High efficiency stimulated rotational Raman scattering of hydrogen pumped by 1064 nm.

Laser-induced breakdown (LIB) and the competition of other Raman processes are major reasons restricting photon conversion efficiency (PCE) of Raman lasers. In this work, 1064 nm was used as the pump source, and stimulated rotational Raman scattering of hydrogen was investigated. The configuration of zooming out and focusing pump beam was applied, and the dimension of the pump beam at the focus spot increased significantly; consequently, LIB was suppressed, and Raman PCE was improved dramatically. With the help of the Raman gas pressure optimization, vibrational Raman could be fully suppressed, and other competition Raman processes could be well controlled. The optimal PCEs of different rotational Raman lasers could be achieved under different conditions. The maximum PCE of the first rotational Stokes (RS1) was improved to 60.7%, and the maximum energy of RS1 reached 204.5 mJ. With the increment of hydrogen pressure, the maximum PCE of the second rotational Stokes (RS2) was improved to 28.2%, and the maximum energy of RS2 reached 123.9 mJ. Furthermore, a 2.1 µm Raman laser was also generated, the maximum PCE of 2.1 µm reached 44.8%, and its pulse energy reached 106.1 mJ.

Different radiation treatment in esophageal carcinoma: a clinical comparative study.

PURPOSE: Conventional fractionation radiation therapy (CFRT), 3-dimensional conformal radiation therapy (3DCRT) and intensity modulated radiation therapy (IMRT), are always applied to treat esophageal carcinoma. The purpose of this study was to analyse the therapeutic results and acute radiation side effects of radiotherapy in the treatment of esophageal carcinoma. METHODS: From March 2008 to May 2010, 117 patients with esophageal carcinoma treated at our hospital were included into this study. Thirty-eight (32.48%?) patients were treated with CFRT, 32 with 3DCRT and 47 with IMRT. The data were retrospectively collected and analysed. RESULTS: The objective response rates (complete/CR plus partial response/PR) in the CFRT group, 3DCRT group and IMRT group were 96.88, 92.11, and 91.49%, respectively (p=0.617). Furthermore, the one-year survival of the 3 groups was 77.9, 87.5 and 86.7%, respectively (p=0.193), and the 2-year survival 38.6, 55.1 and 57.7%, respectively (p=0.211). The incidence of acute radiation esophagitis in the IMRT+3DCRT groups was significantly higher compared with the CFRT group (p=0.012) and the incidence of acute radiation- induced pneumonitis, bronchitis and myelosuppression in the IMRT+3DCRT groups were lower compared with the CFRT group (p<0.01, p=0.028, and p=0.01, respectively). CONCLUSION: Both IMRT and 3DCRT methods can improve the clinical therapeutic outcome of patients with esophageal carcinoma and decrease the incidence of acute radiation pneumonitis, radiation bronchitis and bone marrow suppression.

Quantitative study of lung perfusion SPECT scanning and pulmonary function testing for early radiation-induced lung injury in patients with locally advanced non-small cell lung cancer.

Radiation lung injury is a common side-effect of pulmonary radiotherapy. The aim of this study was to quantitatively assess early changes in lung perfusion single photon emission computed tomography (SPECT) scanning and pulmonary function testing (PFT) prior to and after intensity modulated radiotherapy (IMRT) for patients suffering from locally advanced non-small cell lung cancer (LANSCLC). Twenty patients with LANSCLC received lung perfusion SPECT scanning and PFT prior to IMRT and immediately after IMRT. Lung perfusion index (LPI) was calculated after the quantification of perfusion SPECT images. The LPI of the two groups was analyzed by matched t-test. The radioactive count of each layer of single lung was added to obtain the sum of the irradiated area. The percentage of the irradiated area of single lung was calculated. Linear correlation analysis was carried out between the percentage of the irradiated area and LPI in order to verify the validity of LPI. In this study, LPI and the percentage of the irradiated area of single lung exhibited an excellent correlation either prior to or after IMRT (r=0.820 and r=0.823, respectively; p<0.001). There was no statistically significant difference between pre-IMRT LPI and post-IMRT LPI (p=0.135). LPI in the group receiving a radical dose had no statistically significant difference (p=0.993), however, it showed a statistically significant difference in the group receiving a non-radical dose (p=0.025). In the non-radical dose group, the post-IMRT LPI was larger compared to pre-IMRT. None of the parameters of PFT exhibited a statistically significant difference prior to and after IMRT (p>0.05). The quantitative method of lung perfusion SPECT scanning can be used to evaluate changes in perfusion early in patients receiving a non-radical dose (BED ≤126,500 cGy) IMRT. Evaluating early changes in global lung function using the current method of PFT is difficult, since time can be a contributing factor for radiation-induced lung injury.