paediatrics Brussels 17

I. J. Radiation Oncology d Biology d Physics

982

Volume 71, Number 4, 2008

Table 2. Comparison of plans (IMPT, protons, and IMRT) for a representative patient with a supratentorial ependymoma

IMPT

Protons

IMRT

Mean

D 5

D 50

D 90

Mean

D 5

D 50

D 90

Mean D 5

D 50

D 90

Whole-brain CTV 5

27 19 57

0 8 4

<0.1 <0.1 <0.1

7

37 30 56

0.2 <0.1

12 23 23

45 47 58

3

0.5

Temporal lobe

8

11 22

14

<0.1 <0.1

23

3 2 2 2 2 1 6

Brainstem Pituitary

21

7

8 2 3 3 2

<0.1 <0.1 <0.1 <0.1 <0.1

0.1 <0.1 <0.1 0.3 <0.1 <0.1 0.1 <0.1 <0.1

2 3 3 2

3 4 4 2

Optic chiasm Left cochlea Right cochlea Hypothalamus

<0.1 <0.1 <0.1 <0.1

0.1

<0.1 <0.1 <0.1 <0.1 <0.1

<0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

15 56 57

47 57 57

13 56 57

0.3

22 56 56

49 57 56

20 56 56

4

22 57 57

50 58 58

22

CTV GTV

56 56

56 56

57 56 57 56

Abbreviations: IMPT = intensity-modulated proton therapy; IMRT = intensity-modulated radiation therapy; CTV = clinical tumor volume; GTV = gross tumor volume; D x = Dose in gray to structures for x% of tissue volume.

to or encompassed by the CTV. The IMPT provided further normal tissue sparing for most structures. Figure 3 shows axial views of the IMRT, proton, and IMPT plans for treatment of an infratentorial ependymoma. Dose

distributions are shown at the level of the cochlea and tempo- ral lobes. For the infratentorial plan, the left cochlea received a mean dose of 37 Gy with IMRT, 2 CGE with protons, and less than 0.1 CGE with IMPT. Mean dose received by the

Fig. 1. Comparison dose–volume histogram (DVH) for intensity- modulated radiation therapy (IMRT), proton (3DC proton), and in- tensity-modulated proton therapy (IMPT) plans for infratentorial ependymoma: (A) clinical tumor volume (CTV), temporal lobes (TL), pituitary (PT), hypothalamus (HT), (B) gross tumor volume (GTV), right cochlea (RC), left cochlea (LC), brainstem (BS), and whole brain (WB).

Fig. 2. Comparison dose–volume histogram (DVH) for intensity- modulated radiation therapy (IMRT), proton (3DC Prot.), and inten- sity-modulated proton therapy (IMPT) plans for supratentorial ependymoma: (A) clinical tumor volume (CTV), brainstem (BS), whole brain (WB), (B) gross tumor volume (GTV), temporal lobes (TL), pituitary (PT), and hypothalamus (HT).