APPLICATON OF NUCLEAR PHYSICS - NUCLEAR ENGINEERING
IN MEDICAL BIOLOGY
The Medical Physics Group studies the application of physics concepts, theories and methods to medicine or healthcare, especially the application of nuclear technology in diagnosis and treatment of cancer disease.
In average, 15 - 20 students enroll in the Medical Physics program each year. Besides basic knowledge of Physics and Nuclear Physics, students are equipped with specialized subjects such as human body and physiology, radiation biology, radiation physics fundamental, physics fundamental in radiotherapy, physics fundamental in imaging diagnosis, medical image processing, physics fundamental in medical physics, etc. Students are also sent to large hospitals such as Cho Ray Hospital, Oncology Hospital HCMC, 175 Military Hospital, 115 Hospital etc. for clinical practice and doing research.
The major research interests of the Medical Physics Group include three main areas: radiation safety, radiotherapy, and medical image processing.
I. RESEARCH TOPICS
1.1 Radiation safety: Until now we have focused our research on radiation safety for some medical diagnostic devices such as routine radiographs, CT, ... using Monte Carlo simulation techniques. From simulation models, we study dose rate distribution around diagnostic devices in working modes, estimate the impact of secondary scattering rays, assess radiation safety for shielding, assess the absorbed dose in patients...
Figure 1. 2D dose distribution surrounding conventional radiograph at the spine X-ray mode.
Figure 2. 2D dose distribution surrounding conventional radiograph at the chest X ray mode.
1.2 Radiotherapy:
Proton therapy: Up to now, in the world, the margin concept for both the PTV (ICRU, 1994) and the PRV (ICRU, 1999) are used to account for geometrical uncertainties in treatment planning. This method is valid only when PTV DVH and PRV DVHs are representative of CTV DVH and OAR DVHs each. In proton therapy, the average margin as in used the PTV concept and the PRV concept have limits due to the geometrical errors in the direction perpendicular to the beam are more significant than in the direction parallel with the beam, especially in intensity modulated proton therapy (Lomax, 1999; Lomax, 2008b). There have been some authors optimized the treatment plan was not using CTV-PTV margin and OAR-PRV margin. However, these methods result in the plans not having not high appearance probability in treatment because of assumption of ideal worst dose distribution such as worst plan (Pflugfelder et al., 2008) or not investigating the moving organ errors (Albin Fredriksson et al., 2011). In this work, we used DVPH concept (T B Nguyen et al., 2009) to evaluate proton therapy treatment plan. This method simulates directly the errors in the treatment process to evaluate CTV DVHs with desired confidence level. We used CERR program and LAP program ( Joseph O. Deasy et al., 2003) written by the School of Medicine of University of Washington in St. Louis to simulate CTV DVHs and OAR DVHs of prostate tumor. The results show the DVH CTVs in a meaningful way and the PTV and PRV concept are no longer valid in proton therapy. DVPH tool is the best method for evaluating the treatment plan in proton therapy and overcome the limits of traditional method using margin concept. However, calculating DVPH by recalculation method is very time-consuming. To reduce the computational time, we will find out the algorithm to calculate the dose distribution which approximates the real dose distribution as close as possible. With the reasonable calculating DVPH time, we will optimize the intensity modulated proton therapy plan with high reliability.
The results showed that the PTV concept for ensuring the prescribed dose actually delivered to the CTV is invalid in proton therapy. Even a good PTV DVH might result in an underdose to the target. For OARs, the conventional evaluation might underestimate the dose for same area and overestimate the dose for another area. The concept DVPH applied for proton therapy has been proved to provide a more accurate CTV and OAR DVH evaluation in proton therapy.
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Figure 3. 2197 CTV DVHs with geometrical uncertainties. |
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Figure 5. CTV DVPH. |
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Figure 7. PTV DVH and DVPH with 90% confidence level. |
Figure 8. Static Rectum DVH and DVPH with 90% confidence level. |
Jaw-only intensity modulated radiation therapy: In this study, we calculate and analysis the beam profiles and dose distribution of Intensity modulated radiation therapy for the linear accelerators using standard collimator jaws (JO-IMRT). The results are compared with the Prowess Panther planning system for head and neck cancer cases. Besides, we also study the distribution of edge scattering effects on the dose distribution.
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Figure 9. Siemens Primus Linear Accelerator. |
Figure 10. Jaw-Only Collimator |
1.3 Medical image processing:
Automated segmentation and registration 4DCT lung images: Registration and segmentation 4D-CT lung images: 4D-CT lung cancer treatment planning strategies requires highly accurate anatomical segmentation of tumor volumes to reduce the geometric uncertainty from respiratory motion. In this work, we study methods for automatically creating contours surround each lung and finding the geometrical relationships between respiratory phases on the 4D-CT dataset.
II. SELECTED PUBLICATIONS
1. Truong Thi Hong Loan, Tran Ai Khanh, Vo Thi Thuy Dung, Dang Nguyen Phuong, Le Thanh Xuan, Nguyen Thi Cam Thu, Nguyen Thi Truc Linh, “Study on dose rate distribution surrounding to diagnostic X ray facilities and estimate the influence of scattering effect from the shielding by MCNP5 code”, The annual meetings of Japan Radiology Society and Japan Society of Radiological Technology from April 11 to 14, 2013, JSMP, in Yokohama, Japan.
2. Trần Ái Khanh, Võ thị Thùy Dung, Trương Thị Hồng Loan, Mai Văn Nhơn, Đặng Nguyên Phương, “Mô phỏng phổ tia X và các ảnh hưởng lên phổ bằng chương trình MCNP5”, Báo cáo Hội nghị Khoa học lần thứ 8, Trường Đại học Khoa học Tự nhiên, Đại học Quốc Gia TP. Hồ Chí Minh, 2012.
3. Trương Thị Hồng Loan, Nguyễn Thị Trúc Linh, Trần Ái Khanh, Nguyễn Thị Cẩm Thu, Lê Thanh Xuân, Thái Mỹ Phê, Lỗ Thái Sơn, Ngô Thị Ánh Quy, Tăng Hồng Phước, “Tính toán an toàn che chắn cho phòng X quang chẩn đoán quy ước”, Hội nghị Khoa học và Công nghệ Hạt nhân toàn quốc lần thứ 10, tại Vũng Tàu (15-16/8/2013).
4. Trương Thị Hồng Loan, Lê Thanh Xuân, Nguyễn Thị Cẩm Thu, Trần Ái Khanh, Nguyễn Thị Trúc Linh,Thái Mỹ Phê, Lỗ Thái Sơn, “Đánh giá phân bố suất liều mặt của chùm tia X từ thiết bị X quang nha khoa bằng chương trình MCNP5”, Hội nghị Khoa học Thường niên Bệnh viện Chợ Rẫy tháng 4/2014.
5. Trần Ái Khanh, Trương Thị Hồng Loan, Mai Văn Nhơn, Đặng Nguyên Phương, “Nghiên cứu các thông số ảnh hưởng lên phổ tia X sử dụng phương pháp Monte Carlo”, Hội nghị Khoa học Thường niên Bệnh viện Chợ Rẫy tháng 4/2014.
6. Truong Thi Hong Loan, Le Thanh Xuan, Tran Ai Khanh, Nguyen Thi Cam Thu,Thai My Phe, Lo Thai Son, Nguyen Thi Truc Linh, “Study on distribution of surface dose rates from X ray tube and evaluation for radiation safety of shieldings at conventional diagnostic radiology room using MNCN5 code”, 14th Asia-Oceania Congress of Medical Physics & 12th South East Asia Congress of Medical Physics (AOCMP/SEACOMP 2014), 23‐25 October 2014, at Hotel Novotel Saigon Centre, Ho Chi Minh City, Vietnam.
7. Tran Ai Khanh, Truong Thi Hong Loan, Dang Nguyen Phuong, Le Thanh Xuan, Nguyen Thi Cam Thu, Thai My Phe, Lo Thai Son, Nguyen Thi Truc Linh, “Survey to radiation doses of X ray room in HCM city”, 14th Asia-Oceania Congress of Medical Physics & 12th South East Asia Congress of Medical Physics (AOCMP/SEACOMP 2014), 23-25 October 2014, at Hotel Novotel Saigon Centre, Ho Chi Minh City, Vietnam.
8. Trần Ái Khanh, Đặng Nguyên Phương, Trương Thị Hồng Loan, Mai Văn Nhơn, “Sử dụng tính toán song song trong MCNP5 trong mô phỏng phân bố liều tia X”, Kỹ yếu Hội nghị khoa học Trường Đại học Khoa học Tự nhiên lần 9, tháng 11/2014.
9. Trần Ái Khanh, Trương Thị Hồng Loan, Đặng Nguyên Phương, Nguyễn Thị Kim Xuyến, Nguyễn Anh Tuấn, Mai Văn Nhơn, “Khảo sát phổ phát tia X bằng phương pháp mô phỏng Monte Carlo và tính toán bán thực nghiệm”, Kỹ yếu Hội nghị Khoa học Trường Đại học Khoa học Tự nhiên lần 9, tháng 11/2014.
10. Dose Volume Population Histogram (DVPH): A New Method to Evaluate Intensity Modulated Proton Therapy Plans With Geometrical Uncertainties, T Nguyen, B Nguyen, N Mai, the 57 American Association of Physics in Medicine Meeting (accepted), 2015.
11. Comparison of Intensity Modulated Photon Therapy and Intensity Modulated Proton Therapy plans for Prostate Cancer, Nguyen Thi Cam Thu, Nguyen Thai Binh, Mai Van Nhon, Science & Technology Development Journal, VNU,Vietnam ( accepted), 2015
12. Lập kế hoạch xạ trị điều biến cường độ chùm proton bằng hệ thống lập kế hoạch CERR, Nguyễn Thị Cẩm Thu, Nguyễn Thái Bình, Mai Văn Nhơn, Hội nghị Khoa học và Công nghệ Hạt nhân toàn quốc lần thứ 10, 2013.
