Translational and rotational intra- and inter-fractional errors in patient and target position during a short course of frameless stereotactic body radiotherapy

Figures & data

Table I. Patient characteristics.

Tumour size					Tumour motion (4DCT based)
Patient	Age	Gender [cm^3]		Primary disease	Lesion site	AP [mm]	CC [mm]	LR [mm]
1	75	M	29.43	NSCLC	LLL	1	1	1
2	43	M	12.67*	Stomach cancer*	LUL/LLL	0	3	0
3	76	M	9.32	NSCLC	LUL	0	1	1
4	74	M	15.07	NSCLC	LUL	0	3	0
5	57	M	10.48	Adrenal gland cancer	LUL	1	4	2
6	65	M	11.47	colon cancer	LLL	0	20	0
7	71	F	33.97	NSCLC	LUL	4	1	2
8	62	F	16.06	NSCLC	RML	1	4	5
9	91	F	64.61	NSCLC	RLL	2	8	3
10	85	M	156.33	NSCLC	LLL	0	12	0
11	55	M	4.09	rectal cancer	LUL	0	11	0
12	65	M	5.58	NSCLC	RUL	0	0	0
13	76	M	7.40	NSCLC	LLL	0	7	0
14	58	F	26.25	Malignant melanoma	LLL	7	14	5
15	82	M	8.89	NSCLC	RUL	1	4	2

AP, anterior-posterior; CC, cranio-caudal; 4DCT, four-dimensional computed tomography; LLL, left lower lobe; LR, left-right; LUL, left upper lobe; NSCLC, non-small cell lung cancer; RLL, right lower lobe; RML, right middle lobe; RUL, Right upper lobe.

*Two metastases with overlapping PTV hence treated as a single target. Tumour size provided as the sum of the two tumour volumes.

Table II. Residual positioning error when correcting for three degrees of freedom compared to six degrees of freedom, i.e. when rotational errors are not corrected for.

	AP [mm]	CC [mm]	LR [mm]	pitch [°]	roll [°]	rot [°]
M	20.1	0.1	20.1	0.31	20.06	20.56
∑	1.3	1.0	0.8	1.20	1.23	1.42
σ	1.5	1.0	1.1	0.79	1.33	0.85

AP, anterior-posterior; CC, cranio-caudal; LR, left-right.

Table III. Errors introduced when using bone match as the image guidance instead of soft tissue tumour match.

	AP [mm]	CC [mm]	LR [mm]	pitch [°]	roll [°]	rot [°]
M	0.8	0.8	20.2	0.47	20.24	20.69
∑	1.2	2.4	1.2	1.09	1.41	1.01
σ	1.2	1.1	1.1	0.82	1.20	0.67

AP, anterior-posterior; CC, cranio-caudal; LR, left-right.

Table IV. Intra-fractional differences in tumour and patient position and baseline shift.

	AP [mm]	CC [mm]	LR [mm]	pitch [°]	roll [°]	rot [°]
Changes in target position
M	0.9	20.6	0.0	20.27	0.36	0.03
∑	1.5	1.5	1.3	0.62	1.08	0.58
σ	1.7	2.1	1.6	0.93	0.98	1.09
Changes in patient position
M	0.4	20.4	0.1	0.00	0.00	0.08
∑	1.0	1.6	0.9	0.33	0.18	0.27
σ	1.4	2.0	0.8	0.29	0.31	0.34
Baseline shift
M	0.5	20.2	20.1	20.27	0.36	20.05
∑	1.7	1.1	0.8	0.49	1.12	0.51
σ	1.6	1.1	1.3	0.90	1.07	1.07

AP, anterior-posterior; CC, cranio-caudal; LR, left-right.

Figure 1. Three-dimensional baseline shift as a function of tumour motion in cranio-caudal direction: linear regression analysis does not indicate any baseline shift dependence on peak-to-peak tumour motion.

Figure 2. Intra-fractional three-dimensional baseline shift as a function of duration of treatment fraction: linear regression analysis does not indicate any baseline shift dependence on duration of treatment fraction.