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Adjuvant radiotherapy is indicated in differentiated thyroid cancer patients with post-op gross residual disease or microscopic disease with high-risk features. Intensity-modulated radiotherapy (IMRT) is now the standard radiotherapy technique. This is a dosimetric study to compare the static-field IMRT and volumetric modulated arc therapy (VMAT) for patients with differentiated thyroid cancer. Consecutive 15 patients with differentiated thyroid cancer needed post-operative radiotherapy were recruited. A pair IMRT and VMAT plan was generated for each patient. Comparison of dosimetric parameters was performed between IMRT and VMAT. The monitor units (MU) and delivery time by each radiation technique were also compared. All pairs of treatment plans in IMRT and VMAT fulfilled the acceptance requirement in terms of target coverage and critical organ sparing. The conformity index and homogeneity index between IMRT and VMAT for PTV66 and PTV60 were not statistically significant. For the organs at risk, the mean dose to parotids was significantly increased by 4.8 Gy (14.4 %) in VMAT when compared to that in IMRT (IMRT vs. VMAT, 33.35 ± 6.86 Gy vs. 38.15 ± 7.82 Gy, p = 0.01). The dose parameters of the spinal cord, brain stem, esophagus, and lungs were not statistically significant between the two techniques. Compared to IMRT, the mean MU and delivery time of VMAT were reduced by 71.6 % (p = 0.0004) and 63.1 % (p = 0.004), respectively. For adjuvant radiotherapy for differentiated thyroid cancer, IMRT resulted in better parotid sparing at the expense of longer treatment time. Otherwise, the tumor coverage is essentially the same between these two techniques.

BACKGROUND: Coronary artery bypass grafting (CABG) is carried out for prognosis and symptomatic relief. Smoking is associated with increased postoperative complications, although its precise influence on long-term survival is unclear. We examined the influence of smoking and other risk factors on survival and myocardial ischaemia seven years after CABG. METHODS: 208 patients underwent elective CABG; 25 % were persistent smokers. 165 were alive at seven years. 128 (78 % of survivors) agreed to reexamination and 79 had thallium scans. RESULTS: Angina and dyspnoea were reported by 52 % and 69 %, respectively, of survivors; these were associated with smoking ( P = 0.029 and 0.0 009) but with no other risk factors. Smokers had higher stress thallium scores ( P = 0.057) and ischaemia scores (10.6 +/- 6.5 vs. 6.8 +/- 6.0; P = 0.036); ejection fractions were equivalent. Obesity was prevalent and worsened in men. 33 patients (17 %) died during follow-up. Initially there was no survival difference between smokers and nonsmokers but as early as three years postoperation smoking was associated with an increased mortality ( P = 0.011; log-rank test). CONCLUSIONS: Patients experienced almost universal improvement with the operation. However, persistent smoking completely removed the prognostic benefits of CABG by accelerating late mortality which was higher than previously reported. Higher indices of ischaemia in smokers were suggested by symptoms and confirmed by perfusion scans.

Victor Ho-Fun Lee,1,* Dennis KC Leung,1,* Mai-Yee Luk,1 Chi-Chung Tong,1 Martin WM Law,2 Sherry CY Ng,1 Ka-Kin Wong,3 Ronnie TP Poon,4 Dora LW Kwong,1 To-Wai Leung1 1Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 2Department ofNuclear Medicine, 3Department of Radiology, QueenMary Hospital, 4Department of Surgery, Li KaShing Faculty of Medicine, The University of Hong Kong, Hong Kong *These authors contributed equally to this work Background: Advanced inoperable hepatocellular carcinoma (HCC) conferring a grave prognosis may benefit from yttrium-90 (90Y) radioembolization.Methods: Thirty patients with advanced inoperable HCC including those with any lesion>8cm in maximal diameter or multiple bi-lobar lesions (totally more than five lesions), or portal vein thrombosis treated with radioembolization were reviewed. Treatment efficacy and safety were evaluated. Univariate and multivariate analyses were performed for identifying potential prognostic factors.Results: After a median follow-up of 18.3months, the response rate was 30.0%, and the disease control rate was 50.0%. Median overall progression-free survival (PFS) and overall survival (OS) were 3.3months and 13.2months, respectively. Longer median PFS was noted in those who had transarterial chemoembolization before radioembolization (7.3months vs 3.1months; P=0.021) and duration of alfa-feto protein (AFP) response ≥6months (11.8months vs 3.0months; P

Until recently, the radiation dose to patients undergoing the 90Y selective internal radiation treatment (SIRT) procedure is determined by applying the partition model to 99mTc MAA pretreatment scan. There can be great uncertainty in radiation dose calculated from this approach and we presented a method to compute the 3D dose distributions resulting from 90Y SIRT based on 90Y positron emission tomography (PET) imaging. Five 90Y SIRT treatments were retrospectively analyzed. After 90Y SIRT, patients had 90Y PET/CT imaging within 6 hours of the procedure. To obtain the 3D dose distribution of the patients, their respective 90Y PET images were convolved with a Monte Carlo generated voxel dose kernel. The sensitivity of the PET/CT scanner for 90Y was determined through phantom studies. The 3D dose distributions were then presented in DICOM RT dose format. By applying the linear quadratic model to the dose data, we derived the biologically effective dose and dose equivalent to 2 Gy/fraction delivery, taking into account the spatial and temporal dose rate variations specific for SIRT. Based on this data, we intend to infer tumor control probability and risk of radiation induced liver injury from SIRT by comparison with established dose limits. For the five cases, the mean dose to target ranged from 51.7 ± 28.6Gy to 163 ± 53.7 Gy. Due to the inhomogeneous nature of the dose distribution, the GTVs were not covered adequately, leading to very low values of tumor control probability. The mean dose to the normal liver ranged from 21.4 ± 30.7 to 36.7 ± 25.9 Gy. According to QUANTEC recommendation, a patient with primary liver cancer and a patient with metastatic liver cancer has more than 5% risk of radiotherapy‐induced liver disease (RILD). PACS number: 87.53.Bn