Khảo sát phân bố liều hấp thụ trong trái vú sữa chiếu xạ bởi chùm điện tử 10 MeV sử dụng mô phỏng Monte Carlo

 Cao Van Chung, Tran Hoai Nam / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 01(44) (2021) 51-58 51 
 01(44) (2021) 51-58
 Investigation of dose distribution inside Lo Ren Star apple irradiated 
 by 10 MeV electron beam using Monte Carlo simulation 
 Khảo sát phân bố liều hấp thụ trong trái vú sữa chiếu xạ bởi chùm điện tử 10 MeV 
 sử dụng mô phỏng Monte Carlo 
 Cao Van Chunga,b*, Tran Hoai Namc,d** 
 Cao Văn Chunga,b*, Trần Hoài Namc,d** 
 aResearch and Development Center for Radiation Technology, Ho Chi Minh city, Viet Nam 
 aTrung tâm Nghiên cứu và Triển khai Công nghệ Bức xạ, Thành Phố Hồ Chí Minh, Việt Nam 
 bFaculty of Physics and Engineering Physics, VNUHCM-University of Science, Ho Chi Minh city, Viet Nam 
 bKhoa Vật Lý - Vật Lý Kỹ Thuật, Trường Đại học Khoa học Tự nhiên, Thành Phố Hồ Chí Minh, Việt Nam 
 cInstitute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City, Viet Nam 
 cViện Nghiên cứu Khoa học Cơ bản và Ứng dụng, Trường Đại học Duy Tân, Thành phố Hồ Chí Minh, Việt Nam 
 dFaculty of Natural Sciences, Duy Tan University, Da Nang, 550000, Vietnam 
 (Ngày nhận bài: 20/02/2021, ngày phản biện xong: 11/03/2021, ngày chấp nhận đăng: 12/03/2021) 
Tóm tắt 
Investigation of electron absorbed dose distribution inside a Lo Ren star apple irradiated by 10 Mev electron beam has 
been performed based on Monte Carlo simulation using the MCNP4c code. Dose uniformity ratio (DUR) inside the Lo 
Ren star apple has also been evaluated and optimized using additional medium density fiberboards (MDF) outside the 
carton box. The DUR inside the fruit without using the additional MDF boards was estimated of about 2.47, which is 
excessively high for fruit irradiation compared to a desirable value of less than 1.5. By optimizing the arrangement and 
thickness of the MDF boards, the DUR inside the fruit can be reduced to about 1.42. This is a desirable value for fruit 
irradiation. 
Keywords: Lo Ren star apple; dose uniformity ratio; electron beam. 
Abstract 
Nghiên cứu khảo sát phân bố liều hấp thụ trong trái vú sữa Lò Rèn chiếu xạ bằng chùm điện tử 10 Mev được thực hiện 
bằng các mô phỏng Monte Carlo sử dụng chương trình MCNP4c. Hệ số đồng đều của liều hấp thụ (DUR) trong trái vú 
sữa Lò Rèn cũng được khảo sát và tối ưu hóa thông qua việc sử dụng các tấm chắn MDF. Kết quả cho thầy hệ số DUR 
bên trong trái vú sữa không sử dụng các tấm chắn MDF là khoảng 2.47, khá lớn để áp dụng cho chiếu xạ trái cây so với 
giá trị mong muốn dưới 1.5. Thông qua việc tối ưu cách sắp xếp và kích thước của các tấm chắn MDF, hệ số DUR có 
thể giảm xuống 1.42. Đây là giá trị mong muốn trong chiếu xạ thực phẩm phục vụ xuất khẩu. 
Từ khóa: Vú sữa Lò Rèn; hệ số đồng đều liều hấp thụ; chùm điện tử. 
* Corresponding Author: Cao Van Chung; Research and Development Center for Radiation Technology, Ho Chi Minh 
city, Viet Nam; Tran Hoai Nam; Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh 
City, Viet Nam; Faculty of Natural Sciences, Duy Tan University, Da Nang, 550000, Vietnam. 
Email: *chungvinagamma@gmail.com, **tranhoainam4@dtu.edu.vn 
52 Cao Van Chung, Tran Hoai Nam / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 01(44) (2021) 51-58 
1. Introduction The present work aims at investigating the 
 Star apple, one of the agricultural specialties absorbed dose distribution inside the Lo Ren star 
of the Mekong Delta in Southern Vietnam, is apple irradiated by double-sided electron beam 
being favored in both domestic and based on Monte Carlo simulations using the 
international markets. A mature Lo Ren star MCNP4c code. Since the size of the Lo Ren star 
apple has an average mass of 200-300 g and the apple is quite small (diameter of 5-7 cm) 
diameter of about 5-7 cm. The quality of Lo compared to a desirable value of about 9.6 cm 
Ren star apples can only be preserved for 3-5 used for food products irradiated by 10 Mev 
days after harvest in ambient conditions [1] [2]. lectron beam, the dose distribution inside the fruit 
Therefore, it is a challenge to preserve the would be nonuniform, and the DUR would be 
quality of the fruits long enough after harvest excessively high. To treat the nonuniformity of 
 dose distribution, the use of wooden boards, i.e., 
for the exportation activity. Ionizing irradiation 
 medium density fiberboards (MDF), arranged 
using gamma ray, electron beam or X-ray is a 
 outside of the carton box of the fruits has been 
powerful technique to lengthen the postharvest 
 proposed. Monte Carlo simulations have been 
life of fruits by preventing the growth of living 
 conducted to optimize the arrangement and the 
organisms [3] [4] [5]. The effect of irradiation 
 thicknesses of the MDF boards in order to 
depends on the absorbed dose. For instance, 
 minimize the DUR inside the fruit. 
irradiation dose greater than 1.0 kGy can 
prevent the fungal infection. The doses in the 2. Materials and methods 
range of 1.0-10 kGy reduce microbial loads on 2.1. UERL-10-15S2 linear accelerator 
food. The doses from 10 to 25 kGy kill most of The UERL-10-15S2 linear accelerator 
fungi and bacterial pests. While doses higher supplied by Corad Service Ltd, Russia is a 
than 25 kGy sterilize medical equipment, common system used for industrial irradiation 
hospital food and pet food [5]. However, the applications of foods, fruits and medical devices, 
dose greater than 600 Gy could reduce the etc [9]. This facility was equipped at Research 
quality of the fresh fruits, e.g. sensory quality and Development Center for Radiation 
of odor, flavor, appearance and vitamin content, Technology in 2012 for generating 10 MeV 
while higher doses would cause more damage electron beam with the intensity of 1.5 mA. The 
[5] [6] [7]. According to APHIS 2016, the maximum power of the EB is 15 kW. Fig. 1 
exported fruits from Vietnam are required to be depicts the cross-sectional view of the UERL-
irradiated at a minimum absorbed dose of 400 10-15S2 linear accelerator. The system consists 
Gy using one of the three irradiation sources of double-sided EBs from upper and lower sides. 
[8]. Therefore, it is desirable to irradiate the The irradiated products are transported by a 
fruit by a minimum dose of 400 Gy, whereas conveyor system. The irradiation dose for 
the maximum dose should be lower than 600 specific purposes can be controlled by setting up 
Gy to preserve the fruit quality. This means that the operation parameters. In particular, to 
the dose distribution inside the fruit should be produce the irradiation dose of 400 Gy of each 
kept uniform, and the dose uniformity ratio beam, the system was set up at pulse beam 
(DUR), which is defined as the ratio of highest frequency of 35 Hz, scan width of 500 mm, 
to lowest doses inside the product, should be conveyor speed of 0.85 m/min and time duration 
lower than a desirable value of 1.5. for each pulse of 4 s. 
 Cao Van Chung, Tran Hoai Nam / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 01(44) (2021) 51-58 53 
1 - Accelerating structure (diaphragmatic waveguide); 9 - The conveyor dragging irradiated boxes through 
2 - Chamber of a scanning electromagnet; ribbons electron beams; 
3 - Chamber of banding and scanning electromagnet; 10 - Electron gun pulse transformer; 
4 - Electron beam canal; 11 - Electron gun; 
5 - Scanning electromagnet; 12 - Ferrite isolator (circulator); 
6 – Banding and scanning electromagnet; 13 - 16 - Ion pump; 
7 - Bending electromagnets; 17 and 18 - Magnetic induction sensors of beam current; 
8 - A box with irradiated products; 19 - Beam stops. 
 Fig. 1 Cross-sectional view of the UERL-10-15S2 electron beam facility. 
2.2. Monte Carlo simulation inside the fruits [10]. The simulations aim at 
 Monte Carlo simulations have been optimizing the arrangement of the MDF boards 
performed using the MCNP4c code to design to reduce the DURs to lower than a desirable 
the arrangement of the MDF boards to treat the value of 1.5. The parameters considered in the 
nonuniformity of the absorbed dose distribution design process include the number and 
54 Cao Van Chung, Tran Hoai Nam / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 01(44) (2021) 51-58 
thickness of the MDF boards and their distribution inside the fruit. Fig. 3 shows the 
arrangement outside the carton box. Fig. 2 absorbed dose distribution inside the Lo Ren 
displays the arrangement of the MDF boards star apple without the MDF boards. The 
selected to treat the nonuniformity of the absorbed dose distribution inside the Lo Ren 
absorbed dose distribution inside the Lo Ren star apple is relatively nonuniform with high 
star apple irradiated by double-sided electron values inside of and on the surface of the fruit. 
beam. Then, the design parameters which need The highest dose is about 1011 Gy is found at 
to be surveyed are D1, D2, D3, R1 and R2 as the surface of the fruit. This value corresponds 
shown in Fig. 2. In the MCNP4c simulations, to the DUR of about 2.48. Compared to a 
the number of particle history was chosen as desirable value of 1.5, the DUR of 2.48 is 
2.7x106 to obtain the statistic error of the considerably high for fruit irradiation. Thus, a 
calculated absorbed dose rate within 2%. treatment of dose nonuniformity is necessary in 
 the irradiation of the star apple. 
 e e e e 
 410 425 420
 443 443 527 439
 MDF boards 717 758 757 769 606
 880 993 959 955 880
 870 975 904 925 1011
 L O R E N
 S T A R A P P L E
 D1 Fig. 3 Dose distribution inside the Lo Ren star apple 
 without the use of MDF boards. 
 D2
 D3 3.2. Dose distribution inside the fruits with the 
 R1 use of MDF boards 
 R2 In order to treat the nonuniformity of 
 e e e e absorbed dose distribution inside the fruit and 
Fig. 2 Model of the Lo Ren star apple with MDF boards reduce the DUR, the use of MDF boards 
 using MCNP4c code. arranged outside the carton box as shown in 
3. Results and discussion Fig. 2 has been proposed. Table 1 summarizes 
 the design parameters of the MDF boards 
3.1. Dose distribution inside the fruit without 
 selected from seven cases in this survey. Fig. 4 
MDF boards 
 shows the absorbed dose distribution inside the 
 Monte Carlo simulation has also been fruit obtained from MCNP4c simulation 
conducted for the Lo Ren star apple irradiated corresponding to Cases 1-4 of the MDF 
by double-sided electron beam without the use arrangement. The DURs are reduced to 2.02, 
of MDF boards to investigate the absorbed dose 1.65, 2.05 and 1.96 corresponding to Cases 1-4 
 Cao Van Chung, Tran Hoai Nam / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 01(44) (2021) 51-58 55 
of the MDF boards. Fig. 5 displays the same found with Case 6 with the design parameters 
quantity as in Fig. 4 but for Case 5-7 of the presented in Table 1. The results indicate that 
MDF arrangement. It can be seen that the by using the MDF boards with the optimal 
absorbed dose distributions inside the fruits arrangement designed by Monte Carlo 
become relatively uniform with the use of MDF simulations, the nonuniformity of the absorbed 
boards compared to that without MDF boards electron dose distribution inside the fruits can 
as shown in Fig. 3. Fig. 6 depicts the be treated effectively. The DUR value of 1.42 
comparison of the DUR values obtained with for the Lo Ren is less than the desirable value 
the seven cases of MDF arrangement. It can be of 1.5. 
seen that the DUR is reduced from 2.48 to 1.42- Table 1: Summary of the design parameters 
2.05 by using the MDF boards outside the of the MDF boards. 
carton box. The lowest DUR value of 1.42 is 
 Case D1 (cm) D2 (cm) D3 (cm) R1 (cm) R2 (cm) DUR 
 1 0.4 0.8 0.8 2.3 3.8 2.02 
 2 0.8 0.8 0.8 2.3 3.8 1.65 
 3 0.8 0.8 1.2 2.3 3.8 2.05 
 4 0.8 0.8 1.2 2.3 4.2 1.96 
 5 0.8 0.8 1.2 2.3 4.6 1.79 
 6 0.8 0.6 1.6 2.3 4.6 1.42 
 7 1.0 0.8 0.8 2.3 4.6 2.03 
 459 526
 544 500 631 544 563 547 599 637
 615 586 652 609 518 510 632 634 646 595 561 649
 678 717 666 656 569 574 504 657 695 611 598 589 585 537
 746 762 729 786 642 626 790 620 613 643 584 627 622 667
 866 831 817 815 779 745 842 632 651 580 574 593 654 755 663 526
 868 877 866 909 889 874 886 788 649 604 547 623 644 702 802 831
 928 836 884 925 927 922 880 839 657 547 540 613 552 631 763 869
 a) Case 1 b) Case 2 
 574 545
 620 605 592 649 640 590 559 650
 637 654 657 622 568 521 637 651 603 644 563 533
 648 640 565 584 555 572 506 680 666 596 644 547 583 525
 703 593 603 552 546 568 604 702 583 620 608 539 596 616
 608 576 485 439 526 557 674 559 650 617 548 503 539 599 699 593
 574 516 492 384 457 568 648 650 611 537 544 429 492 647 679 697
 603 509 528 400 480 539 694 786 651 523 580 450 526 594 714 843
 c) Case 3 d) Case 4
 459 526
 544 500 631 544 563 547 599 637
 615 586 652 609 518 510 632 634 646 595 561 649
 678 717 666 656 569 574 504 657 695 611 598 589 585 537
 746 762 729 786 642 626 790 620 613 643 584 627 622 667
 866 831 817 815 779 745 842 632 651 580 574 593 654 755 663 526
 868 877 866 909 889 874 886 788 649 604 547 623 644 702 802 831
 928 836 884 925 927 922 880 839 657 547 540 613 552 631 763 869
56 Cao Van Chung, Tran Hoai Nam / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 01(44) (2021) 51-58 
 a) Case 1 b) Case 2
 574 545
 620 605 592 649 640 590 559 650
 637 654 657 622 568 521 637 651 603 644 563 533
 648 640 565 584 555 572 506 680 666 596 644 547 583 525
 703 593 603 552 546 568 604 702 583 620 608 539 596 616
 608 576 485 439 526 557 674 559 650 617 548 503 539 599 699 593
 574 516 492 384 457 568 648 650 611 537 544 429 492 647 679 697
 603 509 528 400 480 539 694 786 651 523 580 450 526 594 714 843
 c) Case 3 d) Case 4 
 Fig. 4 Absorbed electron dose inside the star apple with seven models of MDF boards. 
 537 416
 636 610 580 650 465 413 430 467
 641 640 639 623 573 512 498 493 453 448 452 407
 659 660 579 615 591 616 555 482 477 453 446 441 441 415
 739 615 612 627 553 641 633 441 470 420 423 412 425 499
 699 633 556 553 601 636 756 604 513 468 412 405 420 412 461 427
 635 582 568 473 555 671 763 718 574 473 466 427 461 459 552 546
 675 572 627 479 604 629 760 849 554 534 483 427 475 467 484 539
 e) Case 5 f) Case 6
 561
 579 551 581 662
 630 637 669 708 473 498
 608 582 641 666 644 574 517
 571 558 613 591 595 565 663
 490 446 534 570 603 591 683 515
 460 435 426 450 573 527 604 712
 471 424 383 414 510 665 664 779
 g) Case 7 
 Fig. 5 Absorbed electron dose inside the star apple with seven models of MDF boards (continued). 
 Cao Van Chung, Tran Hoai Nam / Tạp chí Khoa học và Công nghệ Đại học Duy Tân 01(44) (2021) 51-58 57 
 Fig. 6 DURs inside the Lo Ren star apple obtained from MCNP4c simulations. 
4. Conclusions Acknowledgements 
 Investigation of the absorbed dose This work was supported by International 
distribution inside the Lo Ren star apple Atomic Energy Agency under Coordinated 
irradiated by 10 MeV electron beam has been Research Project D61024 (Contract Number 
conducted based on Monte Carlo simulations. 18984). 
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