J Korean Soc Ther Radiol.  1993 Jun;11(1):183-191.

Homogeneous Dose Planning to Paranasal Sinus with the Partial Attenuation filters and Wedged Beams in 6 MV Photon Beam

• Choi TJ
• Lee HJ
• Kim OB

Abstract

The homogeneous dose planning is one of the most important roles in radiation therapy. But, it is not easy to obtain a homogeneous dose to paranasal sinus region including the ethmoidal sinus with conventional irradiation techniques. In this experimental study, the authors tried to get a homogeneous dose at PNS region, but the nasal cartirage does not exceed the tolerance dose, with anterior-posterior beam and two both lateral wedged beams. Used three fields were shielded with full thickness of blocks to preserve the eye-balls and with blocks of one half value layer to create a homogeneous dose at the whole treatment volume. The dose computations are based on the three dimensonal structure with modified scatter contributions of partial shielders and attenuated beams in 6 MV photon beams. The dose distributions of mid-plane is examined with Kodak verification films and teflon-embedded TLD rod (1mm diameter and 6mm length) to confirm the computed dose. In our study, the whole PNS regions have shown within 85% of the resultant isodose cuties with relatively homogeneous dose distribution. The results of dose computation and measurements are agree well within 5% uncertainties.

Keyword

Partial Filter; Homogeneous Dose