Dosimetric evaluation of the feasibility of stereotactic body radiotherapy for primary XXXX with lobe-specific selective elective nodal irradiation.

@entity1 @entity1313 @entity2 @entity343 @entity177 @entity3
UNASSIGNED: More than 10% of all @entity1 treated with stereotactic body radiotherapy (SBRT) for primary @entity2 develop regional lymph node recurrence. We evaluated the dosimetric feasibility of SBRT with lobe-specific selective elective nodal irradiation (ENI) on dose-volume histograms. A total of 21 @entity1 were treated with SBRT for Stage I primary @entity2 between January 2010 and June 2012 at our institution. The extents of lobe-specific selective ENI fields were determined with reference to prior surgical reports. The ENI fields included lymph node stations (LNS) 3 + 4 + 11 for the @entity1313 , LNS 7 + 11 for the right middle or lower @entity1313 , LNS 5 + 11 for the @entity1313 , and LNS 7 + 11 for the @entity1313 . A composite plan was generated by combining the ENI plan and the SBRT plan and recalculating for biologically equivalent doses of 2 Gy per fraction, using a linear quadratic model. The V20 of the lung, D1cm(3) of the spinal cord, D1cm(3) and D10cm(3) of the esophagus and D10cm(3) of the tracheobronchial wall were evaluated. Of the 21 @entity1 , nine @entity1 (43%) could not fulfill the dose constraints. In all these @entity1 , the distance between the planning target volume ( @entity343 ) of ENI (PTVeni) and the @entity343 of SBRT (PTVsrt) was  <=2.0 cm. Of the three @entity1 who developed regional @entity3 , two @entity1 had isolated @entity177 , and the lymph node @entity3 was included within the ENI field. When the distance between the PTVeni and PTVsrt is >2.0 cm, SBRT with selective ENI may therefore dosimetrically feasible.
