This doctoral thesis explains the reasons that have encouraged the author and his associates to develop a new Active Electronic Dosemeter( AED) of ALARA OD type x for measurement of ionising radiation. The aim was to enhance and improve measurement reliability in comparison with existing passive and commercially available electronic dosemeters in the region of low and very low doses and dose rates.T he achieved reliability lies inside variation range of ionizing background radiation. The thesis also describes the author's contribution in the AED development; AED has unique measuring characteristic. Software supporting two operating modes, in addition to real-time measurement, provides resolution of measured dose rate data from natural background radiation (BG). These measurements enable temporal distinction between dose receipt (i.e. dose rate) and creation of typical temporal templates for each interventional procedure performed on a patient. Investigation of low and very low doses of radiation, and in particular interaction of x-ray radiation with human body is of great importance for epidemiological research on the health effects of radiation to humans. Over the past 30 years overall human exposure to x-rays in the range of low photon energies (less than 300 keV) has significantly increased and it is therefore of great importance to detect as many as possible potential effects of low dose radiation on living matter. Collecting sufficient amount of dose measurement data would enable further biological, genetic and related researchesa nd developmento f more suitable radiation protection methods. The thesis introduces a model of the spatial distribution of scattered x-ray radiation produced within a patient's body and propagated within the interventional radiology and cardiology rooms, based on real diagnostic and interventional x-ray procedures. Modeled isodose curves and surfaces presented, represent results obtained from experimental measurements performed using twenty active electronic dosemeters ALARA OD 3 properly placed in interventional room. Model validity is checked becauset he final goal of understanding the distribution of scattered x -ray radiation is to enable a prompt and easy estimation of maximum exposure for both medical workers and patients and to provide an appropriate level of protection. The example is given to demonstrate how the model of scattered radiation, isodose curves and simple geometry model for worker could be used to estimate maximum personal dose equivalent (or/and total body effective dose) which is a new and original approach. This doctoral thesis extends the concept of dynamic dosimetry to the interventional radiology and cardiology which is made possible owing to temporal distinction capability of AED. The efforts were described that have been invested to acknowledge / recognize the use of AED of ALARA PD 4 type in regulatory sense as a personal dosimeter in radiation protection.