Scientific publications

Quality assurance in IMRT: importance of the transmission through the jaws for an accurate calculation of absolute doses and relative distributions

Azcona J.D., Siochi R.A., Azinovic I.
Department of Oncology, Division of Radiation Physics, Clínica Universitaria de Navarra, Pamplona, Spain.

Magazine: Medical Physics Online

Date: Mar 1, 2002

Radiation Oncology

The goal of IMRT is to achieve an isodose distribution conformed to the tumor while avoiding the organs at risk.

For these tasks several gantry angles are selected, each one containing a series of different leaf configurations for the multileaf collimator (MLC) (segments). Verifying the relative distributions as well as the absolute doses is an important step for quality assurance issues. We have observed that an accurate modeling of the transmission of the primary x-ray fluence through the jaws and MLC as well as the head scatter is crucial for a precise calculation of relative doses and monitor units. Also, an inaccurate calculation of the output factor for small size segments can lead to important differences in the absolute dose for points under these segments.

Incorrect models could lead to systematic errors of around 5% to 10% in the calculated monitor units and a shift in the isodose curves.

CITATION  Med Phys. 2002 Mar;29(3):269-74



The Clínica is the greater private hospital with technological equipment of Spain, all in a single center.

Imagen de un PET, tecnología de vanguardia en la Clínica Universidad de Navarra


The professionals of the Clínica perform continuous research and training, always to the benefit of the patient.

Imagen profesionales de la Clínica Universidad de Navarra


Learn why we are different from other healthcare centers. Quality, speed, comfort and results.

Imagen del edificio de la Clínica Universidad de Navarra