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SU‐E‐I‐65: Estimation of Secondary Cancer Risk Induced by Diagnostic Imaging Radiations during Proton Therapy
Author(s) -
Jeong H,
Shin D,
Lee S,
Yoo S,
Min B
Publication year - 2011
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 - 10.1118/1.3611638
Subject(s) - nuclear medicine , proton therapy , medical imaging , radiation therapy , medicine , radiation treatment planning , cancer , effective dose (radiation) , dosimetry , radiology
Purpose: To quantify the secondary cancer risk (SCR) induced by daily‐anatomical imaging during proton therapy. Methods: First, we measured the characteristic radiation properties of a diagnostic imaging system used in proton therapy in our institute, digital imaging positioning system (DIPS, IBA, Belgium). Subsequently, we incorporated the measured beam data into a commercial radiation treatment planning system, Eclipse (Varian Medical System, USA) to efficiently calculate the distribution of dosage due to image‐guided procedure. The secondary cancer risk additionally induced by the diagnostic‐imaging radiation was estimated based on organ‐equivalent dose concept. For the analysis, we select a 43‐years‐old female patient case, in which the patient underwent proton treatment at the treatment site of lumbar spine with prescribed dose of 4600 cGy and 23 fraction size. Results: It was calculated that the diagnostic‐imaging radiation for daily‐patient imaging produced relatively small dose of ∼4.7 cGy in average in the patient body, which corresponded about 0.1 % to the prescribed dose of 4600 cGy. However, this small dose substantially raise the radiation‐induced SCR upto ∼8 % in the ordinary patient treatment regimen and can further increase the SCR depending on irradiation conditions, particularly the imaging‐field size with respect to targeted‐tumor volume. Conclusions: The present findings strongly suggest that not only the therapeutic radiation but also imaging radiation must be carefully managed in image‐guided proton therapy.