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Dosimetric characteristics of a double-focused miniature multileaf collimator

Journal Article


Abstract


  • The dosimetric characteristics of a double-focused miniature multileaf collimator (mMLC) attached to a Philips SL75/5 linear accelerator (linac) have been investigated. Output factors, percentage depth-dose, penumbra, leaf transmission, and leakage between the leaves were measured for the 6 MV x- ray beam on this accelerator. Because leakage both through and between the leaves is minimal, the linac jaws can be kept fixed while the mMLC leaf configuration is modified for different aperture shapes. This allows for accurate output prediction using the equivalent square formalism. Percent depth-dose measured for fields defined by the mMLC show little deviation from the percent depth-dose measured for fields defined by the machine jaws or Lipowitz metal blocks. Because the mMLC matches beam divergence in both directions, allows minimal beam transmission, and has a large source-to- collimator distance, the penumbra is sharper for fields defined by the mMLC than for fields defined by the linac jaws or Lipowitz metal blocks. Based on these data, dose calculations for mMLC-defined fields can be applied with no change in procedures from those used for fields defined using conventional methods.

UOW Authors


  •   Tome, Wolfgang (external author)

Publication Date


  • 1999

Citation


  • Meeks, S. L., Bova, F. J., Kim, S., Tomé, W. A., Buatti, J. M., & Friedman, W. A. (1999). Dosimetric characteristics of a double-focused miniature multileaf collimator. Medical Physics, 26(5), 729-733. doi:10.1118/1.598579

Scopus Eid


  • 2-s2.0-0032955179

Start Page


  • 729

End Page


  • 733

Volume


  • 26

Issue


  • 5

Abstract


  • The dosimetric characteristics of a double-focused miniature multileaf collimator (mMLC) attached to a Philips SL75/5 linear accelerator (linac) have been investigated. Output factors, percentage depth-dose, penumbra, leaf transmission, and leakage between the leaves were measured for the 6 MV x- ray beam on this accelerator. Because leakage both through and between the leaves is minimal, the linac jaws can be kept fixed while the mMLC leaf configuration is modified for different aperture shapes. This allows for accurate output prediction using the equivalent square formalism. Percent depth-dose measured for fields defined by the mMLC show little deviation from the percent depth-dose measured for fields defined by the machine jaws or Lipowitz metal blocks. Because the mMLC matches beam divergence in both directions, allows minimal beam transmission, and has a large source-to- collimator distance, the penumbra is sharper for fields defined by the mMLC than for fields defined by the linac jaws or Lipowitz metal blocks. Based on these data, dose calculations for mMLC-defined fields can be applied with no change in procedures from those used for fields defined using conventional methods.

UOW Authors


  •   Tome, Wolfgang (external author)

Publication Date


  • 1999

Citation


  • Meeks, S. L., Bova, F. J., Kim, S., Tomé, W. A., Buatti, J. M., & Friedman, W. A. (1999). Dosimetric characteristics of a double-focused miniature multileaf collimator. Medical Physics, 26(5), 729-733. doi:10.1118/1.598579

Scopus Eid


  • 2-s2.0-0032955179

Start Page


  • 729

End Page


  • 733

Volume


  • 26

Issue


  • 5