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At present, only a correction factor for photon transmission, k(l), is systematically applied for the entrance diaphragm of free-air chamber standards for air kerma. In the present work, the Monte Carlo code PENELOPE is used to re-evaluate k(l) for the BIPM standards and new correction factors are calculated for photon scatter and for fluorescence(More)
Atomic force microscopy (AFM) is a recent technique generating tridimensional images at nanometric scale whatever the nature of the chemical sample. An AFM microscope affords the measurement of interatomic forces exerting between a probe associated to a cantilever and a chemical sample. A force spectrum f (z) shows the force evolution as a function of the(More)
A graphite-walled cavity ionization chamber of modular design and variable volume has been used to determine the air-kerma rate in the reference 60Co field at the BIPM. The chamber can be configured in five sizes. High-accuracy mechanical measurements of the volume of the air cavity were made for each configuration using a co-ordinate measuring machine.(More)
The BIPM graphite calorimeter standard for absorbed dose to water has been used in conjunction with an ionization chamber of known volume and with Monte Carlo simulations of these arrangements to determine the value for Wair in (60)Co radiation and in accelerator photon beams up to 25 MV. The results show no evidence for a variation in Wair at the 0.2%(More)
Because of its binding to specific cerebral amine receptor sites 123I-N-isopropyl-amphetamine (IMP) tracer activity can be used as a measure for the regional cerebral blood flow (rCBF) in the human brain. In 21 psychiatric in-patients an IMP perfusion study was performed using a rotating gamma camera system. The findings at single photon emission computed(More)
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