Response to "Comment on 'Objective assessment in digital images of skin erythema

We appreciate the interest of Carrara et al.1 in our recent article
on the assessment method in digital images of skin erythema
caused by radiotherapy.2 Matsubara et al. presented a linear
relationship between skin blood flow and skin dose, while
Carrara et al. suggest that their clinical data do not reproduce
it even though their sample number of patients treated is ten
times larger than that of Matsubara et al. We would like to
suggest that the disagreement between the data by Carrara
et al. and Matsubara et al. is qualitatively reasonable because
it arises from neglecting the recovery process of damaged
skin as is explained below.
Skin erythema is physiologically caused by expansion of
capillaries due to increased blood flow, which is a part of the
biological skin repair response. As long as the skin erythema
is an acute toxicity, the skin recovers and the symptom usually
disappears in several months. This indicates that skin blood
flowincreases owing to the repair process just after irradiation,
but decreases owing to the recovery process from the damaged
skin a few tens of days later.
Matsubara et al. treated six patients who had the carbon
beam therapy with a total prescription dose of 50 Gy (RBE).2
It should be noted that the prescription dose was delivered by
a single fraction from four ports, indicating that the treatment
was completed in one day. On the other hand, Carrara et al.
treated 61 patients who had the 6/15 MV photon therapy with
a total prescription dose of 50 Gy but with a 2 Gy fraction,
indicating that the treatment was completed in 25 days. The
recovery process for skin erythema is assumed to work during
the treatment. This would result in the reduction of skin blood
flow per accumulated skin dose, causing nonlinearity between
skin blood flow and skin dose. The disagreement between the
data by Carrara et al. and Matsubara et al. can be qualitatively
understood by taking the recovery process into account. That
is why Matsubara et al. selected only the cases of a single
fraction in order to avoid the recovery effect.
As Carrara et al. suggest, however, we agree that the
linearity observed by Matsubara et al. is not based on physical
evidence. What Matsubara et al. discussed was just that the
gross trend of the obtained data could be expressed by the
linear relationship with moderate accuracy, where several
variations due to individuality of patient or time dependence
of skin erythema were assumed to be negligible as discussed
in Ref. 2. There is no known numerical relationship between
accumulated skin dose and time dependence of skin erythema.
The new data suggested by Carrara et al., therefore, are
assumed to be important for further investigation of skin
erythema.

書誌情報

Medical physics

巻 43, 号 5, p. 2689, 発行日 2017-02

出版者

John Wiley and Sons, Inc.

ISSN

収録物識別子タイプ

ISSN

収録物識別子

0094-2405

戻る

views

See details

	Views

Versions

Ver.1

2023-05-15 22:13:11.532980

Show All versions

Cite as

エクスポート

OAI-PMH

JPCOAR 2.0
JPCOAR 1.0
DublinCore
DDI

Other Formats

JSON
BIBTEX

インデックスリンク

インデックスツリー

アイテム