Last updated date: 04-Mar-2023
Originally Written in English
Lasers are increasingly being used in modern medicine to treat a wide range of illnesses as demand in less intrusive treatment techniques grows. The physics of lasers permits the same basic concepts to be applied to a wide range of tissue types with little system adjustments. Several laser technologies have been investigated in each discipline of medicine.
What is Laser Surgery?
Laser therapies are medical procedures that employ concentrated light to treat patients. Light from a laser (which stands for light amplification by stimulated emission of radiation) is adjusted to certain wavelengths, unlike most other light sources. This enables it to be concentrated into strong beams. Laser light is so powerful that it can shape diamonds and cut steel.
Laser energy may be utilized safely and efficiently for lithotripsy, cancer therapy, a variety of aesthetic and reconstructive operations, and the ablation of aberrant conductive pathways. Treatment with lasers is equivalent to, and perhaps superior than, management using more traditional approaches for each of these diseases.
A basic laser is made up of a laser medium (which controls the system's wavelength) surrounded by two parallel mirrors, one of which is partially reflecting and partially transmitting. An electrical source excites the medium until the number of atoms in the excited state exceeds the number in the ground state (population inversion).
When the laser medium is energized, it begins to spontaneously emit excited photons in all directions. However, a tiny minority of these photons travels in unison down the laser system's centerline between the mirrors. The mirrors then reflect these photons, amplifying the process of stimulated emission. The partly transmitting mirror thus enables for the emission of a strong, coherent beam of photons as laser light.
The impact of a laser on a sample of tissue is determined by both the tissue's and the laser's qualities. Structure, water content, thermal conductivity, heat capacity, density, and the ability to absorb, disperse, or reflect radiated energy are all tissue attributes. Power, density, energy content, and wavelength are all important laser qualities.
The major biological targets under consideration absorb light in many varied ways, and their optimal absorption spectra are determined by the wavelength of the input photon energy. The major target chromophores (any material that absorbs light) for visible light and some near-infrared lasers are hemoglobin and melanin, but water is the only chromophore for CO2 lasers.
To achieve selective photothermolysis (the use of energy at high peak powers and short pulse widths to destroy the intended target alone) without damaging the surrounding tissue, the target tissue must contain chromophores that absorb a specific laser wavelength that are not found in the surrounding tissue.
The most frequent lasers used in medicine and surgery are the CO2, Nd:YAG, and Argon lasers. The CO2 laser generates radiation at 10,600 nm and uses carbon dioxide gas as its medium. CO2 lasers, although being tissue-selective, cannot be employed for selective photothermolysis because its chromophore, water, occurs everywhere. All impact energy is absorbed in the tissue water to a certain depth, preventing deeper tissue injury.
CO2 lasers operate in the invisible infrared waveband, necessitating the use of an aiming beam for precise therapy. When the laser is focused on the tissue, it generates extremely high power density, resulting in quick vaporization and ablation of the tissue. Because the irradiance of the laser beam is related to the inverse of the square of the beam's diameter, the surgeon may quickly switch the laser from incision mode to bulk vaporization or coagulation by defocusing the beam.
The CO2 laser has several beam modes, each of which has a particular effect on the tissue. Continuous wave (CW) is the most basic mode, in which the laser beam is generated, operated for a set period of time, and then shut off. However, more contemporary lasers are quasi-CW (ultrapulsing), which means they produce brief high-peak power pulses with extremely lengthy inter-pulse intervals. Because each pulse given is shorter than the time it takes for the target tissue to cool, this allows for more accurate incisions with less heat buildup.
Clinical applications of lasers
As minimally invasive procedures for treating various pathologic conditions become more prominent, the use of lasers has grown in popularity in modern medicine. Lasers have a wide range of applications in ophthalmology, lithotripsy, the detection and treatment of various malignancies, as well as dermatologic and aesthetic operations, in addition to their practical use in the operating room.
For the past few decades, laser lithotripsy has been a generally established therapy for fragmenting urinary and biliary stones. Lasers can perform lithotripsy by a photoacoustical/photomechanical effect (laser-induced shockwave lithotripsy) or a primarily photothermal effect. the 1-µsec pulsed-dye laser is the most used shockwave laser in lithotripsy and has received substantial research. The excitation of coumarin dye produces the monochromatic light that fragments the calculi in this apparatus.
As the stone absorbs laser light, the excited ions produced form a rapidly growing and pulsing cloud surrounding the stone, causing a shock wave that splits the calculus into shards. Because this laser is inefficient against nonabsorbent colorless calculi such as cystine, photosensitizers (dye) have been effectively utilized as irrigation fluids and absorbents to commence the fragmentation process.
The long-pulsed Holium:YAG laser, on the other hand, fragments calculi mostly by photothermal mechanisms. The laser emits light with a wavelength of 2,100 nm that is easily absorbed by water. In the suitable atmosphere, fluid absorbs the energy and is therefore heated. A cloud of vapor forms, dividing the water and allowing the remaining laser light to directly hit the calculus surface, boring holes into it and fragmenting it.
When compared to pneumatic lithotripsy, Ho:YAG laser lithotripsy is a more effective endoscopic technique for the treatment of ureteral stones, with higher stone fragmentation rates, and a review conducted by Teichman concluded that this laser is safe, effective, and works just as well, if not better, than other modalities, and that it may also be used for biliary stones.
Lasers are now being utilized safely to treat malignancies in multiple organ systems. For individuals who are not excellent surgical candidates, laser interstitial thermal therapy (LITT) is a favored therapeutic option in neurosurgery. Lasers have grown more safe to employ in neurosurgery since their inception, and they have been effectively used to treat unresectable gliomas as well as hard and hemorrhagic tumors such as meniniomas, tumors of the deep skull base, and tumors deep in the ventricles.
Laser-assisted mucosal ablation methods are now widely and effectively utilized to treat superficial gastrointestinal malignancies such as early gastric cancer, superficial esophageal cancer, colorectal adenoma, and high-grade Barrett's esophagus. Furthermore, laser-assisted photodynamic therapy (PDT) has been found to be an effective therapeutic technique for some kinds of lung cancer lesions.
Through its photochemical, photomechanical, and photothermal effects, direct laser ablation has been utilized to directly destroy cancer cells. The photochemical reactions that occur eventually generate harmful radicals that cause tissue death, the photomechanical responses cause tissue stress and fragmentation, and the photothermal reactions cause heating and coagulation, both of which promote cell death.
PDT was created about a century ago to improve this technique and more precisely target the intended tumor cells, and it has garnered widespread appeal since then. This therapy approach comprises the delivery of a photosensitizing medication, followed by the lighting of the target region with visible light matching to the photosensitizing drug's absorption wavelength.
When the photosensitizer is activated, it first creates the excited singlet state and then transitions to the triplet state, which produces reactive oxygen species that are harmful to neoplastic cells in the presence of oxygen. Selective photothermal treatment, on the other hand, employs targeted light-absorbing dye to increase laser-induced tumor cell death.
Aesthetic and reconstructive surgery
Lasers' unique ability to target particular structures and layers of tissue makes them a very effective tool in aesthetic and reconstructive surgery. In modern years, laser resurfacing has been a prominent technique utilized for anti-aging treatment, since the production of new collagen creation is known to reduce the effects of photoaging. The first skin resurfacing procedures used ablative CO2 and Er: YAG laser systems to target a specific region of the dermis.
However, because these methods also remove a large quantity of epidermis, recuperation time is longer and adverse effects like as infections and erythema are enhanced. Nonablative lasers, such as powerful pulsed light, Nd:YAG, diode, and Er:glass lasers, which mostly emit infrared light, were later created to address these concerns.
The purpose of these systems is to target the water in the dermis, which warms collagen and causes remodeling throughout the process. Tissue evaporation does not occur, and no external wound is generated, since there is a mechanism that concurrently cools the epidermis. Recently, fractionated laser resurfacing has become the standard method of skin resurfacing. Fine beams of high-energy light are employed in fractionated lasers to induce tiny zones of thermal injury ("microscopic thermal zones") and treat just sections of skin at a time.
Laser-assisted lipolysis, which employs an optical fiber put into a 1-mm cannula, is also becoming more popular in cosmetic surgery. Because of the tiny size of the cannula, a smaller incision is required, resulting in less bleeding and scar development. 920 nm lasers have the lowest absorption coefficient in adipose tissue of any laser accessible for medical use, allowing them to penetrate deeper layers of tissue.
Those with wavelengths in the 1,320-1,444 nm range have the highest absorption coefficient in fat, resulting in a shallower penetration depth and the ability to treat such tissues superficially. The most extensively used laser lipolysis device is the Nd:YAG laser, since the absorption coefficient of fat tissue at this wavelength results in good penetration depth with medium absorption, generating only mild temperature increase and consequently little tissue damage.
Furthermore, laser light at this wavelength coagulates tiny blood vessels, resulting in substantially reduced blood loss during the treatment. When compared to standard procedures, Abdelaal and Aboelatta were able to demonstrate a considerable reduction in blood loss (54%). Furthermore, Mordon and Plot discovered that laser lipolysis creates more even skin outcomes.
Finally, because lasers can specifically target diseased vasculature, they are an excellent source for treating vascular abnormalities such as port-wine stains. Patients did not have many therapeutic options for these sorts of anomalies prior to the usage of lasers. Lasers that are preferentially absorbed by hemoglobin over melanin are being employed for this purpose, causing less harm to the epidermis. Lasers with longer wavelengths, and hence the potential to penetrate deeper into tissue, have recently been introduced.
Ablation of conductive pathways
After it was recognized that the pulmonary veins (PV) are a major source of ectopic beats that cause atrial fibrillation (AF) paroxysms, the development of catheter ablation devices for circumferential PV isolation (PVI) was motivated. The laser balloon catheter is now one of the most regularly utilized endoscopic ablation systems (EAS) for the treatment of AF. The catheter has a compliant balloon at its tip that is continually flushed with deuterium oxide.
After inserting the catheter into the left atrium, an endoscope is placed into the catheter shaft to provide direct view of the ablation target inside the heart. A 980-nm diode laser is placed in the center lumen and emits laser energy perpendicular to the catheter shaft, covering a 30° arc and facilitating circular ablation around each PV.
Deuterium oxide does not absorb laser at this wavelength. As a result, it penetrates past the endothelium and is absorbed by water molecules, causing heating and coagulation necrosis. The given energy may be titrated by varying the power in a series of specified settings. Depending on which heart wall is targeted, the energy levels change.
A totally transmural lesion in the heart is required to successfully result in a complete conduction block. demonstrated electrical impulses, both timed and AF, could still travel over 1 mm gaps in the ablation line When the effects of different energy levels are compared, research reveal that using greater energy levels leads in higher rates of PVI with lower AF recurrence rates and no compromise of the safety profile.
MRI-guided laser-induced thermal treatment (MRgLITT) is extensively utilized in neurological surgery to treat refractory epilepsy, either as a way of ablating the epileptic foci or as a disconnection technique. MRgLITT combines a diode laser (980-nm) with imaging technology to offer intraoperative data required for regulating the amount of energy supplied.
How are lasers used during cancer surgery?
Laser surgery is a type of surgery in which specific laser beams, rather than devices such as scapels, are used to execute surgical procedures. There are various types of lasers, each with unique features that perform specialized purposes during surgery. Laser light can be administered continuously or intermittently, and it can be used in conjunction with fiber optics to treat parts of the body that are frequently difficult to reach. Some of the numerous types of lasers used for cancer therapy are as follows:
- Carbon dioxide (CO2) lasers:
CO2 lasers may remove a very thin layer of tissue from the skin's surface without damaging deeper layers. Skin tumors and some precancerous cells may be removed with the CO2 laser.
- Neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers:
Lasers containing neodymium:yttrium-aluminum-garnet (Nd:YAG) can penetrate deeper into tissue and induce blood to coagulate faster. Laser light may be sent using optical cables to reach less accessible inside organs. The Nd:YAG laser, for example, can be used to treat throat cancer.
- Laser-induced interstitial thermotherapy (LITT):
laser-induced interstitial thermotherapy (LITT) heats specific parts of the body with lasers. The lasers are focused at interstitial regions (between organs) near tumors. The laser's heat raises the temperature of the tumor, shrinking, injuring, or eliminating cancer cells.
- Argon lasers:
Argon lasers can only penetrate the most superficial layers of tissue, such as skin. Photodynamic therapy (PDT) is a treatment that employs argon laser light to activate molecules in cancer cells.
Who shouldn’t have laser therapy?
Cosmetic skin and eye operations, for example, are considered elective laser surgeries. Some patients determine that the hazards of these sorts of operations exceed the advantages. Laser procedures, for example, may worsen some health or skin issues. Poor general health, like with traditional surgery, increases your chance of problems.
Before electing to have laser surgery for any type of operation, consult with your doctor. Your doctor may advise you to pick traditional surgical treatments based on your age, overall health, healthcare plan, and the cost of laser surgery. For example, if you are under the age of 18, you should not get Lasik eye surgery.
How do I Prepare for Laser Therapy?
Plan ahead of time to allow for recovery time following the procedure. Make sure you have someone to drive you home after the surgery. You will almost certainly be under the effects of anesthetic or drugs. You may be recommended to take measures such as quitting any drugs that might impact blood clotting, such as blood thinners, a few days before the operation.
How is Laser Therapy Done?
Laser treatment procedures differ depending on the operation. An endoscope (a thin, illuminated, flexible tube) may be used to steer the laser and observe tissues within the body when treating a tumor. The endoscope is introduced through a bodily orifice, such as the mouth. The surgeon next directs the laser to reduce or eliminate the tumor. Lasers are typically used directly to the skin during cosmetic operations.
What are the risks?
Laser therapy has some risks. The risks for skin therapy include:
- Changes in skin color
Furthermore, the anticipated results of therapy may not be durable, necessitating further sessions. Some laser surgery is conducted while you are sedated, which has its own set of dangers. They are as follows:
Treatments can also be costly, making them inaccessible to everyone. Depending on your healthcare plan and the practitioner or facility you pick for your procedure, laser eye surgery can cost anywhere from $600 to $8,000 or more.
What happens after laser therapy?
Recovery after laser surgery is comparable to that of traditional surgery. You may need to relax for a few days following the surgery and use over-the-counter pain relievers until the discomfort and swelling have subsided.
The amount of time it takes to recover after laser treatment depends on the type of therapy you had and how much of your body was impacted by the therapy. You should strictly adhere to any directions issued by your doctor. If you have laser prostate surgery, for example, you may need to wear a urinary catheter. This can help you urinate soon after surgery.
You may suffer swelling, itching, and rawness surrounding the treated region if you had treatment on your skin. Your doctor may apply an ointment and dress up the affected region to make it airtight and waterproof. Make careful to perform the following in the first several weeks after treatment:
- Use over-the-counter medications for pain, such as ibuprofen (Advil) or acetaminophen (Tylenol).
- Clean the area regularly with water.
- Apply ointments, such as petroleum jelly.
- Use ice packs.
- Avoid picking any scabs.
Once the region has been overrun with new skin, you can apply foundation or other cosmetics to conceal any visible redness.
Peripheral nerves, which are not found in the brain or spinal cord, are responsible for much of the pain and numbness produced by nerve injury. Neuropathy is the medical term for this form of nerve injury. Lasers are used in neuropathy laser therapy to enhance blood circulation to the affected regions. Because blood transfers nutrients and oxygen to the region, the nerves have a higher chance of healing and the pain is reduced.
Energy is discharged into the surrounding tissue when the laser penetrates the skin. The light energy from the laser is converted into cellular energy and used to increase blood circulation. Skeletal muscles are essential for blood circulation. These muscles flex around blood arteries to help the heart pump blood. Infrared lasers absorb energy from muscle cells, making them more active and efficient.
Laser surgery is the use of a laser (which stands for light amplification by stimulated emission of radiation) for a variety of medical and aesthetic operations. A laser is a type of light source that may be utilized in a range of surgical applications. Depending on the location and goal of the procedure, several laser wavelengths are chosen.