IVD TIMING test 1 test at 1 fraction 2 test at 2 fraction 3 test at 3 fraction 4 test during next week 5 test during next week 6 test during next week

Transcription

1 IVD TIMING test 1 test at 1 fraction 2 test at 2 fraction 3 test at 3 fraction 4 test during next week 5 test during next week 6 test during next week

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4 Causes of discrepancies due to inadequate quality controls: 1.Patient Set-up 2.Occasional morphological changes 3.Systematic morphological changes 4.Attenuators on the beams (patient supports) 5.TPS implementation 6.CT number implementation 7.Laser misalignments 8.Output dose variations 9.Inaccurate MLC positions

5 Some frequent warnings obtained in the italian Centers participating at the DISO project are here reported showing the 2 tests

6 Brest irradiation, at the 3 test an incorrect setup, well evident by the green signal profile,the dose at the isocenter point increase (R= 1.062) off tolerance and. R=1.062

7 .also the analysis shows the change of setup of about 1.5 cm and the P <1 = 72.6% out of tolerance level, the red area shows an over dosage

8 ABDOMEN of patient setup, the second test with R = is off tolerance and..

9 ..the change of setup is more evident by the gamma analysis where the P <1 = 47.8% Once corrected the setup the R ratios and the P <1 values were within the pass-rate.

10 Attenuating support not included in the TPS computation, R=0.906 R=0.906

11 Attenuating support now included in the TPS computation R=0.982 R=0.982

12 Brest tumor. All the R tests are within the tolerance level of 5% All but.. R= 1.001

13 .the presence of the couch border on the beam is detected by the analysis that shows a P <1 =80.5% the under dosages can be responsible of recurrences.

14 the program can estimate an under dosage equal to 8%. 8%.

15 Pelvic tumor. The R ratios are within the tolerance level of 5% even if the beam at 180 intercept a couch support but..

16 .the presence of coch -attenuator on the beam is well detected by the analysis that shows a P <1 = 25%. these under dosages (about 10%) can be responsible of recurrences.

17 in this case dose variations of 10%. are in large area of the field

18 . Pelvic tumor gas pockets in the TC scan used for planning. The R ratios are within the tolerance but the profiles are irregular, and.

19 the -analysis P <1 = 75.9%, the signal profiles show dose variations of 10%. In a large area

20 Pelvic tumor. Large gas pocket in the TC scan used for planning. The R ratios are within aa the tolerance but the profiles are irregular, and.

21 ...the -analysis supplied a P <1 = 76.8%, under dosages up to 15% can be estimated by the profiles, and they are responsible of recurrences.

22 Prostate TC-scan with small distended rectum, the occasional presence of gas-pocket at the 3th fraction, with R values up to Moreover a couch attenuator is present in 1/3 of tha field (under dosage up to 10%)

23 ..the -analysis supplied a P <1 = 93.0% and the dose variations estimated by the profiles are about 10%. The couch-attenuators are always present

24 Prostate TC-scan without gas pockets, the occasional presence of gas- pocket is during the second fraction, where resulted R= 1.07, but... R= 1.071

25 ..the -analysis supplied a P <1 = 95.5% and the dose delivery can be accepted

26 Presence of a gas pocket in rectum on the CT-scan used for the planning. During the 1 and 3 tests the rectum is distended, and R ratios are within the tolerance, but at the 2 test the pocket size decreased and R= i.e. a underdosage at the tumor of 10%. R= 0.907

27 ...even if the -analysis P <1 = 95.5%, the signal profiles confirmed dose variations of 10% in small areas, but the couch-attenuators are always present

28 . The distended rectum is stable enough in the sections even if the R values show an under dosage

29 .even if the -analysis P <1 = 90.5 %, is within the tolerance level dose variations u p to 10%. are due to the presence of a couch attenuator

30 The presence of a couch attenuator is half field means a large underdosage and the the isocenter dose is over estimated due to a large gas poket.

31 In the recent years IVD tests have been obtained in 8 Italian Centers participating at the DISO Project. Those results are similar to that reported here obtained using the BEST SOFTDISO-3DCRT for 281 patients treated since January 2014 with 3D CRT techniques.

32 R P <1 R ratio for single test (5603) 89% of tests within 5% Mean R ratio for patient (281) 100% of tests within 5% Gamma analysis for 5241 test 87% of tests show Pg>90%

33 In conclusion even if 11% of the R tests and 13% of P <1, tests were out-tolerance levels, once removed the causes of the dose discrepancies for each patient the mean value R ratio was within 5% and P <1 90%

34 SUMMARIZING THE ROLE OF INDEXES R and P <1 We observed cases where R=1.02 (within the tolerance level) and P <1 = 80.5% (outside tolerance level) Attenuator off-axis b) and cases where R=1.08 (outside the tolerance level) and P <1 = 95.5% (within tolerance level) Gas pocket on-axis