 300 HU were used to determine the differences in distance between MR-based DRRs and CT-based DRRs, and to evaluate the geometrical accuracy of MR-based DRRs. RESULTS: The bony structures were visible in the MR-based DRRs. The mean geometric difference and standard deviation between the ten anatomical control points on MR- based and CT-based DRRs were -0.03±1.11 mm (including uncertainty of image fusion). The maximum distance difference was 1.67mm. CONCLUSIONS: The study provides a practical method to generate MR- based DRRs from MR-only simulations of the head and neck regions. The image quality and anatomical accuracy of MR-based DRRs is comparable to that of CT-based DRRs.

Equivalence of the boson peak in glasses to the transverse acoustic van Hove singularity in crystals.

We compare the atomic dynamics of the glass to that of the relevant crystal. In the spectra of inelastic scattering, the boson peak of the glass appears higher than the transverse acoustic (TA) singularity of the crystal. However, the density of states shows that they have the same number of states. Increasing pressure causes the transformation of the boson peak of the glass towards the TA singularity of the crystal. Once corrected for the difference in the elastic medium, the boson peak matches the TA singularity in energy and height. This suggests the identical nature of the two features.

Stability assessment of o/w parenteral nutrition emulsions in the presence of high glucose and calcium concentrations.

The purpose of the present study was to examine how the colloid stability features of o/w parenteral nutrition emulsions made with SMOFlipid (lipid emulsion based on soybean oil, medium chain triglycerides, olive oil and fish oil) will change in the presence of high concentration of calcium and glucose if usual micronutrients are also present, according to the needs of the clinical nutrition patient. Particle size analysis, zeta potential, dynamic surface tension measurements and light microscopic screening were carried out to evaluate the possible changes in the kinetic stability of the emulsions. Our results indicate that the higher glucose concentration of 15 or 20% could not compensate the emulsion-destabilizing effect of higher (5 mM) calcium concentration even in the presence of a modern fat emulsion. Therefore calcium demand of undernourished patient requiring 5 mM or higher final Ca²âº content in nutrient solution should be supplemented in another way.

Stream water nutrient enrichment in a mixed-use watershed.

Eutrophic conditions, in both saline and freshwater systems, result from nutrient export from upstream watersheds. The objective of this study was to quantify the surface runoff losses of nitrate-nitrogen (NO3-N), total nitrogen (TN), dissolved reactive phosphorus (DRP), and total phosphorus (TP) resulting from prevailing practices on a managed golf course. Inflow and outflow discharge waters on a sub-area of Northland Country Club (NCC) located in Duluth, Minnesota were measured for both quantity and quality from April through November from 2003 to 2008. Nutrient losses were detectable throughout the year, had a seasonal trend, and routinely exceeded recommended levels to minimize eutrophication. The median outflow TN concentration (1.04 mg L⁻¹) was significantly greater (p < 0.05) than the median inflow (0.81 mg L⁻¹) concentration. Similarly, the median outflow TP concentration (0.03 mg L⁻¹) was significantly greater (p < 0.05) than the median inflow concentration (0.02 mg L⁻¹). Maximum recorded concentrations during the study period were 1.9 mg L⁻¹ NO3-N, 3.93 mg L⁻¹ TN, 0.34 mg L⁻¹ DRP, and 1.11 mg L⁻¹ TP. Mean annual export coefficients at NCC were 0.7 kg ha⁻¹ NO3-N (1.7% of applied), 4.43 kg ha⁻¹ TN (10.7% of applied), 0.14 kg ha⁻¹ DRP (2.6% of applied), and 0.25 kg ha⁻¹ TP (4.6% of applied). The findings of this study highlight the need for adopting conservation practices aimed at reducing offsite nutrient transport.

Extramammary Paget disease: review of patients seen in a non-melanoma skin cancer clinic.

Extramammary Paget disease (EMPD) is a rare skin disease commonly found in the anogenital region. In this study, we aimed to identify EMPD patients seen in the non-melanoma skin cancer clinic at Odette Cancer Centre and to describe the treatments delivered and outcomes achieved. From 2000 to 2009, 14 patients were seen. Initial treatment recommendations included imiquimod and surgical excision, although half the patients required more than one treatment modality, highlighting the difficulty of achieving complete eradication of this disease.

Palliative radiotherapy for non-melanoma skin cancer.

AIMS: The primary objective of this study was to assess the rate of tumour response to the palliative radiotherapy regimen used at our centre (8 Gy/fraction on days 0, 7, 21) for non-melanoma skin cancer. The secondary objective was to evaluate symptom palliation. MATERIALS AND METHODS: A retrospective chart review identified patients treated with this palliative radiotherapy regimen from August 2003 to December 2008. Patient age, gender, tumour histology, location, size, presenting symptoms and radiation treatment factors were recorded at baseline. The tumour size and tumour-related symptoms were recorded at each fraction and follow-up visit. The results were analysed on an intent to treat basis. RESULTS: Twenty-eight patients received 31 courses of palliative radiation for basal cell (five) or squamous cell (26) carcinoma of the skin. Twenty-one patients with 23 tumours attended at least one follow-up visit, and seven patients had incomplete follow-up data. At the time of last follow-up (median 17 weeks), the response rate was 58.1% (complete response 15/31; partial response 3/31). A complete response to treatment was correlated with a smaller tumour size at day 21 (P=0.0143). Presenting symptoms were alleviated in 61.3% (19/31) of symptomatic sites. No severe late toxicities were seen. CONCLUSIONS: This palliative regimen offers impressive response rates and effective symptom palliation for patients with non-melanoma skin cancer.

The value of periodic follow-up in the detection of recurrences after radical treatment in locally advanced head and neck cancer.

AIMS: To determine the value of routine follow-up in detecting and salvaging recurrence after radical treatment of locally advanced head and neck squamous cell carcinoma and to identify clinical or pathological prognostic factors that predicted for survival. MATERIALS AND METHODS: A retrospective medical chart review was conducted at the Odette Cancer Centre between January 2000 and May 2006. Two hundred and twenty-three patients with advanced (stage III or IV) squamous cell carcinoma of the head and neck who were treated with curative intent were reviewed. Recurrences were divided into local, regional or distant recurrences. The detection method for each recurrence was categorised as self or physician detected. A self-detected recurrence arose from symptoms that led to investigations that confirmed a recurrence (even if initiated at the time of a routine visit), whereas a physician-detected recurrence was found during the routine follow-up examination and was asymptomatic. RESULTS: There was no evidence to suggest a significant improvement in disease-free or overall survival in the physician-detected versus patient-detected groups. Regional and distant recurrences were only detected by physicians in one-fifth of cases and, overall, patients self-detected their own recurrence in two-thirds of the cases that experienced disease progression within the sample. Of the 12 clinical/pathological variables considered, only the response to treatment and perineural invasion were associated with survival. CONCLUSIONS: Current surveillance methods do not appear to improve cancer control in the stage III/IV head and neck squamous cell carcinoma population. However, technological advances and biomarker development may lead to surveillance technique enhancements. Also, post-treatment follow-up remains important for the evaluation of treatment results, emotional support and management of late complications. Among the clinical and pathological factors considered, only the treatment response and perineural invasion predicted survival.

Chlorothalonil and 2,4-D losses in surface water discharge from a managed turf watershed.

Managed turf sites (golf courses) are the most intensively managed landscapes in the urban environment. Yet, long-term watershed scale studies documenting the environmental transport of agrichemicals applied to these systems are rare. The objective of this study was to quantify the surface discharge losses of two commonly applied pesticides (chlorothalonil and 2,4-D) resulting from prevailing practices on a managed golf course. Inflow and outflow discharge waters on a subarea of Northland Country Club located in Duluth, MN were measured for both quantity and quality from April through November from 2003 to 2008. The median chlorothalonil outflow concentration (0.58 microg L(-1)) was significantly greater (p < 0.05) than the inflow concentration, which was below the detection limit (0.07 microg L(-1)). Similarly, the median outflow 2,4-D concentration (0.85 microg L(-1)) was significantly greater (p < 0.05) than the inflow concentration (0.31 microg L(-1)). Chlorothalonil concentrations occasionally exceeded acute toxicity levels (7.6 microg L(-1)) reported for rainbow trout. No 2,4-D concentrations exceeded any human or aquatic species published toxicity level; however, the maximum measured 2,4-D concentration (67.1 microg L(-1)), which rarely occurred, did approach the 70 microg L(-1) maximum contaminant level (MCL) for that compound. Losses of both pesticides were detectable throughout the annual sampling period. Mean annual chlorothalonil loading was 10.5 g ha(-1) or 0.3% of applied, while mean annual 2,4-D loading was 4.9 g ha(-1) or 0.5% of applied. The findings of this study provide quantifiable evidence of agrichemical transport resulting from typical turfgrass management and highlight the need for implementation of best management practices to combat the offsite transport of agrichemicals used in professional turf management.

Ecosystem scale carbon dioxide balance of two grasslands in Hungary under different weather conditions.

The carbon balance of the sandy pasture (Bugac) and the mountain meadow (Mátra) varied between -171 and 96 gC m(-2) year-1, and -194 and 14 gC m(-2) year(-1), respectively, during the study period (2003-2009). Large part of interannual variability of net ecosystem exchange (NEE) was explained by the variation of the annual sum of precipitation in the sandy grassland ecosystem, while this relationship was weaker in the case of the mountain meadow on heavy clay soil. These different responses are largely explained by soil texture characteristics leading to differences in soil water contents available to plants at the two grasslands. The grassland on heavy clay soil was more sensitive to temporal distribution of rainfall for the same reason. The mountain meadow therefore seems to be more vulnerable to droughts, while the sandy grassland is better adapted to water shortage. The precipitation threshold (annual sum), below which the grassland turns into source of carbon dioxide on annual basis, is only 50-80 mm higher than the 10 years average precipitation sum. In extremely dry years (2003, 2007 and 2009), even the sandy grassland ecosystem was not stable enough to maintain its sink character.

Comparison of the physicochemical properties of MCT-containing fat emulsions in total nutrient admixtures.

The physical stability of two types of MCT-emulsions made by different technologies - physical mixture vs. structured lipids - was studied as a function of storage time and temperature. Particle size analysis, zeta potential and dynamic surface tension measurements were carried out to evaluate the possible changes in the kinetic stability of the emulsions. Our results indicate that the physical mixture technology of MCT-emulsions resulted in impaired physicochemical stability compared to the ones containing structured triglycerides. In the case of structured lipids, both medium and long chain fatty acids can be found in one triglyceride molecule, leading to a favorable interfacial location of structured triglycerides. Besides the advantageous metabolic effects of structured triglycerides, their application is recommended to improve the physical stability of TPN admixtures.

Treating recurrent cases of squamous cell carcinoma with radiotherapy.

Patients with chronic lymphocytic leukemia (CLL) are at a significantly increased risk of developing cutaneous squamous cell carcinoma (SCC), in part because of their impaired immunosurveillance. Here, we report the cases of 4 patients with CLL who had locally aggressive cutaneous scc managed with radiotherapy for local recurrence following surgical excision. All tumours were located in the head-and-neck region. All patients initially achieved complete regression of disease; however, 2 had local recurrence a mean of 8 months after treatment completion. One patient died from progressive SCC. Our findings agree with the high rates reported in literature of multiple tumours, local recurrence, metastases, and mortality from scc in patients with cll. Radiotherapy plays an important role in patient management, and it is the recommended treatment modality when complete surgical excision of disease would result in anatomic and functional defects. Radiotherapy is often used in the case of local recurrence after one or more attempts at surgical excision. Dose escalation through intensity-modulated radiotherapy, hyperfractionation, or novel treatment techniques such as high-intensity focused ultrasound may be explored to improve local control of scc lesions. To optimize patient outcomes, cutaneous SCC arising in patients with a history of cll should be managed and followed in a multidisciplinary clinic, with regular skin surveillance and prompt treatment.

Nutrient load generated by storm event runoff from a golf course watershed.

Turf, including home lawns, roadsides, golf courses, parks, etc., is often the most intensively managed land use in the urban landscape. Substantial inputs of fertilizers and water to maintain turf systems have led to a perception that turf systems are a major contributor to nonpoint source water pollution. The primary objective of this study was to quantify nutrient (NO(3)-N, NH(4)-N, and PO(4)-P) transport in storm-generated surface runoff from a golf course. Storm event samples were collected for 5 yr (1 Apr. 1998-31 Mar. 2003) from the Morris Williams Municipal Golf Course in Austin, TX. Inflow and outflow samples were collected from a stream that transected the golf course. One hundred fifteen runoff-producing precipitation events were measured. Median NO(3)-N and PO(4)-P concentrations at the outflow location were significantly (p < 0.05) greater than like concentrations measured at the inflow location; however, median outflow NH(4)-N concentration was significantly less than the median inflow concentration. Storm water runoff transported 1.2 kg NO(3)-N ha(-1) yr(-1), 0.23 kg NH(4)-N ha(-1) yr(-1), and 0.51 kg PO(4)-P ha(-1) yr(-1) from the course. These amounts represent approximately 3.3% of applied N and 6.2% of applied P over the contributing area for the same period. NO(3)-N transport in storm water runoff from this course does not pose a substantial environmental risk; however, the median PO(4)-P concentration exiting the course exceeded the USEPA recommendation of 0.1 mg L(-1) for streams not discharging into lakes. The PO(4)-P load measured in this study was comparable to soluble P rates measured from agricultural lands. The findings of this study emphasize the need to balance golf course fertility management with environmental risks, especially with respect to phosphorus.

Nutrient flux in storm water runoff and baseflow from managed turf.

The urban landscape is comprised of many land uses, none more intensively managed than turfgrass; however, quantification of nutrient losses from specific land uses within urban watersheds, specifically golf courses is limited. Nitrate (NO(3)-N) and dissolved reactive phosphorus (DRP) were measured on a golf course in Austin, TX, USA from April 1, 1998 to March 31, 2003. NO(3)-N and DRP concentrations measured in storm flow were significantly greater exiting the course compared to those entering the course. Significant differences were also measured in baseflow NO(3)-N concentrations. The measured loading from the course was 4.0kg NO(3)-Nha(-1)yr(-1) (11% of applied) and 0.66kg DRPha(-1)yr(-1) (8% of applied). The resulting concentrations contributed by the course were 1.2mgL(-1) NO(3)-N and 0.2mgL(-1) DRP. At these levels, NO(3)-N poses minimal environmental risk. However, the DRP concentration is twice the recommended level to guard against eutrophication.