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A high precision patient dosimetry method has been developed, based on the use of p-type diodes. First, entrance as well as exit dose calibration factors have to be determined under reference irradiation conditions. Secondly, a set of correction factors must be added for situations deviating from the reference conditions, i.e. for different source-skin(More)
High precision in vivo entrance and exit dose measurements have been performed with p-type diodes on patients during 8 MV X-ray irradiation of the pelvis, to investigate the accuracy of dose calculations in this region. Based on phantom measurements the accuracy of the p-type diode measuring system itself, i.e. the agreement with ionisation chamber dose(More)
Quality assurance (QA) in radiotherapy is of particular importance if a new irradiation technique is introduced. The dosimetric aspects of such a QA program concern the check of the dose calculation procedure, i.e. the prediction of the relative dose distribution, as well as the verification of the absolute value of the target absorbed dose specified at a(More)
The purpose of this study was to determine the dosimetric accuracy of the treatment of parotid gland tumours using 8 MV X-ray beams. These tumours are generally situated near the patient's skin. Entrance in vivo dose measurements with diodes were obtained for 20 patients during 5 sessions per patient, in the anterior-oblique and posterior-oblique wedged(More)
To test the accuracy and reproducibility of the tangential breast treatment set-up used in The Netherlands Cancer Institute, a portal imaging study was performed in 12 patients treated for early stage breast cancer. With an on-line electronic portal imaging device (EPID) images were obtained of each patient in several fractions and compared with simulator(More)
The head scatter dose contribution to the output of a treatment machine has been determined for an open and wedged 60Co gamma-ray beam and for open and wedged x-ray beams of 4, 8, and 16 MV. From those data wedge factor values "in air" have been deduced, expressed as the ratio of the dose to water, measured in air, for the situation with and without wedge,(More)
PURPOSE Conformal radiotherapy requires accurate knowledge of the actual dose delivered to a patient. The impact of routine in vivo dosimetry, including its special requirements, clinical findings and resources, has been analysed for three conformal treatment techniques to evaluate its usefulness in daily clinical practice. MATERIALS AND METHODS Based on(More)
The head and phantom scatter contribution to the output of a treatment machine have been determined for open and wedged 60Co gamma-ray beams and 4, 8, 16 and 25 MV X-ray beams, using an extended and a small-sized phantom. The wedge factor variation with field size and phantom depth have been analysed as a function of both scatter components. For the wedged(More)
PURPOSE To determine the accuracy of dose calculations based on CT-densities for lung cancer patients irradiated with an anterio posterior parallel-opposed treatment technique and to evaluate, for this technique, the use of diodes and an Electronic Portal Imaging Device (EPID) for absolute exit dose and relative transmission dose verification, respectively.(More)
The 3-dimensional (3-D) dose distribution as calculated in clinical practice for tangential breast treatment was verified by means of in vivo dosimetry. Clinical practice in our institution implies the use of 8 MV X-ray beams, a 2-D treatment planning system, collimator rotation and a limited set of patient data for dose calculations. By positioning diodes(More)