Experimental and Monte Carlo evaluation of effects of temporary tissue expanders (TTE) on radiotherapy dose distribution

Aim: The purpose of this study was to model the metallic port which included samarium cobalt magnet in breast tissue expandersand to improve the accuracy of dose calculations with nanoDot optically stimulated luminescence dosimeter (nanoDot OSLD)measurements.Material and Methods: Mentor TTE (Temporary Tissue expander) (at a depth of 3 cm) was modeled by DOSXYZnrc Monte Carlo codeand the nanoDot OSLD were used for dose measurements in solid water phantoms.Results: In present study, dose increases in tissue at 3 cm due to the backscatter of electrons was 16.3% for metallic port at 6 MVusing the Monte Carlo method. It was observed 12 % in the experimental results. Additionally, while the decrease in dose behind theport was 17.4 % by Monte Carlo program code, it was observed 25.8 % in the experimental resultsConclusions: In present study, the low dose region remains in saline solution within the tissue expander. It can be negligible clinically.In a clinical setting, the breast patients are treated with tangent beam fields. It was thought that unless the frontal direct field wasnot used in clinics for these patients, the dose reduction and dose increase would not do not play a role in influencing the treatment.

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1. Tao Z, Shi A, Lu C, et al. Breast Cancer: Epidemiology and Etiology. Cell Biochem Biophys 2015;72:333-8.
2. Bellini E, Pesce M, Santi P, et al. Two-Stage TissueExpander Breast Reconstruction: A Focus on the Surgical Technique. Biomed Res Int 2017;1791546.
3. Moni J, Graves-Ditman M, Cederna P, et al. Dosimetry around metallic ports in tissue expanders in patients receiving postmastectomy radiation therapy: an ex vivo evaluation. Med. Dosim 2004;29:49-54.
4. Damast S, Beal K, Ballangrud A, et al. Do metallic ports in tissue expanders affect postmastectomy radiation delivery?Int J Radiat Onco Biol Phys 2006; 66:305-10.
5. Strang B, Murphy K, Seal S and Dal Cin A. Does the presence of an implant including expander with internal port alter radiation dose? An ex vivo model Can J Plast Surg 2013;21:37-40.
6. Asena A, Kairn T, Crowe S, et al. Establishing the impact of temporary tissue expanders on electron and photon beam dose distributions. Physica Medica 2015;31:281-5.
7. Chatzigiannis C, Lymperopoulou G, Sandilos P, et al. Dose perturbation in the radiotherapy of breast cancer patients implanted with the Magna-Site: a Monte Carlo study. J App Clin Med Phys 2005;12:58-70.
8. Trombetta DM, Cardoso SC, Facure A, et al. Influence of the presence of tissue expanders on energy deposition for post-mastectomy radiotherapy. PLoS One 2013;8:55430.
9. Park JM, Kim K, Park JI, et al. Dosimetric effect of internal metallic ports in temporary tissue expanders on postmastectomy radiation therapy: a Monte Carlo study. Physics in Medicine & Biology 2017;62:4623- 36.
10. Jursinic P. Characterization of optically stimulated luminescent dosimeters, OSLDs, for clinical dosimetric measurements. Medical Physics 2007;34:4594-604.
11. AAPM Task Group No.65 of the Radiation Therapy Committee. Madison, AAPM Tissue inhomogeneity corrections for megavoltage photon beams, Report No. AAPM-85. WI: Medical Physics Publishing 2004.
12. Product information, mentor ® CPXTM 2 breast tissue expander, 201 Mentor drive, Santa Barbara, CA 93111 USA
13. Product information, microstar® dosimeter system, Landauer
14. Walters BR and Rogers DW (2002) DOSXYZnrc users manual. PIRS 709. Ottawa: National Research Council of Canada.
15. Zabihzadeh M, Ghahfarokhi M, Razmjoo-Ghalaei S, et al. Dose perturbation due to the magnetic port of tissue breast expander in patient undergoing the postmastectomy radiation therapy. Biomed Pharmacol J 2016;9:285-91.
16. Chatzigiannis C, Lymperopoulou G, Sandilos P, et al. Dose perturbation in the radiotherapy of breast cancer patients implanted with the Magna-Site: a Monte Carlo study. J Appl Clin Med Phys 2011;12:3292.
17. Thompson R, Morgan AM. Investigation into dosimetric effect of a MAGNA-SITETM tissue expander on postmastectomy radiotherapy. Med Phys 2005;32:1640-6.
18. Landauer I. Inlight complete dosimetry system solution: nanoDot dosimeter. Landauer Inc, Glenwood 2012.
19. ICRU Report No. 24. Determination of Absorbed Dose in Patient Irradiated by Beams of X or Gamma Rays in Radiotherapy 1976.