Planning quality and delivery efficiency of sMLC delivered IMRT treatment of oropharyngeal cancers evaluated by RTOG H-0022 dosimetric criteria. J Appl Clin Med Phys 2004;5(4):80-95
Date
03/02/2005Pubmed ID
15738923Pubmed Central ID
PMC5723523DOI
10.1120/jacmp.v5i4.2014Scopus ID
2-s2.0-85024952370 (requires institutional sign-in at Scopus site) 8 CitationsAbstract
The time required to deliver intensity-modulated radiation therapy (IMRT) treatments can be significantly longer than conventional treatments, especially for the segmented multileaf collimator (sMLC) delivery system with a large record and verification (R&V) overhead. In this work, we evaluate the impact of the number of intensity-modulated beams (IMBs) and the number of intensity levels (ILs) on the quality and delivery efficiency of IMRT plans, generated by the Corvus planning system for sMLC delivery on a Siemens LINAC with the Lantis R&V system. Detailed studies were performed for three image data sets of previously treated oropharyngeal patients. Treatment plans for patient 1 were developed using 5, 7, 9, or 15 evenly spaced axial IMBs as well as one with 7 axial IMBs whose directions were user-selected, each using ILs of 3, 5, 10, or 20. For patients 2 and 3, plans with 15 IMBs and 20 ILs were not attempted. A total of 42 plans were developed using three oropharyngeal cancer CT image data sets. Plan quality was evaluated by assessing compliance with the Radiation Therapy Oncology Group (RTOG) H-0022 protocol criteria and the physician's clinical judgment. Plan efficiency was accessed by the number of segments of each plan. We found that for our treatment-planning and delivery system, an IMRT plan that uses a moderate number of IMBs and ILs, such as 7 or 9 IMBs with 3 or 5 ILs, would appear to be the optimal approach when both quality of the plan and delivery efficiency are considered. Based on this study, we have routinely used 9 IMBs with 3 ILs or 7 IMBs with 5 ILs for head and neck patients. A retrospective comparison indicates that delivery efficiency is improved on the order of 30% compared to plans generated with 9 IMBs with 5 ILs.
Author List
Zhu XR, Schultz CJ, Gillin MTAuthor
Christopher J. Schultz MD Chair, Professor in the Radiation Oncology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Body BurdenHumans
Oropharyngeal Neoplasms
Practice Guidelines as Topic
Quality Assurance, Health Care
Radiometry
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Conformal
Relative Biological Effectiveness
Treatment Outcome
United States