Analysis of mask CD error by dose modulation for fogging effect

2004 ◽  
Author(s):  
Hojune Lee ◽  
Seung-Hune Yang ◽  
Byung-Gook Kim ◽  
Sung-Yong Moon ◽  
Sung-Woon Choi ◽  
...  
Keyword(s):  
Dose Modulation ◽  
Fogging Effect

Analysis of dose modulation method for fogging effect correction at 50-KeV e-beam system

2004 ◽  
Author(s):  
Sung-Hoon Jang ◽  
Seung-Hune Yang ◽  
Byoung-Sup Ahn ◽  
Won-Tai Ki ◽  
Ji-Hyeon Choi ◽  
...  
Keyword(s):  
Modulation Method ◽  
Beam System ◽  
Dose Modulation ◽  
Fogging Effect

scholarly journals Modulation of temozolomide dose differentially affects T-cell response to immune checkpoint inhibition

2019 ◽  
Vol 21 (6) ◽  
pp. 730-741 ◽  
Author(s):  
Aida Karachi ◽  
Changlin Yang ◽  
Farhad Dastmalchi ◽  
Elias J Sayour ◽  
Jianping Huang ◽  
...  
Keyword(s):  
T Cell ◽  
Immune Checkpoint ◽  
Standard Dose ◽  
Antibody Therapy ◽  
Tumor Infiltrating Lymphocytes ◽  
T Cell Response ◽  
Checkpoint Inhibition ◽  
Immune Checkpoint Inhibition ◽  
Dose Modulation ◽  
Infiltrating Lymphocytes

Abstract Background The changes induced in host immunity and the tumor microenvironment by chemotherapy have been shown to impact immunotherapy response in both a positive and a negative fashion. Temozolomide is the most common chemotherapy used to treat glioblastoma (GBM) and has been shown to have variable effects on immune response to immunotherapy. Therefore, we aimed to determine the immune modulatory effects of temozolomide that would impact response to immune checkpoint inhibition in the treatment of experimental GBM. Methods Immune function and antitumor efficacy of immune checkpoint inhibition were tested after treatment with metronomic dose (MD) temozolomide (25 mg/kg × 10 days) or standard dose (SD) temozolomide (50 mg/kg × 5 days) in the GL261 and KR158 murine glioma models. Results SD temozolomide treatment resulted in an upregulation of markers of T-cell exhaustion such as LAG-3 and TIM-3 in lymphocytes which was not seen with MD temozolomide. When temozolomide treatment was combined with programmed cell death 1 (PD-1) antibody therapy, the MD temozolomide/PD-1 antibody group demonstrated a decrease in exhaustion markers in tumor infiltrating lymphocytes that was not observed in the SD temozolomide/PD-1 antibody group. Also, the survival advantage of PD-1 antibody therapy in a murine syngeneic intracranial glioma model was abrogated by adding SD temozolomide to treatment. However, when MD temozolomide was added to PD-1 inhibition, it preserved the survival benefit that was seen by PD-1 antibody therapy alone. Conclusion The peripheral and intratumoral immune microenvironments are distinctively affected by dose modulation of temozolomide.

Image Denoising Technique for CT Dose Modulation

2018 ◽  
Author(s):  
Haneen A. Elyamani ◽  
Samir A. El-Seoud ◽  
Essam A. Rashed
Keyword(s):  
Image Denoising ◽  
Ct Dose ◽  
Dose Modulation

Coronary flow quantification estimated by dynamic 320-detector CT angiography: validation by 13N ammonia PET myocardial flow reserve

2021 ◽  
Author(s):  
Yuka Matsuo ◽  
Michinobu Nagao ◽  
Atsushi Yamamoto ◽  
Kiyoe Ando ◽  
Risako Nakao ◽  
...  
Keyword(s):  
Ct Angiography ◽  
Coronary Flow ◽  
Clinical Work ◽  
Myocardial Flow Reserve ◽  
Flow Quantification ◽  
Flow Index ◽  
Characteristic Analysis ◽  
Flow Reserve ◽  
Dose Modulation ◽  
Myocardial Flow

Objectives: Resting coronary flow index (rCFI) estimated by 320-detector low-dose dynamic coronary CT angiography (CCTA) is a direct flow quantification using intracoronary attenuation. We propose modified-rCFI from new protocol combining dynamic scan and standard CCTA using dose-modulation, and validate its consistency with quantitative values and ischemia depicted by 13N-ammonia PET (NH3-PET). Methods: 46 patients who underwent dynamic CCTA and NH3-PET for coronary artery disease were evaluated using original rCFI in 21 patients and modified-rCFI in 25 patients. Two types of rCFI were calculated for three major coronary arteries. Myocardial blood flow (MBF) at rest and stress, myocardial flow reserve (MFR), and the presence or absence of ischemia for three major territories were depicted by NH3-PET. Coronary territories were categorized as territories with MFR <2.0, ≥2.0, or with and without ischemia. Receiver operating characteristic analysis was performed to determine the optimal cut-off of rCFI to distinguish territories with MFR <2.0 or the presence of ischemia. Results: rCFI and modified-rCFI had significant positive correlations with stress MBF and MFR. The optical cut-offs of rCFI and modified-rCFI of 0.39 and 0.61 could detect territories with MFR <2.0, with AUCs of 0.75 and 0.73, sensitivities of 48 and 34%, and specificities of 97 and 98%. Optimal cut-offs of rCFI and modified-rCFI distinguished ischemic segments from non-ischemic segments, with AUCs of 0.75 and 0.91, sensitivities of 53 and 50%, and specificities of 93 and 95%. Conclusion: Two types of rCFI correlated with quantitative values from NH3-PET, and were consistent with a high specificity in detecting functional ischemia. Advances in knowledge: rCFI can contribute as additional functional test over standard CCTA in clinical work-up.

Spatial Resolution and Frequency Characteristics for Dose Modulation on the TrueBeam Medical Accelerator

2021 ◽  
Vol 91 (3) ◽  
pp. 17-26
Author(s):  
V. N. Vasiliev ◽  
A. Yu. Smyslov
Keyword(s):  
Power Spectrum ◽  
Frequency Domain ◽  
Spatial Resolution ◽  
Dose Response ◽  
Peak Width ◽  
Multi Leaf Collimator ◽  
Useful Signal ◽  
Significant Difference ◽  
Dose Modulation ◽  
Statistical Noise

Purpose: To study the spatial resolution achievable by dose modulation in a water phantom using a multi-leaf collimator, jaws and their combination. To estimate the power spectrum density of the useful signal (dose distribution) and statistical noise, evaluate the frequency interval containing the useful signal. Material and methods: Using the Gafchromic EBT2 radiochromic film, nested squares dose patterns formed in a water-equivalent phantom by 6 and 15 MV photon beams of the TrueBeam medical accelerator, jaws, a multi-leaf collimator, and a combination of these devices were measured. Dose response to step function (ESF) data was extracted from the penumbra and the linear photon source dose response function (LSF) was calculated. To move to frequency domain, fast Fourier transform was performed over the obtained datasets, as well as over individual LSF peaks, and then power spectra densities were calculated. The Nyquist frequency associated with data sampling was 1.42 mm-1, the Hann window was used to minimize leakage effect. Results: The shape of the obtained LSF peaks was approximated by a sum of two Gaussian distributions with the same center positions but different widths. The LSF peak width at half maximum (FWHM) was 1.7-3.9 mm depending on the modulation device. No significant difference was observed in the peak widths at energies of 6 and 15 MV. In most cases, the width of the peak along the X-axis was wider than along the Y-axis. The power spectrum of the useful signal had a maximum near zero frequency, a 50 % level was near 0.09 mm-1 and its high frequency limit was about 0.4 mm-1. Above this value, only the spectrum of statistical noise was recorded, uniformly distributed over frequency. Conclusion: The obtained values of the LSF peak width in the range 1.7-3.9 mm characterize the ability of dose modulation by the considered devices or their combination, which can be significant for treatment of small targets (less than 3-4 cm), where these limits of spatial resolution can be reached. The obtained relationships in frequency domain can be used for optimal removal of statistical noise using Wiener filters from profiles or two-dimensional dose distributions.

scholarly journals Fast dose modulation in proton therapy with continuous line scanning

2016 ◽  
Vol 118 ◽  
pp. S56-S57
Author(s):  
G. Klimpki ◽  
S. Psoroulas ◽  
P. Fernandez ◽  
C. Bula ◽  
D.C. Weber ◽  
...  
Keyword(s):  
Proton Therapy ◽  
Continuous Line ◽  
Line Scanning ◽  
Dose Modulation

scholarly journals Reduction of patient radiation dose with a new organ based dose modulation technique for thoraco-abdominopelvic computed tomography (CT) (Liver dose right index)

2018 ◽  
Vol 99 (7-8) ◽  
pp. 483-492 ◽  
Author(s):  
M. Fillon ◽  
S. Si-Mohamed ◽  
P. Coulon ◽  
A. Vuillod ◽  
P. Klahr ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Radiation Dose ◽  
Modulation Technique ◽  
Dose Modulation ◽  
Patient Radiation Dose
Sign in / Sign up

Export Citation Format

Share Document