Dose prescription and optimisation based on tumour hypoxia

Figures & data

Figure 1.  Simulated oxygen distribution in a theoretical tumour used in this study. It was assumed that the simulated tumour has two hypoxic islands surrounded by cells that are better oxygenated. The local oxygen distributions for each region are indicated in the insets.

Figure 2.  Different patterns of oxygenation simulated in the study. (a) The reoxygenation affects the distribution at the microscopic level only, while the overall regional oxygenations remain the same. (b) The hypoxic islands in the tumour shrink during the course of the treatment. (c) The regional oxygenations might change location due to complex patterns of vascular failure that may occur during the treatment.

Figure 3.  Dose distributions calculated to give a predefined tumour control level of 90%; (a) – heterogeneous distribution, , calculated with Equation6 from the derived radioresistance map of the tumour; (b) – segmented dose distribution, D_P, calculated with Equation9.

Figure 4.  Variations in the achievable tumour control probability due to modifications of the hypoxic pattern in the tumour. Solid symbols show the response to uniform doses delivered to the target. Open symbols show the response to a segmented dose distribution derived with Equation9.

Table I.  Predicted tumour control probabilities for various numbers of reoxygenations

	Tumour control probability (%)
			Uniform dose distribution with the specified value
Number of reoxygenations	Heterogeneous dose distribution	Segmented dose distribution	60 Gy	70 Gy	80 Gy	90 Gy
Reoxygenation of acute hypoxia
0	90	0	0	0	0	0
1	55	1	0	0	0	27
2	46	49	0	0	26	77
4	50	84	0	12	77	97
9	57	92	0	47	94	99
14	60	93	0	59	96	100
29	63	94	0	68	98	100
Reoxygenation of acute and chronic hypoxia
0	90	0	0	0	0	0
1	62	5	0	0	1	30
2	58	75	0	0	34	82
4	67	94	0	26	85	98
9	80	95	2	76	98	100
14	84	95	12	89	99	100
29	87	96	34	97	100	100
Complex reoxygenation patterns
0	90	0	0	0	0	0
1	59	11	0	0	3	44
2	69	48	0	56	94	99
4	82	90	16	93	100	100
9	85	94	29	96	100	100
14	86	95	35	97	100	100
29	87	95	39	98	100	100