Pencil Beam and Collapsed Cone Algorithm Calculations for a Lung-Type Volume Using Ct and the Omp Treatment Planning System

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Pencil Beam and Collapsed Cone Algorithm Calculations for a
Lung-type Volume Using CT and the OMP Treatment Planning System
Methods
Measurements have been carried out in both phantom and a specifically designed phantom which simulated human lung volume. Samples were taken from the Lung Planning CT images for 15 patients using the Oncentra Masterplan OMP Treatment Planning System. The X-axis was, following convention, taken to be horizontal, and the Y-axis to be vertical; accordingly, abscissa and ordinate distances to the skin, heart and the lungs were measured (see figure 8). Figures 4 and 5 show typical CT images for a patient’s lungs, while Tables 1 and 2 give the beam information and dose information for typical patients. The X-ray
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The Oncology Management System: Impac, MOSAIQ was used to transfer the data from the OMP treatment planning system to the Linac before running the Linac to determine the points’ ISO center, Beam Information and Dose Information, as shown in figure 14, 15, 16 and 17 for the first and second phantom.
The phantoms were positioned on the Elekta Precise linac, isocentre and aligned with lasers, and the ion chamber was placed at each dose point, for example Iso, DP1, DP2, DP3 and DP4 (see figure 12 and 13). Doses were measured for the dosimeters and chambers.
The field size and gantry angles chosen are typical of clinical plans for the same 15 patients as used to design phantom 2. A field size of 10 x 10cm, was used for all fields. Gantry angles of 00-3150-2700 and 00-600-1200 were used for phantom 1 and 2 respectively. Tables 4 and 5 show beam information for the first and second phantoms, respectively. The energy used for the plans was 6MV because lung cancer is treated clinically with 6MV in HOF Hospital 10 MV beam is not used because considered very high energy and risky to the lungs. Wedges were used for beam one and three- the angle of the wedge is 60/60 for each beam. Figure 12 and 13 show the plan for phantoms 1 and 2, with the isocentre and dose points measured.
For the first phantom was generated using three 6 MV photon beams, all with a 10 x 10

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