Table 8.

Equivalent doses (in mSv) for thyroid, lung and stomach due to neutron radiation calculated in this work considering a 70 Gy treatment (averaged over all fields; only 5 out of 8 fields were used for the 9 month old who thus misses the large volume fields). Note that the therapeutic dose was not modified with a scaling factor to account for fractionation. The values are compared to the radiation to be expected from a chest CT scan as a function of patient’s age (Lee et al 2007). All values are in mSv.

	9-month old	4-year old	11-year old	14-year old	Average
H to thyroid from proton therapy	121.2	195.4	166.0	155.1
H to thyroid from chest CT scan	8.0	9.0	5.2	6.9
Therapy / CT scan (thyroid)	15.1	21.6	31.8	22.4	22.7
H to lung from proton therapy	118.7	128.2	54.7	34.7
H to lung from chest CT scan	15.0	13.9	12.0	12.6
Therapy / CT scan (lung)	7.9	9.3	4.5	2.8	6.1
H to stomach from proton therapy	79.2	28.5	13.5	3.8
H to stomach from chest CT scan	11.0	4.9	5.9	5.0
Therapy / CT scan (stomach)	7.2	5.8	2.3	0.7	4.0