TITLE:
A Study of the TPS Based Beam-Matching Concept for Medical Linear Accelerators at a Tertiary Hospital
AUTHORS:
Ntombela N. Lethukuthula, Rovetto J. Nicolas, Nethwadzi C. Lutendo, Mpumelelo Nyathi
KEYWORDS:
Radiotherapy, Beam-Matching, Linear Accelerator, Dosimetry
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.13 No.1,
March
1,
2024
ABSTRACT: The flexibility in radiotherapy can be improved if patients can be moved
between any one of the department’s medical linear accelerators (LINACs)
without the need to change anything in the patient’s treatment plan. For this
to be possible, the dosimetric characteristics of the various accelerators must
be the same, or nearly the same. The purpose of this work is to describe
further and compare measurements and parameters after the initial vendor-recommended
beam matching of the five LINACs. Deviations related to dose calculations and
to beam matched accelerators may compromise treatment accuracy. The safest and
most practical way to ensure that all accelerators are within clinical
acceptable accuracy is to include TPS calculations in the LINACs matching
evaluation. Treatment planning system (TPS) was used to create three photons
plans with different field sizes 3 × 3 cm, 10 × 10 cm and 25 × 25 cm at a depth
of 4.5 cm in Perspex. Calculated TPS plans were sent to Mosaiq to be delivered by five LINACs. TPS plans were compared with five
LINACs measurements data using Gamma analyses of 2% and 2 mm. The results
suggest that for four out of the five LINACs, there was generally good
agreement, less than a 2% deviation between the planned dose distribution and
the measured dose distribution. However, one specific LINAC named “Asterix” exhibited a deviation of 2.121% from the planned dose. The
results show that all of the LINACs’ performance were within the acceptable
deviation and delivering radiation dose consistently and accurately.