Radiation Therapy - Side effects, procedure, uses of Rediation Therapy

In recent years, ionization radiation therapy has vastly changes due to number of factors like easy availability of antimetabolities, cytotoxic agents and steroids, improvement in cutaneous surgical procedures, resistance of patients because of publicity in lay press and poor training in radio-therapy to both under- and post-graduates.

Despite these developments, there is no doubt of the usefulness of radiation therapy in selected dermatoses.

Important radiation therapy methods

Clinically, these physio-biological effects help to control pruritus, reduce inflammation, cure or control infections, reduce sebaceous and sweat secretion, cause falling of hair, and last of all, kill pathological tissues, as in warts and malignant radio-sensitive tumours.

To determine the quality of radiation, we take two major factors into consideration.

1. Half value layer (HVL). This is defined as that thickness of aluminium which reduces the intensity of radiation to 50%.

2. Half value tissue depth (D 1/2H.V.D.).This refers to depth of the tissue at which the absorbed dose is 50% of that at the surface. This phenomenon of penetration of X-rays should always be co-related with the depth of the pathological process.

Untoward effects of over-radiation therapy

Over-radiation is the greatest danger of X-ray therapy; a better understanding of dosage will minimize this hazard. The effects of over radiation are:

1. Acute-Erythema, vesicles, swelling and even eczema-going on to necrosis and ulceration..

2. 'Chronic-Redness, atrophy, keratoses, telangiectasia, and pigmentation; later reactions like ulcer and even epitheliomata may occur.

Chronic effects usually come up years after the X-ray treatment. In dark skinned patients, hyper-pigmentation, though transient, is a great drawback when treating exposed areas. There is also risk of causing epilation in employing X-ray therapy on hairy regions and sterility when X-ray therapy is employed over the gonads.

X-ray is an invisible energy and one must always respect its destructive powers when making use of its beneficial effects. Since X-rays are cumulative in effect, erythema doses should never be repeated within 12 months. Large areas of the body should never be exposed to X-ray therapy for fear of causing depression of bone marrow and other serious systemic reactions.

The testes, uterus, ovaries and eyes must always be protected and never exposed to X-ray therapy.

Strict accuracy must be maintained regarding line voltage, kV, mA, filter, distance and there should be screening of the sensitive surrounding areas with lead rubber. Proper records must be maintained.

Last of all, the author emphatically adds, that X-ray therapy must be prescribed in properly selected cases as a last resort.