This study seeks to compare fixed‐field intensity‐modulated radiation therapy (FF IMRT), RapidArc (RA), and helical tomotherapy (HT) to discover the optimal treatment modality to deliver SBRT to the peripheral lung. Eight patients with peripheral primary lung cancer were reviewed. Plans were prescribed a dose of 48 Gy and optimized similarly with heterogeneity corrections. Plan quality was assessed using conformality index (CI100%), homogeneity index (HI), the ratio of the 50% isodose volume to PTV (R50%) to assess intermediate dose spillage, and normal tissue constraints. Delivery efficiency was evaluated using treatment time and MUs. Dosimetric accuracy was assessed using gamma index (3% dose difference, 3 mm DTA, 10% threshold), and measured with a PTW ARRAY seven29 and OCTAVIUS phantom. CI100%,HI, and R50% were lowest for HT compared to seven‐field coplanar IMRT and two‐arc coplanar RA (p<0.05). Normal tissue constraints were met for all modalities, except maximum rib dose due to close proximity to the PTV. RA reduced delivery time by 60% compared to HT, and 40% when compared to FF IMRT. RA also reduced the mean MUs by 77% when compared to HT, and by 22% compared to FF IMRT. All modalities can be delivered accurately, with mean QA pass rates over 97%. For peripheral lung SBRT treatments, HT performed better dosimetrically, reducing maximum rib dose, as well as improving dose conformity and uniformity. RA and FF IMRT plan quality was equivalent to HT for patients with minimal or no overlap of the PTV with the chest wall, but was reduced for patients with a larger overlap. RA and IMRT were equivalent, but the reduced treatment times of RA make it a more efficient modality.PACS numbers: 87.53.Ly87.55.N‐, 87.55.D‐, 87.56.bd

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Purpose Novel strategies are needed to improve the long-term outcomes of patients with high-risk prostate cancer treated with androgen deprivation and external beam radiation therapy (XRT). Preclinical data suggest that angiogenesis inhibitors improve the therapeutic index of XRT. To assess the feasibility of combined vascular endothelial growth factor receptor (VEGFR)/platelet-derived growth factor receptor (PDGFR) inhibition in combination with androgen deprivation and XRT, a Phase I study with sunitinib was initiated. Methods and Materials Seventeen men with localized adenocarcinoma of the prostate with cT2c-cT4 or Gleason 8–10 or PSA > 20ng/ml received initial androgen deprivation (leuprolide 22.5mg every 12 weeks + oral bicalutamide 50mg daily) for 4–8 weeks prior to oral sunitinib 12.5, 25, or 37.5 mg daily for 4 weeks as lead-in, then concurrently with and 4 weeks following XRT (75.6 Gy in 42 fractions to prostate and seminal vesicles). A 3+3 sequential dose-escalation design was employed to assess the frequency of dose-limiting toxicity (DLT) and establish a maximal tolerated dose (MTD) of sunitinib. Results Sunitinib at 12.5 and 25 mg dose-levels was well tolerated. The first 4 patients enrolled at 37.5 mg experienced a DLT during lead-in and a drug-interaction between sunitinib and bicalutamide was suspected. The protocol was revised and concurrent bicalutamide omitted. Of the next 3 patients enrolled at 37.5 mg, 2 of 3 on concurrent therapy experienced DLTs during radiation: Grade 3 diarrhea and Grade 3 proctitis respectively. Only 1/7 patients completed sunitinib at 37.5mg daily whereas 3/3 patients (25mg as starting dose) and 3/4 patients (25mg as reduced dose) completed therapy. Conclusions The feasibility of combined VEGFR/PDGFR inhibitor therapy, androgen deprivation, and radiation therapy for prostate cancer was established. Using a daily dosing regimen with lead-in, concurrent and post-XRT therapy, the recommended Phase 2 dose of sunitinib is 25mg daily.