Between Dec 2000 and May 2002, 14 patients were successfully treated with IMRT. How long did the treatments take and how is the duration compared to conventional (conformal, static) treatments?
The VARiS database logs each treatment with a timestamp after completion. If we could, we would count the real duration between the time the patient enters the treatment room and the time he /she leaves after the treatment. Unfortunately, there is no timestamp for these times. So we calculate the duration in two different ways:
Both methods have their drawbacks. The first method gives long durations if there is a pause between patients (e.g., the IMRT patient has not arrived yet). The second method misses the setup time of the IMRT patient, because it only starts with the completion of the first setup field.
The average treatment timee for each patient are given in the following table, together with the standard deviations (values in [mm:ss]):
|
Patient
#
|
Location
|
#
of IMRT Fields
|
Last2last
|
StdDev
|
First2last
|
StdDev
|
|
1
|
Brain
|
3
|
23:18
|
12:48
|
08:53
|
01:45
|
|
2
|
Head/Neck
|
3
|
19:55
|
07:36
|
08:51
|
01:54
|
|
3
|
Brain
|
3
|
16:21
|
04:12
|
09:18
|
03:06
|
|
4
|
Head/Neck
|
3
|
26:17
|
09:53
|
11:06
|
02:04
|
|
5
|
Head/Neck
|
3
|
19:07
|
07:22
|
08:56
|
00:50
|
|
6
|
Head/Neck
|
3
|
15:10
|
02:23
|
07:16
|
00:55
|
|
7
|
Head/Neck
|
4
|
17:41
|
02:48
|
10:05
|
02:14
|
|
8
|
Head/Neck
|
4
|
20:34
|
07:02
|
09:21
|
01:58
|
|
9
|
Head/Neck
|
6
|
21:11
|
03:27
|
12:22
|
01:25
|
|
10
|
Head/Neck
|
4
|
23:06
|
04:27
|
09:44
|
02:58
|
|
11
|
Head/Neck
|
2
|
13:11
|
03:42
|
04:32
|
00:41
|
|
12
|
Head/Neck
|
3
|
11:27
|
04:36
|
03:37
|
01:52
|
|
13
|
Head/Neck
|
3
|
12:02
|
06:34
|
04:08
|
02:03
|
|
14
|
Prostate
|
7
|
23:23
|
10:29
|
11:15
|
02:29
|
Here is a histogram of treatment durations. Bin 16:00 for example counts all fractions that took between 15 and 16 minutes. This was the most probable treatment duration for the first 14 patients, if you count it that way (last2last). Values are given in percent of all treated fractions:
The second possible method to count treatment durations is first2last. Most probable time is 8 to 9 minutes, but the patient setup time is missed. Counting starts with the timestamp of the IMRT patient's first field (usually a setup field):
Here the same data in tabular form:
|
Duration [minutes]
|
Last2last
[%]
|
First2last
[%]
|
|
Less
than 2
|
0
|
7.6
|
|
2
to 3
|
0
|
9.4
|
|
3
to 4
|
0
|
2.9
|
|
4
to 5
|
0
|
7.1
|
|
5
to 6
|
1.8
|
6.5
|
|
6
to 7
|
2.4
|
8.8
|
|
7
to 8
|
3.5
|
12.9
|
|
8
to 9
|
3.5
|
13.5
|
|
9
to 10
|
6.5
|
8.2
|
|
10
to 11
|
4.1
|
8.8
|
|
11
to 12
|
4.7
|
4.1
|
|
12
to 13
|
6.5
|
3.5
|
|
13
to 14
|
5.9
|
2.4
|
|
14
to 15
|
5.3
|
2.9
|
|
15
to 16
|
11.8
|
0
|
|
16
to 17
|
4.1
|
0.6
|
|
17
to 18
|
4.1
|
0
|
|
18
to 19
|
6.5
|
0.6
|
|
19
to 20
|
5.3
|
0
|
|
20
to 21
|
2.4
|
0
|
|
21
to 22
|
2.4
|
0
|
|
22
to 23
|
2.4
|
0
|
|
23
to 24
|
1.8
|
0
|
|
24
to 25
|
1.8
|
0
|
|
25
to 26
|
2.9
|
0
|
|
26
to 27
|
0
|
0
|
|
27
to 28
|
1.2
|
0
|
|
28
to 29
|
1.8
|
0
|
|
29
to 30
|
0
|
0
|
|
30
to 31
|
0
|
0
|
|
31
to 32
|
1.8
|
0
|
|
32
to 33
|
0
|
0
|
|
33
to 34
|
0
|
0
|
|
34
to 35
|
0.6
|
0
|
|
35
to 36
|
0.6
|
0
|
|
36
to 37
|
0.6
|
0
|
|
37
to 38
|
0
|
0
|
|
38
to 39
|
0.6
|
0
|
|
39
to 40
|
1.2
|
0
|
|
More
than 40
|
2.4
|
0
|
The durations will be compared to conventional conformal treatments in a different section (work in progress).