To investigates point dose differences in measurement and calculation between Monte Carlo (MC) and Pencil beam (PB) algorithms, aiming to validate theoretical significance.

The PTW Roos ionization chamber was positioned at the spread-out Bragg peak (SOBP) isocenter in Gammex solid water phantom. All plans in RayStation 2024 A were calculated by MC and PB algorithms. These plans covered various depths of 5, 10, and 15 cm, SOBP ranges of 4, 6, and 10 cm, field sizes of 4, 6, 10, and 20 cm², and range shifter (RS) thicknesses of no RS, 2, 3, and 5 cm.

MC showed the mean dose difference of 0.67 ± 1.58%, and PB showed 1.19 ± 2.47%. PB demonstrated the least agreement with calculated doses, which was improved with MC.

The calculated point doses of PB and MC were compared to the measured doses for all plans and found to be within ± 3%.