medical linear accelerators are one of the most widespread methods for cancer treatment. despite their advantages, unwanted photoneutrons are produced by high energy linacs. this photoneutrons are as undesired doses to patients and a significant problem for radiation protection of the staffs and patients. photoneutrons radiological risk must be evaluated because of their high let and range.in o...

Aim: To evaluate the dosimetric outcomes of two different three dimensional conformal radiation therapy (3D-CRT) of concomitant boost delivery to the intact breast. Methods: Ten patients were evaluated using two standard opposed tangents conformal to the whole breast PTV, plus a pair of wedged fields conformal to the boost PTV; all fields have the same isocenter, placed in the whole breast plan...

The objective of this work was to measure patient eye lens dose for different cone-beam computed tomography (CBCT) acquisition protocols of Varian's On-Board Imaging (OBI) system using optically stimulated luminescence dosimeter (OSLD) and to study the variation in eye lens dose with patient geometry and distance of isocenter to the eye lens. During the experimental measurements, OSLD was place...

The workload for shielding purposes of modern linear accelerators (linacs) consists of primary and scatter radiation which depends on the dose delivered to isocenter (cGy) and leakage radiation which depends on the monitor units (MUs). In this study, we report on the workload for 10 treatment vaults in terms of dose to isocenter (cGy), monitor units delivered (MUs), number of treatment sessions...

In the present paper, we describe the results of a prospective trial that compared isocenter shifts produced by BAT Ultrasound (Nomos, Sewicky, PA) to those produced by a computed tomography (CT) unit in the treatment room to aid in positioning during image-guided radiation therapy. The trial included 15 consecutive patients with localized prostate cancer. All patients underwent CT and MR simul...

Rapid advancements in imaging technology have led to remarkable improvements in identification and localization of tumors, ushering the era of high-precision techniques in contemporary radiotherapy practice. However, uncertainties in patient set-up and organ motion during a course of fractionated radiotherapy can compromise precision of radiation therapy. Excellent accuracy has been achieved wi...

A commercially available open MRI unit is under routine use for radiation therapy simulation. The effects of a gradient distortion correction (GDC) program used to post process the images were assessed by comparison with the known geometry of a phantom. The GDC reduced the magnitude of the distortions at the periphery of the axial images from 12 mm to 2 mm horizontally along the central axis an...

BACKGROUND High-energy linear accelerator (linac) is a valuable tool and the most commonly used device for external beam radiation treatments in cancer patients. In the linac head, high-energy photons with energies above the threshold of (γ,n) interaction produce photoneutrons. These photoneutrons deliver the extra dose to the patients undergoing radiation treatment and increase the risk of sec...

background: high-energy linear accelerator (linac) is a valuable tool and the most commonly device for external beam radiation treatments in cancer patients. in the linac head, high-energy photons with energies above the threshold of interaction produce photoneutrons. these photoneutrons deliver the extra dose to the patients in the planning treatment and increase the risk of secondary cancer. ...