PURPOSE By default, the 4-mm wide leaf-pairs of the Elekta Beam Modulator MLC not used for field shaping are moved to under the primary collimator to minimize the leakage dose. The trade-off is the increased beam delivery time in the case of IMRT. This study examines the dosimetric impact and improved delivery efficiency by allowing the unused leaf-pair as 2mm gap to stay within the PTV apertur...

We evaluate the impact of an air gap and optimization of this air gap for the MP512 silicon detector array when operated in dosimetry mode for small photon field measurements in solid water. We present output factor measurements for 6MV and 10 MV photon beams with the square field sizes ranging from 0.5 to 10 cm2. The size of the air gap above the MP512 detector was changed from 0.5, 1.0, 1.2, ...

As regards, the selection of appropriate energy in radiotherapy tumors that are placed in non-homogen areas is important, so the aim of the present study is evaluating the effect of 6 and 15MV photon beam energies on dose distribution in 3D-CRT for lower esophageal and rectal cancers. 12 patients with lower esophageal cancer and 12 patients with rectal cancer respectively, with the prescription...

Multileaf collimator (MLC) tracking represents a promising technique for motion management in radiotherapy. However, the conflict between limited leaf speed/acceleration and the demand for tracking fast target motion is now a prominent issue. Conventional MLCs typically have a maximum leaf speed of 3-4 cm/s and a maximum leaf acceleration of 50-70 cm/s2, which are inadequate to track fast targe...

BACKGROUND A new algorithm for photon dose calculation, Acuros XB, has been recently introduced in the Eclipse, Varian treatment planning system, allowing, similarly to the classic Monte Carlo methods, for accurate modelling of dose deposition in media. Aim of the present study was the assessment of its behaviour in clinical cases. METHODS Datasets from ten breast patients scanned under diffe...

Abstract Funding Acknowledgements Type of funding sources: None. Purpose Current guidelines for the management patients undergoing radiotherapy with cardiac implantable electronic devices (CIEDs) were published in 1994. They recommend that total dose received by device should be estimated before treatment, not placed direct radiation beam and cumulative exceed 2Gy to any part a pacemaker (0.5Gy...

background: new treatment modalities are developed with the aim of escalating tumor absorbed dose and simultaneously sparing the normal structures. the use of nanotechnology in cancer treatment offers some possibilities including destroying cancer tumors with minimal damage to healthy tissues. zinc oxide nanoparticles (zno nps) are wide band gap semiconductors and seem to have a good effect on ...

Small fields smaller than 4 × 4 cm2 are used in stereotactic and conformal treatments where heterogeneity is normally present. Since dose calculation accuracy in both small fields and heterogeneity often involves more discrepancy, algorithms used by treatment planning systems (TPS) should be evaluated for achieving better treatment results. This report aims at evaluating accuracy of four model-...

Dynamic sliding gap multileaf collimator (MLC) fields are used to model MLC properties within the treatment planning system (TPS) for dynamic treatments. One of the key MLC properties in the Eclipse TPS is the dosimetric leaf gap (DLG) and precise determination of this parameter is paramount to ensuring accurate dose delivery. In this investigation, we report on how the spacing between control ...