Radiosurgery :

Many studies have shown that radiowave surgery is comparable or superior to lasers for incision, biopsy, and lateral tissue damage. Less tissue damage means faster healing, and less scarring and discomfort. Radiowave surgery offers advantages over scalpel incision, including a combined cutting and coagulation, and an increased tactile ability and a pressureless incision. When scalpels are used on thin tissue such as the eyelid, there is a tendency to drag, whereas the fine radiowave electrode glides with minimal contact in a nearly laser-like manner. Finally, the energized radiowave electrode is self-sterilizing.

If you are interested in this subject, then please read the following scientific presentation by Dr. Elkins, DVM, MS; DACVS board certified veterinary surgeon who works at the Veterinary Specialty Center in Indianapolis.


Radiosurgery: An Alternative to Laser in Veterinary Medicine
Western Veterinary Conference 2004
A.D. Elkins, DVM, MS; DACVS
Veterinary Specialty Center, LLC
Indianapolis, IN, USA

Introduction

Over the last few years, a great interest has emerged in the use of lasers in veterinary surgery. Various types of lasers are being actively marketed to veterinarians. They are proposed to cause less pain and shortened healing time, while controlling hemorrhage intraoperatively. The purpose of this article is to compare laser surgery with radiosurgery as to tissue damage, healing time, postoperative pain and cost.

Electrosurgery is not a new technology. Early electrosurgery units were essentially soldering irons that heated an electrode and seared the tissue. Advances in the early 1900's allowed electrodessication and fulguration by using a spark gap to destroy tissue and cauterize bleeding. The problem with these types of units is the degree of lateral tissue damage which delays healing. Advances in the 1920's and 1930's created the bipolar systems which are the basis for human hospital units used today. The units transfer energy to an electrode through the patient to a grounding electrode. The units will both cut and coagulate, but still cause the electrode to generate heat with lateral tissue damage.

Radiosurgery is a more advanced concept from electrocautery in that no heat is produced at the electrode. The ideal radiosurgery unit operates at a frequency of approximately 4.0 MHz. At this frequency wave, minimal lateral heat destruction occurs. Many older units operate at a lower frequency and produce more tissue damage.

A recent university study compared the CO2, Nd:YAG and KTP-532 lasers, electrocautery and radiofrequency instruments to access the degree of tissue damage in human oviducts. Transmission electron microscopy revealed that the 3.8-4.0 radiofrequency instrument produced the least damage to surrounding healthy tissue.

Both lasers and radiosurgery produce less damage than cold steel. Today in many human surgical specialties, the trend is away from lasers to ultra-high frequency radiosurgical devices.

New patented high frequency (4MHz) devices that are now available give the surgeon treatment options and increases safety to the patient. With the recent interest in laser surgery, many veterinarians have forgotten about the range of uses and benefits of radiosurgery.

There is a ten to forty-fold difference in purchase price of laser equipment compared to radiosurgery units. Safety factors and cost of operation and maintenance are other considerations. It takes a large number of procedures to justify the financial outlay for a laser. The learning curve is relatively steep with lasers. To me as a surgeon, there are not enough advantages of lasers over newer ultra-high frequency radiosurgical units to justify the cost.

Many veterinarians have some type of electrocautery/electrosurgical unit in their hospital. A complete review of radiosurgery can be found in other publications. These traditional, low frequency devices may not be used frequently due to the poor results and/or lack of versatility. Ultra-high frequency technology and its clinical results must not be confused with diathermy, electric cauterization, spark gap producers or even traditional radiofrequency generators. These units are adequate for electrocoagulation, but not for skin incisions or tissue dissection.

The main problem with older electrocoagulation units is the generation of a large amount of lateral heat through tissues adjacent to the area that is being incised or coagulated. Lateral heat is what damages tissue and must be minimized to avoid delays in healing and dehiscence. The following factors play a role in the production of lateral heat:

The power setting on the machine determines the amount of energy that is transferred to the tissue. This setting should be high enough to prevent drag of the electrode through the tissue but not high enough to create sparking. The power setting will need to be adjusted according to other electrical appliances in the operating room. Once set, it should require adjusting only as the waveform changes.

The waveform chosen determines the amount of cutting vs. coagulation. Generally, the more coagulation, the more lateral heat generated.

The smaller the electrode tip, the less lateral heat produced. A fine-wire electrode should be used for incisions, and a ball electrode should be used for hemostasis or coagulation.

The less time the electrode is in contact with the tissue, the less lateral heat generated when making an incision. A smooth, quick stroke is required to minimize tissue damage.

Laser vs. Radiosurgery

The wavelength of the laser medium (i.e.; CO2 or Nd:YAG) dictates the tissue effect achieved due to specific absorption coefficients. In the case of radiosurgery, the frequency and waveform determines the resultant effect.

Pulsed carbon dioxide (CO2) lasers target water molecules. The laser incises the epidermis by vaporizing intracellular water and coagulating intracellular protein. However, most of the dermis contains collagen with much of its water content in the extracellular matrix. Full-thickness skin incisions require pulse stacking, with successively increasing lateral thermal injury to the reticular dermis. The CO2 laser develops virtually bloodless skin incisions.

The CO2 gas laser has a long wavelength of 10,600 nanometers with an absorption coefficient of water. Due to the high water content of tissue, cellular absorption of the CO2 produces superficial tissue effects. Cutting with minimal hemorrhage is the primary application of the CO2 laser. The Nd:YAG lasers operate a 1064nm and can penetrate water (cells) multiple millimeters. The absorption distance is variable and can be problematic to avoid interaction with healthy tissues.

The term "radiosurgery" is used when radiowaves are utilized to produce simultaneous cutting and hemostatic effects. A frequency range between 350kHz and 4MHz may be considered "radiofrequency." Histologic evaluation has determined frequencies at 3.8 to 4MHz to produce optimal surgical results. Heat is produced by the tissue resistance to the passage of high frequency radio waves. It is the heat generated that causes the intracellular water to boil. Cellular volatilization occurs when the cell explodes form the expanding internal pressure and is the mechanism of action that produces precise tissue effects similar to that seen by surgical lasers.

Many studies have shown that radiowave surgery is comparable or superior to lasers for incision, biopsy, and lateral tissue damage. Less tissue damage means faster healing, and less scarring and discomfort. Radiowave surgery offers advantages over scalpel incision, including a combined cutting and coagulation, and an increased tactile ability and a pressureless incision. When scalpels are used on thin tissue such as the eyelid, there is a tendency to drag, whereas the fine radiowave electrode glides with minimal contact in a nearly laser-like manner. Finally, the energized radiowave electrode is self-sterilizing.

A comparison study of cone biopsies using the surgical blade, CO2 laser, YAG lasers and the radiofrequency unit indicated that in many instances the blade and radiosurgery had similar surgical margins with lack of thermal damage. Also, compared with the two lasers, radiosurgery showed 10 to 14 times less thermal damage.

A recent study in human blepharoplasty found that disruption of the cellular architecture at the mid-incised depth was less in tissue incised with ultra-high frequency radio waves compared to the CO2 laser.

Clinically, tissues incised using radiosurgery have no visible thermal artifact when compared to incision from the CO2 laser. The thermal effect of radiosurgical incisions closes small-to-medium dermal vessels in the cutting mode. Ultrahigh-frequency radiosurgery will minimize lateral heat dispersion only if the time of application is brief. Vessels not coagulated during quick brush-stroke movements can be selectively coagulated with a longer duration of tissue contact. Minimizing lateral thermal damage to incision edges should allow more rapid wound maturation and minimize scarring. Both ultrahigh-frequency radio waves and the CO2 laser interact with water molecules. The laser vaporizes the epidermis with little collateral thermal damage.

Conclusions

Radiosurgery has been shown to rival laser and cold steel methods for healing and precision and should be in the armamentarium of all surgeons. Only radiosurgery units that can produce a waveform that is fully filtered and fully rectified should be used for making skin incisions. Other waveforms produce too much lateral heat, which can delay wound healing.

Recommendations for Use of Radiosurgery

Electrode Selection

The smallest wire electrode possible should be used for making incisions.

Eight seconds should be allowed between cutting strokes to allow heat to dissipate.

Incision Techniques

Unlike with a scalpel blade, no pressure is required.

The stroke should be smooth and rapid (minimum rate of 7 mm/sec).

The electrode should be kept perpendicular to the tissue surface.

Buildup of charred, coagulated tissue on the electrode tip should be periodically removed.

Power to the electrode should not be engaged until the tip is in contact with the tissue when making an incision.

Power Level

The power level is relative to every procedure and may need to be adjusted.

Slowly increase the power setting until no drag on the electrode is noticed.

The power setting is too high if sparking occurs between the electrode and the tissue.

A higher power setting may be required for coagulation. The field must be dry to get complete coagulation, except when using bipolar forceps. The use of a ball electrode is recommended for coagulation. The ball electrode should be in contact with the tissue prior to engaging the foot or finger switch.

Comparison of Lasers to Radiosurgery

Disadvantages of Lasers

Requires protective eyewear for all persons within the surgical environment. Eyewear is typically uncomfortable and fogs which inhibits visualization.

Capital expenditure, high utilization is required to justify purchase.

Dedicated laser operator is required to position the laser in "Ready" or "Standby" modes as well as to manage parameter adjustments.

Fragile fiber optic or articulating arms can be a hindrance to the movement in and around the surgical field, not to mention present hazards to the operating personnel.

Ten to forty-fold price differential over radiosurgery instruments.

Benefits of Ultra High-Frequency Radiosurgery

Perform more delicate surgery with a larger margin of safety for the patient.

No specially coated instruments to prevent reflection.

Equipment less likely to breakdown or need adjustment.

Much wider array of applications is possible compared to the laser.

High voltage outlets are required to operate most surgical lasers.

No protective eyewear is required.

High tech, optimal results, affordable costs.