The advantage of 3D conformal treatment of lumbar spine metastases in comparison to traditional PA or AP-PA techniques: restoring an intermediate niche of therapeutic sophistication.

BACKGROUND: To evaluate the effect of the 3D radiation field design on normal tissues compared with commonly used appositional fields in patients with lumbar spine metastases. METHODS AND MATERIALS: Ten comparative treatment plans for radiation of lumbar spine metastases were compared for posterior and anterior- posterior fields with 3D plans. RESULTS: The PTV coverage in all comparative plans was similar. V 15 of the bowel in 3D, AP-PA and PA plans was 6.7 Gy (SD 6.47), 39.8 Gy (SD 11.4) and 37.3 Gy (SD15.7), respectively (p < 0.0001). The mean dose to both kidneys was 9.6 Gy (SD 4.8), 4.1 Gy (SD 3.9) and 4.6 Gy (SD 4.4) for appropriate plans (p = 0.002). Maximal dose to the spinal cord was 30.6 Gy (SD 2.1), 33.1 Gy (SD 9.8) and 37.7 Gy (SD 2) for 3D, AP-PA and PA plans. CONCLUSION: 3D conformal treatment planning of lumbar vertebral metastases was significantly better in term of bowel and spinal cord exposure compared to AP-PA and PA techniques. The exposure of the kidneys in 3D plans, while greater than in the comparative plans, did not violate accepted dose-volume thresholds.

Three-dimensional non-coplanar conformal radiotherapy yields better results than traditional beam arrangements for adjuvant treatment of gastric cancer.

PURPOSE: The current standard of adjuvant treatment for gastric cancer after curative resection is concurrent administration of radiotherapy and 5-fluorouracil-based chemotherapy. The radiation fields are often arranged as anterioposterior-posteroanterior opposed parallel fields with general recommendations for sparing at least two-thirds of one kidney. We investigated whether a better radiation distribution would be achievable with three-dimensional conformal approaches compared with the classic anterioposterior-posteroanterior fields. METHODS AND MATERIALS: A total of 19 patients with adenocarcinoma of the stomach were treated with adjuvant chemoradiotherapy using a non-coplanar four-field arrangement. In each case, parallel planning using an anterioposterior-posteroanterior arrangement and a four-field "box" was performed, and the generated plans were subsequently compared for coverage of target volumes and doses to irradiated organs next to the tumor bed. A separate analysis was performed for kidneys exposed to greater and lower doses in each patient. The mean radiation dose and percentage of kidney volume receiving a dose >20 Gy were registered. Statistical analysis was performed using the two-tailed t test. RESULTS: The clinical target volume was adequately covered in all three plans. In the greater-dose kidney group, all the differences were statistically significant with a benefit for the three-dimensional plan. In the lower-dose kidney group, the differences in the mean radiation dose did not reach the level of statistical significance, and the differences in the kidney volume receiving a dose >20 Gy showed a statistically significant benefit for the three-dimensional plan. CONCLUSION: Non-coplanar three-dimensional-based conformal planning for postoperative radiotherapy for gastric cancer provided the best results regarding kidney and spinal cord exposure with adequate clinical target volume coverage. This technique was readily implemented in clinical practice.