ESTRO 2024 - Abstract Book

S4051

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2024

Table 1. CTV coverage per individual sCT (method A) and deformed sCT dose (method B) and average per patient using both methods.

Breast

Boost

LN L1/L2

LN L3/L4

IMN

PB

Axilla

Total # sCTs = total # deformed sCT doses

336

206

162

164

44

50

45

Method A sCTs D98>90% (#)

336

206

162

146

40

50

44

Method B Deformed sCT doses >90% (#)

314

201

162

147

27

50

44

p -value method A vs B

<0.001

<0.001

<0.001 0.024

<0.001 <0.001 0.198

# Patients

20

10

9

9

2

10

3

Method A D98 average sCT >90% (#)

20

10

9

8

2

10

3

Method B D98 total accumulation >90% (#)

19

10

9

9

1

10

3

p -value method A vs B

<0.001

0.007

0.008

0.011

0.180

0.169

0.593

The overall average CTV D98 was very high at >95% for all CTVs, except for IMN: 94.3% (method A), and 92.1% (method B), respectively (Table 2). The CI was similar for all CTVs for both methods, as well as the IQR, except for PB. Time trend analysis showed, with each subsequent fraction, an average D98 increase for breast, boost and L1/L2, although insignificant for method B for breast. In contrast, an average D98 decrease was found for method B for axilla and IMN, but this was based on only 3 and 2 patients, respectively.