To ensure metrological reliability, ISO established the ISO4037-1 standard applied to the production of x and gamma reference radiations for calibration and energy dependence determination of dosimeters used in radiological protection. The ISO4037-1:2019 version, that replaced the old 1996, introduced the matched and characterized reference field concepts. Besides, it established new quite strict requirements for the reference radiation parameters like high voltage, filter purity and filter thickness. The aim is that the overall uncertainty (k = 2) of about 6 % to 10 % for the phantom related operational quantities is not exceeded. Only for matched reference fields, that are those fields that comply with all new requirements, a validation procedure based on half-value layer determination is requested, considering the depths d of 0.07, 3 and 10 mm, which are related to the dose equivalent operational quantity H(d), for instance. In this case, no additional characterization is needed and the conversion coefficients from air kerma, K_a, to H(d) given in ISO4037-3:2019 shall be used. For characterized reference fields, more relaxed requirements were recommended, but radiation field characterization is necessary by one of two methods: direct H(d) determination with a secondary standard or energy spectrum determination by spectrometry and calculation of the conversion coefficients from K_a to H(d). For both methods, the targeted limits for the overall uncertainty of H(d) must be fulfilled. The ISO 4037-1:2019 requirements need a critical analysis to verify if they are achievable by Brazilian metrology calibration laboratories. This work aimed to verify the compliance with ISO 4037-1:2019 of N-60, N-100, N-120 and N-150 narrow spectrum x-reference radiations produced by the CDTN Dosimeter Calibration Laboratory to be used for calibration and performance test in terms of the personal dose equivalent, H_p(d). Against the ISO recommendation, the spectrometry method was studied and proved to be feasible to determine the maximum high voltage applied to the x-ray tube. The methodology of half-value layer determination was also studied and applied as the validation procedure to show that some CDTN N-reference radiations fulfilled the ISO requirements.