What is a good laser?
Should I choose a laser, an LED, or a combination of both?
There are about 25 scientific studies comparing effectiveness of laser (coherent) light with non-coherent light, (e.g. LED’s). In all of these comparisons, the laser has come out on top, even though the other light sources, under certain conditions, can give a positive effect.
Mixing lasers with LED is not as good as pure laser light. In general, it seems that the narrower the bandwidth, the better the therapeutic effect. It can also be said that the closer we are to common daylight (i.e. the more wavelengths we mix in) the less the therapeutic effect. In other words, therapeutic light should be laser light.
Is a cluster probe with different types of laser diodes (different wavelengths) optimal?
No. Similar to the answer above, the fewer the wavelengths that are mixed in, the better the results.
Is a laser with built-in “recipes” better than an instrument giving fix doses?
It has become popular to sell instruments with built-in treatment “recipes”, or treatment programs. While this may sound good (“The instrument knows!”), it is actually unfortunate. Let’s look at an example: You choose “arthritis” from the menu of an instrument with built-in treatment programs. The instrument may give the following program:
30 Hz for one minute, 156 Hz for 2 minutes, and 5000 Hz for 45 seconds. Then the owner of the instrument thinks that this is the best treatment for arthritis. But this is wrong! Why?
First, the pulse frequency is one of the least important parameters. The result will probably be just as good if another indication had been chosen from said table, e.g. acne treatment. Pulse frequency is on the fifth or sixth place of parameter importance.
Second, in the example above, the instrument will emit the same number of joules for a knee as for a finger, taking no account for the difference in treatment area.
So, “recipes” are just a sales trick. It is important that you choose a laser system that is flexible and allows you to control the frequency and dose depending on what and where you treat.
Is super pulsing better than switching with 50% duty cycle?
Yes, it can be, if the average power to tissue is high enough. The high peak powers that you often get with superpulsed lasers increases the penetration of the light into the tissue. So as long as the average power is high enough, super pulsing may be an advantage over regular switching..
Does pulsed light penetrate deeper than continuous light?
No. Not if they have the same power / peak power. However, super pulsed lasers usually have higher peak powers than continuous or switched lasers, which allows for a non-linear penetration profile. Though tissue has the highest transparency for wavelengths of about 800 nm, superpulsed lasers with a wavelength of 904 nm (GaAs-lasers), and with high enough peak powers have the highest penetration depth of all laser types. See question above.
Are there optimal laser types for certain indications?
Basically, YES. An additional factor is the power. However, since the penetration also depends on the tissue, it is not possible to give a simple answer to that question. More important is “working depth”, i.e. the actual penetration plus the cell cascade effect passing from one cell to the next (systemic effects).
Is an expensive laser better than a cheap laser?
It depends. If it’s not easy to use and doesn’t produce good results for your clients, then it doesn’t matter what it cost. A therapeutic laser is always an investment, so the important thing is that you carefully evaluate what you get with your purchase. Is the service good? What support is given with your purchase? Is the company that manufactures / distributes the laser knowledgeable? See also other questions on this web page.
Which laser type has the best documentation?
The HeNe laser. Second is GaAs (904 nm).
Are strong lasers better than weaker ones?
YES and NO.
Output power should not be too low for its purpose. If the power is too low, it causes unnecessarily long treatment time in order to achieve the required total dose. Also, if output power is too low, it could result in the power density being too low which is an important parameter in treatment.
Nor should output power be too high for its purpose. If the power is too high, the light could burn tanned, colored, or skin with dark hair. Furthermore, in most countries, there is a power limit of 500 mW (= 0.5 watt), above which the laser will be a Class 4 laser. If so, it usually means that it requires oversight by an MD or DD. Also, if the power is too high it can result in unintentionally high doses which can treatment results.
And finally, time is also a factor. Administering an optimal dose during a very short time will not necessarily give as good a result as an optimal dose during longer treatment time.
Some laser companies claim that a Class 4 laser ‘by default’ is better than a Class 3B laser (4 is higher than 3, so it has to be better… right?). This is simply not true. The classification of lasers is a measure of eye hazard, nothing else. While defocused Class 4 lasers may well be used successfully in laser therapy, this does have anything to do with the laser classification. The factors which must be considered are 1) the dose 2) the time over which the dose is administered 3) type of laser.
Does the instrument have a power meter?
This is important. The human eye is a lousy power meter (visible light) and not working at all in the infra- red spectrum. So, the output can be zero without you knowing. A power meter can be built-in or separate.
How much do spare parts cost?
This is an important question to ask a salesman. A laser producer has a monopoly on many spare parts such as printed circuits and can hence charge customers up to the cost of a new laser.
What happens if it breaks?
For some therapists, the laser instrument is their main source of income, so this question is highly relevant.
Is any educational support included
In order to get good results, you need two things: a good instrument and good knowledge.
What literature is included in your purchase?
It is important that your laser come with documentation and educational materials to enable to use it successfully.
Is it important who manufactures and distributes the laser
In the beginning (from about 1985 to mid -90′s) many laser producing companies went bankrupt. For many of their customers, this became a big service problem. Often their customers had to buy a new instrument. It is important to choose a stable company with a good reputation.
Instrument start-up time
When you work with an instrument daily, it is important that you can use your time efficiently. Some instruments have to be “programmed” before you can start the treatment. Sometimes this is a long procedure. Be sure that your instrument can start quickly. To spend a minute with settings is not so much work, but to do it thousands of times is a waste of valuable time.
Quality of buttons
Whenever you need to set parameters, the buttons, thumb wheels, slide switches or other electromechanical components must be both safe and easy to maneuver. The most common problems emanate from such components.
Quality of Cables
For a stationary unit, it is important that the cables are of good quality, flexible, resistant to massage oil (and similar), and are long enough to reach the whole patient from the place where the laser base unit is placed.
The aperture
The opening where the light comes out is called aperture. This opening can be open or closed with a lens or a glass window. It is good if it is covered so that dust and skin particles not are collected in the cavity in front of the laser diode.
The area of the beam where it hits the skin, when the probe is held in contact, is of importance – it influences the lights penetration into the tissue. If this area is in the order of a square millimeter, and if the laser is relatively strong, the power density can be so high that bleaching effect radically can increase the penetration through the skin. This is specially noticed for the super pulsed GaAs-laser.
A flexible instrument
The development will go on and new laser types may come. A professional instrument is built so that it can include coming wavelengths or powers, usually by updating of software. A professional instrument should also be rugged and be able to stand large temperature differences, mechanical mishandling, static electricity, cleaning procedures and transport.
Service
All instruments can break. Even a Rolls Royce breaks. That is not a problem if the service is good. Find out if you can borrow a replacement probe or instrument during the time of repair. In the beginning, almost every therapist is uncertain of treatment parameters and treatments. Can you get a mentor to contact? Is there a laser society that you can join? Are there regular meetings you can join?