Data Availability StatementAdditional file was included, which contains Additional file 1: Table S1, Additional file 2: Table S2, Additional file 3: Table S3 and Additional file 4: Table S4, natural data for Figs. 35-mm dishes and irradiated by Ir-192 HDR-RALS under normoxic and hypoxic conditions. A 6 French (Fr) catheter was used as an applicator. A radiation dose of 6?Gy was prescribed at hypothetical treatment point A, located 20?mm from the radiation resource. Changes in Fucci fluorescence after irradiation were visualized for cells from 5 to 20?mm from your Ir-192 resource. Several indices, including 1st green phase period after irradiation (FGPD), were measured by analysis of time-lapse images. Results Cells located 5 to 20?mm from your Ir-192 resource became green, reflecting arrest in G2, in a similar manner up to 12?h after irradiation; at more distant positions, however, cells were gradually released from your G2 arrest and became reddish. This could be explained from the observation the FGPD was longer for cells closer to the radiation resource. Detailed observation exposed that FGPD was significantly longer in cells irradiated in the green phase than in the red phase at positions closer to the Ir-192 resource. Unexpectedly, the FGPD was significantly longer after irradiation under hypoxia than normoxia, due in large part to the elongation of FGPD in cells irradiated in the red phase. Summary Using HeLa-Fucci cells, we acquired the 1st temporo-spatial information about BX-912 cell-cycle kinetics following irradiation by Ir-192 HDR-RALS. Our findings suggest that the potentially surviving hypoxic cells, especially those arising from positions around point A, show different cell-cycle kinetics from normoxic cells destined to be eradicated. Electronic supplementary material The online version of this article (doi:10.1186/s13014-016-0669-8) contains supplementary material, which is available to authorized users. test or chi-square test was utilized for statistical determinations. ideals? ?0.05 were considered BX-912 statistically significant. Results Dose distribution under our experimental conditions The experimental conditions are defined in Fig.?1a. Simulation of dose distribution by the treatment planning system, which is actually used in the medical establishing in our hospital, is definitely depicted in Fig.?1b by some iso-dose curves (remaining panel). The dose absorption within the X-axis measured by a TLD plate like a function of range from the radiation resource is demonstrated in Fig.?1b (right panel). The actual absorption dose at 5, 10, 15, and 20?mm was 24, 14, 9, and 6?Gy, respectively. Temporo-spatial cell-cycle kinetics in low-power field images Like a main goal of this study, we attempted to visualize the cell-cycle kinetics of cells at different distances from the radiation resource. For this purpose, we used HeLa cells expressing the Fucci system . In our earlier reports using HeLa-Fucci cells, we showed that elongation of the 1st green phase period after irradiation (FGPD) and subsequent appearance of reddish cells perfectly displays the G2 arrest kinetics following X-irradiation [10, 11]. We reasoned the fluorescence kinetics could be used to obtain information concerning G2 arrest kinetics like a function of range from your Ir-192 resource. The results are demonstrated in Fig.?2. In general, ~50?% of exponentially growing HeLa-Fucci cells indicated green fluorescence. After irradiation, the proportion of green cells gradually improved, irrespective of the distance from your Ir-195 source up to 20?mm, reaching almost 100?% 12?h after irradiation of cells within the field. However, in cells more distant from your Ir-192 source, reddish SMAD9 cells (representing cells entering G1 phase after release from G2 arrest) began to appear, and the proportion of green cells gradually decreased. The reddish BX-912 fluorescence wave reached 7C8?mm from the radiation source 24?h after irradiation, as shown in the middle panel. This result indicated that G2 arrest occurred similarly in cells up to hypothetical point A, and that release from G2 arrest strongly depended on distance from your Ir-192 source. Forty-eight hours after irradiation, reddish cells appeared even 5?mm from the source. Cell density was clearly lower closer to the Ir-192 source, and higher at more distant positions, 72?h after irradiation. Thus, we succeeded for the first time in visualizing the BX-912 cell-cycle kinetics in cells located at different distances from an Ir-192 HDR-RALS. Open in a separate windows Fig. 2 Low-power images of Fucci fluorescence following irradiation. Cells produced on 35-mm dished were.