Duong Thanh Tai MP

My Research Works Overview

I started as a medical physicist at Dong Nai Hospital with a lot of challenges. Firstly, the medical physics field was very new in Vietnam at that time. Second, I was a fresh graduate who lacked experience, working with barely any training or guidance. Last one, there was very few experts and documents for references. Therefore, my motivation was to be become an expert to help newbies like me, and my research journey started from here. With available equipment in Dong Nai General Hospital, I suggested to be the first one carry out the project about validating and translating the jaws-only IMRT technique into clinical practice. Then I found there were many spaces for applications and improvements which I passionated to work on and do deeper researches as the topics for my PhD thesis.

In 2019, I had an opportunity with a new role of supporting Shing Mark Hospital in establishing a new radiotherapy department. Then I become more familiar and experienced with the system selection, installation, and commissioning an Halcyon LINAC. Until now, I still keep supporting them by introducing my medical physics students to work there as well as consulting them to develop the department.

Since 2022, I have been involving in a significant project at Western University focusing on Monte Carlo simulation for radiotheranostics

Overall, after fifteen years working and doing research at the same time, I have gained solid working knowledge in both radiation therapy and nuclear medicine. Therefore, I’m confident in approaching new research directions in medical physics.

TrueBeam™ system at Chulabhorn Hospital, Thailand

Siemens SPECT at Dong Nai General Hospital

Proton therapy at The Proton Beam Therapy Center of Hokkaido University Hospital

Introducing the first Halcyon in Vietnam.

Commissioning Eclipse Treatment planning

Practicing planning for Proton therapy

Visiting Varian True beam at Thailand

Radiotheranostics project:

Theranostics is a new treatment modality in medicine which refers to techniques that integrate diagnostic imaging and therapeutic delivery of the same biological target. Radiotheranostics is an example of theranostics, which integrates radiolabeled target imaging (primarily PET and SPECT) followed by targeted radionuclide therapy (TRT) to deliver radiation to identified targets.

Project 1: Personalized Dosimetry for Targeted Radionuclide Therapy

TRT has been approved by the US Food and Drug Administration (FDA) for neuroendocrine tumors and metastatic castration-resistant prostate cancer patients with 177Lu-DOTATATE and ¹⁷⁷Lu-PSMA-617 respectively. However, there is some limitation in current clinical practice. Presently, all patient is treated based on One-size-fits-all protocol, resulting in uniform dosing for all patients, thereby neglecting personalized dosimetry. Moreover, the prevailing dose calculation method, the MIRD scheme, relies on phantom models rather than actual human physiology, leading to potential inaccuracies. Another significant issue is that standard dose calculation requires patients to undergo multiple scans, leading to logistical challenges and added patient discomfort (Fig. 2 (a)).

To address these challenges, I propose a novel approach utilizing only diagnostic PET/CT data. This strategy eliminates the need for repeated SPECT or PET scans in each treatment cycle (Fig. 2 (b)). In this advanced method, I plan to utilize Logan graphical analysis to determine the Logan distribution volume (LDV) from diagnostic PET/CT scans. The TIA in tissues will then be calculated by multiplying this LDV with the area under the curve (AUC) of extrapolated arterial curves. Following this, the MC program that we developed will be employed to precisely calculate the absorbed dose in the prostate tumor, the overall prostate, and the bone marrow in the femurs. Additionally, I aim to convert these absorbed dose measurements to Biological Effective Dose (BED) for a more comprehensive investigation of the biological effects (Fig 3).

Research Objectives:

Developing a patient-specific dosimetry method for TRT, leveraging diagnostic PET/CT data to eliminate the need for repetitive SPECT or PET scans.
Improving the accuracy of dose calculation in TRT by replacing the conventional MIRD method by Monte Carlo simulations.
Converting absorbed dose to Biological Effective Dose (BED) to facilitate a comprehensive investigation of the radiobiological effects, enhancing the overall efficacy and safety of TRT treatments.

Figure 1. Overview of the concept of radiotheranostics

Figure 2. Comparisons of our proposed method (a) and normal method (b) to determine absorbed dose

Figure 3: Proposed workflow for patient-specific TRT dosimetry using Monte Carlo simulation

Project 2: Exploring alternative radionuclides for TRT: In-Silico Monte Carlo Simulation and pre-clinical animal models.

The effectiveness of TRT hinges on the radiation characteristics of the labeling radionuclide, particularly the radiation range and linear energy transfer (LET). A shorter range is advantageous for sparing adjacent healthy tissue, while high LET is more effective in inducing cell damage and killing tumor cells. Commonly used radionuclide Lu has a range of a few millimeters in tissue and a low LET (<0.3 keV/µm), making it less optimal compared to Ac, which has a shorter range (<80 µm) and significantly higher LET (50-220 keV/µm), making it a preferable choice for TRT. Prior research has already reported positive results in patients treated with beta and alpha TRT, which utilize prostate-specific membrane antigen (PSMA) labeled with lutetium-177 (Lu-177) and actinium-225 (Ac-225), respectively. However, the limited availability of these crucial radionuclides poses a challenge4. Terbium radioisotopes emerges as a particularly promising candidate, displaying characteristics akin to both Lu-177 and Ac-225. It includes four notable isotopes - Terbium-155 and Terbium-152, which are relevant for SPECT and PET imaging, respectively, as well as Terbium-149 and Terbium-161, suitable for alpha and beta-particle-based radionuclide therapy. My future research will focus on evaluating the safety and efficacy of these Terbium isotopes, particularly Tb-149 and Tb-161, using a combination of in-silico studies monte Carlo simulation and pre-clinical animal models. This endeavor aims to optimize TRT for better patient outcomes.

We will first utilize comprehensive TOPAS Monte Carlo codes to rigorously assess the radiation doses and DNA damage caused by current radioisotopes 177Lu and 225Ac, and then compare these with the effects of 161Tb and 149Tb. This comparison will be executed for both single-cell and cluster-cell models to provide a detailed understanding of their impacts at varying biological scales. We aim to compile and analyze the data gathered in this phase to clearly illustrate the superior therapeutic efficacy of 161Tb and 149Tb over the currently used 177Lu and 225Ac. This data will be crucial in demonstrating the ability of these isotopes in enhancing the effectiveness of targeted radionuclide therapy. We then intend to conduct pre-clinical animal studies using mice models that bear human epidermal growth factor receptor type 2 (HER2) tumors. This choice of model will allow for a realistic and relevant estimation of the absorbed doses delivered to various organs and tissues, a critical factor in assessing the suitability and safety of these novel radioisotopes for therapeutic use. Through these studies, we aim to gain insightful data on the distribution and localization of the radiation dose, further supporting the conclusions drawn from the Monte Carlo simulations. This approach ensures a comprehensive evaluation of 161Tb and 149Tb, paving the way for their application in advanced cancer treatments.

Research Objectives:

Assessing the efficacy and safety of alternative radionuclides, particularly Terbium-149 (Tb-149) and Terbium-161 (Tb-161), for use in TRT.

2. Establishing a solid foundation of pre-clinical data into clinical trials, thereby optimizing TRT for more effective patient outcomes.

Project 3: Combining Targeted Radionuclide Therapy (TRT) with External Beam Radiotherapy (EBRT) for Prostate Cancer: A Dosimetric and Radiobiological Study

Prostate cancer is a common type of cancer among men, and various treatment options are available, including surgery, radiotherapy, and chemotherapy. External beam radiotherapy (EBRT) is one of the standard treatment options for these patients with various fractionation options. Brachytherapy (BT), which is using either low-dose-rate (LDR-BT) permanent seed implantation or high-dose-rate (HDR-BT) temporary source implantation, is an acceptable treatment option for many patients. BT can be either as monotherapy or in combination with EBRT.

In recent years, the targeted radionuclide therapy (TRT) has emerged as a promising strategy for cancer treatment. TRT involves the use of radiotracers to kill the cancer cells. These radiotracers typically consist of two main components: a targeted agent and a radioactive substance (radionuclide). EBRT, on the other hand, delivers high-energy radiation beams to the cancerous cells from a machine outside the body. While both TRT and EBRT have been shown to be effective in treating prostate cancer, there is still a debate on the optimal treatment strategy. Ongoing clinical trials will determine the most effective dosing methods and identify patient groups that may benefit from this combining treatment approach. Several studies have shown that combining EBRT and TRT can lead to improved therapeutic results.

The recommended dose for TRT is 7.4 GBq every 6 weeks for up to 6 doses or until disease progression or toxicity occurs. It is surprising that there has been little research into their combined use both TRT and EBRT on the same clinical data due to the complexity of the dosimetry resulting from the combination of treatments with distinct radiobiological effects.

This study aims to investigate variations in tumor and normal tissue doses when comparing the efficacy of EBRT/Boost versus EBRT/TRT. By investigating these differences, we hope to gain insights into the potential of TRT as a substitute for the proven focal boost technique in EBRT, thereby contributing to the evolving landscape of prostate cancer treatment.

Research Objectives:

1. Exploring the combined impact of TRT and EBRT on prostate cancer, particularly in terms of dosimetric variations between tumor and normal tissues.

2. Developing a comprehensive procedural framework and flowchart for the combination of TRT with EBRT in treating prostate cancer.

Figure 1. Dose calculation workflow for the EBRT/Boost and EBRT plus TRT treatment plan

Poster and Pitch

Deep learning and Radiomic project

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