4D CT analysis of organs at risk (OARs) in stereotactic radiotherapy

• Published in: Radiotherapy and oncology Vol. 151; pp. 10 - 14
• Main Authors: Nardone, Valerio, Giugliano, Francesca Maria, Reginelli, Alfonso, Sangiovanni, Angelo, Mormile, Maria, Iadanza, Luciano, Cappabianca, Salvatore, Guida, Cesare
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01-10-2020
• Subjects: 4DCT; Dosimetry; Four-Dimensional Computed Tomography; Humans; Organs at Risk; Prospective Studies; Radiosurgery; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; SABR; Stereotactic radiotherapy; SABR; 4DCT; Organs at risk; Dosimetry; Stereotactic radiotherapy
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2020.06.048

Internal organs at risk volumes (IRV) represent the propagation of organs at risk (OARs) in 4DCT.
Sixty consecutive patients that underwent 4DCT for thoracic stereotactic radiotherapy were analyzed and IRVs for heart, trachea, esophagus, bronchial tree, great vessels, and spinal cord were calculated. IRVs were then tested for the respect of dose constraints.
IRVs were significantly bigger than standard OARs (p-value <0.001 for all the IRVs).
IRVs that did not respect the dose constraints were, respectively, 7/60 (11.7%) for Heart IRV, 6/60 (10%) for Esophagus IRV, 11/60 (18.3%) for Trachea IRV, 16/60 (26.6%) for Bronchial Tree and 0/60 (0%) for great vessel and spinal cord IRV.
In the subset of central targets, the percentage of plans that can be unacceptable taking into consideration OARs motion reaches 42%. The correlation of IRVs with clinical parameters and toxicity deserves future investigations in prospective trials.