Multileaf collimator: Difference between revisions

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[[File:MLCShape.svg|thumb|''MLC shape of an X-MLCs'']]

A '''multileaf collimator''' ('''MLC''') is used on linear accelerators to provide conformal shaping of [[radiotherapy]] treatment beams, specifically conformal radiotherapy and Intensity Modulated Radiation Therapy (IMRT) can be delivered using MLC’s. It is made up of individual 'leaves' of a high atomic numbered material, usually tungsten, that can move independently in and out of a beams path in order to block the beam.

A '''multileaf collimator''' ('''MLC''') is a [[collimator]] or beam-limiting device that is made of individual "leaves" of a high [[atomic number]]ed material, usually [[tungsten]], that can move independently in and out of the path of a [[external beam radiotherapy|radiotherapy beam]] in order to shape it and vary its intensity.

MLCs are used in external beam radiotherapy to provide conformal shaping of beams. Specifically, [[Radiation therapy#External beam radiation therapy|conformal radiotherapy]] and [[Intensity Modulated Radiation Therapy]] (IMRT) can be delivered using MLCs.

The MLC has improved rapidly since its inception and the first use of leaves to shape structures in 1965 (Takahashi 1965) to modern day operation and use. MLC’s are now widely used and have become an integral part of any radiotherapy department. MLC’s were primarily used for conformal radiotherapy, and have allowed the cost effective implementation of conformal treatment with significant time saving (Brewster et al 1995, Helyer and Heisig 1995), and also have been adapted for use for IMRT treatments. For conformal radiotherapy the MLC allows conformal shaping of the linear accelerator (LINAC) beam to match the borders of the target tumour. For intensity modulated treatments the leaves of a MLC can be moved across the field to create IMRT distributions (it should be noted here that MLC’s really provide a fluence modulation rather than intensity modulation).

The MLC has improved rapidly since its inception and the first use of leaves to shape structures in 1965 (<ref>{{cite journal | last=Takahashi | first=S | title=Conformation radiotherapy. Rotation techniques as applied to radiography and radiotherapy of cancer. | journal=Acta Radiologica: Diagnosis | year=1965) | issn=0567-8056 | pmid=5879987 | page=Suppl 242:1+}}</ref> to modern day operation and use. MLC’sMLCs are now widely used and have become an integral part of any radiotherapy department. MLC’sMLCs were primarily used for conformal radiotherapy, and have allowed the cost -effective implementation of conformal treatment with significant time saving,<ref>{{cite (journal | last1=Brewster et| alfirst1=Linda 1995| last2=Mohan | first2=Radhe | last3=Mageras | first3=Gig | last4=Burman | first4=Chandra | last5=Leibel | first5=Steven | last6=Fuks | first6=Zvi | title=Three dimensional conformal treatment planning with multileaf collimators | journal=International Journal of Radiation Oncology, HelyerBiology, andPhysics Heisig| publisher=Elsevier BV | volume=33 | issue=5 | date=1995-12-01 | issn=0360-3016 | pmid=7493834 | doi=10.1016/0360-3016(95),02061-6 | pages=1081–1089}}</ref> and also have been adapted for use for IMRT treatments. For conformal radiotherapy the MLC allows conformal shaping of the linear accelerator (LINAC) beam to match the borders of the target tumour. For intensity modulated treatments the leaves of a MLC can be moved across the field to create IMRT distributions (it should be noted here that MLC’sMLCs really provide a [[fluence]] modulation rather than intensity modulation).

The MLC is an important tool for radiation therapy dose delivery. It was originally used as a surrogate for alloy block field shaping and is now widely used for IMRT. As with any tool used in radiotherapy the MLC must undergo commissioning and quality assurance. Additional commissioning measurements are completed to model a MLC for treatment planning. Various MLC’s are provided by different vendors and they all have unique design features as determined by specifications of design (Galvin 1993), and these differences are quite significant.

[[File:Collimatore multilama.jpg|thumb|Leaves, changing shape, direct the beam to the right [[cancer]] area]]

The MLC is an important tool for radiation therapy dose delivery. It was originally used as a surrogate for alloy block field shaping and is now widely used for IMRT. As with any tool used in radiotherapy the MLC must undergo commissioning and quality assurance. Additional commissioning measurements are completed to model a MLC for [[treatment planning]]. Various MLC’sMLCs are provided by different vendors and they all have unique design features as determined by specifications of design,<ref>{{cite (journal | last1=Galvin | first1=James M. | last2=Smith | first2=Alfred R. | last3=Lally | first3=Brian | title=Characterization of a multileaf collimator system | journal=International Journal of Radiation Oncology, Biology, Physics | publisher=Elsevier BV | volume=25 | issue=2 | date=1993-01-15 | issn=0360-3016 | pmid=8420867 | doi=10.1016/0360-3016(93),90339-w | pages=181–192}}</ref> and these differences are quite significant.

'''References:'''<br />

Brewster L Mohan R Mageras G Burman C Leibel S and Fuks Z Three dimensional conformal treatment planning with multileaf collimators Int. J. Rad. Onc. Biol. Phys. 33 (1995) 1081–9

'''==References:'''<br />==

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{{Reflist}}

Helyer S J and Heisig S Multileaf collimation versus conventional shielding blocks: a time and motion study of beam shaping in radiotherapy Rad. Onc. 37 (1995) 61–4

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[[Category:Medical equipment]]

Galvin J M Smith A R and Lally B Characterization of a multi-leaf collimator system Int. J. Rad. Onc. Biol. Phys. 25 (1993) 181–92

[[Category:Medical physics]]

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[[Category:Particle accelerators]]

Takahashi S Conformation radiotherapy: rotation techniques as applied to radiography and radiotherapy of cancer Acta Radiol. Suppl. 242 (1965) 1–142

[[Category:Radiation therapy]]

{{medical-equipment-stub}}