Evaluation of photon beam dose calculation accuracy of treatment planning systems using in vivo dosimetry

Abstract

Abstract Objective The treatment planning system currently represents one of the basics of radiation therapy, because it is the only method to estimate patient dose delivery fast forward and accurately represent estimated tumor location of the tumor with the possibility of estimating densities in the tissue surrounding the tumor to overcome dose calculation defects but radial estimated the patient. Despite the flaws associated with the systems and calculates the dose of your programs in all programs currently existing in the world. Than necessary, to the existence of a review of the accuracy of accounts and how to confirm the radiation dose to the patient programs. Methods A total of 35 cancer patients were considered for this study, with 245 field measurements made with low- and high-energy diode detectors for brain and prostate cases. The treatments for all patients were planned using Eclipse Treatment Planning System version 13.6. Results Of the 105 field measurements made for the prostate cancer patients, 16 included discrepancies outside the ±5% action level. Of the 145 measurements taken of the brain cases, there were four outside the ±5% action level. The results indicated a higher degree of accuracy. The study revealed that, for the prostate measurements, the higher discrepancy in the doses for the particular fields (exceeding the action level) may have been due to the isocenter being very close to the jaws and multi-leaf collimator of the linear accelerator machine. As a result, scatter from the jaws and the multi-leaf collimator could have contributed to the high dose delivered to the diode; hence, a probable higher discrepancy of the dose in more brain cases due highest quality of VMAT technique and fixation system. Conclusion A greater percentage of the observed discrepancies were well within the set tolerance level. However, it is recommended that the positioning of the diode on the patient’s skin and the angular sensitivity of the diodes be reconsidered. It is also recommended that a more accurate calculation of expected diode values be performed, especially for fields that pass through the table. These efforts would achieve action levels of ±5%.