Purpose: Although ionization chambers are widely used to measure beam commissioning data, point-by-point measurements of all the profiles with various field size and depths are timeconsuming tasks. As an alternative, we investigated the feasibility of a linear diode array for commissioning a treatment planning system.
Methods: The beam data of a Varian TrueBeam^® radiotherapy system at 6 and 10 MV with/without a flattening filter were measured for commissioning of an Eclipse Analytical Anisotropic Algorithm (AAA) ver.15.6. All of the necessary beam data were measured using an IBA CC13 ionization chamber and validated against Varian “Golden Beam” data. After validation, the measured CC13 profiles were used for commissioning the Eclipse AAA (AAA_CC13). In addition, an IBA LDA-99SC linear diode array detector was used to measure all of the beam profiles and for commissioning a separate model (AAA_LDA99). Finally, the AAA_CC13 and AAA_LDA99 dose calculations for each of the 10 clinical plans were compared.
Results: The agreement of the CC13 profiles with the Varian Golden Beam data was confirmed within 1% except in the penumbral region, where ≤2% of a discrepancy related to machinespecific jaw calibration was observed. Since the volume was larger for the CC13 chamber than for the LDA-99SC chamber, the penumbra widths were larger in the CC13 profiles, resulting in ≤5% differences. However, after beam modeling, the penumbral widths agreed within 0.1 mm. Finally the AAA_LDA99 and AAA_CC13 dose distributions agreed within 1% for all voxels inside the body for the 10 clinical plans.
Conclusions: In conclusion, the LDA-99SC diode array detector was found to be accurate and efficient for measuring photon beam profiles to commission treatment planning systems.

Patients with breast cancer can be positioned with their head turned to the contra lateral side or with their head straight during the radiation therapy treatment set-up. In our hospital, patients with locally advanced breast cancer who were receiving radiation therapy have experienced swallowing difficulty after 2 weeks of irradiation. In this pilot study, the impact of head position on reducing dysphagia occurrence was dosimetrically evaluated. Patients were divided into two groups viz., HT (head turned to the contra lateral side of the breast) and HS (head straight) with 10 members in each. Treatment planning was performed, and the dosimetric parameters such as Dmin, Dmax, Dmean, V₅, V₁₀, V₂₀, V₃₀, V₄₀, and V₅₀ of both groups were extracted from the dose volume histogram (DVH) of esophagus. The target coverage in the supraclavicular fossa (SCF) region was analyzed using D₉₅ and D₉₈; moreover, the dose heterogeneity was assessed with D₂ from the DVHs. The average values of the dose volume parameters were 27.6%, 58.6%, 35.4%, 19%, 13.8%, 14.1%, 11.8%, 8.4%, and 8.1% higher in the HT group compared with those in the HS group. Furthermore, for the SCF, the mean values of D₉₈, D₉₅, and D₂ were 42.4, 47.5, and 54 Gy, respectively, in the HS group and 38.9, 45.35, and 55.5 Gy, respectively, in the HT group. This pilot study attempts to give a solution for the poor quality of life of patients after breast radiotherapy due to dysphagia. The findings confirm that the head position could play a significant role in alleviating esophageal toxicity without compromising tumor control.