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Abstract
Double-focused micro-Multileaf Collimator (μMLC) is able to create radiation fields having sharper dose gradients at the field edges than common MLC. Therefore, μMLC has been used for the stereotactic radiosurgery (SRS) and Stereotactic Radiotherapy (SRT). We evaluated the dosimetric characteristics of a double-focused Dynamic-μMLC (DMLC) attached to the Elekta Synergy linear accelerator. For this study, the dosimetric parameters including, Percent Depth Dose (PDD), Leaf leakage and penumbra, have been measured by using of the radiochromic films (GafChromic EBT2), EDGE diode detector and three-dimensional water phantom. All datas were measured on 6 MV x-ray. As a result, The DMLC shows transmission below to 1% and because of double-focused construction of the DMLC, the penumbras of fields with DMLC are independent from the field sizes. In this paper, the resulting dosimetric evaluations proved the applicability of the DMLC attached to the Elekta Synergy linear accelerator.
References
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Fig. 1.
Dynamic micro-multileaf collimator (DMLC) attached to the Elekta Synergy linear accelerator. The electrical connection between the DMLC and the gantry is established by only on cable.
Fig. 2.
(a) Scheme of the transverse view of the DMLC. (b) Detail of the leaves of the DMLC. All distance are in mm.
Fig. 4.
In-plane profile about interleaf leakage and intra-leaf transmission. The field closed at isocenter.
Fig. 5.
Cross-plane profile about abutted leaf setup field. The position of 5 peaks shown the abutted leaf position.
Table 1.
Physical characteristics of the 3D Line DMLC and BrainLAB m3.
Table 3.
Penumbras (mm) for 3.6×3.6, 4.8×4.8, 6.0×6.0 cm2 field sizes defined using the DMLC and Linac jaws. The data were measured at SSD 100 cm at depths of 1.5 cm and 5 cm in water using a EDGE Detector.
| 3.6×3.6 cm2 | 4.8×4.8 cm2 | 6.0×6.0 cm2 | ||||
|---|---|---|---|---|---|---|
| Field Size | DMLC | Linac jaws | DMLC | Linac jaws | DMLC | Linac jaws |
| 80∼20% | 2.6 | 2.8 | 2.7 | 2.9 | 2.7 | 2.9 |
| d=1.5 cm | ||||||
| 80∼20% | 3.0 | 3.0 | 3.1 | 3.2 | 3.1 | 3.1 |
| d=5.0 cm | ||||||
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