Accuracy of small field measurements and calculation algorithms is critical for accurate calculation of dose distribution in Radiotherapy. In inhomogeneous and homogeneous phantoms, measurements (1x1, 2x2, 3x3, 4x4, 5x5cm2 field sizes) were made with CC04 and CC01 Razor ion chambers using 6MV, 6MV-FFF, 10MV and 10MV-FFF energies. In the Monaco treatment planning system, dose distribution was calculated by Monte Carlo-Dose to Medium (MC-Dm), Monte Carlo-Dose to Water (MC-Dw), Collapse Cone (CC) and Pencil Beam (PB) algorithms and compared with measurements. The homogeneous phantom water equivalent was generated from RW3 solid phantoms, and the inhomogeneous phantom was created using a water-equivalent RW3 solid phantom and a lung equivalent balsa phantom. When both the homogeneous and inhomogeneous phantom measurements were evaluated with CC04 and CC01Razor ion chambers, results consistent with MC-Dm, MC-Dw, CC and PB were obtained. The greatest differences in both phantoms were obtained in 1x1cm2 fields. When the results in the inhomogeneous phantom were compared with the results in the homogeneous phantom, the compliance ratio was observed to be better in the homogeneous phantom. The CC01 Razor ion chamber has a volume of 0.01cm3 and its central electrode is graphite. With the CC01 Razor ion chamber, reliable results were obtained. As the field size becomes smaller, the differences between measurements and calculations increase.