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Keywords:
ionizing radiation, infrared thermogrammetry, human
biology, radiation injury
The thermal approach to the quantitative measurement of radiodermatitis
due to ionizing irradiation is an up-to-date technique in the research of the
effects of the skin radiation exposure.
At different doses of external
irradiation the thermography (IR-TGM) could be applied as a
useful tool in diagnosis of local radiation injury. The examples presented
suggest an early detection of temperature alterations, the sensitivity and the
thermoregulatory reactions of irradiated tissues.
In Hungary, the technique of infrared thermogrammetry (IR-TGM) in the
field of radiation biology was first applied in 1984, when the authors
published two case study on a local radiation injury and suggested that both
contact and IR-TGM were useful tools in detection of the areas of radiation
injury [1,2,3].
While in 1984 a serious injury of a hand (20-30 Gy, locally) was
described, later in 1990 an injury caused by a much lower dose (1-2 Gy,
locally) was reported when IR-TGM would still assist the diagnosis.
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2.
Experiences through injuries of hands |
2.1.
Injury in a
defectoscopic measurement
In the first case an industrial
radiographer, while performing defectoscopy, experienced a radiation injury of
his left hand from an 192Ir source (1.11 TBq) during
disassembling the containment. It was not an approved action! The assessment of
dose to the most exposed distal parts of the fingers yielded
values between
20 and 30 Gy. Thermography indicated higher temperatures in average of 1.5 -
2.4 oC on the affected hand as compared with the counterlateral one
[1,2,3]. By this
technique a much larger area was found to be damaged than that covered by
clinical signs of radiation burns.
2.2. Injury in a nuclear power station
In second case a moderate injury caused by a mixed field of
g and neutron sources to a specialist
of dosimetry in a nuclear power station has occurred
[3]. In this case the dose was estimated
between 1.2 and 1.7 Gy. The average increase of temperature was observed as 0.5
oC. No clinical signs have been arisen.
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These two cases provided information on advantages of thermographic
techniques which are important for medical handling, i.e.
the detection on injuries if compared with the
relevant counterlateral part of the body;
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visualization of the extent of area injured;
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the possibility of follow-up of pathological
conditions as the effectsof exposure could also be detected in the latent phase of pathological
process.
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3.
Thermal skin-reaction of ionizing radiation |
Based on the previous experiences we wished to complete our results with
data obtained on clinical cases. Accordingly,
in 1994 a series of measurements were initiated on patients submitted to
ionizing radiation after surgical mastectomy. This approach offered the quantitative measurement and observation of
thermal skin-reaction in function of localization and time [4,5,6].
Following the post-operative
radiation treatment (Fig.1.) over a period of 3 weeks the characteristics of
the thermal reactions were identified more successively as before in the cases
of local radiation injuries (Fig.9.and 10.).
3.1
Tissue reactions in fractionated irradiation
The next approach was intended to
reveal the minimum dose range (Fig.2.) signaling the change of local
temperature following radiation injury or burns. Measurements had been
initiated on oncotherapy patients submitted to accelerated electron irradiation
after mastectomy. By a computerized image analysis of the distribution of
altered temperature, it was found that alterations could be detected following
even a dose of 2.5 Gy (Fig.9.and 10.a.). This result is in good agreement with
the case in chapter 2.2. as above, i.e. even 1 or 2 Gy doses cause signs
detectable by thermography.
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4.
Representation by histograms |
From the
further analyses of temperature distribution like on Fig.9. additional
informations could be obtained by the histograms plotted against the consecutive daily treatments (Fig.11.). A
histogram by the graphical form and the corresponding statistical parameters
(maximum, minimum, average, median, standard deviation and skewness of the
temperature distribution
[7]), represents the field of temperature of an area
under scrutiny.
On Fig.11. two
principal series of histograms show the changes of the temperature field
of an irradiated femal chest during the session days of treatment. The first is
(Fig.11.a.) before the treatment and the second (Fig.11.b.) 30 minutes after
that (the number of session day is marked with star). For a better comparison
the histograms are fitted to a vertical line of 34 oC value.
The changes of
the form of histograms during the first 30 minutes after 1st day
irradiation (Fig.9.and 10.a.) could be compared with Fig.11.a./1 and
Fig.11.b./1* and the immediate changes of the corresponding average temperature
difference is 0.5 K (Fig.5.). The maximum and minimum values of histograms are representing
by Fig.3.
Comparison of
thermal state of the irradiated area in 1st and 2nd days
after irradiation could be made with
Fig.11.b./1* and Fig.11.b./2* and the changes of corresponding average
temperature difference is 2.2 K (Fig.4.).
The average
temperatures and temperature differences developed during the first 30 minutes
after irradiation against the days could be seen on Fig.4. and Fig.5. and
against of the cumulative absorbed beta-dose on Fig.8. Summing up what has been
presented, changes of radiation-induced thermal effect in various phases of
radiation treatment can be seen on Fig.6. based
on Fig.5.
From practical
point of view the changes of the parameters of histograms as on Fig.3.-Fig.8.
are very useful, but it could not be omit to investigate the graphical form of
histograms (peak and width of the temperature, etc.).
Rather sensitive tissue reactions were experienced, i.e.:
- during the progress of treatment
the average of temperatures on skin surfaces increased;
- there was always an immediate reaction after irradiation, the
temperature alterations of which was continuously increased
from appr. 0.5 K to more than 1 K following cumulated dose of 25 Gy but then this
reaction vanished;
- within 24 hours following each
irradiation the initially developed temperature has been decreased. This value was high after 2.5 Gy, then deeply down-regulated
despite of the next fraction and only slight decreases were detected up to 15 Gy.
Afterwards negative values, i.e. less than the temperatures before the actual irradiation
appeared indicating
probably the
appearances of tiny necrotic areas (Fig.8.).
Accepting that the increased temperature is a normal tissue reaction, it
can be seen that at the end of the first session the skin temperature increased
in contrast with the second and third sessions weekends when it was decreased
(Fig.7.). This may indicate that the regulatory functions of the skin have been
relaxed. On further irradiation, the radiation reactions were not additive;
just a decrease of the average temperature was observed (Fig.4.) especially
when there was a break of 2 days in the treatment protocol (Fig.2.). Accordingly,
the tissue reactions but, in contrast, induce a modulation.
Thermography proved to be a valuable
tool to complete other diagnostic procedures for cases of local radiation
injuries. The evaluation of thermogrames by computerized image analysis
provided a sensitive method to detect altered temperature distribution
expressed through the histograms. By this complex approach of evaluation,
tissue reactions could be observed and followed.
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Fig.1. Various
beta-irradiated areas on the chest of patient after operation of breast
cancer (broken line indicates the scar of operation)
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Fig.2. Cumulative absorbed beta-dose values during the
treatment
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Fig. 3. Maximum and
minimum values of temperature-histogram of the irradiated area before and
after irradiation at various days
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Fig. 4.Immediate changes of the average temperatures on
the irradiated surfaces before and after each radiotherapy sessions
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Fig. 5. Changes of
average temperature differences as measured before and after radiotherapy
sessions during the treatment
(based on Fig. 4.)
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Fig. 6. Changes of
radiation-induced thermal alterations in various phases of radiation
treatment (based on average temperature values).
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Fig. 7. Alterations
of local skin temperature differences on chest between the irradiated and
counterlateral sites during treatment.
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Fig. 8. Changes of
average temperature values of irradiated area before and 24 hours after each
irradiation in function of the cumulative absorbed beta-dose
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Fig.9. IR-thermogram
of femal chest before the radiation treatment at the 1st day
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a. |
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Fig.10.
IR-thermograms of beta irradiated femal chest area 30 minute after radiation
treatment at a.
/ 1st day and b./ 2
nd
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Fig.11.a.
Series of
histograms of beta irradiated areas before each irradiation session |
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Fig.11.b.Series of
histograms of beta irradiated areas 30 minutes after each irradiation session |
[1] BENKO, I., KOTELES, G.J., “Thermotechnical approaches to the
investigation of local injuries caused by ionising radiation”,
Periodica Polytechnica, Ser. Mech. Eng. 37, 1993, pp. 197-213.
[2] BENKO, I.,
“Histographical analysis of infrared images for medical diagnosis”,
8th Int. Conf. on Thermal Engineering and Thermogrammetry,
Budapest, Hungary, 1993, pp. 307‑308.
[3]BENKO, I., “Possibilities
of infrared imagery in the field of biology of ionising radiation”, Proceedings of the Workshop on Advanced
Infrared Technology and Applications. Casa Malaparte - Capri (Italy),
September 20-21, 1993. Fondazione “Giorgio Ronchi”, Firenze, 1994, pp. 255-270.
[4]
BENKO, I.,
KOTELES, G.J., NEMETH, G., “Thermal imaging of the effects of beta-irradiation
on human body surface”, Quantitative
Infrared Thermography QIRT ‘96, Stuttgart, Germany, September 2-5, 1996,.
Eurotherm Series 50) Edizioni ETS, Pisa, Italy. pp. 354-359.
[5] BenkO, I.,
KOteles, G.J., NEmeth, G., “New infrared histographic investigation of
the effect of beta-irradiation in medical field”, Proceedings of MIRT'98, edited by D. Balageas, G. Busse, G.M.
Carlomagno and B. Wiecek, PKOptoSEP, Lodz, 1998, pp. 40-45.
[6] BENKO, I., KOTELES, G.J. and NEMETH, G., "Image processing of
medical infrared images for monitoring local conditions during
radiotherapy", The Imaging Science
Journal, 48, 2000, pp.9-13.
[7] BenkO, I., KOteles, G.J., NEmeth,
G., "The use of statistical parameters in medical IR-image analysis",
Proceedings of QIRT'2002, edited by
D. Balageas, J.-L. Beaudoin,G. Busse, G.M. Carlomagno,UTAP,Reims, 2000, pp.
399-404.
[8]
BenkO, I., KOteles, G.J., NEmeth, G.,
“Series of methods for the analysis
of infrared images” ,
12 th Int. Conf. on Thermal Engineering and
Thermogrammetry, Budapest, Hungary, 2001, pp. 8-14.
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