An apparatus includes: a structure having a lumen for accommodating a beam, wherein the structure is a component of a medical radiation machine having a target for interaction with the beam to generate radiation; and a first beam position monitor comprising a first electrode and a second electrode, the first electrode being mounted to a first side of the structure, the second electrode being mounted to a second side of the structure, the second side being opposite from the first side; wherein the first beam position monitor is located upstream with respect to the target.

An apparatus includes: a structure having a lumen for accommodating a beam (e.g., electron beam, proton beam, or a charged particle beam), wherein the structure is a component of a medical radiation machine having a target for interaction with the beam to generate radiation; and a first beam position monitor comprising a first electrode and a second electrode, the first electrode being mounted to a first side of the structure, the second electrode being mounted to a second side of the structure, the second side being opposite from the first side; wherein the first beam position monitor is located upstream with respect to the target.

An apparatus includes: a structure having a lumen for accommodating a beam (e.g., electron beam, proton beam, or a charged particle beam), wherein the structure is a component of a medical radiation machine having a target for interaction with the beam to generate radiation; and a first beam position monitor comprising a first electrode and a second electrode, the first electrode being mounted to a first side of the structure, the second electrode being mounted to a second side of the structure, the second side being opposite from the first side; wherein the first beam position monitor is located upstream with respect to the target.

A method of generating X-rays includes providing a field-emission diode including two electrodes separated by a gap, a first conductor, a first insulator on a surface of the first conductor, a second insulator on a surface of the first insulator that is not in contact with the first conductor, and a second conductor. The first insulator and the second insulator have trapped electrons at an interface therebetween, and are provided between the first conductor and the second conductor. The method further includes moving the second conductor with respect to the first conductor to induce electrons on the second conductor via electrostatic induction; accelerating the induced electrons across the gap of the field-emission diode; and striking a target with accelerated electrons to produce an X-ray. The first insulator and the second insulator are not the same.

A method of generating X-rays includes providing a field-emission diode including two electrodes separated by a gap, a first conductor, a first insulator on a surface of the first conductor, a second insulator on a surface of the first insulator that is not in contact with the first conductor, and a second conductor. The first insulator and the second insulator have trapped electrons at an interface therebetween, and are provided between the first conductor and the second conductor. The method further includes moving the second conductor with respect to the first conductor to induce electrons on the second conductor via electrostatic induction; accelerating the induced electrons across the gap of the field-emission diode; and striking a target with accelerated electrons to produce an X-ray. The first insulator and the second insulator are not the same.

A method of generating X-rays includes providing a field-emission diode including two electrodes separated by a gap, a first conductor, a first insulator on a surface of the first conductor, a second insulator on a surface of the first insulator that is not in contact with the first conductor, and a second conductor. The first insulator and the second insulator have trapped electrons at an interface therebetween, and are provided between the first conductor and the second conductor. The method further includes moving the second conductor with respect to the first conductor to induce electrons on the second conductor via electrostatic induction; accelerating the induced electrons across the gap of the field-emission diode; and striking a target with accelerated electrons to produce an X-ray. The first insulator and the second insulator are not the same.