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SU‐F‐T‐421: Dosimetry Change During Radiotherapy and Dosimetry Difference for Rigid and Deformed Registration in the Mid‐Thoracic Esophageal Carcinoma
Author(s) -
Tao C,
Liu T,
Chen J,
Zhu J,
Yin Y
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4956606
Subject(s) - dosimetry , medicine , nuclear medicine , radiation therapy , radiation treatment planning , significant difference , plan (archaeology) , lung , radiology , history , archaeology
Purpose: This study aimed to analyze dosimetry changes during radiotherapy for the mid‐thoracic esophageal carcinoma, and investigate dosimetry difference between rigid and deformed registration. Methods: Twelve patients with primary middle thoracic esophageal carcinoma were selected randomly. Based on first CT scanning of each patient, plans‐o were generated by experience physicists. After 20 fractions treatment, the corresponding plans‐re were created with second CT scanning. And then, these two CT images were rigid and deformed registration respectively, and the dose was accumulated plan‐o with plan‐re. The dosimetry variation of these plans (plan‐o: with 30 fractions, plan‐rig: the accumulated dose with rigid registration and plan‐def: the accumulated dose with deformed registration) were evaluated by paired T‐test. Results: The V20 value of total lung were 32.68%, 30.3% and 29.71% for plan‐o, plan‐rig and plan‐def respectively. The mean dose of total lung was 17.19 Gy, 16.67 Gy and 16.51 Gy for plan‐o plan‐rig and plan‐def respectively. There were significant differences between plan‐o and plan‐rig or plan‐def for both V20 and mean dose of total lung (with p= 0.003, p= 0.000 for V20 and p=0.008, p= 0.000 for mean dose respectively). There was no significant difference between plan‐rig and plan‐def (with p=0.118 for V20 and p=0.384 for mean dose). The max dose of spinal‐cord was 41.95 Gy, 41.48 Gy and 41.4 Gy for plan‐o, plan‐rig and plan‐def respectively. There were no significant differences for the max dose of spinal‐cord between these plans. Conclusion: The target volume changes and anatomic position displacement of mid‐thoracic esophageal carcinoma should not be neglected in clinics. These changes would cause overdose in normal tissue. Therefore, it is necessary to have another CT scanning and re‐plan during the mid‐thoracic esophageal carcinoma radiotherapy. And the dosimetry difference between rigid and deformed fusions was not found in this study.