A readout apparatus for time-of-flight and energy measurements, for a positron emission tomography, PET, system, suitable for providing accurate time-of-flight information when used in a PET system with fast crystals and confining the origin of the two 511 keV photons with a position uncertainty of 30 mm along a line-of-response, the readout apparatus comprising: a plurality of silicon photomultipliers, SiPM, each SiPM being associated with a channel from a plurality of channels; a plurality of front-end conditioning circuits configured to receive an input pulse, each front-end conditioning circuit being associated with a channel and each front-end conditioning circuit comprising: a low impedance input differential amplifier comprising a regulated-gate cascode circuit with low-noise and high bandwidth, the regulated-gate cascode circuit being configured to have the ability to fine tune the DC node voltage of said input pulse and to provide a corresponding output, and a dual-threshold mechanism comprising first and second threshold discriminators, each threshold discriminator having an independently adjustable threshold, each threshold discriminator being configured to receive the output of the low impedance input differential amplifier as an input and to provide a corresponding output, wherein the first threshold discriminator is set to a very low threshold in order to generate a trigger on the first photo-electron of the input pulse for measuring time, and wherein the second threshold discriminator is set to a threshold higher than the threshold of the first threshold discriminator in order to validate or discard the input pulse, characterized in that the readout apparatus further comprises first and second analogue time-to-digital converters, TDCs, per channel, the first TDC being configured to receive the output of the first threshold discriminator as input, the second TDC being configured to receive the output of the second threshold discriminator as input, each of the TDCs being configured to generate an output based on time interpolation of the respective received inputs, wherein the first and second TDCs are configured to measure independently the timing of the rising and the falling edges of the input pulse, thereby providing time stamps consisting of coarse and fine time information, where the said coarse time is given by a global Gray-encoded coarse time 10-bit counter, and the said fine time is derived from an 8-bit 50 ps time binning, and wherein said front-end conditioning circuits and TDCs have a power consumption smaller than 10 mW per channel, suitable for use in Time-of-Flight Positron Emission Tomography, TOP-FET, systems. a plurality of silicon photomultipliers, SiPM, each SiPM being associated with a channel from a plurality of channels; a plurality of front-end conditioning circuits configured to receive an input pulse, each front-end conditioning circuit being associated with a channel and each front-end conditioning circuit comprising: a low impedance input differential amplifier comprising a regulated-gate cascode circuit with low-noise and high bandwidth, the regulated-gate cascode circuit being configured to have the ability to fine tune the DC node voltage of said input pulse and to provide a corresponding output, and a dual-threshold mechanism comprising first and second threshold discriminators, each threshold discriminator having an independently adjustable threshold, each threshold discriminator being configured to receive the output of the low impedance input differential amplifier as an input and to provide a corresponding output, wherein the first threshold discriminator is set to a very low threshold in order to generate a trigger on the first photo-electron of the input pulse for measuring time, and wherein the second threshold discriminator is set to a threshold higher than the threshold of the first threshold discriminator in order to validate or discard the input pulse, characterized in that the readout apparatus further comprises first and second analogue time-to-digital converters, TDCs, per channel, the first TDC being configured to receive the output of the first threshold discriminator as input, the second TDC being configured to receive the output of the second threshold discriminator as input, each of the TDCs being configured to generate an output based on time interpolation of the respective received inputs, wherein the first and second TDCs are configured to measure independently the timing of the rising and the falling edges of the input pulse, thereby providing time stamps consisting of coarse and fine time information, where the said coarse time is given by a global Gray-encoded coarse time 10-bit counter, and the said fine time is derived from an 8-bit 50 ps time binning, and wherein said front-end conditioning circuits and TDCs have a power consumption smaller than 10 mW per channel, suitable for use in Time-of-Flight Positron Emission Tomography, TOP-FET, systems.