For canine patients with nasal tumors a radiation oncologist would normally pres

Question

For canine patients with nasal tumors a radiation oncologist would normally prescribe a dose of 57 Gy delivered in 3 Gy fractions Monday through Friday (19 fractions) (Protocol A). The dose limiting structure in these patients is bone (alpha-beta ratio = 2.2). The radiation oncologist decides to alter this regimen and deliver the radiation dose in 4 Gy fractions (still treating Monday through Friday) (Protocol B).

What total dose could be administered in 4 Gy fractions (Protocol B) that would allow for a similar probability of late effects to bone compared with the regular 3 Gy per fraction protocol (Protocol A)? (Show your work).

Explanation / Answer

The canine patient with nasal tumors.

The radiation oncologist prescribed the dose = 57Gy

Mon - Friday = 19Gy fractions

Doctor devided dose in = 3Gy fractions

Protocol A:

Mon - Friday = 19Gy

In 3 Gy fraction= 19*3

= 57Gy

Protocol B:

Increased dose upto = 4Gy

Mon - Friday = 19Gy

19*4=76Gy

But the similar probability showed in the protocol A and B.

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