Safety margin in irradiation of colorectal liver metastases: assessment of the control dose of micrometastases

Radiation Oncology

Table 1 Results of the ANOVA analysis

Distance of the local recurrence to the former tumor margin (mm)	Maximum upper 97.5% tolerance limit with coverage of 87.5% (Gy)	Maximum upper 97.5% tolerance limit with coverage of 75% (Gy)
1	18.66	17.56
2	18.49	17.40
3	18.32	17.23
4	18.16	17.06
5	17.99	16.90
6	17.82	16.73
7	17.66	16.57
8	17.49	16.41
9	17.33	16.24
10	17.17	16.08
11	17.01	15.92
12	16.85	15.76
13	16.69	15.59
14	16.53	15.43
15	16.37	15.27
16	16.22	15.11
17	16.06	14.96
18	15.90	14.80
19	15.75	14.64
20	15.60	14.48
21	15.45	14.33
22	15.30	14.17
23	15.15	14.01

Maximum upper 97.5% tolerance limits with coverage of 87.5% and 75%. 87.5% means that 87.5% of the data (dose measured in the center of the micrometastasis) are below the upper limit of the tolerance interval (with a confidence of 97.5%).
The Maximum upper 97.5% tolerance limit with coverage of 87.5% for the distance of 21 mm was 15.4 Gy: 87.5% of the doses in the isocenters of the micrometastases with a distance of < 21 mm to the initial tumor margin were less than 15.4 Gy. Thus < 15.4 Gy at a distance of < 21 mm was insufficient to avoid tumor growth from micrometastases in 87.5% of the cases.

ISSN: 1748-717X