Journal of Lasers in Medical Sciences
Volume:2 Issue: 3, Summer 2011

This study seeks to discuss the light wave transport characteristics variation along the pericardium Meridian under different pressures. We selected 36 healthy students at the school for this study, tied up the desktop blood pressure cuff onto subjects’right proximal arms, fixed the detection probe immovably on the Neiguan (PC6) acupoint and the reference point which was 1cm off the PC6, and collected the light signal along the meridian and non-meridian when the laser irradiate Jianshi(PC5), Ximen(PC4) and the corresponding reference points respectively under pressure of 0, 100, 130 and 160. The differences in optical transport properties between meridian and non-meridian were significant: under the same pressures(0s, 100s, 130s, and 160mmHg), the relative attenuation rate of optical signal at the same distance between meridian and non-meridian were significant(p0.05). Under four different pressure situations, the optical signal at acupoint(PC5) and non-acupoint(NP) along the meridian were significantly different with the corresponding reference points along the non-meridian(P

Basal cell carcinoma (BCC) is the most common cutaneous malignancy. Proffered treatment for these lesions is surgery. Based on patient’s age, drug allergies, and place of lesions, surgery may not be the best option, and alternative treatments should be considered. Pulsed dye laser (PDL) may be a good alternative therapy. The aim of the present study was to determine the effectiveness and safety of this laser in the treatment of BCCs in Iranian patients. Patients with definite diagnosis of BCC enrolled in the study. For each patient, one lesion proved to be superficial, or nodular BCC via histopathology was treated with PDL for four sessions and after the last session, re-biopsy was done to determine any remnant of tumor. All patients were followed for 6 to 13 months to capture any recurrence of as soon as possible. A total of 12 patients including eight male and four female were selected. All patients completed the study in accordance to the treatment protocol. All patients cleared clinically resulting flat hypo pigmented scar, but in pathology, two patients showed remnants of tumor and were referred for surgery. No side effects, but mild erythema and irritation were noted in all patients. No recurrences were found during the follow up period. It seems that PDL may be an effective alternative therapy for some subtypes of BCCs with acceptable safety profile. Further studies with larger sample sizes are required to support this opinion.

Tooth pain and sensitization are the two main causes of discomfort after periodontal flap surgery. Effects of low level laser therapy for reducing pain have already been established; these kinds of lasers have been used for tooth desensitization as well. This controlled blind study sought to compare tooth pain and sensitization after 660nm laser irradiation in a split mouth and also in a control group after periodontal flap surgery. Forty patients were enrolled in this study. In these entire patients periodontal flap surgery was done in the upper anterior segment. In the test group, by tossing of a coin the left or right side was determined for laser irradiation, so central incisor, lateral incisor and canine were irradiated by swiping motion of 660nm laser (AZOR, Russia) 25mW, 4.5 J, and 3 min every other day starting one day after surgery; and in collateral segment a placebo probe was put to blind the patients. In the control group, dressing was used after surgery. One, 3, 5 and 7 days after surgery for both groups visual analog score (VAS) for tooth pain and sensitization were recorded for both sides in each patient. In the laser group, both sides had lower VAS for pain than the control group (P< 0.05) after the first day. There was no statistical difference in the laser group between laser irradiated, or non-irradiated segment and for sensitization between groups. Pain can be reduced after periodontal surgery by using low level 660nm laser therapy. Lower pain in both sides in the laser group may be the result of the spread of mediators and neurotransmitters secreted after laser irradiation, or may be because of scattered radiation in the collateral part.

Due to the importance of laser light penetration and propagation in biological tissues, many researchers have proposed several numerical methods such as Monte Carlo, finite element and green function methods. Among them, the Monte Carlo method is an accurate method which can be applied for different tissues. However, because of its statistical nature, Monte Carlo simulation requires a large number of photon pockets to be traced, so it is computationally expensive and time-consuming. Although other numerical methods based on the diffusion method are fast, they have two important limitations: first, they are not valid near the bounder of sample and source, and second, their accuracy is less than Monte Carlo method. In this study, we combine the accuracy of Monte Carlo method and speed of the diffusion method. This hybrid method is faster than Monte Carlo Method and its accuracy is higher than the diffusion method. We first evaluate this hybrid model and the reflectance of a biological phantom is calculated by Monte Carlo method and this hybrid model. Then the propagation of laser light in the skin tissue has been studied. In this study, a combined method based on the Monte Carlo method and the diffuse equation is introduced. This hybrid method is five times faster than Monte Carlo Method, and its accuracy is higher than the diffusion method. The propagation of laser light in skin has also been studied by this hybrid method and its accuracy shows that it can be applied for laser penetration in biological tissues. It seems that this method is good for photo dynamic therapy (PDT) and optical imaging.

Endovenous Laser Therapy (EVLT) for Greater Saphenous vein (GSV) insufficiency is a newly established method of treatment only recently made available in Iran. The present study seeks to describe the results of the first 20 patients treated with EVLT at Shohada-e Tajrish Hospital, Tehran, Iran. 20 patients (16 male, 4 female) with the mean age of 38.9 and an average length of symptoms of 5.9 years, were treated with a 980-nm laser diode under local anesthesia. CEAP classification (Clinical Severity, Etiology, Anatomy, Pathophysiology) and AVSS scores (Aberdeen Varicose Vein Symptom Severity Score) were used to determine disease severity and symptoms before and after the procedure. Outcome was measured by the rate of recurrence as shown in Doppler ultrasonography evaluation. The mean procedure time was 49 minutes, and the mean admission time was 1.1 days. A success rate of 85% percent was recorded at 6-12 months of follow up. The patients showed a significant reduction in AVSS and CEAP scores (PV=0.0001), Pain (PV=0.00001), Parasthesia and Edema (PV=0.001). EVLT seems promising as a novel method of treatment for GSV insufficiency in the Iranian population with many advantages, including higher success rates in comparison with conventional methods of treatment.

Today, lasers are widely used in biology and medicine, and the majority of health centers and hospitals utilize modern laser systems for diagnosis and therapy applications. Researchers have introduced different medical applications for different lasers used in surgeries and other medical treatments. Medical lasers can be categorized in both diagnosis and therapy branches. Main difference between diagnosis and therapy applications is the type of laser-tissue interactions. In diagnosis, one tries to arrange a noninvasive method to study the normal behavior of tissue without any damage or clear effect on tissue. But in therapy, such as surgery, a surgeon uses laser as a knife or for affecting a specific region. So, the medical laser applications are defined by the interaction type between laser light and tissues. The knowledge of laser-tissue interaction can help doctors or surgeons to select the optimal laser systems and modify the type of their therapy. Therefore, we seek to review the mechanisms of laser- tissue interaction. In this paper, the optical properties of biological tissue such as absorption, scattering, penetration and fluorescence are reviewed. Also, the effects of these properties on laser penetration in tissue have been explained.

Male urethral stricture is a complicated urologic disease that could be successfully treated using internal urethrotomy. Laser internal urethrotomy has been used in many cases with favorable outcome in many studies. Holmium: YAG laser with its incisional properties on tissue is one of the laser types applied for internal urethrotomy. We present a 19 year-old male with history of aortic valve stenosis and metallic aortic valvoplasty on prescription of oral anti-coagulant therapy (Warfarin) who was a candidate for internal urethrotomy due to bulbar urethral stricture. Holmium laser core-through urethrotomy was performed for him. Internal urethrotomy was done using the ablative 50-watt Holmium: YAG laser 2140 nm (manufactured by the Atomic Energy Organization of Iran [AEOI]). No complication was observed intra- and post-operatively. After 6 months of follow-up no evidence of urethral stricture was observed. According to our study, Ho-YAG laser core through urethrotomy is a safe and effective procedure. It is a less invasive alternative to more complex urethroplasty procedures for patients with post-traumatic urethral stricture with high risk of urethral bleeding due to anti-coagulant therapy.