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A comparative study on the risk of second primary cancers in out‐of‐field organs associated with radiotherapy of localized prostate carcinoma using Monte Carlo‐based accelerator and patient models
Author(s) -
Bednarz Bryan,
Athar Basit,
Xu X. George
Publication year - 2010
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3367012
Subject(s) - medicine , prostate cancer , radiation therapy , imaging phantom , prostate , dosimetry , cancer , nuclear medicine , medical physics , radiology
Purpose: A physician's decision regarding an ideal treatment approach (i.e., radiation, surgery, and/or hormonal) for prostate carcinoma is traditionally based on a variety of metrics. One of these metrics is the risk of radiation‐induced second primary cancer following radiation treatments. The aim of this study was to investigate the significance of second cancer risks in out‐of‐field organs from 3D‐CRT and IMRT treatments of prostate carcinoma compared to baseline cancer risks in these organs. Methods: Monte Carlo simulations were performed using a detailed medical linear accelerator model and an anatomically realistic adult male whole‐body phantom. A four‐field box treatment, a four‐field box treatment plus a six‐field boost, and a seven‐field IMRT treatment were simulated. Using BEIR VII risk models, the age‐dependent lifetime attributable risks to various organs outside the primary beam with a known predilection for cancer were calculated using organ‐averaged equivalent doses. Results: The four‐field box treatment had the lowest treatment‐related second primary cancer risks to organs outside the primary beam ranging from 7.3 × 10 − 9to 2.54 × 10 − 5 % / MU depending on the patients age at exposure and second primary cancer site. The risks to organs outside the primary beam from the four‐field box and six‐field boost and the seven‐field IMRT were nearly equivalent. The risks from the four‐field box and six‐field boost ranged from 1.39 × 10 − 8to 1.80 × 10 − 5 % / MU , and from the seven‐field IMRT ranged from 1.60 × 10 − 9to 1.35 × 10 − 5 % / MU . The second cancer risks in all organs considered from each plan were below the baseline risks. Conclusions: The treatment‐related second cancer risks in organs outside the primary beam due to 3D‐CRT and IMRT is small. New risk assessment techniques need to be investigated to address the concern of radiation‐induced second cancers from prostate treatments, particularly focusing on risks to organs inside the primary beam.