EVALUATION OF THE ACCURACY AND REPRODUCIBILITY OF THE PLANNING ISOCENTRE USING AUTOMATIC AND MANUAL COUCH MOVEMENTS

Abstract

The present study delves into the subject of analyzing the accuracy and reproducibility of the planned isocenter using automatic and manual couch movements, a pivotal issue within the broader context of radiotherapy. This research was driven by the compelling need to ascertain the deviation from the tumor isocenter during the delivery of radiation to cancerous cells and check whether they are within the acceptable clinical tolerance using the AAPM TG-142 protocol. The methodology adopted for this study was hinged on the analysis of the distances between the treatment isocenter from the planned isocenter. The research process involved a detailed collection of shifts using RANDO phantom from three regions of the body (head and neck, thoracic, and pelvic regions) using both automatic and manual couch movements. Sixty shifts; twenty for each region were recorded from where the distances were calculated. The distances offered a more objective evaluation of the accuracy of both couch movements as opposed to the shifts in coordinates. Moreover, the data was analyzed using MS Excel functions that ensured a comprehensive exploration of the topic and an in-depth understanding of the findings. It was found that automatic couch movements were more accurate in reproducing the planned isocenter as compared to manual couch movement techniques. In addition, the present study records a relatively high shift from the planned isocenter for the thoracic region. Only 20% and 17% of the shifts were within the acceptable limits for automatic and manual couch movement respectively compared to the pelvic, head and neck regions whose shifts tolerance was above 70% for both couch movements These results have far-reaching implications for radiation dose delivery as slight deviations from the planned isocenter could potentially lead to an important under dose to the target, which could lead to tumor recurrence and an excessive dosage to healthy tissue, which could have serious repercussions to normal tissues. In conclusion, the findings from this research not only fill a critical gap in the existing literature but also could potentially influence clinical practices and guidelines in the use of couch movements during treatment planning. Future research endeavors could build upon these findings, thereby paving the way for more comprehensive studies in this field.