Background: Lung cancer patients are often in poor physical condition, and a shorter treatment time would reduce\ntheir discomfort. Dynamic conformal arc therapy (DCAT) offers a shorter treatment time than conventional 3D\nconformal radiotherapy (3D CRT) and is usually available even in departments without inverse planning possibilities.\nWe examined its suitability as a treatment modality for lung cancer patients.\nMethods: On a cohort of 35 lung cancer patients, relevant dosimetric parameters were compared in respective DCAT\nand 3D CRT treatment plans. Radiochromic film dosimetry in an anthropomorphic phantom was used to compare\nboth DCAT and 3D CRT dose distributions against their planned counterparts.\nResults: In comparison with their 3D CRT counterparts, DCAT plans equal or exceed the agreement between the\ncalculated dose and the dose measured using film dosimetry. In dosimetric comparison, DCAT performed significantly\nbetter than 3D CRT in dose conformity to PTV and the number of monitor units used per plan, and significantly worse\nin dose homogeneity, mean lung dose and lung volume exposed to 5 Gy or more (V5Gy). No significant difference\nwas found in the V20Gy value to lung, dose to 1 cm3 of spinal cord, and the mean dose to oesophagus.\nImprovements in V20Gy and V5Gy were found to be negatively correlated. DCAT plans differ from 3D CRT by\nexhibiting a moderate negative correlation between target volume sphericity and dose homogeneity.\nConclusions: With respect to the agreement between the planned and the irradiated dose distribution, DCAT\nappears at least as reliable as 3D CRT. In specific conditions concerning the patient anatomy and treatment\nprescription, DCAT may yield more favourable dosimetric parameters. On average, however, conventional 3D CRT\nusually obtains better dosimetric parameters. We can thus only recommend DCAT as a complementary technique to\nthe conventional 3D CRT.
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