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KMID : 1164220170290020019
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Journal of Korean Society for Radiotherapeutic Technology
2017 Volume.29 No. 2 p.19 ~ p.26
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The Evaluation of Hybrid-Volumetric Modulated Arc Therapy for Lung Cancer Radiation Therapy
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Lee Geon-Ho
Kang Hyo-Seok
Choi Byoung-Joon
Park Sang-Jun
Jung Da-Ee
Lee Du-Sang
Ahn Min-Woo
Jeon Myeong-Su
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Abstract
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Objectives: In the Lung, the VMAT rotates continuously and examines radiation. That increases the low doses to normal lung. Due to that, the incidence of radiation pneumonia among radiation side effects may increase. The cause of radiation pneumonia is the lower dose area of the lungs. The H-VMAT was applied to patients who applied to reduce radiation in the lower doses of the lungs. We wanted to assess the usefulness of the H-VMAT by comparing the radiation
doses to the low dose areas of the lungs and the normal organs.
Materials and Methods: A total of 26 patients who applied for a H-VMAT procedure were applied to the patient. The prescription dose applied to total dose 44 Gy from 22 divisions. For each patient, a plan was implemented with Conventional RT, VMAT and H-VMAT. Conventional RT was carried out in four to five fields each, considering the size, location, shape, and location of the PTV. In the case of a VMAT plan, the two Half ARC, three Half ARC method and
the two Full ARC were planned. The H-VMAT was planned by adding two Static fields in the VMAT, taking into account the dose of the lung and the tolerance dose of the organs.
Results: In the NSCLC, the lung doses V5 and V10 of the lungs except for the treatment plan volume were the lowest with 55.40±13.39 % and 32.05±11.37 % of H-VMAT. And, in the SCLC, the lung doses of V5 and V10 were the lowest at 64.32±16.15 % and 35.50±9.91 %, respectively. The spinal dose of VMAT in NSCLC was 21.15±4.02 Gy, which was 7.94 Gy lower than other treatment methods. The lowest spinal dose was delivered at 19.72±1.82 Gy for SCLC. The
mean dose delivered to the esophagus was also 17.44±2.04 Gy and 17.84±9.20 Gy in SCLC and NSCLC, respectively.
Conclusion: When comparing the value of the surrounding normal organ dose, the VMAT showed that less doses were transmitted from the heart, esophagus and spinal cord than the rest of the treatment plan. However, it was similar to VMAT in normal organs except for the spinal cord. VMAT has increased doses of some normal organs but did not exceed the tolerance dose. It showed a low value in V5, V10. When comparing Conventional RT, VMAT, and HVMAT, If the dose to the heart, esophagus and spinal cord is lower than the tolerance dose, it is thought to reduce the incidence of radiation pneumonia by applying H-VMAT that show the benefits of low doses of the lungs.
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KEYWORD
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Conventional RT , H-VMAT , VMAT , Lung
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