Background and purpose: To investigate the molecular mechanism for the effect of auranofin on the induction of cell differentiation, the cellular events associated with differentiation were analysed in acute promyelocytic leukaemia (APL) cells. Experimental approach: The APL blasts from leukaemia patients and NB4 cells were cotreated with auroanofin and all-transretinoic acid (ATRA) at suboptimal concentration. The HL-60 cells were treated with auroanofin and a subeffective dose of 1a,25-dihydroxyvitamin D 3 (1,25(OH) 2 vit D 3 ) in combination. The effect of auroanofin was investigated on histone acetylation at the promoter of differentiation-associated genes and expression of cell cycle regulators. Key results: Treatment with auroanofin and ATRA cooperatively induced granulocytic differentiation of fresh APL blasts isolated from patients and NB4 cells. The combined treatment also increased reorganization of nuclear PML bodies and histone acetylation at the promoter of the RARb2 gene. Auroanofin also promoted monocytic differentiation of the HL-60 cells triggered by subeffective concentration of 1,25(OH) 2 vit D 3 . The combined treatment of auroanofin and 1,25(OH) 2 vit D 3 stimulated histone acetylation at p21 promoters and increased the accumulation of cells in the G 0 /G 1 phase. Consistent with this, the expressions of p21, p27 and PTEN were increased and the levels of cyclin A, Cdk2 and Cdk4 were decreased. Furthermore, the hypophosphorylated form of pRb was markedly increased in cotreated cells. Conclusions and implications: These findings indicate that auroanofin in combination with low doses of either ATRA or 1,25(OH) 2 vit D 3 promotes APL cell differentiation by enhancing histone acetylation and the expression of differentiationassociated genes.

Purpose:The present study was designed to investigate the displacement of heart using Deep Inspiration Breath Hold (DIBH) CT data compared to free‐breathing (FB) CT data and radiation exposure to heart.Methods:Treatment planning was performed on the computed tomography (CT) datasets of 20 patients who had received lumpectomy treatments. Heart, lung and both breasts were outlined. The prescribed dose was 50 Gy divided into 28 fractions. The dose distributions in all the plans were required to fulfill the International Commission on Radiation Units and Measurement specifications that include 100% coverage of the CTV with ≥ 95% of the prescribed dose and that the volume inside the CTV receiving > 107% of the prescribed dose should be minimized. Displacement of heart was measured by calculating the distance between center of heart and left breast. For the evaluation of radiation dose to heart, minimum, maximum and mean dose to heart were calculated.Results:The maximum and minimum left‐right (LR) displacements of heart were 8.9 mm and 3 mm, respectively. The heart moved > 4 mm in the LR direction in 17 of the 20 patients. The distances between the heart and left breast ranged from 8.02–17.68 mm (mean, 12.23 mm) and 7.85–12.98 mm (mean, 8.97 mm) with DIBH CT and FB CT, respectively. The maximum doses to the heart were 3115 cGy and 4652 cGy for the DIBH and FB CT dataset, respectively.Conclusion:The present study has demonstrated that the DIBH technique could help to reduce the risk of radiation dose‐induced cardiac toxicity by using movement of cardiac; away from radiation field. The DIBH technique could be used in an actual treatment room for a few minutes and could effectively reduce the cardiac dose when used with a sub‐device or image acquisition standard to maintain consistent respiratory motion.

Purpose: Beam modeling performed based on the results of the present study, measuring the amount of radiation from a variety of small field of radiation measurement equipment beam modeling is based on the results of clinical practice, such as stereotactic radiosurgery and radiation therapy planning system applied to the treatment plan of each radiation dose distribution is to compare and analyze. Methods: A RapidArc medical linear accelerator was used with norminal 6 and 15 MV photon beam energies in this study. The small beams were generated that field sizes were 1×1, 2×2, 3×3 cm2 and reference field size was 10×10 cm2 to compare small field. We were generated the beam modeling and performed the automatic modeling with adjusted the mean and standard deviation of energy with the spectrum modeling base on the generated the PDD of the beam model. And, we were the lateral profile modeling by using adjusted each horn factor, effect source size, jaw transmission factor, MLC transmission factor, softening factor. Results: In this study, the edge detector measured a narrower penumbra width than the other detectors for small field sizes. For the 20–80% penumbra, the penumbra width measured with the ion chamber was approximately two times wider than the penumbra measured with the edge detector in all cases. The CC13 measured a penumbra width that was 25% wider for all field sizes. We found that the PDD measured with film had some signal fluctuation at the buildup region(6 MV: 1.5 cm, 15 MV: 2.9 cm) for the smallest field size when compared to the standard ionization chamber. Conclusion: The edge detector showed a greater suitability for small field dosimetry than the other detectors tested. We compared the detectors and evaluated the beam modeling results that as they have relatively large volumes, significant discrepancies could occur during the small field dosimetry.

Purpose: In this study, we evaluated the effect of grid size on dose calculation accuracy using 2 head & neck and 2 prostate IMRT cases. Methods: Dose distribution of four IMRT plan data were calculated at four calculation grid sizes (1.25, 2.5, 5, and 10 mm) and the calculated dose distributions were compared with measured dose distribution using 2D diode array detector. Results: there was no obvious difference in pass rate of gamma analysis with 3 mm/3% acceptance criteria except 10 mm grid size, we found that the pass rates of 2.5, 5 and 10 mm grid size were decreased 5%, 20% and 31.53% respectively. The calculation time were about 11.5 min, 4.77 min, 2.95 min, and 11.5 min at 1.25, 2.5, 5, and 10 mm, respectively and as the grid size increased to double, the calculation time decreased about one‐half. The grid size effect was observed more clearly in the high gradient area than the low gradient area. Conclusions: In conclusion, 2.5 mm grid size is considered acceptable for most IMRT plans but at least in the high gradient area, 1.25 mm grid size is required to accurately predict the dose distribution.