Determination of the radiation dose scattered outside the target volume treated with IMRT technique

• Published in: Radiation measurements Vol. 71; pp. 319 - 323
• Main Authors: Matsushima, Luciana C., Veneziani, Glauco R., Sakuraba, Roberto K., Cruz, José C., Campos, Letícia L.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2014; Elsevier
• Subjects: Beams (radiation); Computer simulation; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geochronology; Holes; IMRT quality assurance; Isotope geochemistry. Geochronology; LiF:Mg,Ti; Organs; Out-of-target doses; Polymethyl methacrylates; Radiation measurement; Radiation therapy; Thermoluminescent dosimetry; Three dimensional; Tumors; LiF:Mg,Ti; Out-of-target doses; IMRT quality assurance; Thermoluminescent dosimetry; radiation; accuracy; specific surface; computers; quality
• ISSN: 1350-4487; 1879-0925
• DOI: 10.1016/j.radmeas.2014.08.001

Intensity Modulated Radiation Therapy (IMRT) is an advanced mode of high precision radiation therapy that uses computer controlled linear accelerators to deliver precise radiation doses to a malignant tumor or specific areas within the tumor. This is achieved using a more precise adjustment of the beam to the three dimensional shape of the tumor by modulating or controlling the intensity of the radiation beam in multiple small volumes. IMRT also allows higher radiation doses to be focused to regions within the tumor while minimizing the dose to surrounding normal critical structures. This work aims at determining the radiation dose in two target volumes (tumors) treated at same time and the scattered dose distribution in organs at risk using thermoluminescent dosimeters of LiF:Mg,Ti for IMRT treatment technique and a polymethylmethacrylate (PMMA) phantom. The shortest distance between the cavities 1 and 2 that simulate tumors is 1.5 cm and the shortest distances from the cavity 1 to the cavities 3, 4 and 5 are, respectively, 1.9 cm, 2.2 cm and 2.65 cm. The shortest distance from the cavity 2 to cavities 3, 4 and 5 are, respectively, 5.4 cm; 5.7 cm and 1.5 cm. The relative difference for the doses measured by TLD-100 and provided by the TPS were +3.7% and −1.38%. The out-of-target doses received by cavities 3, 4 and 5 corresponded on average to 19.36, 17.84% and 6.72% of the highest dose received by the cavity 1 and the doses received by cavities 3, 4 and 5 corresponded on average to 29.51%, 27.20% and 10.24% of the dose received by cavity 2. •Comparison of doses with LiF:Mg,Ti and doses calculated by the TPS.•Irradiations have been performed in a PMMA phantom with five cavities.•Measurements out-of-target doses in IMRT.•Results showed a variation from 6.72 to 29.51% for out-of-target doses.•Doses evaluated with LiF:Mg,Ti corresponding to the estimated doses given by the TPS.