Volume 31, Issue 12 (March 2021)
Studies in Medical Sciences 2021, 31(12): 934-943 |
Back to browse issues page
Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:
Olfat S, Banaee N. THE EFFECTS OF METAL IMPLANT AND METAL ARTIFACT ON THE DOSE DISTRIBUTION DURING RADIATION THERAPY OF THE PELVIC REGION. Studies in Medical Sciences 2021; 31 (12) :934-943
URL: http://umj.umsu.ac.ir/article-1-5055-en.html
URL: http://umj.umsu.ac.ir/article-1-5055-en.html
Department of Medical Radiation Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran (Corresponding Author) , nooshin_banaee@yahoo.com
Abstract: (1871 Views)
Background & Aims: In some cancer patients, there are metal implants in pelvic and femoral regions. Due to the interactions of the photon with matter and location of treating region and metal implant, such high atomic numbered elements can influence absorbed dose compared to predicted values. Also, metal implants cause metal artifacts in CT images due to their highly effective atomic number compared to body texture. The aim of this study was to evaluate the effect of metal implants and metal artifacts on the dose distribution in the treatment volume.
Materials & Methods: In this study, CT images of seven prostate cancer patients who were referred to Imam Khomeini hospital, Tehran for treatment with titanium metal implant in femur region were investigated. In these patients, initially dose distributions were calculated by Monaco treatment planning system considering the effects of metal artifacts (plan A), correcting CT images and modifying electron density of artifact regions to soft tissue (plan B), transmission of photon through metal (plan C) and modifying electron density of metal to bone (plan D). The obtained results from Monaco treatment planning system were then transferred to Verisoft software. The quantitative differences of plans A and B were analyzed using a gamma index of 3%/3mm in this software. Also, the effects of metal implant in beam attenuation (Plans C and D) were analyzed quantitatively.
Results: This study showed that the difference of calculated monitor units in corrected and not-corrected electron density of metal artifact regions ranged between 0.81-3.78 monitor units per fraction. Also the presence of metal in beam path can lead to a 3% difference compared to beam passing through bone.
Conclusion: Therefore, for the precise implementation of the treatment, necessary corrections on CT images should be considered before the treatment planning to minimize the errors related to the monitor unit calculations.
Materials & Methods: In this study, CT images of seven prostate cancer patients who were referred to Imam Khomeini hospital, Tehran for treatment with titanium metal implant in femur region were investigated. In these patients, initially dose distributions were calculated by Monaco treatment planning system considering the effects of metal artifacts (plan A), correcting CT images and modifying electron density of artifact regions to soft tissue (plan B), transmission of photon through metal (plan C) and modifying electron density of metal to bone (plan D). The obtained results from Monaco treatment planning system were then transferred to Verisoft software. The quantitative differences of plans A and B were analyzed using a gamma index of 3%/3mm in this software. Also, the effects of metal implant in beam attenuation (Plans C and D) were analyzed quantitatively.
Results: This study showed that the difference of calculated monitor units in corrected and not-corrected electron density of metal artifact regions ranged between 0.81-3.78 monitor units per fraction. Also the presence of metal in beam path can lead to a 3% difference compared to beam passing through bone.
Conclusion: Therefore, for the precise implementation of the treatment, necessary corrections on CT images should be considered before the treatment planning to minimize the errors related to the monitor unit calculations.
Type of Study: Research |
Subject:
فیزیک پزشکی
References
1. Perez CA, Brady LW. Principle and Practice of Radiation Oncology. Philadelphia: Lippincott -Raven; 2008. P. 79-119, 1269-1445. [URL]
2. Hasani M, Mohammadi K, Gholami S. Evaluation of Accuracy of TPS Algorithms in Predicting the Dose of Hip Prosthesis Using Monte Carlo Code. Razi Journal of Medical Sciences 2016; 23(147): 64-73. [Google Scholar]
3. Son SH, Kang YN, Ryu MR. The Effect of metallic implants on radiation therapy in spinal tumor patients with metallic spinal implants. Med Dosim 2012;37(1):98-107. [DOI:10.1016/j.meddos.2011.01.007] [PMID]
4. Xiaobin T, Changran G, Wei H, Diyun S, Xiaoxiao S, Da C. Dosimetry effects of metal implants in patient body during radiation therapy. Journal of Nanjing University of Aeronautics & Astronautics 2013; 45(6):819-23.
5. Clements M, Schupp N, Tattersall M, Brown A, Larson R. Monaco treatment planning system tools and optimization processes. Medical Dosimetry 2018; 43(2):106-7. [DOI:10.1016/j.meddos.2018.02.005] [PMID]
6. Graham MV. Predicting radiation response. Int J Radiat Oncol Biol Phys 1997; 39(3):561-2. [DOI:10.1016/S0360-3016(97)00353-2]
7. Kutcher GJ, Burman C. Calculation of complication probability factors for non-uniform normal tissue irradiation: the effective volume method. Int J Radiat Oncol Biol Phys 1989; 16(6):1623-30. [DOI:10.1016/0360-3016(89)90972-3]
8. Min Park J, Kim J, Park S, Hoon Oh D, Kim S. Reliability of the gamma index analysis as a verification method of volumetric modulated arc therapy plans. Radiat Oncol 2018; 13:175. [DOI:10.1186/s13014-018-1123-x] [PMID] [PMCID]
9. Yazdi M, Gingras L, Beaulieu L. An adaptive approach to metal artifact reduction in helical computed tomography for radiation therapy treatment planning: experimental and clinical studies. Int J Radiat Oncol Biol Phys 2006; 62:1224-31. [DOI:10.1016/j.ijrobp.2005.02.052] [PMID]
10. Khan FM, Gibbons JP. Khan's the physics of radiation therapy. Lippincott Williams & Wilkins; 2014. [URL]
11. Yazici G, Sari SY, Yedekci FY, Yucekul A, Birgi SD, Demirkiran G, et al. The dosimetric impact of implants on the spinal cord dose during stereotactic body radiotherapy. Radiat Oncol 2016; 25 (11):71. [DOI:10.1186/s13014-016-0649-z] [PMID] [PMCID]
12. Ziemann C, Stille M, Cremers F, Buzug TM, Rades D. Improvement of dose calculation in radiation therapy due to metal artifact correction using the augmented likelihood image reconstruction. J Appl Clin Med Phys 2018;19:227-33. [DOI:10.1002/acm2.12325] [PMID] [PMCID]
13. Akpochafor MO, Adeneye SO, Habeebu MY, Omojola AD, Aweda MA, Orotoye TA, et al. Dosimetric Effect of Metal Implant on Absorbed Dose. Eurasian Journal of Medical Investigation 2018;2(2):90-4. [DOI:10.14744/ejmi.2018.57966]
Send email to the article author
| Rights and permissions | |
 |
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. |
