Which of the following reduce patient radiation dose?

The correct choice is the combination of a collimator and high-speed intensifying screens for reducing patient radiation dose.

A collimator is a device used to limit the size and shape of the X-ray beam. By defining the area being exposed and eliminating unnecessary radiation to surrounding tissues, collimators significantly help in minimizing the radiation dose that patients receive during radiographic procedures. This precise targeting reduces scatter radiation, ultimately protecting the patient from excess exposure.

High-speed intensifying screens are used in conjunction with X-ray film to enhance the image quality while allowing for a lower dose of radiation to be used. These screens convert X-ray photons into visible light, which the film is more sensitive to, requiring less radiation exposure to achieve a diagnostic image. This efficient use of radiation further contributes to a reduction in patient dose while maintaining image integrity.

While combinations that include a grid also play a role in reducing scatter radiation and improving image quality, the standout features of collimators and high-speed screens specifically focus on minimizing the radiation dose received by the patient. Other options either include components whose primary function is not dose reduction or combine factors that do not enhance the reduction as effectively as the correct choice does.