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Implementation of the isocenter‐shift technique for smoothing MLC field edge on a 3D treatment planning system
Author(s) -
Xue Jinyu,
Zhang Pengpeng,
Wu Jackie,
Wang Zhiheng,
Sibata Claudio
Publication year - 2002
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1485061
Subject(s) - isocenter , multileaf collimator , radiation treatment planning , dosimetry , enhanced data rates for gsm evolution , computer science , mathematics , nuclear medicine , optics , artificial intelligence , physics , medicine , radiation therapy , surgery , imaging phantom
Stepped leaf edges are the major limitation of conforming to the prescribed treatment contour defined by the conventional multileaf collimator (MLC), which produces a scalloped dose pattern. The commercial HD‐270 MLC™ (HDI) technique provides a software solution of the conventional MLC to achieve smoothed edge and optimal penumbra of the MLC shaped field. We implemented the HDI functionality on a 3D treatment planning system and compared the dosimetric effects of the HDI delivery in simulation with those in experiment for a number of the MLC fields. The fields from the contour of varied shapes with different sizes of the leaf stepping were tested for the HDI delivery. There is a good agreement of the dose distribution between the calculation as implemented in the planning system and the measurement performed on the treatment machine. It has been shown that the HDI delivery significantly smoothes the stepped field edge with the reduced isodose undulation and effective penumbra. A problem may be present when the HDI is applied for the treatment of the circular contour of smaller diameter, and the conformity of the MLC shaping may not be achievable satisfactorily with the existing system. The optimization of leaf configuration is suggested to improve the conformity of the HDI technique. The HDI planning then can be used to assist in the decision making of applying the HDI treatment delivery.