Modulated electron radiotherapy treatment planning using a photon multileaf collimator for post-mastectomized chest walls

作者：Javier Salguero Francisco; Palma Bianey; Arrans Rafael; Rosello Joan; Leal Antonio^*

来源：Radiotherapy and Oncology, 2009, 93(3): 625-632.

DOI：10.1016/j.radonc.2009.08.021

• Modulated electron radiotherapy
• Monte Carlo treatment planning
• Chest wall

Background and purpose To evaluate the feasibility of using a photon MLC (xMLC) for modulated electron radiotherapy treatment (MERT) as an alternative to conventional post-mastectomy chest wall (CW) irradiation. A Monte Carlo (MC) based planning system was developed to overcome the inaccuracy of the 'pencil beam' algorithm MC techniques are known to accurately calculate the close distributions of electron beams, allowing the explicit simulation of electron interactions within the MLC
Materials and method Four real clinical CW cases were planned using MERT which were compared with the conventional electron treatments based on blocks and by a straightforward approach using the MLC. and not the blocks (as an intermediate step to MERT) to shape the same segments with SSD between 60 and 70 cm depending on PTV size. MC calculations were verified with an array of ionization chambers and radiochromic films in a solid water phantom
Results. Tests based on gamma analysis between MC dose distributions and radiochromic film measurements showed an excellent agreement Differences in the absolute dose measured with a plane-parallel chamber at a reference point were below 3% for all cases MERT solution showed a better PTV coverage and a significant reduction of the doses to the organs at risk (OARs)
Conclusion MERT can effectively improve the current electron treatments by obtaining a better PTV coverage and sparing healthy tissues More directly, block-shaped treatments could be replaced by MLC-shaped non-modulated segments providing similar results.

• 出版日期2009-12