PMID- 34259116 OWN - NLM STAT- MEDLINE DCOM- 20210917 LR - 20220426 IS - 1651-226X (Electronic) IS - 0284-186X (Linking) VI - 60 IP - 10 DP - 2021 Oct TI - Planning target volume density impact on treatment planning for lung stereotactic body radiation therapy. PG - 1296-1300 LID - 10.1080/0284186X.2021.1950926 [doi] AB - BACKGROUND: To evaluate the impact of the planning target volume (PTV) density on treatment planning for lung Stereotactic Body Radiation Therapy (SBRT). MATERIAL AND METHODS: The PTV coverage was analyzed in two groups of 40 lung SBRT patients. One group had PTV density <0.5 g/cm(3), while the other group had PTV density >0.5 g/cm(3). The treatments were planned in Pinnacle 9.10, using the collapsed cone convolution (CCC) algorithm. The prescribed dose was 60 Gy to the PTV in 4-8 fractions. Respecting constraint for the PTV coverage (D98% > 95%), we compared changes in the isodose line prescription, the number of monitor units (MU), maximum dose (D(max)), irradiated volume covered with 30 Gy (V(30Gy)), and the optimization planning volume (OPV). RESULTS: For the same median values of the PTV coverage (98.3%), the differences are presented with median values between lower and higher density than 0.5 g/cm(3). The isodose line prescription was 83 vs. 90% (p < 0.0001), the MUs were 2294 vs. 1655 MU (p < 0.0001), D(max) was 74.26 vs. 68.09 Gy (p < 0.0001), V(30Gy) was 117.03 vs. 104.81 cc (p = 0.04), and OPV was 28.48 vs. 39.35 cc (p < 0.001). By overriding the ITV density to 0.8 g/cm(3), the isodose line prescription decreases. The D(max) and MUs decrease by 7%, V(30Gy) by 34%, and OPV by 70%. CONCLUSION: To obtain similar PTV coverage for PTV which is <0.5 g/cm(3), a larger margin irradiating a large OPV was used. More MUs and a higher maximum dose were delivered. For the PTV density of