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Full-Text Articles in Medicine and Health Sciences
Effect Of Inter-Observer Delineation Variability On Radiomics Features In Nasopharyngeal Cancer, Pongpitch Panyura
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
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 Of Small-Field High Energy Photon Using Plastic Scintillation Detector In Heterogenous Media Compared With Model-Based Algorithm Calculation, Thanat Kaewsuksri
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 …
Development Of End-To-End Test Phantom For Stereotactic Radiosurgery Using Alanine Dosimeter, Aungsumalin Intang
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 …
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
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. …
Accuracy In Classification Of Liver Lesion Ultrasound Using Artificial Intelligence, Sutthirak Tangruangkiat
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 …
In Vivo Dosimetry Of 3d Gynecological Brachytherapy Using The Glass Dosimeter: A Phantom Study, Itsaraporn Konlak
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 …
Hepatic Lesion Detectability On Dual Energy Computed Tomography Imaging : Phantom Study, Hataipat Jantawong
Hepatic Lesion Detectability On Dual Energy Computed Tomography Imaging : Phantom Study, Hataipat Jantawong
Chulalongkorn University Theses and Dissertations (Chula ETD)
The purpose of this study is to determine the hepatic lesion detectability in abdomen from various phantom sizes by dual-energy computed tomography (DECT) imaging and to investigate the factors affecting the detectability of hepatic lesion in abdomen by dual-energy CT in phantom study. The anthropomorphic liver with nodule inserted phantom with extension rings simulating the small, medium, and large patients were scanned under DECT acquisitions by varying three kVp combinations (80/-,90/-, and 100/Sn150-kVp). The series of 40-,50-,60-, and 70-keV VMI were generated from DECT data set. All images were used to assess the task-based image quality; task transfer function (TTF), …
Evaluation Of Integral Depth-Dose Curves In Proton Pencil Beam Scanning Using Plane-Parallel Ionization Chambers, Phatthraporn Thasasi
Evaluation Of Integral Depth-Dose Curves In Proton Pencil Beam Scanning Using Plane-Parallel Ionization Chambers, Phatthraporn Thasasi
Chulalongkorn University Theses and Dissertations (Chula ETD)
Proton therapy is an advanced form of radiation therapy treatment that can potentially decrease side effects and increase tumor control probability. The integral depth-dose curve is an essential parameter that has to be determined and introduced into the proton treatment planning system for the dose calculation. Besides the halo, the integral depth-dose curve measurements should be performed with a large-diameter plane-parallel ionization chamber. The purpose of this research is to determine the integral depth-dose curves and assess the geometrical collection efficiency at intermediate depths of different detector diameters in proton pencil beam scanning. The integral depth-dose curves with a proton …
Moderated Neutron Detector For Accumulated Ambient Dose Equivalent In Proton Therapy, Tanawat Tawonwong
Moderated Neutron Detector For Accumulated Ambient Dose Equivalent In Proton Therapy, Tanawat Tawonwong
Chulalongkorn University Theses and Dissertations (Chula ETD)
The Varian ProBeam compact was installed at Her Royal Highness Princess Maha Chakri Sirindhorn Proton Center. Since 2017, the project has started at the King Chulalongkorn Memorial Hospital and after 4 years, during Covid19 pandemic, the 1st patient treatment received proton therapy on August, 2021. The radiation safety of the center was accomplished through firstly, the shielding calculation and secondary, the radiation survey at the milestone points such as cyclotron installation and 1st Beam ON at the treatment room. The only one WENDI-II dosimeter was used in radiation survey. The main purpose of this study is to validate the in-house …
Baselines Of Daily Quality Assurance For Proton Pencil Beam Scanning Using The Sphinx Compact, Tanapat Tiajaroen
Baselines Of Daily Quality Assurance For Proton Pencil Beam Scanning Using The Sphinx Compact, Tanapat Tiajaroen
Chulalongkorn University Theses and Dissertations (Chula ETD)
Quality assurance (QA) is a systematic process used to determine whether the product meets specified requirements. The American Association of Physicists in Medicine (AAPM) published a comprehensive proton therapy machine QA in TG-224 to provide confidence in use. King Chulalongkorn Memorial Hospital (KCMH) recently operated the first proton therapy center in Thailand, and the data of daily QA are not available or established. This study aims to apply the control chart for establishing the baselines of daily QA for the proton pencil beam scanning system using the Sphinx Compact detector. The Sphinx Compact was used to perform the proton daily …
Dosimetric Comparison Of Rapidplan And Manually Optimized Plans For Hippocampus Avoidance Whole Brain Radiation Therapy, Laksamon Phimolasawakun
Dosimetric Comparison Of Rapidplan And Manually Optimized Plans For Hippocampus Avoidance Whole Brain Radiation Therapy, Laksamon Phimolasawakun
Chulalongkorn University Theses and Dissertations (Chula ETD)
Nowadays, whole-brain radiation therapy (WBRT) is a good method to cure brain metastases. However, it has been noted that whole-brain radiation therapy could be a cause to neurological toxicity which could damage the hippocampus that is an important part of forming long-term memories. The HA-WBRT is a complicated plan depending on planner skills, the researcher would like to simplify this problem using knowledge-based planning called RapidPlan. The objective of this study was to compare the dosimetric difference of RapidPlan and manually optimized plans for the treatment of HA-WBRT. The RapidPlan model was created for HA-WBRT. The PTV and OARs constraints …
Determination Of Field Output Correction Factors In Elongated Small Field Photon Beams, Mananchaya Vimolnoch
Determination Of Field Output Correction Factors In Elongated Small Field Photon Beams, Mananchaya Vimolnoch
Chulalongkorn University Theses and Dissertations (Chula ETD)
IAEA along with AAPM have published a code of practice TRS 483 for small field dosimetry. The field correction output factors of various detectors were introduced to correct detector response changes in relative dosimetry. However, the publication of TRS 483 has focused on symmetry field sizes, the correction factors for elongated small fields are not included in the protocol. The overall objective of this work is to determine the field output correction factor in elongated small field. The correction factors of IBA CC01, Sun nuclear EDGE, and Exradin W2 PSD for 6 MV photon beam were determined using Monte Carlo …
Dosimetric Impact Of Interplay Effects Instereotactic Body Radiation Therapy (Sbrt) Lung Cancer, Vanida Poolnapol
Dosimetric Impact Of Interplay Effects Instereotactic Body Radiation Therapy (Sbrt) Lung Cancer, Vanida Poolnapol
Chulalongkorn University Theses and Dissertations (Chula ETD)
Lung cancer patient breathing induced interplay effects in the volumetric modulated arc therapy (VMAT) together with stereotactic body radiation therapy (SBRT), which lead to non-uniform doses within the target volume and unwanted dose to the surrounding tissues. The purpose of this study was to investigate the dosimetric impact of interplay effects in 6 MV FFF of photon beams for lung cancer and to calculate the novel interplay effects factor (IEF) for VMAT-SBRT lung cancer. This study performed the static and dynamic measurements using two dimensions (2D) robotic platform and diode array for 3D-conformal radiation therapy (3D-CRT) plans, while using three …
The Labeling Of 99mtc-Psma-Hbed-Cc For Prostate Cancer Imaging, Benchamat Phromphao
The Labeling Of 99mtc-Psma-Hbed-Cc For Prostate Cancer Imaging, Benchamat Phromphao
Chulalongkorn University Theses and Dissertations (Chula ETD)
Prostate cancer (PCa) is the second most common cancer and the fifth leading cause of death worldwide in 2018 (1). Initially, PCa diagnosis is based on Prostate Specific Antigen (PSA) blood test, which is low sensitivity and low specificity, and sonography guided needle biopsy, which is invasive. Therefore, molecular imaging recently enrolls as an important technique in PCa diagnosis using some small molecules which are well developed to bind to overexpressed Prostate Specific Membrane Antigen (PSMA). The small molecules, for example PSMA-HBED-CC, PSMA I&T, can be chelated with Ga-68 for diagnostic purpose using positron emission tomography (PET) scan. Even though …
The Study Of Local Diagnostic Reference Levels At Unit Of Vascular And Interventional Radiology, King Chulalongkorn Memorial Hospital, Kornkamol Prajamchuea
The Study Of Local Diagnostic Reference Levels At Unit Of Vascular And Interventional Radiology, King Chulalongkorn Memorial Hospital, Kornkamol Prajamchuea
Chulalongkorn University Theses and Dissertations (Chula ETD)
Interventional Radiology (IR) procedures are minimally invasive surgery using angiographic equipment which the patients and staffs may receive high radiation dose. DRLs, based on 75th percentile of the median dose for a sample of standard sized of patients, are an effective tool for optimization of protection in the medical exposure of patients for diagnostic and interventional procedures (ICRP Publication 135, 2017). The objective of this study is to establish the local DRLs distribution of patient radiation dose and related parameters in interventional radiology procedures in standard-sized of Thai patients. Local DRLs of radiation dose and related parameters of patients (45-75kg …
Evaluation Of Patient Doses From 177lu-Psma In Metastases Prostate Cancer Treatment At King Chulalongkorn Memorial Hospital, Kotchakorn Chatachot
Evaluation Of Patient Doses From 177lu-Psma In Metastases Prostate Cancer Treatment At King Chulalongkorn Memorial Hospital, Kotchakorn Chatachot
Chulalongkorn University Theses and Dissertations (Chula ETD)
177Lu-PSMA I&T has increasingly used for targeted radionuclide therapy of metastatic castration-resistant prostate cancer (mCRPC). Dosimetric calculation, therefore, is critical to achieve the optimal therapeutic activity while sparing side effects to the normal tissues. The purpose of this study was to determine the radiation dosimetry for metastases prostate cancer patients treated by 177Lu-PSMA I&T at King Chulalongkorn Memorial Hospital (KCMH). Whole-body planar images were acquired in eight patients (12 treatment cycles) at immediately, 4 and 24 h after 177Lu-PSMA I&T injection (range 4.36 to 8.58 GBq). Region of interests (ROIs) were manually contoured on the whole-body, liver, spleen, urinary bladder, …
Development And Dosimetric Verification Of 3d Customized Bolus In Radiotherapy, Nichakan Chatchumnan
Development And Dosimetric Verification Of 3d Customized Bolus In Radiotherapy, Nichakan Chatchumnan
Chulalongkorn University Theses and Dissertations (Chula ETD)
Bolus is a tissue equivalent material that is commonly used to reduce the skin-sparing effect in radiotherapy. The commercial flat bolus cannot form perfect contact with the irregular surface of the patient's skin, resulting in an air gap, especially in irregular surface shape. The purpose of this study was to evaluate the feasibility of two types of silicone rubber bolus, RA-00AB, and RA-05AB that were made as to the fabricated flat and 3D customized bolus using 3D printing technology. The 1 cm thick boluses were made from two types of silicone rubber solutions. The point dose and planar dose differences …
Surface And Build-Up Region Dose Measurement In Head And Neck Region Using Radio - Photoluminescent Glass Dosimeter, Sonam Choki
Surface And Build-Up Region Dose Measurement In Head And Neck Region Using Radio - Photoluminescent Glass Dosimeter, Sonam Choki
Chulalongkorn University Theses and Dissertations (Chula ETD)
The use of commercially available radio-photoluminescent glass dosimeter (RPLGD) for radiation measurement has increased in recent years. It has been shown to have superior dosimetric characteristics as compared to other dosimeters. The purpose of this research is to evaluate the suitability of the GD-302M glass dosimeter for surface and build-up region dose measurement in head and neck region. The glass dosimeter was analyzed for its dosimetric properties in photon beam. Then, the study was performed for surface and build-up region dose comparison between EBT3 film and RPLGD in solid water phantom at 0, 2, 3, 5, 10 and 15mm depths …
Determination Of Field Output Correction Factors Of Radiophoto Luminescent Glass Dosimeter In 6 Mv Small Photon Beams, Sumalee Yabsantia
Determination Of Field Output Correction Factors Of Radiophoto Luminescent Glass Dosimeter In 6 Mv Small Photon Beams, Sumalee Yabsantia
Chulalongkorn University Theses and Dissertations (Chula ETD)
The objective of this study was to determine the field output correction factors of radiophotoluminescent glass dosimeter (RPLGD) for 6 MV photon beams by using Monte Carlo (MC) simulation. The ratios of absorbed dose of water and RPLGD were calculated using egs_chamber code for 6 MV, 90-cm SSD, 10-cm depth, and field size range from 0.5 × 0.5 to 10 × 10 cm2. Then the field output correction factors of RPLGD in perpendicular and parallel orientations were determined. Also, the volume averaging correction factors were discovered for supporting our results. Moreover, the comparison of measurement field output factors of RPLGD …
Patient-Specific Organ Dose Calculated By Dose Tracking Software Based On Monte Carlo Simulation In Pediatric Abdominal Ct, Yuparak Innan
Patient-Specific Organ Dose Calculated By Dose Tracking Software Based On Monte Carlo Simulation In Pediatric Abdominal Ct, Yuparak Innan
Chulalongkorn University Theses and Dissertations (Chula ETD)
This study aimed to determine the patient-specific organ doses using Radimetrics dose tracking software in pediatric abdominal CT at Praram9 Hospital. The organ doses were measured using the anthropomorphic Rando phantom inserted with radiophotoluminescent glass dosimeters (RPLGDs) to verify the organ doses calculated by Radimetrics program. The retrospective data were collected from pediatric abdominal CT 164 studies (78 patients), age range 0-15 years-old), who underwent single phase abdominal CT at Praram9 Hospital. The tube voltages ranged between 80 and 135 kVp were adjusted according to the size and age of patients, and rotation time 0.35-0.5 sec. All patients were acquired …
Dosimetric Comparison Between Single And Double Isocenters Volumetric Arc Therapy For Stereotactic Radiotherapy With Multiple Targets, Wai Lwin Lwin Kyaw
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 Feasibility Study Of Diffusion Weighted Imaging And Parametric Response Map Analysis For Treatment Response Prediction In Nasopharyngeal Cancer, Titiya Jirawatwanith
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 …