Radiotherapeutic implications of the updated ICRP thresholds for tissue reactions related to cataracts and circulatory diseases

Abstract

Radiation therapy of cancer patients involves a trade-off between a sufficient tumour dose for a high probability of local control and dose to organs at risk that is low enough to lead to a clinically acceptable probability of toxicity. The International Commission on Radiological Protection (ICRP) reviewed epidemiological evidence and provided updated estimates of 'practical' threshold doses for tissue injury, as defined at the level of 1% incidence, in ICRP Publication 118. Particular attention was paid to cataracts and circulatory diseases. ICRP recommended nominal absorbed dose threshold for these outcomes as low as 0.5 Gy. Threshold doses for tissue reactions can be reached in some patients during radiation therapy. Modern treatment planning systems do not account for such low doses accurately, and doses to therapy patients from associated imaging procedures are not generally accounted for. While local control is paramount, the observations of ICRP Publication 118 suggest that radiation therapy plans and processes should be examined with particular care. The research needs are discussed in this paper.

A systems radiation biology approach to unravel the role of chronic low-dose-rate gamma-irradiation in inducing premature senescence in endothelial cells

“…A further interesting aspect arising from this analysis is the possible presence of a dose-threshold of 0.7 Gy, independent of the dose rate, below which no effects on the angiogenic functions have be seen. Of note, the International Commission on Radiological Protection (ICRP) notes an acute dose threshold of approximately 0.5 Gy for circulatory disease (both cardiovascular and cerebrovascular diseases) [ 51 ]. An almost total loss of angiogenic function (20% of the control condition) is seen at approximately 7 Gy.…”

Tissue Reactions and Mechanism in Cardiovascular Diseases Induced by Radiation

“…Although the cardiovascular system, particularly the heart, was formerly assumed to be rather resistant to radiation-induced damage [ 69 ], RICVD is a recognized source of morbidity and death in radiotherapy patients [ 3 , 4 , 5 , 70 ], and low-dose, or occupational, radiation exposures [ 71 , 72 , 73 ]. Coronary artery disease (CAD), valvular heart disease, pericardial disease, heart failure (HF), right ventricular injury, arrhythmia, peripheral arterial disease, systemic hypertension, pulmonary hypertension, and thromboembolism disease are currently established as radiation-related cardiovascular complications [ 4 , 74 , 75 , 76 ].…”

“…Consequently, the risk of non-cancer diseases as the late effect consequences of tissue damage reactions is becoming a critical challenge. Evidence has accumulated that the incidence and mortality of non-cancer diseases have also increased along with the increase in survival time and long-term survival rate of cancer patients after radiotherapy [ 3 , 4 ]. Cardiovascular disease is a class of common non-cancer diseases and has drawn wide attention and concern [ 5 , 6 ].…”