Evaluation of Risk of Secondary Thyroid Cancer Caused by Neutron Dose Equivalent from Brain Tumor 3D-Conformal Radiation Therapy (3D-CRT)

Document Type : Original Article (s)

Authors

1 MSc Student, Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

2 Assistant Professor, Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

3 Assistant Professor, Reactor and Nuclear Safety Research School, Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, Isfahan, Iran

4 Associate Professor, Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

Abstract

Background: Thyroid cancer is one of the most common secondary malignancies as a result of receiving therapeutic doses to the head and neck. In this study, the probability of secondary thyroid cancer risk due to neutron contamination of 15 MV Siemens Linear Accelerator (LINAC) in brain tumor 3D-Conformal Radiation Therapy (3D-CRT) was calculated.Methods: Neutron fluence and neutron dose were measured at different points at the treatment table using an energy-independent neutron detector consisting of a sphere moderator and a Boron Trifluoride (BF3) counter, and the neutron dose equivalent to the thyroid was determined to calculate the probability of secondary cancer risk.Findings: The neutron dose equivalent was obtained at the central axis (0.304 mSv/Gy) and at 4 cm (0.285 mSv/Gy), 15 cm (0.229 mSv/Gy), 45 cm (0.125 mSv/Gy), and 150 cm (0.02 mSv/Gy) inferior. The neutron dose equivalent reaching the thyroid for the total prescribed dose was 12.366 mSv. According to that, the probability of secondary thyroid cancer risk was obtained as 0.001%.Conclusion: The thyroid dose in high-energy radiation therapy of brain tumor cannot cause significant biological damage. Therefore, the risk of secondary thyroid cancer due to neutron contamination is relatively low.

Keywords

References

  1. National Council on Radiation Protection and Measurements (NCRP). Neutron Contamination from Medical Electron Accelerators: Recommendations of the National Council on Radiation Protection and Measurements. Bethesda, MD: NCRP; 1984.
  2. Linton OW, Mettler FA. National conference on dose reduction in CT, with an emphasis on pediatric patients. AJR Am J Roentgenol 2003; 181(2): 321-9.
  3. McCall RC, Jenkins TM, Shore RA. Transport of accelerator produced neutrons in a concrete room. IEEE Trans Nucl Sci 1979; 26(1): 1593-602.
  4. Howell RM, Hertel NE, Wang Z, Hutchinson J, Fullerton GD. Calculation of effective dose from measurements of secondary neutron spectra and scattered photon dose from dynamic MLC IMRT for 6 MV, 15 MV, and 18 MV beam energies. Med Phys 2006; 33(2): 360-8.
  5. Pena J, Franco L, Gomez F, Iglesias A, Pardo J, Pombar M. Monte Carlo study of Siemens PRIMUS photoneutron production. Phys Med Biol 2005; 50(24): 5921-33.
  6. Mohammadi N, Miri-Hakimabad H, Rafat-Motavlli L, Akbari F, Abdollahi S. Neutron spectrometry and determination of neutron contamination around the 15 MV Siemens Primus LINAC. J Radioanal Nucl Chem 2015; 304(3): 1001-8.
  7. Kry SF, Salehpour M, Followill DS, Stovall M, Kuban DA, White RA, et al. Out-of-field photon and neutron dose equivalents from step-and-shoot intensity-modulated radiation therapy. Int J Radiat Oncol Biol Phys 2005; 62(4): 1204-16.
  8. Karimi AH, Brkic H, Shahbazi-Gahrouei D, Haghighi SB, Jabbari I. Essential considerations for accurate evaluation of photoneutron contamination in Radiotherapy. Appl Radiat Isot 2019; 145: 24-31.
  9. Rose J, Wertheim BC, Guerrero MA. Radiation treatment of patients with primary pediatric malignancies: risk of developing thyroid cancer as a secondary malignancy. Am J Surg 2012; 204(6): 881-6.
  10. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP publication 103. Ann ICRP 2007; 37(2-4): 1-332.
  11. National Council on Radiation Protection and Measurements (NCRP). Report No. 116-Limitation of Exposure to Ionizing Radiation. Bethesda, MD: NCRP; 1993.
  12. Palta JR, Hogstrom KR, Tannanonta C. Neutron leakage measurements from a medical linear accelerator. Med Phys 1984; 11(4): 498-501.
  13. Howell RM, Kry SF, Burgett E, Hertel NE, Followill DS. Secondary neutron spectra from modern Varian, Siemens, and Elekta linacs with multileaf collimators. Med Phys 2009; 36(9): 4027-38.
  14. Mao XS, Kase KR, Liu JC, Nelson WR, Kleck JH, Johnsen S. Neutron sources in the Varian Clinac 2100C/2300C medical accelerator calculated by the EGS4 code. Health Phys 1997; 72(4): 524-9.
  15. Karimi AH, Chegeni N, Jabbari I, Hassanvand M. The Effect of Neutron Contamination on Probability of Secondary Cancer in Radiotherapy of Pelvic Region with 18-MV Photons. Journal of Isfahan Medical School 2019; 37: 222-7.
Journal of Isfahan Medical School
Volume 38, Issue 586 - Serial Number 586
July and August 2020
Pages 569-574

Files

History

  • Receive Date: 19 May 2020
  • Revise Date: 01 November 2024
  • Accept Date: 06 April 2022

Share

How to cite

Statistics