Toward fully automated multicriterial plan generation: a prospective clinical study.
OBJECTIVE
To prospectively compare plans generated with iCycle, an in-house-developed algorithm for fully automated multicriterial intensity modulated radiation therapy (IMRT) beam profile and beam orientation optimization, with plans manually generated by dosimetrists using the clinical treatment planning system.


METHODS
For 20 randomly selected head-and-neck cancer patients with various tumor locations (of whom 13 received sequential boost treatments), we offered the treating physician the choice between an automatically generated iCycle plan and a manually optimized plan using standard clinical procedures. Although iCycle used a fixed "wish list" with hard constraints and prioritized objectives, the dosimetrists manually selected the beam configuration and fine tuned the constraints and objectives for each IMRT plan. Dosimetrists were not informed in advance whether a competing iCycle plan was made. The 2 plans were simultaneously presented to the physician, who then selected the plan to be used for treatment. For the patient group, differences in planning target volume coverage and sparing of critical tissues were quantified.


RESULTS
In 32 of 33 plan comparisons, the physician selected the iCycle plan for treatment. This highly consistent preference for the automatically generated plans was mainly caused by the improved sparing for the large majority of critical structures. With iCycle, the normal tissue complication probabilities for the parotid and submandibular glands were reduced by 2.4% ± 4.9% (maximum, 18.5%, P=.001) and 6.5% ± 8.3% (maximum, 27%, P=.005), respectively. The reduction in the mean oral cavity dose was 2.8 ± 2.8 Gy (maximum, 8.1 Gy, P=.005). For the swallowing muscles, the esophagus and larynx, the mean dose reduction was 3.3 ± 1.1 Gy (maximum, 9.2 Gy, P<.001). For 15 of the 20 patients, target coverage was also improved.


CONCLUSIONS
In 97% of cases, automatically generated plans were selected for treatment because of the superior quality. Apart from the improved plan quality, automatic plan generation is economically attractive because of the reduced workload.
Department of Radiation Oncology, Erasmus Medical Center-Daniel den Hoed Cancer Center, Groene Hilledijk 301, Rotterdam 3075EA, The Netherlands. p.voet@erasmusmc.nl
Peter W J
PW
Voet
Maarten L P
ML
Dirkx
Sebastiaan
S
Breedveld
Dennie
D
Fransen
Peter C
PC
Levendag
Ben J M
BJ
Heijmen
D000465:Algorithms; D004947:Esophagus / Q000000981:diagnostic imaging; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D007821:Laryngeal Muscles / Q000000981:diagnostic imaging; D007830:Larynx / Q000000981:diagnostic imaging; D009055:Mouth / Q000000981:diagnostic imaging; D059351:Organ Sparing Treatments / Q000379:methods* / Q000592:standards; D058958:Organs at Risk / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D011832:Radiation Injuries / Q000517:prevention & control; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods* / Q000592:standards; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012796:Sialography