A quality control method for intensity-modulated radiation therapy planning based on generalized equivalent uniform dose

Abstract

To ensure good quality intensity-modulated radiation therapy (IMRT) planning, we proposed the use of a quality control method based on generalized equivalent uniform dose (gEUD) that predicts absorbed radiation doses in organs at risk (OAR). We conducted a retrospective analysis of patients who underwent IMRT for the treatment of cervical carcinoma, nasopharyngeal carcinoma (NPC), or non-small cell lung cancer (NSCLC). IMRT plans were randomly divided into data acquisition and data verification groups. OAR in the data acquisition group for cervical carcinoma and NPC were further classified as sub-organs at risk (sOAR). The normalized volume of sOAR and normalized gEUD (a = 1) were analyzed using multiple linear regression to establish a fitting formula. For NSCLC, the normalized intersection volume of the planning target volume (PTV) and lung, the maximum diameter of the PTV (left-right, anterior-posterior, and superior-inferior), and the normalized gEUD (a = 1) were analyzed using multiple linear regression to establish a fitting formula for the lung gEUD (a = 1). The r-squared and P values indicated that the fitting formula was a good fit. In the data verification group, IMRT plans verified the accuracy of the fitting formula, and compared the gEUD (a = 1) for each OAR between the subjective method and the gEUD-based method. In conclusion, the gEUD-based method can be used effectively for quality control and can reduce the influence of subjective factors on IMRT planning optimization.

Keywords: IMRT; gEUD; quality control; radiation planning.

Figure 1

The red shadow indicates PCTV2, the purple line indicates the right parotid gland, the yellow line indicates the intersection of ring1 and the right parotid gland (the nearest ring area to the right parotid gland), the green line indicates the intersection of ring4 and the right parotid gland (the middle of ring area to the right parotid gland), and the blue line indicates the intersection of ring7 and the right parotid gland (the farthest ring area to the right parotid gland). There are eight rings in total.