Apparatus for irradiating goods loaded in totes

1 . An apparatus for irradiating goods with X-ray or electron beam radiation, the apparatus comprising:

a radiation source configured to emit radiation along an irradiation volume centered around an irradiation axis, wherein the radiation comprises X-rays or an electron beam;

a conveyor configured to drive two or more transport units, along a transverse axis through the irradiation volume to expose the goods in the two or more transport units to the radiation, wherein each of the two or more transport units has a unit height along a vertical axis normal to the irradiation axis, and the transverse axis is normal to the irradiation axis and the vertical axis; and

a plurality of totes each having a tote height along the vertical axis and configured to hold the two or more transport units;

wherein:

one of the plurality of totes holds at least one of the two or more transport units extending over a total height along the vertical axis,

the conveyor is configured to drive the two or more transport units by driving the plurality of totes carrying the two or more transport units containing the goods,

the plurality of totes comprise support elements for supporting the two or more transport units, wherein:

the support elements are positioned at different levels along the tote height of the plurality of totes, to adapt a distance separating two adjacent support elements along the vertical axis,

the support elements are configured to be positioned at the different levels to tailor positions of the two or more transport units in the plurality of totes based on the unit heights of the two or more transport units,

the total height is between 40% and 100% of the tote height,

the at least one transport unit spans over at least 70% of the total height in the one of the plurality of totes, and

the total height is centered relative to the tote height within ±20%.

2 . The apparatus of claim 1 , further comprising a processing control unit configured to perform at least one of:

measuring the unit height of the two or more transport units prior to loading the two or more transport units into the plurality of totes;

weighing the two or more transport units and determining corresponding densities of the two or more transport units;

determining a target total height according to a height of the irradiation volume measured along the vertical axis and selecting the N transport units to be loaded in each tote to reach a total height lower than the tote height and comprised within ±10% of the target total height,

optimizing, for each of the plurality of totes, the height of the irradiation volume to the total height of at least one of the two or more transport units loaded in a corresponding one of the plurality of totes;

determining a loading scheme of the two or more transport units, assigning which of the two or more transport units are to be loaded in which of the plurality of totes, and assigning a loading position of each of the two or more transport units in a corresponding one of the totes along the vertical axis according to at least one of:

unit heights of the two or more transport units, to maximize a filling ratio of the total height to the tote height, or

densities of at least one of the two or more transport units in the corresponding tote, to have similar densities within ±25%; or

assigning a position for each of the support elements according to the unit heights of the two or more transport units to minimize a gap ratio of a total gap separating every two adjacent transport units in a same tote to the total height.

3 . The apparatus of claim 1 , further comprising:

a rotating element configured for rotating the plurality of totes by an angle of rotation,

wherein the conveyor is configured to drive the plurality of totes through the irradiation volume a plurality of times to expose a plurality of portions of the goods to the radiation, wherein the plurality of totes are rotated by the angle of rotation in each of the plurality of times.

4 . The apparatus of claim 1 , further comprising one of:

a first scan horn coupled to the radiation source for one-level irradiation of the plurality of totes, wherein the radiation source with the first scan horn is configured to over-scan such that the irradiation volume entirely covers the tote height and first portions of the goods of at least one of the two or more transport units in the corresponding tote are exposed to a required dose in a single pass; or

a second scan horn coupled to the radiation source for two-level irradiation of the plurality of totes, wherein the radiation source with the second scan horn is configured to under-scan such that the irradiation volume does not entirely cover the tote height and the first portions of the goods of the at least one transport unit in the tote are exposed to the required dose in two passes, a first of the two passes being with a first selection of the at least one transport unit in an upper half portion of the tote and a second selection of the at least one transport unit in a lower half portion of the tote, and a second of the two passes being with the first selection of the at least one transport unit in the lower half portion of the tote and the second selection of the at least one transport unit in the upper half portion of the tote.

5 . The apparatus of claim 1 , further comprising:

a swapping unit configured to transfer one or more of the at least one transport unit in an upper half portion of a first of the plurality of totes to a lower half portion of a second of the plurality of totes and one or more of the at least one transport unit in a lower half portion of the first of the plurality of totes to an upper half portion of the second of the plurality of totes for driving the second of the plurality of totes through the irradiation volume.

6 . The apparatus of claim 1 , wherein the conveyor comprises;

an elevated track on which the plurality of totes are suspended and driven, or

a roller conveyor on which the plurality of totes stand and are driven.

7 . The apparatus of claim 1 , wherein:

the tote height is between 500 and 650 centimeters (cm),

the unit height is between 50 and 380 cm, and

a gap separating two adjacent transport units of the two or more transport units in a same tote is between 8 and 30 cm.

8 . The apparatus of claim 1 , wherein a dose uniformity ratio is a ratio of a maximum dose to a minimum dose deposited, by the radiation source, into a good along the irradiation axis as a function of the vertical axis between a bottom of one of the two or more transport units and a top of the one of the two or more transport units, and the dose uniformity ratio is not more than 1.4 for a uniform good density of 0.1 g/cm 3 .

9 . The apparatus of claim 2 , further comprising:

a loading station configured to load the two or more transport units into the plurality of totes according to at least one of the loading scheme or the loading position.

10 . The apparatus of claim 2 , wherein:

ones of the two or more transport units of similar densities are loaded into one or a series of the plurality of totes, and

the conveyor is configured to drive the one or the series of the plurality of totes through the irradiation volume at a speed dependent on an average density of the two or more transport units of similar densities in the one or the series of the plurality of totes.

11 . The apparatus of claim 9 , wherein the loading station is further configured to position each of the one or more support elements at positions according to the unit heights of the two or more transport units to minimize the gap ratio.

12 . A method for irradiating goods with radiation of X-ray or an electron beam, the method comprising:

loading the goods into a plurality of transport units, each of the plurality of transport units having a unit height along a vertical axis,

coupling support elements to a plurality of totes at different heights along the vertical axis, to tailor positions for the plurality of transport units based on unit heights of the plurality of transport units,

loading the plurality of transport units into the plurality of totes and supporting the plurality of transport units at the positions by the support elements;

driving the plurality of totes through an irradiation volume, along a transverse axis normal to the vertical axis to expose a portion of the goods in the plurality of transport units; and

irradiating the plurality of transport units with the radiation as the plurality of totes are driven through the irradiation volume.

13 . The method of claim 12 , wherein the portion of the goods is a first portion of the goods, the method further comprising:

rotating the plurality of totes by a rotating angle, and

driving back the plurality of totes through the irradiation volume, to expose a second portion of the goods in the plurality of transport units to the radiation.

14 . The method of claim 12 , further comprising:

transferring one or more of the plurality of transport units in an upper half portion of a first of the plurality of totes to a lower half portion of a second of the plurality of totes;

transferring one or more of the plurality of transport units in a lower half portion of the first of the plurality of totes to an upper half portion of the second of the plurality of totes; and

driving the second of the plurality of totes through the irradiation volume.

15 . The method of claim 12 , further comprising:

maintaining constant a scanning horn of a radiation source and an irradiation axis of the irradiation volume during a whole process of the irradiation.