Radiology Commons^™

Dosimetric Comparison Between Single And Double Isocenters Volumetric Arc Therapy For Stereotactic Radiotherapy With Multiple Targets, Wai Lwin Lwin Kyaw

Chulalongkorn University Theses and Dissertations (Chula ETD)

The purpose of this study was to evaluate the dosimetric effects between single isocenter (SI) and double isocenters (DI) VMAT SRT of multiple brain metastases. There are two parts of study, which were experimental for energy selection, technique comparison and clinical part to use appropriate technique. As the first part, three lesions with 3 cm distance apart and 1 cm size for all lesions were created as standard plan by varying energy. Twelve VMAT SRT plans by varying energy with 6 MV, 10 MV, 6 FFF and 10 FFF were planned on simulated three lesions of CT image. 18 VMAT …

Measurement Of The Whole Body, Eye Lens And Extremity Occupational Exposures In Nuclear Medicine Staff At King Chulalongkorn Memorial Hospital, Siriwan Sisai

Chulalongkorn University Theses and Dissertations (Chula ETD)

Due to the epidemiology evidence of cataract and eye lens opacity, ICRP Publication 118 in 2012, recommended the new eye lens dose limit of occupational exposure at 20 mSv/year, averaged over 5-year periods, no single year exceeding 50 mSv. For the public eye lens dose limit is 15 mSv/year. After ICRP changed the eye lens dose limit, many reports on eye lens dose measurement using thermoluminescent dosimeter (TLD) from interventional radiologists and interventional cardiologists were published. Few reports on eye lens dose measurement in nuclear medicine (NM) personnel were found. The primary objective of this study is to measure whole …

A Custom Radiopaque Thermoresponsive Chemotherapy-Loaded Hydrogel For Intratumoural Injection: An In Vitro And Ex Vivo Assessment Of Imaging Characteristics And Material Properties, Seóna M. Rossi, Timothy E. Murray, John Cassidy, Michael J. Lee, Helena M. Kelly

Articles

Purpose Thermoresponsive hydrogels are gels which have different properties at varying temperatures. The objective of this study was to assess the material characteristics, imaging properties and chemotherapeutic drug release profile of a novel radiopaque thermoresponsive hydrogel in vitro, which is liquid at room temperature but solidifies at body temperature, to determine potential suitability for intratumoural delivery. Materials and Methods An iodinated radiopaque thermoresponsive hydrogel was formulated using iodixanol at a range of concentrations and assessed for sol–gel transition, radiopacity and imaging using CT and US. A lead formulation containing iodixanol at a concentration of 9.22% weight by weight (w/w, g …

Calibrated Short Tr Recovery Mri For Rapid Measurement Of Brain-Blood Partition Coefficient And Correction Of Quantitative Cerebral Blood Flow, Scott William Thalman

Theses and Dissertations--Biomedical Engineering

The high prevalence and mortality of cerebrovascular disease has led to the development of several methods to measure cerebral blood flow (CBF) in vivo. One of these, arterial spin labeling (ASL), is a quantitative magnetic resonance imaging (MRI) technique with the advantage that it is completely non-invasive. The quantification of CBF using ASL requires correction for a tissue specific parameter called the brain-blood partition coefficient (BBPC). Despite regional and inter-subject variability in BBPC, the current recommended implementation of ASL uses a constant assumed value of 0.9 mL/g for all regions of the brain, all subjects, and even all species.

The …

Sparsity Promoting Regularization For Effective Noise Suppression In Spect Image Reconstruction, Wei Zheng, Si Li, Andrzej Krol, C. Ross Schmidtlein, Xueying Zeng, Yuesheng Xu

Mathematics & Statistics Faculty Publications

The purpose of this research is to develop an advanced reconstruction method for low-count, hence high-noise, Single-Photon Emission Computed Tomography (SPECT) image reconstruction. It consists of a novel reconstruction model to suppress noise while conducting reconstruction and an efficient algorithm to solve the model. A novel regularizer is introduced as the nonconvex denoising term based on the approximate sparsity of the image under a geometric tight frame transform domain. The deblurring term is based on the negative log-likelihood of the SPECT data model. To solve the resulting nonconvex optimization problem a Preconditioned Fixed-point Proximity Algorithm (PFPA) is introduced. We prove …

Radiation Safety Practices Of Dental Hygienists In The United States, Kimberly Lintag, Ann M. Bruhn, Susan Lynn Tolle, Norou Diawara

Dental Hygiene Faculty Publications

Purpose: The As Low As Reasonably Achievable (ALARA) principle was developed to promote awareness and minimization of radiation exposure and is supported by radiation control and professional organizations. The purpose of this study was to determine licensed dental hygienists' current radiation safety practices.

Methods: Data were collected with a 22 item, online survey administered to a convenience sample of 1,500 dental hygienists in the United States. Questions focused on respondents' use of the American Dental Association (ADA) radiographic examination selection guidelines, their individual dental practice policies, and hand-held portable x-ray device use and training. Cross tabulations were obtained using logistic …

A Feasibility Study Of Diffusion Weighted Imaging And Parametric Response Map Analysis For Treatment Response Prediction In Nasopharyngeal Cancer, Titiya Jirawatwanith

Chulalongkorn University Theses and Dissertations (Chula ETD)

Diffusion-weighted imaging (DWI) is an MRI technique which provides functional information of tissue by detecting microscopic motion of water molecules. The change of apparent diffusion coefficient (ADC) derived from DWI was used as an imaging biomarker for treatment response prediction in cancers. However, it was based on whole-tumor analysis which did not reflect heterogeneity within the tumor. To overcome this limitation, a new method called parametric response map (PRM) analysis was proposed to evaluate response by quantifying voxel-wise changes in ADC. Here we investigated the use of PRM analysis on ADC from DWI as an imaging biomarker for treatment response …

Comparison Of Quantitative Analysis To Qualitative Analysis For Interpretation Of Lower‑Limb Lymphoscintigraphy, Edward Nganga, Khalid Makhdomi

Imaging & Diagnostic Radiology, East Africa

Qualitative analysis of lymphoscintigrams is subject to wide variability and may miss subtle differences in ilioinguinal uptake between normal and abnormal limbs. This study compared quantitative analysis to qualitative analysis of lower‑limb lymphoscintigraphy in diagnosing lymphedema. Fifty‑two lymphoscintigrams performed using standardized protocol, 99‑metastable technetium nanocolloid intradermal injection at the first interdigital space, were analyzed quantitatively. Fifty‑three normal and 51 abnormal limbs were analyzed. For each limb, a region of interest (ROI) was drawn around the injection site, and ilioinguinal nodes on the 1.5 h static images and the counts in these ROIs were recorded. Percentage ilioinguinal nodes uptake was then …

Evaluation Of Plan Quality And Treatment Efficiency For Single-Isocenter/Two-Lesion Lung Stereotactic Body Radiation Therapy, Lana Sanford, Janelle A. Molloy, Sameera S. Kumar, Marcus Randall, Ronald C. Mcgarry, Damodar Pokhrel

Radiation Medicine Faculty Publications

Purpose/objectives: To evaluate the plan quality and treatment delivery efficiency of single‐isocenter/two‐lesions volumetric modulated arc therapy (VMAT) lung stereotactic body radiation therapy (SBRT).

Materials/methods: Eight consecutive patients with two peripherally located early stage nonsmall‐cell‐lung cancer (NSCLC) lung lesions underwent single‐isocenter highly conformal noncoplanar VMAT SBRT treatment in our institution. A single‐isocenter was placed between the two lesions. Doses were 54 or 50 Gy in 3 and 5 fractions respectively. Patients were treated every other day. Plans were calculated in Eclipse with AcurosXB algorithm and normalized to at least 95% of the planning target volume (PTV) receiving 100% of the prescribed …

Reviewers' Responses To Medical Research Articles, Saba Sohail, Jamshed Akhtar

Department of Radiology

Objective: To document the reviewers' responses in terms of reviewers' demographic and professional characteristics, promptness of reply, and duration of reply to the request to review medical research articles for a general biomedical research journal.
Study design: Cross-sectional, observational study.
Place and duration of study: Department of Publications, College of Physicians and Surgeons Pakistan (CPSP), from October to December 2015.
Methodology: Peer reviewed articles edited by a single staff editor were included. Editorials and correspondence were excluded. Manuscript category, discipline, and the total number of reviewers per manuscript were noted. Responses were divided into no response, regrets, and responded, i.e. …

Metastatic Vertebral Lesion Mimicking An Atypical Hemangioma With Negative 18f-Fdg Positron Emission Tomography-Computed Tomography, Ana Cecilia Belzarena Genovese

All Publications

Atypical hemangiomas of the spine can mimic metastatic lesions on magnetic resonance imaging, therefore making this distinction is a diagnostic challenge. In most cases, this conundrum can usually be solved with positron emission tomography/computed tomography images, because hemangiomas do not usually present with increased uptake while metastatic lesions do. Here we present a case of a patient with a unique diagnosis, myxoid liposarcoma, in which the vertebral metastatic lesion did not present with increased uptake in positron emission tomography/computed tomography scans. While keeping the imaging particularity of this rare sarcoma in mind, proceeding with a biopsy when the suspicion of …