BACKGROUND AND PURPOSE A comprehensive dosimetry intercomparison has been carried out involving all the radiotherapy centres, all external beam modalities and every radiotherapy treatment unit in the Republic of Ireland. MATERIALS AND METHODS Reference point measurements were made for all megavoltage photon beams. Doses were also investigated in planned three-field distributions. One of these...

Ophthalmic Graves' disease and histiocytosis X involving the orbit are occasionally refractory to treatment, so that vision may be threatened. In these situations megavoltage external beam radiotherapy should be employed, and the indications for this treatment are discussed. A highly accurate technique is described, using precise planning with information obtained from high definition CT scans,...

PURPOSE Megavoltage photon beams are typically used for therapy because of their skin-sparing effect. However, a focused low-energy x-ray beam would also be skin sparing, and would have a higher dose concentration at the focal spot. Such a beam can be produced with polycapillary optics. MCNP5 was used to model dose profiles for a scanned focused beam, using measured beam parameters. The potenti...

the output of x-ray, especially in the field of required energy for diagnosing the disease is very low (in diagnosing lamps, it is less than 1%). in this kind of lamps the rest of the electrical energy is transformed to heat. this considerable amount of heat induces a myriad of too many limitations in choosing higher levels of radiation, particularly in specialized techniques. this process is t...

Linacs equipped with flattening filter-free (FFF) megavoltage photon beams are now commercially available. However, the commissioning of FFF beams poses challenges that are not shared with traditional flattened megavoltage X-ray beams. The planning system must model a beam that is peaked in the center and has an energy spectrum that is softer than the flattened beam. Removing the flattening fil...

Background: An effective method for management of large and bulky malignant tumors. This treatment modality is also known as Specially Fractionated Radiation Therapy (SFRT). In this treatment technique a grid block converted the open radiation field into a series of pencil beams. Dosimetric characteristics of an external beam grid radiation field have been investigated using experimental and Mo...

There is a growing interest in patient exposure resulting from an x-ray imaging procedure used in image-guided radiation therapy. This study explores a feasibility to use a commercially available optically stimulated luminescence (OSL) dosimeter, nanoDot, for estimating imaging radiation exposure to patients. The kilovoltage x-ray sources used for kV-cone-beam CT (CBCT) imaging acquisition proc...

One of the applications of gold nanoparticles (GNPs) in medicine is radiation dose-enhancing effect. Although there are many simulations, in vitro and in vivo evidence that GNPs can enhance significantly the radiation dose effect of orthovoltage beams. These beams compared with megavoltage (MV) beams, have limited applications in radiotherapy. In order to evaluate GNPs radiosensitization perfor...