X-ray flash radiotherapy devices and methods
View Patent ↗An x-ray FLASH radiotherapy device uses an electron beam to generate x-rays on a target element. The focal area on the target element is about 1 to about 12 cm 2 . The target element is separated from a radiotherapy patient by a thin aerogel insulator. Using about 50 to 200 kV of power, the x-ray FLASH radiotherapy device administers 40 Gy/s of radiation or more during short bursts or pulses of one second or less. Due to the short duration of these pulses, heating of the target element is limited, thereby reducing the source to surface distance between the radiation source and the patient.
1 . A method of applying superficial x-ray FLASH radiotherapy to a patient comprising:
Providing an x-ray FLASH radiotherapy device comprising an electron beam generator, a power supply providing 50 to 200 kV to the electron beam generator, an x-ray target element having a diameter between 1 cm and 5 cm, a drift tube extending between the electron beam generator and the x-ray target element, and an insulator covering a distal end of the target element;
placing the distal end of the device between 0.5 mm and 2 cm from an area of the patient's skin to be treated; and,
emitting one or more pulses of x-ray radiation, wherein each pulse is between the 0.1 to and 1 second and a dosage per pulse is greater than 40 Gray/second;
wherein the pulse of x-ray radiation is emitted by the electron gun emitting an electron pulse that impinges on the target element over a focal area having a diameter between 1 cm and 5 cm.
2 . The method of applying superficial x-ray FLASH radiotherapy to a patient of claim 1 , wherein the electron beam generator comprises a filament in an ionization chamber, a proximal electrode and a switch for rapidly alternating the polarity of the proximal electrode.
3 . The method of applying superficial x-ray FLASH radiotherapy to a patient of claim 2 , wherein the switch for rapidly alternating a polarity of the proximal electrode comprises an H bridge.
4 . The method of applying superficial x-ray FLASH radiotherapy to a patient of claim 3 wherein the radiotherapy device further comprises an annular heat sink extending around the target element.
5 . The method of applying superficial x-ray FLASH radiotherapy to a patient of claim 4 wherein the insulator has a width substantially equal to a width of the annular heat sink.
6 . The x-ray FLASH radiotherapy device of claim 5 wherein the electron gun has no control anode on a side of the filament opposite to the proximal electrode.