A planning apparatus for planning a radiation therapy, wherein the planning apparatus comprises: - a medical image provider configured to provide a medical image of a subject, wherein in the medical image a target to be treated with radiation beams is indicated, - a ray geometry provider configured to provide ray geometries for different radiation beams to be used for irradiating the target, wherein a respective radiation beam comprises respective rays and a respective ray geometry defines, for the respective radiation beam, positions of the respective rays of the respective radiation beam, - a reformatter configured to reformat the provided medical image based on the provided ray geometries, resulting in several reformatted medical images (8, 9), wherein a respective reformatted medical image (8, 9) results from reformatting the provided medical image in accordance with a respective ray geometry, - a neural network provider configured to provide a neural network unit which has been trained to output radiation therapy parameters being indicative of intensities of rays of radiation beams to be used during the radiation therapy based on an input which depends on reformatted medical images in which a target to be treated with radiation beams is indicated and which have been reformatted in accordance with ray geometries of the rays of the radiation beams, - a radiation therapy parameters determiner configured to determine radiation therapy parameters being indicative of intensities of the rays of the radiation beams to be used for irradiating the target based on the reformatted medical images (8, 9) by using the provided neural network unit. - a medical image provider configured to provide a medical image of a subject, wherein in the medical image a target to be treated with radiation beams is indicated, - a ray geometry provider configured to provide ray geometries for different radiation beams to be used for irradiating the target, wherein a respective radiation beam comprises respective rays and a respective ray geometry defines, for the respective radiation beam, positions of the respective rays of the respective radiation beam, - a reformatter configured to reformat the provided medical image based on the provided ray geometries, resulting in several reformatted medical images (8, 9), wherein a respective reformatted medical image (8, 9) results from reformatting the provided medical image in accordance with a respective ray geometry, - a neural network provider configured to provide a neural network unit which has been trained to output radiation therapy parameters being indicative of intensities of rays of radiation beams to be used during the radiation therapy based on an input which depends on reformatted medical images in which a target to be treated with radiation beams is indicated and which have been reformatted in accordance with ray geometries of the rays of the radiation beams, - a radiation therapy parameters determiner configured to determine radiation therapy parameters being indicative of intensities of the rays of the radiation beams to be used for irradiating the target based on the reformatted medical images (8, 9) by using the provided neural network unit.