First application of quantum annealing to IMRT beamlet intensity optimization

Area of Science:

• Computational physics and medical physics.
• Application of quantum computing principles to radiation therapy optimization.

Background:

• Radiation therapy, specifically Intensity-Modulated Radiation Therapy (IMRT), relies heavily on optimization methods for treatment planning.
• Quantum annealing (QA) is an emerging technology utilizing quantum mechanics for solving complex discrete optimization problems.

Purpose of the Study:

• To investigate the first application of quantum annealing (QA) for beamlet intensity optimization in IMRT.
• To compare the performance of QA against conventional optimization methods (simulated annealing and Tabu search) in terms of solution quality and speed.

Main Methods:

• Utilized recently developed quantum annealing hardware for beamlet intensity optimization.
• Applied QA to two prostate cancer cases, optimizing a discretized objective function based on clinical dose-volume constraints.
• Compared QA results with simulated annealing and Tabu search run on a conventional computing cluster.

Main Results:

• Quantum annealing achieved objective function values of 16.9 and 70.7 for the two patients, compared to simulated annealing (6.7, 22.9) and Tabu search (10.0, 120.0).
• The QA algorithm was significantly faster, requiring only 27-38% of the time taken by simulated annealing and Tabu search.
• QA performance in solution quality was comparable to Tabu search but less effective than simulated annealing in these initial trials.

Conclusions:

• Hardware-enabled quantum annealing shows promise for accelerating IMRT optimization, despite current limitations in solution quality compared to simulated annealing.
• The significant speed advantage suggests that further research and development in QA-based heuristics could lead to faster clinical optimization methods.
• As quantum annealing hardware scales, it may offer substantial speedups for complex optimization tasks in radiation therapy.