Volumetric modulated arc radiotherapy for limited osteosclerotic myeloma.

AIM: To assess the feasibility of volumetric intensity-modulated arc radiotherapy (VMAT) in patients with limited polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes syndrome. METHODS: A 70-year-old male with histologically confirmed osteosclerotic myeloma was treated in our department in July 2010 with VMAT. Fourty-six Gray in 23 fractions were given on three bone lesions. Doses delivered to target volume and critical organs were compared with a tridimensional conformal radiotherapy (3D-RT) plan. Treatment was well tolerated without any side effects. RESULTS: VMAT improved dose homogeneity within the target volume, as compared to 3D-RT (standard deviations: 2.9 Gy and 1.6 Gy for 3D and VMAT, respectively). VMAT resulted in a better sparing of critical organs. Dose delivered to 20% of organ volume (D20) was reduced from 22 Gy (3D-RT) to 15 Gy (VMAT) for small bowel, from 24 Gy (3D-RT) to 17 Gy (VMAT) for bladder and from 47 Gy (3D-RT) to 3 Gy (VMAT) for spinal cord. Volumes of critical organs that received at least 20 Gy (V20) were decreased by the use of VMAT, as compared to 3D-RT (V20 bladder: 10% vs 99%; V20 small bowel: 6% vs 21%). One year after treatment completion, no tumor progression has been reported. CONCLUSION: VMAT improved dose distribution as compared to 3D-RT for limited osteosclerotic myeloma, with better saving of critical organs.

Correlation of dosimetric parameters obtained with the analytical anisotropic algorithm and toxicity of chest chemoradiation in lung carcinoma.

The purpose of this study was to analyze and revisit toxicity related to chest chemoradiotherapy and to correlate these side effects with dosimetric parameters obtained using analytical anisotropic algorithm (AAA) in locally unresectable advanced lung cancer. We retrospectively analyzed data from 47 lung cancer patients between 2005 and 2008. All received conformal 3D radiotherapy using high-energy linear accelerator plus concomitant chemotherapy. All treatment planning data were transferred into Eclipse 8.05 (Varian Medical Systems, Palo Alto, CA) and dosimetric calculations were performed using AAA. Thirty-three patients (70.2%) developed acute pneumopathy after radiotherapy (grades 1 and 2). One patient (2.1%) presented with grade 3 pneumopathy. Thirty-one (66%) presented with grades 1-2 lung fibrosis, and 1 patient presented with grade 3 lung fibrosis. Thirty-four patients (72.3%) developed grade 1-2 acute oesophagic toxicity. Four patients (8.5%) presented with grades 3 and 4 dysphagia, necessitating prolonged parenteral nutrition. Median prescribed dose was 64 Gy (range 50-74) with conventional fractionation (2 Gy per fraction). Dose-volume constraints were respected with a median V20 of 23.5% (maximum 34%) and a median V30 of 17% (maximum 25%). The median dose delivered to healthy contralateral lung was 13.1 Gy (maximum 18.1 Gy). At univariate analysis, larger planning target volume and V20 were significantly associated with the probability of grade ≥2 radiation-induced pneumopathy (p = 0.022 and p = 0.017, respectively). No relation between oesophagic toxicity and clinical/dosimetric parameters could be established. Using AAA, the present results confirm the predictive value of the V20 for lung toxicity as already demonstrated with the conventional pencil beam convolution approach.