Technical Report: Evaluation of peripheral dose for flattening filter free photon beams

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135019/1/mp8963.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135019/2/mp8963_am.pd

Revisiting fetal dose during radiation therapy: evaluating treatment techniques and a custom shield [JACMP, 17(5), 2016]

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139980/1/acm212191_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139980/2/acm212191.pd

On the role of abnormal DL(CO) in ex-smokers without airflow limitation: symptoms, exercise capacity and hyperpolarised helium-3 MRI

BACKGROUND: The functional effects of abnormal diffusing capacity for carbon monoxide (DLCO) in ex-smokers without chronic obstructive pulmonary disease (COPD) are not well understood. OBJECTIVE: We aimed to evaluate and compare well established clinical, physiological and emerging imaging measurements in ex-smokers with normal spirometry and abnormal DLCO with a group of ex-smokers with normal spirometry and DLCO and ex-smokers with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I COPD. METHODS: We enrolled 38 ex-smokers and 15 subjects with stage I COPD who underwent spirometry, plethysmography, St George\u27s Respiratory Questionnaire (SGRQ), 6 min Walk Test (6MWT), x-ray CT and hyperpolarised helium-3 ((3)He) MRI. The 6MWT distance (6MWD), SGRQ scores, (3)He MRI apparent diffusion coefficients (ADC) and CT attenuation values below -950 HU (RA950) were evaluated. RESULTS: Of 38 ex-smokers without COPD, 19 subjects had abnormal DLCO with significantly worse ADC (p=0.01), 6MWD (p=0.008) and SGRQ (p=0.01) but not RA950 (p=0.53) compared with 19 ex-smokers with normal DLCO. Stage I COPD subjects showed significantly worse ADC (p=0.02), RA950 (p=0.0008) and 6MWD (p=0.005), but not SGRQ (p=0.59) compared with subjects with abnormal DLCO. There was a significant correlation for (3)He ADC with SGRQ (r=0.34, p=0.02) and 6MWD (r=-0.51, p=0.0002). CONCLUSIONS: In ex-smokers with normal spirometry and CT but abnormal DLCO, there were significantly worse symptoms, 6MWD and (3)He ADC compared with ex-smokers with normal DLCO, providing evidence of the impact of mild or early stage emphysema and a better understanding of abnormal DLCO and hyperpolarised (3)He MRI in ex-smokers without COPD

Revisiting fetal dose during radiation therapy: evaluating treatment techniques and a custom shield

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135233/1/acm20001i.pd

Computed tomography density histogram analysis to evaluate pulmonary emphysema in ex-smokers

RATIONALE AND OBJECTIVES: High-resolution computed tomography (CT) measurements of emphysema typically use Hounsfield unit (HU) density histogram thresholds or observer scores based on regions of low x-ray attenuation. Our objective was to develop an automated measurement of emphysema using principal component analysis (PCA) of the CT density histogram. MATERIALS AND METHODS: Ninety-seven ex-smokers, including 53 subjects with chronic obstructive pulmonary disease (COPD) and 44 asymptomatic subjects (AEs), provided written informed consent to imaging as well as plethysmography and spirometry. We applied PCA to the CT density histogram to generate whole lung and regional density histogram principal components including the first and second components and the sum of both principal components (density histogram principal component score [DHPCS]). Significant relationships for DHPCS with single HU thresholds, pulmonary function measurements, an expert\u27s emphysema score, and hyperpolarized (3)He magnetic resonance imaging apparent diffusion coefficients (ADCs) were determined using linear regression and Pearson coefficients. Receiver operator characteristics analysis was performed using forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) as the independent diagnostic. RESULTS: There was a significant difference (P \u3c .0001) between AE and COPD subjects for DHPCS; FEV1/FVC; diffusing capacity of lung for carbon monoxide%predicted; attenuation values below -950, -910, and -856 HU; and (3)He ADCs. There were significant correlations for DHPCS with FEV1/FVC (r = -0.85, P \u3c .0001); diffusing capacity of lung for carbon monoxide%predicted (r = -0.67, P \u3c .0001); attenuation values below -950/-910/-856 HU (r = 0.93/0.96/0.76, P \u3c .0001); and (3)He ADCs (r = 0.85, P \u3c .0001). Receiver operator characteristics analysis showed a 91% classification rate for DHPCS. CONCLUSIONS: We generated an automated emphysema score using PCA of the CT density histogram with a 91% COPD classification rate that showed strong and significant correlations with pulmonary function tests, single HU thresholds, and (3)He magnetic resonance imaging ADCs

Pulmonary ventilation visualized using hyperpolarized helium-3 and xenon-129 magnetic resonance imaging: Differences in COPD and relationship to emphysema

In subjects with chronic obstructive pulmonary disease (COPD), hyperpolarized xenon-129 ((129)Xe) magnetic resonance imaging (MRI) reveals significantly greater ventilation defects than hyperpolarized helium-3 ((3)He) MRI. The physiological and/or morphological determinants of ventilation defects and the differences observed between hyperpolarized (3)He and (129)Xe MRI are not yet understood. Here we aimed to determine the structural basis for the differences in ventilation observed between (3)He and (129)Xe MRI in subjects with COPD using apparent diffusion coefficients (ADC) and computed tomography (CT). Ten COPD ex-smokers provided written, informed consent and underwent MRI, CT, spirometry, and plethysmography. (3)He and (129)Xe MRI ventilation volume was generated using semiautomated segmentation, and ADC maps were registered to generate ADC values for lung regions of interest ventilated by both gases (ADCHX) and by (3)He gas only (ADCHO). CT wall area percentage and the lowest 15th percentile point of the CT lung density histogram (HU15%) were also evaluated. For lung regions accessed by (3)He gas only, mean (3)He ADCHO was significantly greater than for regions accessed by both gases (ADCHO = 0.503 ± 0.119 cm(2)/s, ADCHX = 0.470 ± 0.125 cm(2)/s, P \u3c 0.0001). The difference between (3)He and (129)Xe ventilation volume was significantly correlated with CT HU15% (r = -65, P = 0.04) and (3)He ADCHO (r = 0.70, P = 0.02), but not CT wall area percentage (r = -0.34, P = 0.33). In conclusion, in this small study in COPD subjects, we observed significantly decreased (129)Xe MRI ventilation compared with (3)He MRI, and these regions of decreased (129)Xe ventilation were spatially and significantly correlated with regions of increased pulmonary emphysema, but not airway wall thickness

Analysis of the dynamics of land use change and its prediction based on the integration of remotely sensed data and CA-Markov model, in the upstream Citarum Watershed, West Java, Indonesia

In this research, the integration of remotely sensed data and Cellular Automata-Markov model (CA-Markov) have been used to analyze the dynamics of land use change and its prediction for the next year. Training phase for the CA-Markov model has been created based on the input pair of land use, which is the result of land use mapping using Maximum Likelihood (ML) algorithm. Three-map comparison has been used to evaluate process accuracy assessment of the training phase for the CA-Markov model. Furthermore, the simulation phase for the CA-Markov model can be used to predict land use map for the next year. The analyze of the dynamics of land use change and its prediction during the period 1990 to 2050 can be obtained that the land serves as a water absorbent surfaces such as primary forest, secondary forest and the mixed garden area continued to decline. Meanwhile, on build land area that can lead to reduced surface water absorbing tends to increase from year to year. The results of this research can be used as input for the next research, which aims to determine the impact of land use changes in hydrological conditions against flooding in the research area