Systems and methods for adjusting multi-leaf collimator

A system comprising:

• a multi-leaf collimator (MLC), the MLC including a plurality of cross-layer leaf pairs, each cross-layer leaf pair of the plurality of cross-layer leaf pairs includes a first leaf located in a first layer of leaves and a second leaf opposingly located in a second layer of leaves, wherein:
• for each cross-layer leaf pair of at least one of the plurality of cross-layer leaf pairs,
• an effective cross-layer leaf gap is formed between the first leaf in the first layer of leaves and the second leaf in the second layer of leaves;
• an in-layer leaf gap is formed between the first leaf in the first layer of leaves and an opposing first leaf in the first layer of leaves of the MLC, the first leaf and the opposing first leaf forming an in-layer leaf pair in the first layer of leaves;
• and
• a size of the in-layer leaf gap is no less than a size of the effective cross-layer leaf gap.