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Program Information

Imaging Dose and Cancer Risk in Image-Guided Radiotherapy of Cancers

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L Zhou

L Zhou1*, S Bai2 , Y Zhang3 , X Ming4 , Y Zhang5 , J Deng6 , (1) West China Hospital,Sichuan University, Chengdu, Sichuan, (2) West China Hospital, Sichuan University, Chengdu, Sichuan Province, (3) Beijing Cancer Hospital, Beijing, Beijing, (4) TianJin University, Tianjin, ,(5) Tianjin University, Tianjin, Tianjin, (6) Yale New Haven Hospital, New Haven, CT


SU-D-9A-7 Sunday 2:05PM - 3:00PM Room: 9A

To systematically evaluate the imaging doses and cancer risks associated with various imaging procedures involving ionizing radiation during image-guided radiotherapy of an increasingly large number of cancer patients.

141 patients (52 brain cases, 47 thoracic cases, 42 abdominal cases, aged 3 to 91 years old) treated between October 2009 and March 2010 were included in this IRB-approved retrospective study. During the whole radiotherapy course, each patient underwent at least one type of imaging procedures, i.e., kV portal, MV portal and kVCBCT, besides CT simulations. Based on Monte Carlo modeling and particle transport in human anatomy of various dimensions, the correlations between the radiation doses to the various organs-at-risk (OARs) at the head, the thoracic and the abdominal regions and one’s weight, circumference, scan mAs and kVp have been obtained and used to estimate the radiation dose from a specific imaging procedure. The radiation-induced excess relative risk (ERR) was then estimated with BEIR VII formulism based on one’s gender, age and radiation dose. 1+ ERR was reported in this study as relative cancer risk.

For the whole cohort of 141 patients, the mean imaging doses from various imaging procedures were 8.3 cGy to the brain, 10.5 cGy to the lungs and 19.2 cGy to the red bone marrow, respectively. Accordingly, the cancer risks were 1.140, 1.369 and 2.671, respectively. In comparison, MV portal deposited largest doses to the lungs while kVCBCT delivered the highest doses to the red bone marrow.

The compiled imaging doses to a patient during his/her treatment course were patient-specific and site-dependent, varying from 1.2 to 263.5 cGy on average, which were clinically significant and should be included in the treatment planning and overall decision-making. Our results indicated the necessity of personalized imaging to maximize its clinical benefits while reducing the associated cancer risks.

Funding Support, Disclosures, and Conflict of Interest: Sichuan University Scholarship

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