Apparatus for irradiating goods with a radiation selected from X-rays or electron beam, comprising, • a source of radiation selected from X-rays and electron beam, configured for emitting the radiation along an irradiation volume (Xv) centred on an irradiation axis, transport units (1.i), totes, • a conveyor configured for driving the goods loaded in two or more transport units (1.i) of unit height h1.i measured along a vertical axis normal to the irradiation axis, along a transverse axis normal to both irradiation and vertical axes,, through the irradiation volume such as to expose a first portion of the goods to the radiation, wherein the transport units (1.i) are loaded in totes of tote height h5, wherein h5 = H51 - h50, measured along the vertical axis from a bottom end located at a bottom end height h50 to a top end located at a top end height h51, wherein the conveyor is configured for driving the totes carrying N transport units (1.i) loaded with the goods, wherein • the totes comprise support elements for supporting transport units (1.i), wherein the support elements can be positioned at different levels along the tote height h5 of the totes, • a tote holds N transport units, with N ∈ N and N ≥ 1, arranged on top of one another extending over a total height ht, wherein ht = Ht1 - Ht0, measured along the vertical axis from a bottom of a first transport unit (1.1) located nearest to the bottom end of the tote at a bottom unit height Ht0 to a top of an N th transport unit (1.N) located nearest the top end of the tote at a top unit height Ht1, and wherein each transport unit (1.i) is held in place in a tote by one or more support elements, such that ∘ The total height ht is comprised between 40% and 100% of the tote height h5, i. e., 40% h5 ≤ ht ≤ h5, preferably between 60% and 80% of the tote height, ∘ The N transport units (1.1-1.N) loaded in a tote span over at least 70%, preferably at least 80% of the total height ht, i.e., ∑ i = 1 N h 1. i ≥ 70 % ht, ∘ The total height ht is centred relative to the tote height h5 within ±20%, i.e., (Ht1 - 1⁄2 ht) = 1⁄2 h5 ± 20%, preferably within ±10%, i.e., (Ht1 - 1⁄2 ht) = 1⁄2 h5 ± 10% Characterized in that, the apparatus is configured to position the support elements at different levels along the tote height of the totes so that it is possible to tailor the position of the transport units according to any criterion. • a source of radiation selected from X-rays and electron beam, configured for emitting the radiation along an irradiation volume (Xv) centred on an irradiation axis, transport units (1.i), totes, transport units (1.i), totes, • a conveyor configured for driving the goods loaded in two or more transport units (1.i) of unit height h1.i measured along a vertical axis normal to the irradiation axis, along a transverse axis normal to both irradiation and vertical axes,, through the irradiation volume such as to expose a first portion of the goods to the radiation, wherein the transport units (1.i) are loaded in totes of tote height h5, wherein h5 = H51 - h50, measured along the vertical axis from a bottom end located at a bottom end height h50 to a top end located at a top end height h51, wherein the conveyor is configured for driving the totes carrying N transport units (1.i) loaded with the goods, wherein • the totes comprise support elements for supporting transport units (1.i), wherein the support elements can be positioned at different levels along the tote height h5 of the totes, • a tote holds N transport units, with N ∈ N and N ≥ 1, arranged on top of one another extending over a total height ht, wherein ht = Ht1 - Ht0, measured along the vertical axis from a bottom of a first transport unit (1.1) located nearest to the bottom end of the tote at a bottom unit height Ht0 to a top of an N th transport unit (1.N) located nearest the top end of the tote at a top unit height Ht1, and wherein each transport unit (1.i) is held in place in a tote by one or more support elements, such that ∘ The total height ht is comprised between 40% and 100% of the tote height h5, i. e., 40% h5 ≤ ht ≤ h5, preferably between 60% and 80% of the tote height, ∘ The N transport units (1.1-1.N) loaded in a tote span over at least 70%, preferably at least 80% of the total height ht, i.e., ∑ i = 1 N h 1. i ≥ 70 % ht, ∘ The total height ht is centred relative to the tote height h5 within ±20%, i.e., (Ht1 - 1⁄2 ht) = 1⁄2 h5 ± 20%, preferably within ±10%, i.e., (Ht1 - 1⁄2 ht) = 1⁄2 h5 ± 10% ∘ The total height ht is comprised between 40% and 100% of the tote height h5, i. e., 40% h5 ≤ ht ≤ h5, preferably between 60% and 80% of the tote height, ∘ The N transport units (1.1-1.N) loaded in a tote span over at least 70%, preferably at least 80% of the total height ht, i.e., ∑ i = 1 N h 1. i ≥ 70 % ht, ∘ The total height ht is centred relative to the tote height h5 within ±20%, i.e., (Ht1 - 1⁄2 ht) = 1⁄2 h5 ± 20%, preferably within ±10%, i.e., (Ht1 - 1⁄2 ht) = 1⁄2 h5 ± 10%