Radiology Commons^™

Phase And Dark Field Radiography And Ct With Mesh-Based Structured Illumination And Polycapillary Optics, Uttam Pyakurel

Legacy Theses & Dissertations (2009 - 2024)

Imaging can be performed with a variety of techniques. For example, gamma radiation is used in nuclear medicine and radiation therapy A challenge in using gamma rays is the risk of high radiation exposure, which requires extensive custom shielding. The transmission of gamma rays through 3D printed shielding was measured to evaluate the required thickness of the shielding.Conventional radiography depends on x-ray attenuation. Another imaging technique, X-ray phase imaging, is known to improve the contrast of images relative to conventional imaging for low density materials. Phase differences imparted by soft tissue are roughly 1000 times larger than attenuation differences. Further, …

System Measurements For X-Ray Phase And Diffraction Imaging, Erik Wolfgang Tripi

Legacy Theses & Dissertations (2009 - 2024)

In medical imaging, X rays are used to look inside the body to find fractures in bones, abnormal masses, cavities in teeth, and so on. What makes X rays so good at looking at these types of structures is the X ray’s penetration power. When imaging soft tissue to search for tumors, X-ray images tend to have difficulty performing well. The reason for this is that the background structures, such as fat or fibro glandular tissue have similar absorption coefficients as the tumor. Mammography tends to have a high false positive rate and can miss tumors entirely as well. There …

Development Of End-To-End Test Phantom For Stereotactic Radiosurgery Using Alanine Dosimeter, Aungsumalin Intang

Chulalongkorn University Theses and Dissertations (Chula ETD)

Alanine dosimeters are generally used in high-dose dosimetry, while accurate and precise dose delivery verification procedures are important in stereotactic radiosurgery (SRS). Hence, an end-to-end test is required. In addition, no end-to-end SRS test employing an alanine dosimeter has been established in Thailand. The objective of this study was to determine the dose accuracy of SRS VMAT plans in end-to-end test phantom using alanine dosimeter. The electron paramagnetic resonance (EPR) parameters were optimized in the 1-2000 cGy dose range. Following that, suitable parameters were used to investigate the alanine characteristics and estimate the uncertainty in radiation therapy dose range. The …

Diagnostic Imaging Read By Ai-Assisted Technology Within The Emergency Department, Joshua Leland

Capstone Showcase

Introduction: The emergency department (ED) has had an appreciable increase in volume over the past two decades with more individuals utilizing the ED now than a decade ago which has placed a strain on healthcare resources. Specifically adding to the rising costs in healthcare are diagnostics including chest x-rays. To combat this, institutions across the nation are developing deep-learning and artificial intelligence (AI) programs to assist in reading these diagnostics. Therefore, this systematic review analyzes the use of AI programs by clinicians in the ED to read diagnostic imaging compared to those who do not use these algorithms.

Methods: This …

Comparison Of Radiation Dose And Image Quality Between Fast Kvp Switching Dual-Energy Ct And Routine Single-Energy Ct For Whole Abdomen At King Chulalongkorn Memorial Hospital, Chanthawan Khemkhangboon

Chulalongkorn University Theses and Dissertations (Chula ETD)

Abdominal computed tomography (CT) using a single energy protocol is a common imaging procedure in hospitals. As CT technology has continued to evolve, dual-energy protocols (DECT) have emerged as a new option. A spectral CT scanner with fast kVp switching was installed at King Chulalongkorn Memorial Hospital in 2017, and its clinical utility in emergency patients has not yet been studied. This study aims to compare the radiation dose and image quality between DECT and SECT in abdominal CT for emergency patients. The study retrospectively collected CT data from 130 standard-sized adult patients who underwent contrast-enhanced using the 256-slice MDCT. …

Modeling Of Patient-Specific Periaortic Mechanics And Pulmonary Artery Hemodynamics Based On Phase-Contrast Magnetic Resonance Imaging Sequences., Johane H. Bracamonte

Theses and Dissertations

Inverse modeling in cardiovascular medicine is a collection of methodologies that can provide non-invasive patient-specific estimations of clinical risk factors using medical imaging as inputs. Its incorporation into clinical practice has the potential to improve diagnosis and treatment planning with low associated risks and costs.

Herein, three different phase contrast magnetic resonance imaging (MRI) modalities were implemented as input data, displacement encoding with stimulated echoes (DENSE MRI) applied, and time-resolved velocity encoding phase-contrast MRI, in 1D and 3D, applied to pulmonary artery (PA) hemodynamics.

A model to account for the effect of periaortic interactions due to static and dynamic structures …

Diagnostic Accuracy Of Computed Tomography In Adults With Suspected Acute Appendicitis At The Emergency Department In A Private Tertiary Hospital In Tanzania, Nyamuryekun'ge Miten, Miten Wr Patel, Ahmed Jusabani, Ali Akbar Zehri, Athar Ali

General Surgery, East Africa

Introduction: The increasing incidence of acute appendicitis in sub-Saharan Africa emphasizes the need for accurate and reliable diagnostic tools. However, the variability in the diagnostic performance of computed tomography for suspected acute appendicitis coupled with comparatively higher negative appendectomy rates in this setting highlight a possible concern regarding the diagnostic accuracy. This study evaluated the diagnostic accuracy of a computed tomography scan for suspected acute appendicitis at the emergency department in Tanzania.

Methods: A retrospective diagnostic accuracy study was conducted from July to October 2020. All patients above 14 years of age who presented at the emergency department with …

Strategies For Improving Customer Retention For Medical Imaging Devices, Guillermo Sander

Walden Dissertations and Doctoral Studies

Some sales managers of medical imaging devices lack strategies to improve long-term customer retention. Increasing retention can save these sales managers up to 50% of their customer acquisition costs. Grounded in the service profit chain theory, the purpose of this qualitative multiple case study was to explore strategies sales managers of medical imaging devices use to improve long-term customer retention. The participants comprised seven sales managers of medical imaging devices from three companies who successfully achieved long-term customer retention. Data were collected using semistructured interviews and public documents. Thematic analysis was used to analyze the data. Three themes emerged: value-added …

In Vivo Dosimetry Of 3d Gynecological Brachytherapy Using The Glass Dosimeter: A Phantom Study, Itsaraporn Konlak

Chulalongkorn University Theses and Dissertations (Chula ETD)

Brachytherapy can deliver high doses to the target while sparing healthy tissues due to its steep dose gradient property. However, treatment was only performed according to the dose calculated by a treatment planning system without verification of the dose due to the characteristics. Therefore, the aim of this study was to design the in-house phantom to evaluate the dosimetric differences of gynecological brachytherapy under clinical conditions between calculation by the treatment planning system and measurement by the RPLGDs. An in-house phantom consisting of the glass dosimeter holder and the holder of the applicator was created. This holder was designed to …

Effect Of Inter-Observer Delineation Variability On Radiomics Features In Nasopharyngeal Cancer, Pongpitch Panyura

Chulalongkorn University Theses and Dissertations (Chula ETD)

Nasopharyngeal cancer (NPC) is a type of head and neck cancer that is prevalent in China and Southeast Asia. The standard treatment for NPC is radiation therapy (RT), which requires accurate target volume delineation (TVD) to ensure an effective radiation dose while minimizing damage to surrounding healthy tissues. However, TVD is subject to intra- and inter-observer variability, which can affect the accuracy of RT and lead to unstable results in radiomics analysis. Radiomics is a technique that extracts quantitative data from medical images, but it is currently limited by the manual process of tumor delineation. This study aims to investigate …

Dosimetric Differences Between Scheduled And Adapted Plans Generated From Ethos Adaptive Radiotherapy For Patients With Prostate Cancer, Sarita Suvira

Chulalongkorn University Theses and Dissertations (Chula ETD)

Prostate is one of the organs that can easily move or change during the treatment fractions. Adaptive radiotherapy can help to reduce the uncertainty of interfraction and decrease the side effects produced from the radiation given to the patients. The objective of this study was to provide evidence of the efficiency of adaptive radiotherapy for prostate cancer patients by investigating the dosimetric differences between the scheduled and adapted plans generated from Ethos. The treatment data of 100 fractions of prostate cancer patients who had previously been treated on Ethos daily adaptive radiotherapy were collected. The treatment data in each fraction …

Accuracy In Classification Of Liver Lesion Ultrasound Using Artificial Intelligence, Sutthirak Tangruangkiat

Chulalongkorn University Theses and Dissertations (Chula ETD)

B-mode ultrasound imaging is the standard method for hepatocellular carcinoma (HCC) screening. If a lesion has a unique appearance, a conventional detector can be applied. However, if the lesion shares its appearance with other lesion, a large training dataset is required, which may be unavailable. Therefore, a two-stage method is proposed. In the first stage, lesions are detected but not differentiated into any particular class. The detected lesions are then classified in the second stage using a conventional convolutional neural network (CNN). The aims of the dissertation are to design an artificial intelligent system model and to investigate the most …

Accuracy Of Small-Field High Energy Photon Using Plastic Scintillation Detector In Heterogenous Media Compared With Model-Based Algorithm Calculation, Thanat Kaewsuksri

Chulalongkorn University Theses and Dissertations (Chula ETD)

Some radiotherapy techniques such as stereotactic body radiotherapy (SBRT) has the challenges in small field dosimetry in heterogenous media. This study aims at evaluating the accuracy of W2 plastic scintillation detector (PSD) compared with the calculation from algorithms for small-field high energy photon in heterogenous media. The characteristics of W2-PSD were studied. The percentage depth dose (PDD) of 6 FFF and 10 FFF with various field sizes ranging from 1x1 to 4x4 cm2 were measured in solid water phantom with low-density inhomogeneities slabs of air (Styrofoam) and lung (cork) and high-density inhomogeneity slab of aluminum. The characteristics of W2 plastic …

Validation Of Independent Software-Based Calculation In Patient-Specific Quality Assurance, Yasmine Joy Labagnoy

Chulalongkorn University Theses and Dissertations (Chula ETD)

The Mobius3D software addresses limitations lacking in measurement-based methods in patient-specific QA. The objective of this study is to validate its dosimetric performance against conventionally used portal dose measurements using gamma analysis and confidence limits. First, a total of 240 patient-specific QA plans for the Varian Halcyon linear accelerator were collected. Then, the EPID was characterized and the Mobius3D software commissioned through plan verification. Then all patient-specific plans underwent QA using the Portal Dosimetry software and the Mobius3D. The EPID exhibited high reproducibility, dose linearity, and stable dose rate, gantry speed, and MLC speed responses. QA data were assessed using …

Comparative Dosimetry Between 2d Planar-Based And Hybrid-Based Method For Personalized 177 Lu-Psma I&T And 177lu-Dotatate Therapy, Wuri Handayani

Chulalongkorn University Theses and Dissertations (Chula ETD)

Targeted radionuclide therapy (TRT) uses unsealed radiation sources that are accumulated in the target tissues to deliver a damaging radiation dose to the cancerous cells, and a part of the radiopharmaceutical will end up in non-targeted tissues. To avoid treatment-related side effects, dosimetry is mandatory for TRT for each treatment cycle. This study aimed to evaluate and compare the feasibility of 2D planar-based dosimetry and hybrid-based dosimetry for 177Lu-PSMA I&T and 177Lu-DOTATATE therapy. Whole-body planar images and SPECT/CT images were acquired from 27 treatment cycles, 18 patients (13 patients for 177Lu-PSMA I&T and 5 patients for 177Lu-DOTATATE treatment) at immediately, …

Dosimetric Comparison Between Single-Energy Ct And Dual-Energy Ct For Relative Stopping Power Estimation In Proton Therapy, Thamonwan Chirdchid

Chulalongkorn University Theses and Dissertations (Chula ETD)

In proton therapy treatment planning, dose calculation requires CT calibration curve by relating CT number (HU) to relative stopping power to water (RSP). The CT calibration curve and the RSP validation are described for single-energy CT (SECT) and dual-energy CT (DECT). The focus of this work was given on the dosimetric comparison of treatment plans between SECT and DECT-based dose calculation. The 062M CIRS phantom was scanned to access the HU values by GE kVp switching method with single-energy of 120 kVp and dual-energy of 80/140 kVp. The CT calibration curve was generated using the stoichiometric calibration method and implemented …

Tolerance Levels On Dose And Anatomic Variation For Adaptive Radiotherapy Based On Statistical Process Control For Nasopharyngeal Cancer, Rudjaya Intaprom

Chulalongkorn University Theses and Dissertations (Chula ETD)

Nasopharyngeal cancer (NPC) is one of the most common cancers in Thailand and worldwide. During the long course of treatment, patients often change of anatomy in both the shape and the volume. The deviation of the delivered dose has long been a clinical concern. Adaptive radiotherapy (ART) technique is a treatment process that prevents the dose changes to clinical target volume (CTV) and organs at risk (OARs). The purpose of this study was proposed to method to set the action levels for replanning in NPC and to evaluate the dose differences of CTV and OARs by planning CT and weekly …

The Study Of Local Diagnostic Reference Levels Of Computed Tomography Procedures At Phramongkutklao Hospital, Sutasinee Mahasub

Chulalongkorn University Theses and Dissertations (Chula ETD)

Computed Tomography (CT) is a medical modality of 3D imaging technique using the X-ray photons rotate, transmit and detect the radiation by the multi-detectors. The CT examination results in the higher patient dose than the general radiography. The objective of this study was to establish the Local DRLs of patient radiation dose in CT procedures at Phramongkutklao Hospital. This study is a retrospective analysis at a single center from January-August 2021. Two CT scanners: 160 slices MDCT manufactured by Canon, model AquilionTM Prime and 640 slices MDCT manufactured by Canon, model AquilionTM One Prism have been used to collect the …

Automated Method Of Corrected Effective Diameter For Ssde In Thoracic Imaging Ct Using Cnn, Sakultala Ruenjit

Chulalongkorn University Theses and Dissertations (Chula ETD)

This study aimed to automatically determine the corrected effective diameter (Deffcorr) using convolutional neural network (CNN) for simplified SSDE calculation in thoracic CT. Transaxial images of 108 adult patients underwent thoracic CT without contrast at King Chulalongkorn Memorial Hospital (KCMH) were collected. To calculate the Deffcorr according to Mihailidis et al., the average relative electron densities for lung tissue (ρelung=0.3), for other tissues (ρetissue=1.0) and for bone (ρebone=1.2) were employed to correct the lateral and anteroposterior dimension. The CNN network architecture based on the U-Net algorithm was used for automated image segmentation. The 108 thoracic CT images and generated segmentation …

The Psychological Impact Of The Covid-19 Outbreak On Pregnancy And Mother-Infant Prenatal Bonding, Muhammad O Awiwi, Khaled M Elsayes, Yehia I Mohamed, Lina Altameemi, Migena Gjoni, Omayr Muhammad Irshad, Ahmed Sayed Ahmed, Ahmad O Kaseb, Usama Salem

Faculty, Staff and Student Publications

PURPOSE: To identify prognostic clinical and radiologic features in patients with unresectable hepatocellular carcinoma (HCC) treated with atezolizumab plus bevacizumab.

PATIENTS AND METHODS: Clinical and imaging records of patients with unresectable HCC were retrospectively reviewed, and baseline features were recorded. Patients' records and imaging studies were used to determine the patients' overall survival (OS) and progression-free survival (PFS). Univariate and multivariate analyses were performed to determine prognostic features. Subanalyses of treatment-naïve patients (who never received local or systemic therapy) and previously treated patients were also performed.

RESULTS: Fifty-five patients were included in the final analysis, 23 (41.8%) of whom were …