The Effect of Intensity-Modulated Radiotherapy on Radiation-Induced Second Malignancies

Journal Article · Tue Apr 01 04:00:00 EDT 2008 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2007.08.046· OSTI ID:21124163

Ruben, Jeremy D ^[1]; Davis, Sidney ^[1]; Evans, Cherie; Jones, Phillip; Gagliardi, Frank; Haynes, Matthew ^[1]; Hunter, Alistair ^[2]

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1. William Buckland Radiotherapy Centre, Melbourne (Australia)
2. Department of Radiation Oncology, Groote Schuur Hospital and University of Cape Town, Cape Town (South Africa)

Purpose: To compare intensity-modulated radiotherapy (IMRT) with three-dimensional conformal radiotherapy (3D-CRT) in terms of carcinogenic risk for actual clinical scenarios. Method and Materials: Clinically equivalent IMRT plans were generated for prostate, breast, and head-and-neck cases treated with 3D-CRT. Two possible dose-response models for radiocarcinogenesis were generated based on A-bomb survivor data corrected for fractionation. Dose-volume histogram analysis was used to determine dose and its distribution to nontargeted tissues within the planning CT scan volume and thermoluminescent dosimetry for the rest of the body. Carcinogenic estimates were calculated with and without a correction factor accounting for cancer patients' advanced age and reduced longevity. Results: For the model assuming a plateau in risk above 2-Gy single-fraction-equivalent (SFE), IMRT and 3D-CRT produced risks of 1.7% and 2.1%, respectively, for prostate; 1.9% and 1.8%, respectively, for nasopharynx; 1% each for tonsil; and 1.4-2.2% and 1.5-1.6%, respectively, depending on technique, for breast. Assuming a reduction in risk above 2-Gy SFE, risks for IMRT and 3D-CRT were 1.1% and 1.5%, respectively, for prostate; 1.4% and 1.2%, respectively, for nasopharynx; 1% each for tonsil; and 1.3-1.8% vs. 1.3-1.6%, respectively, for breast. Applying a correction factor of 0.5 for cancer patients halved these risks and their relative differences. Conclusions: Carcinogenic risks were comparable in absolute terms between modalities. Risks are dependant on technique used. Risks with IMRT are influenced by monitor unit demand and are therefore software/hardware dependant. The dose-response model accounting for cell killing at higher doses fitted best with actual observed risks.

• OSTI ID: 21124163
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 5 Vol. 70; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
A-BOMB SURVIVORS
CARCINOGENESIS
CELL KILLING
COMPUTER CODES
COMPUTERIZED TOMOGRAPHY
CORRECTIONS
FRACTIONATION
HEAD
IMAGE PROCESSING
LYMPHATIC SYSTEM
MAMMARY GLANDS
NECK
NEOPLASMS
PATIENTS
PHARYNX
PROSTATE
RADIATION DOSES
RADIOTHERAPY
THERMOLUMINESCENT DOSIMETRY