Re: Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians
This excellent study by Mathews et al, which strongly supports the ‘linear no threshold theory', has significant implications not only for diagnostic radiologists but also for radiotherapists as well. (1).
Rapid technological advances in radiation therapy has meant introduction of novel techniques before full evaluation of benefits and risks. Recent technologies such as Image guided radiotherapy (IGRT) and Intensity modulated radiation therapy (IMRT) has led to a significant increase in the amount of normal tissue being exposed to ‘low dose’ radiation. (2)(3).
For instance, IGRT involves more frequent imaging during a course of radiotherapy to ensure accurate delivery of radiotherapy. IMRT helps to protect selected normal tissues from high-dose radiation at the expense of a large amount of normal tissues receiving low-dose radiation. Whether the benefits of newer radiation technologies outweigh the excess radiation risks needs to be explored urgently, particularly in childhood and adolescent cancers. (2)(3).
1. Mathews JD, Forsythe AV, Brady Z, Butler MW, Goergen SK, Byrnes GB, et al. Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: data linkage study of 11 million Australians. BMJ. 2013 May 21;346:f2360. doi: 10.1136/bmj.f2360
2. Maraldo MV, Brodin NP, Aznar MC, Vogelius IR, Munck Af Rosenschöld P, Petersen PM, Specht L. Estimated risk of cardiovascular disease and secondary cancers with modern highly conformal radiotherapy for early-stage mediastinal Hodgkin lymphoma. Ann Oncol (2013) doi: 10.1093/annonc/mdt156.
3. Kim DW, Chung WK, Yoon M. Imaging doses and secondary cancer risk from kilovoltage cone-beam CT in radiation therapy. Health Phys. 2013 May;104(5):499-503. doi: 10.1097/HP.0b013e318285c685.
Competing interests: No competing interests