BACKGROUND: One of the important prerequisites for using a virtual wedge is the availability of an appropriate method for quality assurance. A simple method to determine wedge angles has been developed. MATERIAL AND METHODS: A formula based on the exponential attenuation curve has been derived, that allows for the calculation of the wedge isodose angles based on 2 measurement points perpendicular to the central ray. The linear attenuation coefficient is the only variable that must be known for the field size under consideration. RESULTS: Using the algorithm introduced, the wedge angle isodoses can be measured with a high degree of accuracy. The deviation of the wedge angle compared to the measurements done according to DIN 6847-4 is less than 1 degree. CONCLUSION: The described procedure is a simple method of performing routine quality assurance for the virtual wedge.
BACKGROUND: One of the important prerequisites for using a virtual wedge is the availability of an appropriate method for quality assurance. A simple method to determine wedge angles has been developed. MATERIAL AND METHODS: A formula based on the exponential attenuation curve has been derived, that allows for the calculation of the wedge isodose angles based on 2 measurement points perpendicular to the central ray. The linear attenuation coefficient is the only variable that must be known for the field size under consideration. RESULTS: Using the algorithm introduced, the wedge angle isodoses can be measured with a high degree of accuracy. The deviation of the wedge angle compared to the measurements done according to DIN 6847-4 is less than 1 degree. CONCLUSION: The described procedure is a simple method of performing routine quality assurance for the virtual wedge.