Keywords:
Ear / Nose / Throat, Head and neck, Oncology, CT, Radiation therapy / Oncology, Radiobiology, Stereotactic radiotherapy, Radiotherapy techniques
Authors:
B. Y. J. Leow1, A. Glenn1, K. Kandasamy1, A. Cullen1, S. P. Ng2, J. Chang1; 1Sydney, NSW/AU, 2Heidelberg, VIC/AU
DOI:
10.26044/ranzcr2021/R-0306
Results
The patient characteristics for the 8 patients are summarized in Figure 2.
The median age of diagnosis was 67 years old (range: 48 – 87 years) and there was an equal distribution of male and female patients. The mean tumour volume was 26.91 cm
3 (range: 15.08 – 37.57cm
3). Target objectives and OAR constraints as defined in the methods section were met in all treatment plans. Figure 3 shows the colourwash representation of the dose distribution of the different plans for patient 1.
The mean TCPs for SABR, CPRT, and CD-VMAT were 100%, 80% and 90%, respectively. SABR had statistically significantly higher TCPs than CPRT and CD-VMAT (P=0.003). The mean NTCPsaliva for the three plans were 23%, 41% and 33%, respectively. SABR had statistically significantly lower NTCPsaliva than CPRT (P=0.014) but the difference was not statistically significant compared with CD-VMAT (P=0.176). Mean NTCPswallow for the three plans were 6%, 12% and 23%, respectively. SABR had statistically significantly lower NTCPswallow than CD-VMAT (P=0.008) but the difference from CPRT was not statistically significant (P=0.101). The mean UTCP values for the three plans were 72%, 42% and 48%, respectively. SABR had statistically significantly higher UTCPs than CPRT and CD-VMAT (P<0.001).
SABR has the best therapeutic ratio (as measured by the UTCP) of the three plans analysed. This was the result of SABR having a statistically significantly higher mean TCP than the other two plans, and mean NTCPs that were lower than the other two plans (some statistically significantly different and some not, as described above). Results are summarised in Figure 4. We have also shown that the dose constraints as described in this study are achievable.