Impact of MLC leaf width on the quality of the dose distribution in partial breast irradiation

• Published in: Medical dosimetry : official journal of the American Association of Medical Dosimetrists Vol. 37; no. 1; pp. 37 - 41
• Main Authors: Height, Felicity J., BAppSc, Kron, Tomas, Ph.D., F.C.C.P.M, Willis, David, M.Sc, Chua, Boon H., M.D., Ph.D
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 2012
• Subjects: Aged; Body Burden; Breast cancer; Breast Neoplasms - radiotherapy; COLLIMATORS; DOSIMETRY; Female; HEALTH HAZARDS; Hematology, Oncology and Palliative Medicine; Humans; IRRADIATION; MAMMARY GLANDS; Middle Aged; Multileaf collimators; NEOPLASMS; OPTIMIZATION; Partial breast irradiation; PATIENTS; PLANNING; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIATION PROTECTION AND DOSIMETRY; Radiation therapy; Radiology; Radiometry - methods; RADIOTHERAPY; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - methods; Radiotherapy, Conformal - instrumentation; Radiotherapy, Conformal - methods; Treatment Outcome; Partial breast irradiation; Breast cancer; Radiation therapy; Multileaf collimators
• ISSN: 0958-3947; 1873-4022
• DOI: 10.1016/j.meddos.2010.12.011

Abstract Partial-breast irradiation (PBI) aims to limit the target volume for radiotherapy in women with early breast cancer after partial mastectomy to the region at highest risk of local recurrence, the tumor bed. Multileaf collimators are used to achieve conformal radiation beam portals required for PBI. Narrower leaf widths are generally assumed to allow more conformal shaping of beam portals around irregularly shaped target volumes. The aim was to compare 5-mm and 10-mm leaf widths for patients previously treated using PBI and assess subsequent planning target volume (PTV) coverage and organ at risk (OAR) doses for 16 patients. Several plans (5-mm leaf width or 10-mm leaf width) were generated for each patient using the original treated plan as the basis for attempts at further optimization. Alternating between different leaf widths found no significant difference in terms of overall PTV coverage and OAR doses between treatment plans. Optimization of the original treated plan allowed a small decrease in ipsilateral breast dose, which was offset by a lower PTV minimum. No significant dosimetric difference was found to support an advantage of 5-mm over 10-mm leaf width in this setting.