Document Type : Original Research
Authors
1 Department of Medical Physics, Faculty of Medicine, Tabriz University of Medical Science, Tabriz, Iran
2 Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
3 Department of Medical Physics, Faculty of Medicine, Mashhad University of Medical Sciences, Iran
4 Radiotherapy and Oncology Reza Center, Mashhad, Iran
5 Department of Medical Bioengineering, Tabriz University of Medical Sciences, Iran
6 Faculty of Medical Sciences, University of Aberdeen, UK
Abstract
Purpose: Fiber carbon is the most common material used in treating couch as it causes less beam attenuation than other materials. Beam attenuation replaces build-up region, reduces skin-sparing effect and causes target volume under dosage. In this study, we aimed to evaluate beam attenuation and variation of build-up region in 550 TxT radiotherapy couch.
Materials and Methods: In this study, we utilized cylindrical PMMA Farmer chamber, DOSE-1 electrometer and set PMMA phantom in isocenter of gantry and the Farmer chamber on the phantom. Afterwards, the gantry rotated 10°, and attenuation was assessed. To measure build-up region, we used Markus chamber, Solid water phantom and DOSE-1 electrometer. Doing so, we set Solid water phantom on isocenter of gantry and placed Markus chamber in it, then we quantified the build-up region at 0° and 180° gantry angels and compared the obtained values.
Results: Notable attenuation and build-up region variation were observed in 550 TxT treatment table. The maximum rate of attenuation was 5.95% for 6 MV photon beam, at 5×5 cm2 field size and 130° gantry angle, while the maximum variation was 7 mm for 6 MV photon beam at 10×10 cm2 field size.
Conclusion: Fiber carbon caused beam attenuation and variation in the build-up region. Therefore, the application of fiber carbon is recommended for planning radiotherapy to prevent skin side effects and to decrease the risk of cancer recurrence.
Keywords
- Hoppe BS, Laser B, Kowalski AV, Fontenla SC, Pena-Greenberg E, Yorke ED, et al. Acute skin toxicity following stereotactic body radiation therapy for stage I non-small-cell lung cancer: who’s at risk? Int J Radiat Oncol Biol Phys. 2008;72:1283-6. doi.org/10.1016/j.ijrobp.2008.08.036. PubMed PMID: 19028267.
- De Ost B, Vanregemorter J, Schaeken B, Van den Weyngaert D. The effect of carbon fibre inserts on the build-up and attenuation of high energy photon beams. Radiother Oncol. 1997;45:275-7. doi.org/10.1016/S0167-8140(97)00118-7. PubMed PMID: 9426122.
- Higgins DM, Whitehurst P, Morgan AM. The effect of carbon fiber couch inserts on surface dose with beam size variation. Med Dosim. 2001;26:251-4. doi.org/10.1016/S0958-3947(01)00071-1. PubMed PMID: 11704460.
- McCormack S, Diffey J, Morgan A. The effect of gantry angle on megavoltage photon beam attenuation by a carbon fiber couch insert. Med Phys. 2005;32:483-7. doi.org/10.1118/1.1852792. PubMed PMID: 15789595.
- Poppe B, Chofor N, Ruhmann A, Kunth W, Djouguela A, Kollhoff R, et al. The effect of a carbon-fiber couch on the depth-dose curves and transmission properties for megavoltage photon beams. Strahlenther Onkol. 2007;183:43-8. doi.org/10.1007/s00066-007-1582-8. PubMed PMID: 17225945.
- Mihaylov IB, Corry P, Yan Y, Ratanatharathorn V, Moros EG. Modeling of carbon fiber couch attenuation properties with a commercial treatment planning system. Med Phys. 2008;35:4982-8. doi.org/10.1118/1.2982135. PubMed PMID: 19070232.
- Njeh CF, Raines TW, Saunders MW. Determination of the photon beam attenuation by the Brainlab imaging couch: angular and field size dependence. J Appl Clin Med Phys. 2009;10:2979. doi.org/10.1120/jacmp.v10i3.2979. PubMed PMID: 19692980.
- Gerig LH, Niedbala M, Nyiri BJ. Dose perturbations by two carbon fiber treatment couches and the ability of a commercial treatment planning system to predict these effects. Med Phys. 2010;37:322-8. doi.org/10.1118/1.3271364. PubMed PMID: 20175495.
- Seppala JK, Kulmala JA. Increased beam attenuation and surface dose by different couch inserts of treatment tables used in megavoltage radiotherapy. J Appl Clin Med Phys. 2011;12:3554. doi.org/10.1120/jacmp.v12i4.3554. PubMed PMID: 22089010.
- Myint WK, Niedbala M, Wilkins D, Gerig LH. Investigating treatment dose error due to beam attenuation by a carbon fiber tabletop. J Appl Clin Med Phys. 2006;7:21-7. doi.org/10.1120/jacmp.v7i3.2247. PubMed PMID: 17533341.
- Khan FM, Gibbons JP. Khan’s the physics of radiation therapy. 5th edition. Philadelphia: Lippincott Williams & Wilkins; 2014.
- Lee KW, Wu JK, Jeng SC, Hsueh Liu YW, Cheng JC. Skin dose impact from vacuum immobilization device and carbon fiber couch in intensity modulated radiation therapy for prostate cancer. Med Dosim. 2009;34:228-32. doi.org/10.1016/j.meddos.2008.10.001. PubMed PMID: 19647634.
- Vanetti E, Nicolini G, Clivio A, Fogliata A, Cozzi L. The impact of treatment couch modelling on RapidArc. Phys Med Biol. 2009;54:N157-66. doi.org/10.1088/0031-9155/54/9/N03. PubMed PMID: 19351984.
- Butson MJ, Cheung T, Yu PK. Megavoltage x-ray skin dose variation with an angle using grid carbon fibre couch tops. Phys Med Biol. 2007;52:N485-92. doi.org/10.1088/0031-9155/52/20/N03. PubMed PMID: 17921572.
- Almond P, Andreo P, Mattsson O, Nahum A, Roos M. The use of plane-parallel ionization chambers in high-energy electron and photon beams. An international Code of Practice for dosimetry. IAEA Technical Reports Series no. 381. 1997.
- Nuutinen J, Lahtinen T, Turunen M, Alanen E, Tenhunen M, Usenius T, et al. A dielectric method for measuring early and late reactions in irradiated human skin. Radiother Oncol. 1998;47:249-54. doi.org/10.1016/S0167-8140(97)00234-X. PubMed PMID: 9681887.
- Nuutinen J, Vaananen A, Lahtinen T, Turunen M, Remes S, Alanen E. Radiobiological depth of subcutaneous induration. Radiother Oncol. 2000;55:187-90. doi.org/10.1016/S0167-8140(99)00147-4. PubMed PMID: 10799731.
- Spezi E, Ferri A. Dosimetric characteristics of the Siemens IGRT carbon fiber tabletop. Med Dosim. 2007;32:295-8. doi.org/10.1016/j.meddos.2006.11.006. PubMed PMID: 17980831.
)