Radiotherapy is now recognized as a pillar in the fight against cancer. Two different types are currently used in clinical practice: (1) external beam radiotherapy, using high-energy X-rays or electron beams, both in the MeV-range, and (2) intraoperative radiotherapy, using low-energy X-rays (up to 50 keV) and MeV-range electron beams. Versatile detectors able to measure the radiation dose independently from the radiation nature and energy are therefore extremely appealing to medical physicists. In this work, a dosimeter based on a high-quality single-crystal synthetic diamond sample was designed, fabricated and characterized under low-energy X-rays, as well as under high-energy pulsed X-rays and electron beams, demonstrating excellent linearity with radiation dose and dose-rate. Detector sensitivity was measured to be 0.299 ± 0.002 µC/Gy under 6 MeV X-ray photons, and 0.298 ± 0.004 µC/Gy under 6 MeV electrons, highlighting that the response of the diamond dosimeter is independent of the radiation nature. Moreover, in the case of low-energy X-rays, an extremely low limit of detection (23 nGy/s) was evaluated, pointing out the suitability of the device to radiation protection dosimetry.

A single-crystal diamond sample grown by high-pressure high-temperature (HPHT) technique was used for the fabrication of a metal–semiconductor–metal (MSM) photoconductor. The sample quality was evaluated by means of spectral photocurrent measurements highlighting the presence of a significant density of defect states within the diamond bandgap, responsible for trap-mediated conduction mechanisms. The photoconductor was fully characterized under 6 MeV pulsed X-rays, sourced by a medical linear accelerator (LINAC), in the 0.05–20 Gy and 0.017–0.100 Gy/s dose (D) and dose-rate (DR) ranges, respectively. Photocurrent measurements performed with a conventional precision electrometer showed that the detector performance is strongly affected by charge-trapping phenomena, resulting in a sublinear dependence with the DR (power-law dependence with an exponent of 0.86). Measurements were repeated in the same experimental conditions by coupling the detector to a specifically developed gated integrator, allowing for a synchronous integration of photocurrent pulses (limited to 40 $\mu \text{s}$ ) centered on each impinging X-ray pulse. In this case, the detector photoresponse showed an excellent linearity with both the D and the DR (power-law dependence with 1.0009 ± 0.0004 and 1.009 ± 0.005 exponents, respectively). Significantly, the proposed synchronous integration technique is then able to mitigate the detrimental effect that defects have on detector performance. The proposed method paves, therefore, the way to the exploitation of HPHT diamond as a low-cost alternative to single-crystal chemical vapor deposition (CVD)-diamond for the fabrication of accurate and linear X-ray dosimeters.

Gated integrating measurement method represents a widely used approach when fast, repetitive analogue signals are concerned. In this work a compact synchronized gated-integrator prototype has been realized and preliminary characterized. Front-end electronics is based on the mature high-precision switched-integrator transimpedance-amplifier IVC102 whose output is connected to a precision LT1911 inverting amplifier, whereas analogue-to-digital conversion, as well as timing control circuitry, are performed by a high-efficiency LPC845 microcontroller. Synchronizing signal detection with the external trigger generated in coincidence with a source, the proposed circuitry amplifies and integrates the signal only when the pulse is generated, displaying excellent performances in terms of linearity, sensitivity and signal-to-noise ratio. Hence, the proposed solution represents an affordable alternative to continuous-time regime measurement-techniques, usually adopted in radiation dosimetry where accuracy and sensitivity are strict requirements for treatment quality assurance.

Some properties of electrochemical systems can be properly characterized by low- and extremely low-frequency impedance measurements. The frequency range down to 1 mHz requires peculiar attention in terms of accuracy, measurement speed, portability and costs, and commercial systems are often unable to guarantee good performances without expensive or bulky solutions. Here, we first review some of the applications of electrochemical impedance spectroscopy and their requirements and then report on recent works proposing circuits and systems focused on optimizing performances, reducing costs, and increasing versatility. Circuits for generating controllable current sources are described, optimizing output impedance and measurable impedance range. Then, integrated systems are taken into account, aiming at realizing portable and versatile instruments.