Mono iso-centric VMAT planning for SBRT of multiple liver metastasis- A case report.

INTRODUCTION: Hepatocellular carcinoma (HCC) is the second most common cause of cancer mortality worldwide. The risk factors associated with the development of HCC are chronic Hepatitis B, Hepatitis C, and alcoholic cirrhosis. The standard care for HCC is surgical resection but the scope is limited for some patients. Continuous advancement of radiation therapy enabled the technique of stereotactic body radiotherapy (SBRT) as an option for the treatment of those cases for which surgery cannot be done. According to recent literature and meta-analysis, SBRT is an optimum treatment method with high local control with low toxicity. In SBRT, radiation is delivered with a smaller number of fractions than conventional radiation and employs high-precision delivery and accuracy with the help of image guidance. From a series of retrospective and prospective studies, it has been confirmed that SBRT achieves excellent local control in patients with early-stage inoperable, intermediate-stage, and advanced diseases. BACKGROUND: A 42-year-old male patient related to HBeAg infection and high AFP levels developed HCC BCLC Stage A was admitted to our department. There were two lesions with PTV volumes of 41.07 cc and 9.573 cc with a distance between them of 3.51 cm. These two lesions were treated with a mono-isocentric VMAT planning with SBRT technique. In this case, we present an unusual clinical practice of mono-isocentric treatment planning for treating multiple liver lesions. Since radiation therapy was viewed as the primary form of treatment because the patient wasn't an ideal candidate for surgery, SBRT was selected as the patient's primary modality of treatment because of the tiny volume of the two lesions and the normal liver volume (>700cc). Triple-phase 4DCT was performed for simulation to account for the motion of target volume and normal structures. After delineating the target volume and other normal structures, treatment planning was done with a dose of 45 Gray which was to be delivered in 5 fractions. Two PTVs were created with a margin of 3.0 mm to IGTV. Considering the positions of the lesions, a single isocentre plan was created using a 6MV FFF photon beam for both the PTVs with the VMAT technique. The treatment was carried through with 3 arcs, one coplanar, and the other 2 non-coplanar. At the time of treatment, after the proper positioning of the patient, one CBCT image was taken to match with the planned CT image acquired at the time of the simulation. After applying the translational and rotational errors, the patient was treated. RESULTS: The patient was treated successfully. After treatment, the condition of the patient was normal, and no toxicities have been observed in follow-up. CONCLUSION: Mono isocentric VMAT planning can be used for closely spaced lesions considering the position of lesions and other normal structures in the vicinity.

Divided target optimization with volumetric modulated arc therapy planning to improve target coverage and homogeneity in lung radiation therapy.

PURPOSE: To investigate and evaluate the feasibility of a simple modified Divided Planning Target Volume (DPTV) optimization method in radiation therapy planning of lung cancer patients. METHODS: A cohort of 15 patients of Non-Small Cell Lung Cancer (13 patients stage III and two patients of stage II) who were previously treated with Concurrent Chemo Radiation Therapy were included in the study. The planning modality was Volumetric Modulated Arc Therapy, and the dose prescription was 60 Gray in 30 fractions. In this study, we attempted to replan by dividing the previous Single Planning Target Volume (SPTV) into a DPTV. All the treatment plans were revised and again optimized for DPTV with required dose constraints as in SPTV. The dosimetric parameters that were achieved for target and normal structures were recorded in both the optimization methods. RESULTS: Dosimetric target coverage (D95%) (p-value = 0.0001), dose homogeneity (p-value =0.0001) and conformity (p-value = 0.044) were improved by the DPTV optimization. The volume of the oesophagus receiving 35 Gy was found to be higher in the DPTV arm (p-value = 0.02) compared to the SPTV arm, but the volume of the oesophagus receiving 50 Gy was found to be similar (p-value = 0.122). CONCLUSION: In radiation therapy planning of lung cancer, the DPTV optimization method has better dose coverage to the target volume, homogeneity, as well as conformity than the stsndsrd SPTV method. Therefore, the DPTV optimization method can be a simple and efficient alternative to the SPTV method in lung cancer.

Cropping practices, soil properties, pedotransfer functions and organic carbon storage at Kuanria canal command area in India.

Effects of cropping practices on soil properties viz. particle size distribution, pH, bulk density (BD), field capacity (FC, -33 kPa), permanent wilting point (PWP, -1500 kPa), available water capacity (AWC) and soil organic carbon (SOC) were assessed. The pedotransfer functions (PTFs) were developed for saturated hydraulic conductivity (Ks), water retention at FC and PWP of soils for different sites under major cropping system in a canal irrigated area. The results revealed that the soils are mainly composed of sand and clay with the clay contents ranging from 29.6 to 48.8%, BD of 1.44-1.72 Mg m(-3), and 0.34 to 0.95% SOC. The Ks decreased, and water retention at FC, PWP and AWC increased significantly with soil depth due to greater clay contents in lower soil depths. The PTFs were best represented as the power functions for prediction of Ks with clay content as predictor variable; whereas the PTFs for water retention at FC and PWP were better represented as the exponential functions. SOC content was higher under rice-sugarcane crop rotation compared to other systems. SOC storage in the surface layer was higher in rice-sugarcane rotation (18.90-20.53 Mg ha(-1)) than other sites. The developed PTFs would be very useful in soil and water management strategies for the study area or elsewhere having similar soil and cropping practices. The information on SOC storage in the Kuanria region would help for better soil and crop planning in future.