ESTRO 2024 - Abstract Book

S3843

Physics - Image acquisition and processing

ESTRO 2024

Results:

Figure 1 shows the GTV normalized to first session and the HF during the course of RT, i.e. as a function of radiation dose. In agreement with other studies [4], both the GTV and HF decrease with delivered dose. The average decrease in GTV at session 3 were 47 % and 28 % for the GTV-T and GTV-N, respectively (figure 1A+B). The average HF decreased from 0.50 to 0.14 (GTV-T) and from 0.26 to 0.08 (GTV-N), see figure 1C+D. The data in figure 1 represents a diverse dataset of tumors and lymph nodes with varying volume, HF, and IC.

Figure 1: GTV and HF at session 1 (beginning), 2 (midway), and 3 (near-end of RT). Top: GTV normalized to volume size at session 1 for GTV-N (A) and GTV-T (B). Volume points of patient 6 (session 2-3) were calculated relative to the simulation CT based delineation. Bottom: HF for GTV-N (C) and GTV-T (D). Figure 2 shows the IC mean and sd as a function of HF for the pooled patient and session data of the GTV-T and GTV N, respectively. An overall decrease in IC mean and sd with HF can be observed (figure 2A+B) although a large spread in the data is seen for well-oxygenated GTVs (HF ~ 0). However, if we combine the IC information taking the IC sd/IC mean ratio, the trend becomes more clear as illustrated with mono-exponential fits (figure 2C).