IMRT plan renormalization and leaf motion calculation

Dec 4, 2015 at 9:21 PM
Edited Dec 9, 2015 at 2:24 AM
Hi Everyone,

I'm running into an issue when trying to calculate if a beam leaf motion sequence should be recalculated due to IMRT plan renormalization. Essentially I'm grabbing the beam log file and calculating LostMU * MaxMU to determine what MUs should be and then comparing it to the actual MUs. An issue comes up with split fields (Not kept as large field IMRT). When using LMC, after the plan is run the carriage groups are split in the log file but not displayed as split in Eclipse, hence giving the summed MUs of the groups (this is before changing plan status to reviewed or planning approved). This would be fine as it seems reasonable to loop through all the carriage groups to sum the LostMU * MaxMU of each group to compare to the total MU. Or go through the control points ( at this point the beam still has all carriage groups) to get the coefficient to calc what each groups MUs are.

The issue arises after the plan is reviewed or planning approved and a split plan is created with the groups split into separate beams. The log files of each beam still contain the information for all groups which makes it difficult to determine which group belongs to which beam. In the log file, you have the number of control points for the group but I feel it would be a fragile approach to compare total control point number in the log file to the beam to determine if there is match as all groups could possibly have the same number of control points.

The issue is in reverse for SmartLMC. Now the the log file only has the total MaxMU and LostMU but if the beams are split out after review or plan approval each beam has that group's MU. Essentially you would have to scale down the total MaxMU*LostMU by a ratio of the control points?

I feel like I may be over complicating this trying to use information in the log file vs maybe doing something with the beam MU Coefficient (MU/Gy) to determine difference between actual and ideal MU? Essentially I'm looking for the easiest way to determine if an IMRT plan needs to have Leaf Motions recalculated.