Dual-Level Pallet Irradiation for X-Ray Dose Uniformity
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Solution Overview
Problem
Current irradiation systems for low-density products, such as medical devices, face challenges in achieving uniform dose distribution and high throughput due to limited penetration depth of radiation and inefficient energy use, particularly when using X-rays or gamma rays for sterilization.
Innovation Solution
The method involves placing products on two superposed levels within an irradiation chamber and alternating their positions during irradiation, using high-energy X-ray beams directed from mid-height, to ensure even exposure and maximize energy utilization, thereby improving dose uniformity and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If X-rays or gamma rays are used for irradiation of low-density products on pallets, then penetration depth is improved, but dose uniformity deteriorates due to energy loss and poor distribution
Solution Approach 1:
The irradiation process is segmented into multiple passes with the pallet rotated at intermediate positions. Instead of attempting to irradiate the entire pallet in one pass, the system divides the irradiation into sequential steps, rotating the pallet to expose different sections to the X-ray beam, thereby achieving more uniform dose distribution across the entire load
Solution Approach 2:
The pallet undergoes periodic rotation during the irradiation process, alternating between different orientations relative to the X-ray source. This periodic repositioning ensures that all regions of the pallet receive comparable radiation exposure, improving dose uniformity while maintaining adequate penetration depth
2Reliability
If high-energy X-ray beams are used to penetrate deep into pallets, then sterilization effectiveness is improved, but energy efficiency deteriorates due to significant energy loss
Solution Approach 1:
The system maintains continuous useful action by rotating the pallet during irradiation to present different sections to the X-ray beam sequentially. This ensures that the high-energy beam continuously interacts with product material rather than traversing empty space, maximizing energy utilization and reducing waste while maintaining sterilization effectiveness
Solution Approach 2:
The pallet is pre-positioned and rotated to optimal orientations before each irradiation pass, ensuring that the X-ray beam targets product-loaded regions. This preliminary positioning prevents energy waste by directing the beam through material that requires sterilization rather than through empty spaces
3Device complexity
If single-level pallet irradiation is used, then equipment simplicity is maintained, but throughput deteriorates due to limited processing capacity
Solution Approach 1:
The pallet is periodically rotated to different positions during the irradiation cycle, allowing multiple sections to be exposed to the X-ray beam in sequence. This periodic repositioning enables more complete utilization of the irradiation capacity within a single processing cycle, thereby increasing throughput without requiring additional equipment
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves a more uniform dose distribution with a lower Dose Uniformity Ratio (DUR) and increased throughput by optimizing the use of X-ray energy, ensuring effective sterilization of low-density products while minimizing energy loss and equipment costs.
Implementation Method 1
the use of an electron accelerator for producing a high-energy electron beam is required. This high-energy electron beam then passes through a foil made of a high-Z metal, therefore producing the required X-rays
Implementation Method 2
irradiating in an irradiation chamber products being stored in the form of pallets or in the form of bulk material in appropriate containers by means of a high energy X-ray beam source
Data Source
AI summary
Method for irradiating in an irradiation chamber products being stored in the form of pallets or in the form of bulk material in appropriate containers by means of a high energy X-ray beam source including the following steps: placing and arranging the products onto two different levels of products, so that a first set of products is placed on an upper level and a second set of products is placed on a lower level; irradiating both sets of products during a first period of time; submitting the products arranged on the two levels to a switch or transposition, so that the set of products arranged on an upper level is arranged on the lower level and vice versa and irradiating during a second period of time the new arrangement formed of the two transposed sets of products.