ABSTRACT
The effective dose under ordinary clinical computed tomography (CT) protocols using three kinds of 64-channel and a 40-channel CT ranged from 0.6 to 15.5 mSv in early 2010s. And the organ dose ranged from 1.6 to 130.4 mGy: orbital and brain doses for brain stroke CT were the highest. For the comparison of the effective dose between late 1990s and early 2010s, multidetector CT (MDCT) for high-resolution lung CT was 2.4 times higher than that of single-detector CT (SDCT) and the ratio was the highest. However, the effective dose at MDCT was 20 % lower than that of SDCT in chest CT due to applying dose-saving techniques. In organ dose comparisons, high-resolution lung CT at MDCT was 3.5-4.5 times higher than that of SDCT, and showed 1.1-1.5 times higher than that of SDCT in the head and chest CT. For the abdomen CT, the primary organ dose at MDCT was â¼30 % lower than that of SDCT.
Subject(s)
Radiation Dosage , Radiometry/methods , Tomography, X-Ray Computed/methods , Angiography/methods , Brain/diagnostic imaging , Equipment Design , Equipment Safety , Head/diagnostic imaging , Humans , Radiation Protection/methods , Radiography, Abdominal/methods , Reproducibility of Results , Republic of Korea , Time FactorsABSTRACT
PURPOSE: Adjuvant radiotherapy of breast cancer using a photon tangential field incurs a risk of late heart and lung toxicity. The use of free breathing (FB), expiration breath hold (EBH), and deep inspiration breath hold (DIBH) during tangential breast radiotherapy as a means of reducing irradiated lung and heart volume was evaluated. METHODS: In 10 women with left-sided breast cancer (mean age, 44 years) post-operative computed tomography (CT) scanning was done under different respiratory conditions using FB, EBH, and DIBH in 3 CT scans. For each scan, an optimized radiotherapy plan was designed with 6 MV photon tangential fields encompassing the clinical target volume after breast-conserving surgery. RESULTS: The results of dose-volume histograms were compared using three breathing pattern techniques for the irradiated volume and dose to the heart. A significant reduction dose to the irradiated heart volume for the DIBH breathing technique was compared to FB and EBH breathing techniques (p<0.05). CONCLUSION: This study demonstrated that the irradiated heart volume can be significantly reduced in patients with left-sided breast cancer using the DIBH breathing technique for tangential radiotherapy.
