Radiation Medicine Commons^™

Quality Control Of Clinical Protocols Of Ct Using The Accreditation Phantom, Walaiporn Suksancharoen, Apawadee Chakrapong, Sakultala Ruenjit, Anchali Krisanachinda

Chulalongkorn Medical Journal

Background: The daily quality control of the Computed Tomography system consists of the measurement of the accuracy of CT Number and the artifact evaluation. The annual quality control includes the clinical protocol review. The CT radiologist is responsible for ensuring that all Quality Assurance (QA) requirements are met. The clinical team reviews and manages the CT protocol to deliver the appropriate radiation dose to the patient for each examination.

Objectives: To verify CT Number Accuracy, to review clinical protocols and to verify that the low-contrast performance of clinical protocols is adequate for diagnosis.

Methods: American College of Radiology (ACR) CT …

Mri-Based Radiomics Model From Mesorectal Fat To Predict Perirectal Lymph Node Status And Extramural Venous Invasion In Colorectal Cancer Patients, Yaniga Swaengdee

Chulalongkorn University Theses and Dissertations (Chula ETD)

Colorectal cancer (CRC) is the third most common cancer worldwide and the incidence rate is rising in Asia. Perirectal lymph node metastasis (PLN) and extramural venous invasion (EMVI) are common and associated with poor prognosis in CRC patients. While total mesorectal excision is the gold standard for confirming PLN and EMVI, MRI is keys modality for staging. Radiomics, a technique that extracts quantitative features from medical images, allows for the development of predictive models for PLN and EMVI. This study aimed to build and evaluate a predictive model based on mesorectal fat radiomics from MRI images to improve PLN and …

Varian Halcyon Cone Beam Computed Tomography Dose Measurement By Radiophotoluminescent Glass Dosimeter, Kantida Jittrakool

Chulalongkorn University Theses and Dissertations (Chula ETD)

Cone beam computed tomography (CBCT) is widely used as the primary imaging method in image-guided radiation therapy. The Varian Halcyon system (Varian Medical Systems, Palo Alto, CA, USA) requires daily imaging prior to each patient’s treatment. This study focuses on comparing the radiation doses to normal organs across all available kV-CBCT protocols on the Varian Halcyon system. Radiophotoluminescent glass dosimeters (RPLGD) were used to measure doses, placed inside an Alderson Rando phantom positioned at specific anatomical sites including the head, thorax, breast, and pelvis. CBCT scans were performed using preset protocols, with no modifications to parameters. The average organ dose …

Dosimetric Comparison Between Volumetric Modulated Arc Therapy On Truebeam And Halcyon Of Boost Plan For Total Body Irradiation, Wanwanut Jaihow

Chulalongkorn University Theses and Dissertations (Chula ETD)

Total Body Irradiation (TBI) is a special treatment technique aimed at immunosuppression. The purpose of this study was to compare the dosimetric results of volumetric modulated arc therapy (VMAT) plans of TBI treatment between TrueBeam and Halcyon treatment machines. Eight TBI patients were planned by 6 MV of two lateral opposing with extended SAD technique to 5 meters to receive the prescribed dose of 1200 cGy in 6 fractions at head and legs. A single fraction boosts up the dose ranging from shoulder to mid-thigh. Plans were optimized and calculated in the Eclipse treatment planning system using VMAT by TrueBeam …

Local Diagnostic Reference Level At Nuclear Medicine Centers In Thailand And Myanmar, Yin Moe Aye

Chulalongkorn University Theses and Dissertations (Chula ETD)

Diagnostic reference level (DRL) has been an effective and practical tool in the optimization of radiation protection in medical exposure to patients. Local DRL represents the median value, or 50th percentile, of the quantity distribution of common nuclear medicine examinations. This study aims to establish LDRL at NM centers in Thailand and Myanmar. Methods: The demographic data of adult patients with body weight 45-75kg, radiation metric parameters including radiopharmaceutical administered activity (MBq), Volumetric CT dose index (CTDIvol, mGy), dose length product (DLP, mGy. cm), and scan length (cm), of SPECT, SPECT/CT, and PET/CT imaging were retrospectively collected from January 2023 …

Evaluating Dosimetric Accuracy Of Aaa And Axb Algorithms In Lung Stereotactic Body Radiation Therapy, May Thu Htet

Chulalongkorn University Theses and Dissertations (Chula ETD)

The accuracy of dose calculation in heterogeneous media is heavily influenced by the choice of dose calculation algorithm. This study aimed to compare the dosimetric performance of the Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) in stereotactic body radiotherapy (SBRT) for lung cancer. Twenty-four lung cancer patients were divided into two groups: free breathing (FB) and deep inspiration breath hold (DIBH). For each patient, three half-arc volumetric modulated arc therapy (VMAT) plans were generated using 6 MV flattening filter-free (FFF) beams, prescribing 50 Gy in five fractions to the planning target volume (PTV), using the Eclipse Treatment Planning System. …

Tumor Prognosis In Nasopharyngeal Carcinoma Using Deep Transfer Learning With Radimagenet From Ct Images, Parida Petiraksakul

Chulalongkorn University Theses and Dissertations (Chula ETD)

Nasopharyngeal carcinoma (NPC) is a common malignant tumor in Southeast Asia. It is characterized by complex anatomical features and aggressive behavior. Accurate prognosis prediction plays a crucial role in the optimization of treatment strategies and improvement of patient outcomes. Although recent advances in deep learning, particularly convolutional neural networks (CNNs), have demonstrated promising results in medical image analysis, the limited availability of annotated medical imaging datasets remains a significant challenge. Transfer learning (TL), particularly using domain-specific pretrained datasets, such as RadImageNet, offers a practical solution to this limitation. This study aimed to evaluate the effectiveness of deep transfer learning models …

Prediction The Dose Distributions Of Prostate Cancer Patients Using Deep Learning, Pumipat Chaikamthorn

Chulalongkorn University Theses and Dissertations (Chula ETD)

Volumetric Modulated Arc Therapy (VMAT) is one of the advanced modalities in recent radiotherapy. It uses the inverse treatment planning system for optimization and dose calculation. However, this approach is a trial-and-error process, which takes a long time. An accurate deep-learning model that can predict the dose would solve this issue. This approach can save more treatment planning time, by guiding the planners to the optimum dose while maintaining the plan quality. The 40 previously treated prostate cancer plans were collected the volumetric information of PTV and OARs, overlapping volume, and the dosimetric information. The regression deep learning model, which …

Optimal Dual-Time-Point Dynamic 68ga-Psma-11 Pet/Ct Protocols For Parametric Imaging Generation In Prostate Cancer Patients, Paphawarin Burasothikul

Chulalongkorn University Theses and Dissertations (Chula ETD)

Globally, prostate cancer is the second most common cancer for men. Prostate cancer patients presenting metastasis exhibit a poor prognosis, consequently leading to diminished survival rates. Thus, 68Ga-PSMA-11 PET/CT examination plays a critical role in prostate cancer diagnosis. Parametric imaging techniques offer the potential to improve the accuracy of quantification analysis in PET/CT diagnosis, but their effectiveness is constrained by lengthy acquisition protocols. This study developed optimal dual-time-point (DTP) parametric imaging using shortened dynamic 68Ga-PSMA-11 PET/CT scans in prostate cancer patients and investigated the feasibility of parametric images in terms of image quality by comparing them with a routine standardized …

Breast Cancer Characterization Using Artificial Intelligence In Screening And Diagnostic Mammogram Of Thai Women, Jaroonroj Wongnil

Chulalongkorn University Theses and Dissertations (Chula ETD)

Breast cancer is a significant health issue in Thailand, necessitating accurate detection and characterization for effective treatment. This thesis focuses on leveraging artificial intelligence techniques to develop breast cancer screening and diagnosis using mammography images of Thai women. Furthermore, detecting and classifying mammography calcifications, crucial indicators of malignant or benign conditions had also been focused using RCNN and YOLOv4 in this study. AlexNet CNN was developed to increase the robustness of the RCNN model. AlexNet was tested with three different datasets, each consisting of 4,000 cropped ROI images. These datasets were divided into an 80% training set and a 20% …

Determination Of Kinetic Parameters For Bone Turnover In Chronic Kidney Disease With Hemodialysis Patients Using Dynamics 18f-Naf Pet/Ct Imaging, Viyada Sanoesan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Bone turnover measurement using 18F-NaF PET/CT serves as a valuable imaging biomarker for studying bone metabolism at various sites of skeleton. This study aimed to determine the kinetic parameters (Ki–Patlak) for bone turnover prediction as a non-invasive biomarker from dynamic 18F-NaF PET/CT in chronic kidney disease (CKD) patients with hemodialysis. Moreover, we aimed to investigate whether Ki–Patlak derived from shortened scan time can provide a prediction equivalent to that obtained from routine dynamic scan. Twenty-seven Thai CKD patients on hemodialysis (48 scans) from December 2021 to December 2023 were recruited. After intravenous injection of 18F-NaF of 133±39.3 MBq, dynamic PET/CT …

Characteristics Of Two-Dimensional Ionization Chamber Array For Patient-Specific Quality Assurance In Pencil Beam Scanning Proton Therapy, Nuttida Rawiwan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Proton therapy is an advanced technique that uses positive particles in external treatment. It can spare normal tissue and increase tumor control probability. In radiotherapy, patient-specific quality assurance is an important part, but according to protons’ characteristics, especially finite range, it is challenging to do verification because when the density has changed the finite range will have drastic changes. Although the two-dimensional ionization chamber array is used for patient-specific quality assurance in pencil beam scanning proton therapy, most studies investigate the IBA MatriXX as the dosimetry device, and few studies explored the PTW OCTAVIUS 1500XDR. This research aims to determine …

Determination Of The Surface Dose Correction Factors For Various Detectors In Proton Scanning Therapy, Pakjira Saruang

Chulalongkorn University Theses and Dissertations (Chula ETD)

Proton therapy delivers tumors doses precisely but concerns about skin toxicity due to energy dispersion beyond the Bragg peak remain. Accurate surface dose measurement is crucial for calculating the radiation dose patients receive. Studying factors that improve measurement accuracy is essential, as current methods are challenging and often inaccurate. This research aims to determine the surface dose correction factors (Scf) for various detectors in spot scanning beam proton therapy and study the effect of surface dose according to various clinical factors. The PTW Advanced Markus, PTW Roos chamber and IBA FC65-G Farmer chamber were utilized to measure the surface dose …

Dosimetric Comparison Of Imrt, Co-Planar Vmat, Non-Coplanar Vmat And Hyperarc For Multiple Brain Metastases Srs, Aksarapak Thawornnittayakul

Chulalongkorn University Theses and Dissertations (Chula ETD)

Multiple brain metastases patients are typically treated by stereotactic radiosurgery (SRS) or whole brain radiation therapy (WBRT). In addition, there are advanced techniques for treating multiple brain metastases such as 3-dimensional Conformal Radiation Therapy (3D-CRT), Intensity Modulated Radiation Therapy (IMRT), and Volumetric Modulated Arc Therapy (VMAT). A new isocentric VMAT technique called HyperArc was developed for non-coplanar, it is an automated setting for couch angle and collimator angle. This study aims to compare the dosimetric effect for a single isocenter among Intensity Modulated Radiation Therapy, Volumetric Modulated Arc Therapy, and HyperArc for multiple brain metastases stereotactic radiosurgery. For 25 patients …

Accuracy Of 177lu Quantification For Dosimetry Calculation Using 12-Swiveling Czt Detectors Spect/Ct Camera, Panattha Damthongsen

Chulalongkorn University Theses and Dissertations (Chula ETD)

Recently, the 12-cadmium zinc telluride (CZT) based digital detectors SPECT/CT system has been introduced for advanced technology in nuclear medicine instrument, which outperforms conventional cameras. Moreover, the voxel S value-based dosimetry is important and offers more accurate in personalized dosimetry treatment using targeted radionuclide therapy. This study aimed to determine the accuracy of 177Lu quantification through an IEC/NEMA phantom study and to evaluate total-body dosimetry in patients undergoing 177Lu therapy using 12-swiveling digital CZT detectors SPECT/CT camera. The NEMA/IEC body phantom inserted with six fillable spheres (10-, 13-, 17-, 22-, 28-, and 37-mm inner diameter), filled with 177Lu solution of …

Impact Of Contrast Agent Administration On Water Equivalent Diameter For Ssde Calculation In Chest Ct Angiography Examination, Nuttanit Kaewsan

Chulalongkorn University Theses and Dissertations (Chula ETD)

This study aimed to determine the impact of intravenous contrast enhancement on the calculation of water equivalent diameter (Dw) for size-specific dose estimate (SSDE) in chest CT angiography (CTA) using different calculation methods in non-contrast and arterial phase images. A cohort of 231 adult patients who underwent chest CT angiography at King Chulalongkorn Memorial Hospital (KCMH) were included. The 3D Slicer image computing software was used to automatically draw the ROI in each axial CT image to measure area and mean CT number. The Dw values were calculated following the American Association of Physicists in Medicine (AAPM) Report No.220 utilizing …

Dose Evaluation Of A Deep Learning-Based Synthetic Ct Generation In Head And Neck Cancer For Photon And Proton Therapy, Ailada Kuibumrung

Chulalongkorn University Theses and Dissertations (Chula ETD)

MRI has been increasingly implemented for the treatment planning process and the MRI-only workflow in both photon and proton therapy. This study aims to investigate and explore the accuracy of dose calculations in head and neck region based on synthetic CT (sCT) images, using the commercial software methods for both volumetric modulated arc therapy (VMAT) and intensity modulated proton therapy (IMPT) plans. The sCT images were generated from MRI images for five head and neck cancer cases that underwent VMAT and IMPT by MRI Planner commercial software. The mean absolute error (MAE) and mean error (ME) within the body, bone …

Comparison Of Modified Formalism Output And Trs-398 Absorbed Dose To Water In Electron Beams Reference Dosimetry In Multiple Radiotherapy Centers, Yasumon Thinka

Chulalongkorn University Theses and Dissertations (Chula ETD)

The study aimed to investigate the feasibility and efficacy of utilizing modified calibration with cylindrical chambers for reference dosimetry in electron beam radiotherapy, challenging the recommendation of using plane-parallel chambers in low-energy electron beams by IAEA's TRS-398 and AAPM's TG-51 standards. Data collection involved six radiotherapy centers in Bangkok using Varian linear accelerators, with chambers including the IBA FC65-G, PTW 30013 cylindrical chambers, and PPC40, Roos plane-parallel chambers. Results of dose comparison between modified and TRS-398 protocols fell within ±2%. For low-energy electron beams, percent dose discrepancies ranged from -1.57% to 0.91%, and from -0.37% to 0.91% for high-energy. The …

Evaluation Of Patient Radiation Dose And Risk Of Cancer From Ct Examinations, Saowapark Poosiri

Chulalongkorn University Theses and Dissertations (Chula ETD)

Computed Tomography (CT) examinations have been increasingly requested and become the major sources of patient exposure. The cancer risk from CT scans is contingent upon the amount of organ absorbed dose. This study aims to evaluate the cumulative effective doses (CED) and risk of cancer incidence and mortality from recurrent CT examinations in a single day. The patient data at aged 15 to 75 years old performed CT examinations during the period of five years from January 2018 to December 2022 were collected from two academic centers. The CED and organ doses were evaluated using Radimetrics™ Enterprise Platform from Monte …

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 …

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, …

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 …

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 …

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 …

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. …

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 …

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 …

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 …

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 …