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Home / MIL-therapy / Method of treatment / 8. Biophotometry as a mean of control over MIL-therapy.

8. Biophotometry as a mean of control over MIL-therapy.

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Application of LILR in clinical practice supposes an individual biophotometric control which allows to reach the most optimal dose in every patient as well as to objectively control laser therapy process, its effectiveness and duration. The absorbed dose defines laser therapeutic effect. That is why a reflection coefficient (absorption) at a fixed wavelength, in particular in the infrared range, may serve as an individual criterion to follow the dynamics of the pathological process resorption in MIL-therapy.

Transmission of LILR through biological tissues depends on their structure and functional state. Some part of LILR which effects biological tissues is reflected from its surface. LILR energy which enters tissues is dissipated many times and is absorbed by different biological structures. The amount of the energy absorbed by biotissues (Dabs) is equal to the difference between the incident light energy (Dinc) and the reflected one (Dref).

Dabs = Dinc - Dref = Dinc * (1- Cref)

where Cref - a coefficient of light reflection from the surface of skin and its deeper structures. This coefficient for human skin varies from 0,3 up to 0,6 on the average. That is why it has to be taken into consideration individually for every patient who is prescribed MIL-therapy. The performed investigations have shown that the reflection of IR radiation in patients aged above 30 is 10-15% less, than in patients over 50. The coefficient of reflection depends on the intensity of skin pigmentation.

A special apparatus has been designed for defining Cref - biophotometer. It allows to estimate the amount of light reflected from the surface of a bioobject. IR-radiation photoreceptors are in-built in the body of the terminal in “MILTA-F” apparatus (see Passport with technical description). An inner cylindrical camera in the terminal where laser, LEDs and photodiodes are placed plays the role of integrating sphere. Thus, the in-built photoregistor serves as a mini-biophotometer with digital indication of the reflected amount of continuous IR radiation. The bottom of a special well for the terminal on the panel of the remote control in the apparatus “MILTA-F” type plays a role of the supporting (“standard”) diffuse reflector. The IR-laser and LED radiation reflected from the supporting reflector or a bioobject is trapped by photo-diodes, increased and processed; then its values are shown on the display of the front panel as “REFLECTION LEVEL”. “00” indicates the absence of radiation.

The described device may be used to measure the reflection coefficient in biological tissues, bandages, skin, surface of ulcers, burns and other lesions on biological tissues. Values of “REFLECTION LEVEL” on the display allow to constantly control the presence of invisible (for human eyes) IR light at any moment during MIL- procedure. Photoregistor output data does not practically depend on curved and longitudinal-transverse movements of the terminal.

Before reading photoregistor data with curative and diagnostic purposes it is recommended to perform a seria of consecutive biophotometrical measurements to find out the differences (variation) in digital indicator data while performing some likewise measurements (for instance, to press the terminal to tissues with different degree of compression, etc.). It is recommended to fix, to collect and to systemise all the data received during these measurements in a special form. The presence of this or that pathology is defined both by standard diagnostic methods and by the results of photometric measurements. Deviations from normal biophotometrical data exceeding the variation indicator data by two times and more indicate the presence of a pathology in the investigated region. Normal photoregistor data are those data which are obtained during the irradiation of patient’s skin on the contralateral area. If the difference in the photoregistor data obtained after measuring a diseased focus is 6-7 units more that those in the symmetrical (healthy) area, a physician may be sure that there is a focus of pathological process there.

It has been found out that during MIL-therapy changes of optical parameters in treated tissues take place from one procedure to the next one; so, if a physician is quite experience, he may evaluate the course of pathological process, predict possible complications and control the effectiveness of the performed treatment as well as to correct exposure time and the number of procedures. Clinical and experimental investigations have shown that IR radiation reflection level at different conditions and diseases lies within the range from 40 relative units (RU) up to 70 RU. (Table 3). On the average this value is equal to 5 RU. In the average this value is mav/bo= 55 RU.

Table 3.
Characteristics of an irradiated Photoregistor values
Standard surface (white paper) 95
Healthy skin (normal) 60-70
Penetrating skin-muscular, postoperative wounds 40-50
Burnt surface 45-60
Hyperemia skin 50-60
Marked edema of soft tissues, edema of joints with bursitis 45-55
Trophic ulcers and unhealing wounds 30-40
Ischemia of tissues in vascular disorders of the extremities 50-55
Cicatricial tissue after wounds and operations 40-60
Mucous 25-35
Hairy surfaces 25-35

Calculations for photodiodes placed inside the camera (apparatus “MILTA-F”) are given in the first edition of Instructions and in authors’ works (see List of Literature).

Some modifications of “Milta-F-8-01” have widened diagnostical possibilities (in comparison to “Milta-F”) due to the placement of additional photo diodes outside the irradiation camera in the magnet apertures (this intervention is protected by Russian patent). IR-signals basically reflected from the inner deep layers of biological objects reach these photodiodes. In congested hyperemia or edema tissue reflection decreases (because more IR radiation is absorbed); in case of ischemia of deep structures, spasms of the vessels - visa versa. A very valuable diagnostic information may be received while comparing photoregistor data obtained from the external photodiodes with the data obtained from the photodiodes placed inside the terminal camera (a button on the terminal allows to change the regime of measurements - either only internal or only external photodiodes). Currently, investigations are being conducted to interpret these comparative photoregistor data more precisely.

Accuracy and reproducibility of digital indications are quite sufficient parameters to have a qualitative evaluation of irradiation doses and doses for comparison. The univocacy of the correlation between the in-built photoregistor data and the power of the reflected IR radiation (mWt but not RU) makes it possible to use this photoregistor as an indicator which gives the information qualitatively and, to some extent, quantitatively about tissue reaction to the combined MIL-irradiation just during the curative procedure.

Example. Biophotometry in chronic bronchitis (the inner photodiodes are used).

Values of reflection coefficient Cref (CR) were determined above the registration fields (Fig.41) I and II (projections of the main bronchi - paravertebral zones of the interscapula area at ThIII- ThVI level) and III, IV ( supra shoulders - Krenigue fields). An arithmetic mean index for the values of two symmetrical fields is written as CR-1 (fields I and II) and as CR-2 (fields III and IV). These values were taken from healthy individuals (norms) and in patients with chronic bronchitis during MIL-therapy (daily). Changes in CR show the dynamics of lung tissue pathology in patients.

It is shown that CR-1 predominatingly reflects an inflammatory process and, to less extent, bronchial obstruction. CR-2, visa versa, reflects bronchial obstruction and its severity rather than inflammation (Table 4, 5).

As it has been shown in studies CR values gradually increase by the 6-7th procedure and after that remain unchanged. It leads to a conclusion that MIL-therapy course in chronic bronchitis should not exceed 7-8 procedures in order to avoid side-effects.

Fig. 41. Fields of CR values registration.
Table 4. Dynamics of photoregistor data in patients with chronic non-obstructive bronchitis treated with MIL-therapy
Coefficient of reflection Basic group (n=31) Comparative group (n=8) Norm
Before treatment After treatment Before treatment After treatment
CR-1 51,99+-2,68 61,28+-2,38 s 51,63+-3,96 * 55,18+-4,19 62,35+-4,28
CR-2 57,72+-3,24 61,38+-3,47 56,91+-4,01 59,03+-4,12 63,35+-3,88
Table 5. Dynamics of photoregistor data in patients with chronic obstructive bronchitis treated with MIL-therapy
Coefficient of reflection Basic group (n=45) Comparative group (n=14) Norm
Before treatment After treatment Before treatment After treatment
CR-1 45,07+-2,17 * 52,02+-2,21 * s 44,18+-3,22 * 49,21+-3,18 * 62,35+-4,28
CR-2 48,56+-3,06 * 56,78+-2,59 s 49,28+-3,37 52,34+-3,61 * 63,35+-3,88
* - deviation from normal values is statistically significant
s - dynamics is statistically significant
Controls - patients treated with conventional therapy.

A simplified calculation of the energy absorbed by a patient during MIL-procedure with “MILTA-F-8-01”

A summarized energy (impulsed and continuous IR radiation) absorbed by a patient during MIL-procedure (an individual dose) is: Di=[1-(mbo/map]*[Pp+(Pip*ti*F)]*te where, Da - absorbed energy in J
mbo and mab - values on a photoregistor in “Milta-F-8-01” when the terminal is applied on a bioobject or put into the apparatus well. Before the procedure mab is tuned to 100 units (mWt).
Pp - LED radiation power (for “Milta-F-8-01” Pp= 100 mWt).
Pip -impulse power of laser radiation equal to about 4 Wt.
ti - is equal to about 150*10-9 sec - duration of LILR impulse.
F (in Hz) - frequency of laser radiation impulse (5, 10, 50, 80, 150, 600, 1500, 5000 Hz).
te ( in seconds, s) - summarized time of exposure for one procedure.

The following simplified formula to determine the absorbed energy may be recommended for practical application:

Da=(1-mbo/100)*(0,1+0,6*10-6*F)*te=(1-mbo/100)*D + [J]

If the attachments are used, the irradiated energy is approximately:

Da=(1-a)*(1- mth/mab)*D + [J],

where a approximately equals 0,35 -a total coefficient of losses for attachments, mth - photoregistor values for the inserted attachment, mab =100 - photoregistor data when the terminal is placed into the apparatus well, D+ - a summarized energy of irradiation [J] during MIL- procedure.