Radiotherapy marks

Published on 05/05/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

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172 Radiotherapy marks

Instruction

Look at this patient’s chest.

Patient 2

Salient features

Examination

• India-ink marks over the chest (Fig. 172.1)

• Localized erythema in the same region.

Fig. 172.1 Radiation therapy marks.

Diagnosis

This patient has India-ink marks over the chest with localized erythema (lesion) indicating that she is currently undergoing radiotherapy treatment (aetiology).

Advanced-level questions

Which other normal tissues, apart from the skin, are affected by radiation therapy?

Tissues that exhibit early or late damage from radiation therapy include mucosa, spinal cord, bone marrow and lymphoid system. To minimize these effects, radiation is normally delivered in a fractionated manner allowing recovery of normal host tissues (but not of tumour).

The most serious potential late complications of radiation therapy to the breast are injury to the lungs and heart and the risk of inducing secondary cancers, such as sarcoma, lung cancer and contralateral breast cancer. Early studies of radiation therapy in patients with breast cancer demonstrated that inclusion of the LV in the high-dose region increased the long-term risk of death from cardiovascular disease.

Radiation treatments for breast cancer are now given from linear accelerators and typically use medial and lateral opposed tangential fields that obliquely cross the anterior chest wall. CT planning of therapy ensures that the heart is outside the radiation field and the included lung volume is minimal.

What modalities may be used to minimize the side effects of radiation?

• Fractionation of dose

• Rendering the tumour more sensitive to radiotherapy by prior chemotherapy, thereby reducing the dose

• Regional hypothermia (40–42°C), particularly in superficial tumours and relatively bulky non-vascular tumours

• Radiolabelled antibodies, which deliver high levels of radiation locally to the tumour bed.

How is radiotherapy usually delivered?

It is usually delivered either as brachytherapy (where the radiation source is close to the tumour) or as teletherapy (where supervoltage radiotherapy is usually delivered with a linear acclerator).

In which conditions is radiotherapy beneficial?

Malignant conditions

• Radiotherapy as the sole agent with a curative intent in Hodgkin’s disease, some neoplasms of brain and spinal cord, oral cavity, pharynx, oesophagus, laryngeal tumours (permitting cure without loss of voice), tumours of cervix and vagina cavity

• Radiation with surgery in cancers of lung, breast, urinary bladder, seminomas, ovary, uterus, sarcomas of soft tissue and testicular seminomas

• Radiation as adjuvant to chemotherapy in lymphomas, lung cancers and childhood cancers

• Radiation as palliative therapy for pain and or dysfunction in superior vena caval obstruction, dysphagia of terminal illness, upper airway obstruction, spinal cord compression and pericardial tamponade secondary to malignant pericardial tumours.

Non-malignant conditions

• Exophthalmos

• Rheumatoid arthritis (total lymphoid irradiation is an experimental therapeutic procedure)

• Ankylosing spondylitis, where local external irradiation of an involved peripheral joint or injected radiation synovectomy can be valuable in ameliorating pain and allowing mobility. Spinal irradiation is no longer used because of the risk of haematological malignancy.

What are the side effects of radiotherapy?

• Acute toxicity: systemic symptoms including malaise, fatigue, anorexia, nausea and vomiting, diarrhoea and local skin and mucosal changes. Bone marrow suppression may occur following irradiation to the pelvis and long bones

• Long-term toxicity: cutaneous hyperpigmentation, impaired function of irradiated viscera, bone necrosis, myelopathy and secondary malignancies.

What is the difference between the units gray and sievert, and which is the unit of radiation dose?

Sievert (Sv) is a measure of the biological effect of a dose, whereas gray (Gy) measures the absorbed dose.

What do you know about the inverse square law?

The inverse square law states that radiation intensity decreases with the square of the distance away from a point source of radiation. The intensity of radiation at any given radius is given by the source strength divided by the area of the sphere. For example, the energy intensity three times as far from a point source is spread over nine times the area, hence one ninth the intensity.

The use of radiation began shortly after the discovery of X-rays by Roentgen in 1895 (Lancet 1997;349(suppl II):1–3).

RAGE (Radiotherapy Action Group Exposure) is a pressure group formed by patients who suffered the side effects of radiotherapy including brachial plexus neuropathy, often resulting in severe pain and the loss of use of the arm.

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