This review discussed the potential of proton FLASH for head and neck cancer reirradiation, highlighting the proton conformal FLASH techniques, which uses the highest single-energy and multiple-field inverse optimization with implementation of range compensator and range shifter and/or range modulator, treatment plans at the desired FLASH dose rate have been reported to have achieved conventional IMPT-equivalent conformality and plan quality. This review also suggested a possible solution of developing the single-energy Bragg peak FLASH technique, which will eliminate the energy selection and transportation systems, reducing the footprint of the proton systems. By reducing the technological barriers and associated costs, the single-energy Bragg peak technique opens up new possibilities for more affordable proton FLASH-RT.