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KMID : 1164220170290010037
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Journal of Korean Society for Radiotherapeutic Technology
2017 Volume.29 No. 1 p.37 ~ p.48
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Correlation analysis of radiation therapy position and dose factors for left breast cancer
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Jeon Jae-Wan
Park Cheol-Woo
Hong Jong-Su
Jin Seong-Jin
Kang Jung-Hun
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Abstract
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Purpose: The most basic conditions of radiation therapy is to prevent unnecessary exposure of normal tissue. The risk factors that are important o evaluate the dose emitted to the lung and heart from radiation therapy for breast cancer. Therefore, comparing the dose factors of a normal tissue according to the radion treatment position and Seeking an effective radiation treatment for breast cancer through the analysis of the correlation relationship.
Materials and Methods: Computed tomography was conducted among 30 patients with left breast cancer in supine and prone position. Eclipse Treatment Planning System (Ver.11) was established by computerized treatment planning. Using the DVH compared the incident dose to normal tissue by position. Based on the result, Using the SPSS (ver.18) analyzed the dose in each normal tissue factors and Through the correlation analysis between variables, independent sample test examined the association. Finally The HI, CI value were compared Using the MIRADA RTx (ver. ad 1.6) in the supine, prone position
Results: The results of computerized treatment planning of breast cancer in the supine position were V20, 16.5 ± 2.6 % and V30, 13.8 ± 2.2 % and Mean dose, 779.1 ± 135.9 cGy (absolute value). In the prone position it showed in the order 3.1 ± 2.2 %, 1.8 ± 1.7 %, 241.4 ± 138.3 cGy. The prone position showed overall a lower dose. The average radiation dose 537.7 cGy less was exposured. In the case of heart, it showed that V30, 8.1 ± 2.6 % and 5.1 ± 2.5 %, Mean dose, 594.9 ± 225.3 and 408 ± 183.6 cGy in the order supine, prone position.
Results of statistical analysis, Cronbach's Alpha value of reliability analysis index is 0.563. The results of the correlation
analysis between variables, position and dose factors of lung is about 0.89 or more, Which means a high correlation. For the heart, on the other hand it is less correlated to V30 (0.488), mean dose (0.418). Finally The results of independent samples t-test, position and dose factors of lung and heart were significantly higher in both the confidence level of 99 %.
Conclusion: Radiation therapy is currently being developed state-of-the-art linear accelerator and a variety of treatment plan technology. The basic premise of the development think normal tissue protection around PTV. Of course, if you treat a breast cancer patient is in the prone position it take a lot of time and reproducibility of set-up problems. Nevertheless, As shown in the experiment results it is possible to reduce the dose to enter the lungs and the heart from the prone position. In conclusion, if a sufficient treatment time in the prone position and place correct confirmation will be more effective when the radiation treatment to patient.
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KEYWORD
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Breast Treatment position, Correlation analysis, MIRADA Rtx, Cronbach's Alpha value
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