Electronic tissue compensation achieved with both dynamic and static multileaf collimator in eclipse treatment planning system for Clinac 6 EX and 2100 CD Varian linear accelerators: Feasibility and dosimetric study

Dynamic multileaf collimator (DMLC) and static multileaf collimator (SMLC), along with three-dimensional treatment planning system (3-D TPS), open the possibility of tissue compensation. A method using electronic tissue compensator (ETC) has been implemented in Eclipse 3-D TPS (V 7.3, Varian Medical Systems, Palo Alto, USA) at our center. The ETC was tested for head and neck conformal radiotherapy planning. The purpose of this study was to verify the feasibility of DMLC and SMLC in head and neck field irradiation for delivering homogeneous dose in the midplane at a pre-defined depth. In addition, emphasis was given to the dosimetric aspects in commissioning ETC in Eclipse. A Head and Neck Phantom (The Phantom Laboratory, USA) was used for the dosimetric verification. Planning was carried out for both DMLC and SMLC ETC plans. The dose calculated at central axis by eclipse with DMLC and SMLC was noted. This was compared with the doses measured on machine with ion chamber and thermoluminescence dosimetry (TLD). The calculated isodose curves and profiles were compared with the measured ones. The dose profiles along the two major axes from Eclipse were also compared with the profiles obtained from Amorphous Silicon (AS500) Electronic portal imaging device (EPID) on Clinac 6 EX machine. In uniform dose regions, measured dose values agreed with the calculated doses within 3%. Agreement between calculated and measured isodoses in the dose gradient zone was within 3 mm. The isodose curves and the profiles were found to be in good agreement with the measured curves and profiles. The measured and the calculated dose profiles along the two major axes were flat for both DMLC and SMLC. The dosimetric verification of ETC for both the linacs demonstrated the feasibility and the accuracy of the ETC treatment modality for achieving uniform dose distributions. Therefore, ETC can be used as a tool in head and neck treatment planning optimization for improved dose uniformity

Secondary signet-ring cell adenocarcinoma of urinary bladder from a gastric primary

Primary bladder tumor is a frequent urological malignancy, whereas the incidence of secondary bladder tumor from a distant organ is quite rare. Secondary bladder neoplasms represent 1% of all malignant bladder tumors, of which distant metastases from stomach account for about 4% of cases. We present the case of a 30-year-old male who underwent partial gastrectomy for Signet-ring cell carcinoma of the stomach and presented 2 years later with hematuria. On computerized tomography scan, a bladder tumor was found which was resected cystoscopically. The histopathological examination revealed secondary Signet-ring cell adenocarcinoma of the urinary bladder

Rhabdoid variant of lung cancer: Clinicopathological details of a case and a review of literature

Primary rhabdoid tumor of lung is a rare histological and clinical entity. Lung tumors with rhabdoid features have been included as variants of large-cell carcinoma in the 1999 World Health Organization (WHO) classification of lung tumors. A large-cell carcinoma with a rhabdoid phenotype (LCCRP) is unusual, with only 38 cases reported till date. We report the clinical details of one such case that was treated with pneumonectomy and adjuvant chemotherapy. We also present a review of the literature. To identify relevant articles, we searched PubMed, Ovid, and IngentaConnect databases using the key words ′rhabdoid,′ ′lung cancer,′ and ′primary rhabdoid tumor of lung.

Dose optimization of intra-operative high dose rate interstitial brachytherapy implants for soft tissue sarcoma

Objective: A three dimensional (3D) image-based dosimetric study to quantitatively compare geometric vs. dose-point optimization in combination with graphical optimization for interstitial brachytherapy of soft tissue sarcoma (STS). Materials and Methods: Fifteen consecutive STS patients, treated with intra-operative, interstitial Brachytherapy, were enrolled in this dosimetric study. Treatment plans were generated using dose points situated at the "central plane between the catheters", "between the catheters throughout the implanted volume", at "distances perpendicular to the implant axis" and "on the surface of the target volume" Geometrically optimized plans had dose points defined between the catheters, while dose-point optimized plans had dose points defined at a plane perpendicular to the implant axis and on the target surface. Each plan was graphically optimized and compared using dose volume indices. Results: Target coverage was suboptimal with coverage index (CI = 0.67) when dose points were defined at the central plane while it was superior when the dose points were defined at the target surface (CI=0.93). The coverage of graphically optimized plans (GrO) was similar to non-GrO with dose points defined on surface or perpendicular to the implant axis. A similar pattern was noticed with conformity index (0.61 vs. 0.82). GrO were more conformal and less homogeneous compared to non-GrO. Sum index was superior for dose points defined on the surface of the target and relatively inferior for plans with dose points at other locations (1.35 vs. 1.27). Conclusions: Optimization with dose points defined away from the implant plane and on target results in superior target coverage with optimal values of other indices. GrO offer better target coverage for implants with non-uniform geometry and target volume