Background: The dynamic phantom is one of the best tools to study the impact of motion on tumor target delineation and absorbed dose verification during dose delivery. Materials and Methods: this study, a 6-DOF (degrees of freedom) phantom was designed following the stacked serial kinematics and assembled by six commercial motion stages to generate 6-DOF motion, which were RotX (pitch, around X), RotY (roll, around Y), TransZ (anterior-posterior), RotZ (yaw, around Z), TransY (superior-inferior) and TransX (left-right). Tumor targets were designed by six plastic spheres for the delineation test. Also, an ionization chamber array detector and RW3 solid water were combined to measure the absorbed dose for dose verification tests. Results: The maximum translation speeds for LineX and LineY were 50mm/s and 35mm/s for LineZ, while the maximum rotation speeds for RotX, RotY, RotZ were 5.33 degrees per second, 6 degrees per second and 15 degrees per second respectively. Spiral-CT and 4D-CT images acquired in the static and dynamic states successfully showed the influences of tumor motion on target delineation. In the absorbed dose verification, all cases did not pass the gamma test; the pass rate for the 6-DOF motion case was only 34.2% and the pass rates of all other cases were less than 90%. Conclusion: The phantom designed in this study is able to simulate complex tumor motion and can be used to study the influence of tumor motion in radiotherapy.
Background: Protection of hematopoietic system has become a primary goal in the development of novel medical countermeasures against ionization radiation and radiotherapy. This study was to explore the role of rapamycin in normal tissues against radiation. Materials and Methods: Mice were pretreated with rapamycin by i.p. every other day for five times before 5 Gy or 8.5 Gy gamma-ray whole body irradiation. Blood cell counts, HE staining of bone marrow and liver, bone marrow transplantation, CFU of spleen were used to measure the damage of hematopoiesis and extramedullary hemopoietic organs. Regular karyotype analysis and expression of gamma-H2AX (by flow cytometry and western blot) were used to measure DNA damage. Rad 50 and DNA Lig 4 expression by western blot were to see the DNA repair ability. Results: The decrease of red blood cells and platelet induced by radiation were alleviated by pretreatment with rapamycin (d 7,15, p<0.01), and the long-term restoration of white blood cells, lymphocytes and bone marrow were enhanced in rapamycin pretreatment group (d 30,40,70, p<0.05). The transplantation experiment also indicates that the long-term reconstitution in lethally irradiated recipient mice was improved in rapamycin group (p<0.05). The hepatocellular injury by radiation was also reduced and the colony formation numbers of spleen after irradiation was improved in rapamycin group (p<0.05). Karyotype analysis indicates that rapamycin protected bone marrow cells from chromosome mutation. Furthermore, expression of DNA repair proteins Rad 50 and DNA Lig 4 was enhanced and DNA damage marker gamma-H2AX was reduced in mice exposed to radiation by rapamycin pretreatment. Conclusion: Rapamycin pretreatment mitigates hematopoietic system from radiation injury in both bone marrow and extramedullary hematopoietic organs by improving genomic stability and increasing survival of hematopoietic stem and progenitor cells (HSPCs).
Background: Boron neutron capture therapy (BNCT) is a binary radiotherapy combining biochemical targeting with neutron irradiation. However, monitoring the boron distribution is a fundamental problem in BNCT. Prompt gamma rays emitted by boron capture reaction can be used to address the issue. Materials and Methods: The general-purpose Monte Carlo toolkits Geant4 and MCNP were used for the simulations. A cubic phantom with so) tissue was used to study the prompt gamma emission during BNCT. The Chinese hybrid phantom with arbitrary tumors was constructed and used to acquire the 0.478 MeV prompt gamma rays in BNCT. Tomographic images were reconstructed with the maximum likelihood expectation maximization (MLEM) algorithm. Results: Comparison between MCNP and Geant4 showed a similar gamma rays emission rate in so) tissue. Up to 30 gamma ray peaks were found in the simulation, and 0.478 MeV prompt gamma ray from boron was clearly observed. The single brain tumor with variable diameter from 1 cm to 4 cm in the heterogeneous anthropomorphic phantom was each time found to be recognizable in the reconstructed image. Furthermore, in a patient with four tumors, the variable distance between the source and the tumors leads to a neutron attenuation thus resulting in an inhomogeneous number of prompt gammas. Conclusion: The SPECT system for a heterogeneous phantom in BNCT was simulated with Geant4. The results show that BNCT-SPECT is valid for the reconstruction of the boron capture interaction position for a heterogeneous patient.
Background: Prospectively electrocardiography (ECG)-triggered high-pitch spiral coronary computed tomography angiography (CCTA) is a unique scan mode for dual -source CT (DSCT). Our reports aim to compare image quality and radiation dose of CCTA using high-pitch spiral or sequential acquisition mode in patients with low and stable heart rates. Materials and Methods: Patients with low and stable heart rates (HR) (HR <= 70 beats per minute [bpm]; heart rate variability [HRV] < 10 bpm) were randomly assigned to high-pitch spiral mode (group A; n = 80) or sequential acquisition mode (group B; n = 80). Image quality scores, image noise, effective radiation dose and influencing factors on image quality were assessed. Results: Mean image quality scores were 1.51 +/- 0.32 and 1.70 +/- 0.38 for groups A and B (P < 0.05), respectively. Image noises of the two groups were 19.05 +/- 4.70 Hu and 27.21 +/- 8.88 Hu (P < 0.05). Contrast media cost in group A was lower than group B (P < 0.05). No statistical difference was found in the rate of diagnostic patients between the two groups (P = 0.416). The estimated radiation dose of group A was 26.0% reduced compared with group B (0.74 +/- 0.34 mSv vs. 1.00 +/- 0.48 mSv, P < 0.05). Conclusion: In patients with regular and low heart rates, the prospectively high-pitch spiral acquisition mode can reduce radiation dose and contrast media cost while maintaining image quality compared with the prospectively sequential mode.
With the development of science and technology, microwave has been used in many fields such as industry, military, medicine and communication. People are living in a lapped and dynamic electromagnetic environment. Concerns about potential hazards of microwave are geting increasing atentions. The single biological effects of microwave were widely discussed which was considered harmful. Relevant safety standards had been formulated and applied. However, the real environment was more complex. Microwave was not the only factor that organisms might be affected. Other physical or chemical factors, such as ionizing radiation (IR), ultraviolet (UV), magnetic field and chemical drugs, often existed with the microwave radiation. Even the microwave itself could create combined exposure situation, because the environment consisted different frequency microwaves. Nuclear weapons and high-power radar could produce microwave and ionizing radiation. The ultraviolet ray and magnetic field generated by the instrument's operation could act on the human bodies along with the microwaves. The combination of radiofrequency therapy and chemotherapeutic agents was also commonly used in cancer therapy. Therefore, the combined biological effects of microwaves and other physical or chemical factors were very important. This review had covered the original articles in this aspect. In order to be er understand the combined biological effects, the comparative studies of different frequency microwaves were also included. Differences in biological effects were found among different frequency microwaves, and the combined biological effects contained both hazards and benefits. Findings in combined biological effects were very practical for rational uses of microwave technologies.
Background To compare the following techniques for hypofractionated whole-breast irradiation (WBI) with simultaneous integrated boost (SIB) after breast -conserving surgery (BCS): three-dimensional conformal radiation therapy plus electron boost (3DCRT-EB), intensity-modulated radiation therapy (IMRT) plus EB (IMRT-EB), field-in-field IMRT plus EB (FIF-IMRT-EB), FIF-IMRT plus IMRT boost (FIF-IMRT-IB), IMRT plus IMRT boost (IMRT-IB), and volumetric-modulated arc therapy (VMAT) plus VMAT boost (VMAT-VB). Materials and Methods: Twenty patients with left breast cancer were enrolled. The prescribed dose was 40.05 Gy in 15 fractions to the whole breast and an SIB to the tumor bed of 3.2 Gy/fraction (total, 48 Gy). Target-volume coverage, dose-conformity index, homogeneity index (HI), doses to organs at risk (OAR), and costs were compared. Results: FIF-IMRT-EB performed the best, while FIF-IMRT-IB, I MRT-IB, and VMAT-VB performed the worst. The mean dose to the planning target volume for breast evaluation (PTV Eval-breast) was significantly lower for IMRT-EB and FIF-IMRT-EB than for the other plans. For both PTV Eval-breast and PTV Eval-boost, VMAT-VB had the lowest target-volume coverage for 95% of the prescription dose and the highest target-volume coverage for >105% of the prescription dose. Among the six plans, VMAT-VB had the best HI for PTV Eval-boost and the highest doses to all OAR, except the coronary artery. Plans with EBs had lower mean doses for the contralateral lung and contralateral breast than plans with IMRT boosts. FIF-IMRT-EB had a low cost; plans with IMRT boosts had the highest costs. Conclusions: FIF-IMRT-EB may be the most suitable irradiation technique for hypofractionated WBI with SIB after BCS.
Background: A method to track liver tumor motion signals from fluoroscopic images without any implanted gold fiducial markers was proposed in this study to overcome the adverse effects on precise tumor irradiation caused by respiratory movement. Materials and Methods: The method was based on the following idea: (i) Before treatment, a series of fluoroscopic images corresponding to different breathing phases and tumor positions were acquired after patient set-up; (iii) The wavelet transform method and Canny edge detection algorithm were used to detect motion trajectory of the diaphragm; (iv) The motion curves of center of lipiodol in the images were obtained by mathematical morphology and median filtering algorithm. The method was evaluated using by five sequences of fluoroscopic images from TACE patients who received transcatheter arterial chemoembolization therapy. Results: The position of liver tumor was significantly affected by respiratory motion; the motion trajectories of the diaphragm and lipiodolagreed well with the manually marked locations in amplitude and period; the motion trajectories of the diaphragm and lipiodol almost had similar period and amplitude in one treatment fraction. The respiratory period and amplitude of the same patient in different fractions had no significant differences; however, the difference was obvious for different patients. The proposed lipiodol detection methods can effectively reflect the relevant rules of tumor location caused by respiratory movement. Conclusion: Direct tracking of liver tumor motion in fluoroscopic images is feasible. The automatic detection method can reflect the characteristics of respiratory and tumor motions, which can save much time and significantly improve measurement precision compared with manual measurement.
Backround: This study evaluated the relation between telomere length in lymph node (LN) and prognosis of esophageal squamous cell carcinoma (ESCC). Materials and Methods: LNs collected from 50 patients were assessed by pathological examination and quantitative reverse transcription polymerase chain reaction (qRT-PCR), which was used for detecting telomere length. The relation between clinical factors and the number of lymph node metastasis (LNM) identified were analyzed by the chi(2) test. The comparison of the pattern of LNM identified by pathological examination and detection of telomere length was assessed by Wilcoxon signed-rank test. Overall survival was assessed using the Kaplan-Meier method, and Cox proportional hazard regression analysis was used to evaluate the relationship between survival and the number of LNM. Results: The best threshold values, which could define the positive metastasis by detecting the telomere length, were 1.50, using the critical value method of statistic. Length of tumor, depth of tumor invasion and differentiation of tumor correlated closely with LNM were identified by detecting telomere length. The rates of LNM identified by detecting telomere length were 34.4%, 22.4%, 22.9%, 5.0% in 108, 107, 7, and 3 LN station, respectively. The number of LNM identified by detecting telomere length was more closely related to the prognosis of ESCC than that of pathological examination (HR: 1.23 VERSUS 1.04). Conclusion: The change of telomere length in LN was closely related to the prognosis of ESCC. Delineation of clinical target volume (CTV) may benefit from the detection of telomere length in regional LN.
ackground: Boron neutron capture therapy (BNCT) is a radiotherapy that combines biological targeting and high linear energy transfer. A potential therapeutic approach for non-small cell lung cancer (NSCLC) is considered. However, dose in lung tumor is not homogeneous, and it will reduce the effect of BNCT treatment. In order to improve the dose distribution of BNCT, the multi-field irradiation strategy and its effects need to be explored. lidaterials and Methods: Common NSCLC model was defined in Chinese hybrid reference phantom and the boron concentration in skin and tumor varied from 6 to 18 ppm and from 30 to 65 ppm, respectively. Monte Carlo method for dose distribution calculation was used. Accelerator-based neutron source called "Neuboron source" was used and multi-field source irradiation plans were designed to optimize the dose distribution. Results: Under one field irradiation, it was not feasible to perform BNCT, because the skin dose is unlikely to meet its dose limit. Under two-and three-field irradiation, the uniformity of tumor dose was improved and the maximum dose to organs at risk (OARs) decreased. If boron concentration in skin was between 6-18 ppm, BNCT was feasible with the boron concentration in tumor reaching about 5760 ppm for two-field irradiation and 41-45 ppm for three-field irradiation, respectively. Conclusion: The multi-field irradiation plan could improve the dose distribution and the feasibility of BNCT for NSCLC. Theoretical distributions of Boron-10 were obtained to meet the treatable requirement of BNCT, which could provide a reference for NSCLC using BNCT in future multiple-field irradiation.
Background: The activity concentrations of Ra-226, Th-232 and K-40 in sand used as building material in Weifang of China were investigated for evaluating the radiation hazard. Materials and Methods: Sand samples were collected from Weifang and their radioactivity levels were measured using gamma-ray spectrometry. The radiation hazard for residents was assessed by radium equivalent activity (Raeq), indoor air absorbed dose rate (D), annual effective dose (AED) and excess lifetime cancer risk (ELCR). Results: The activity concentrations of Ra-226, Th-232 and K-40 ranged from 11.7 to 23.0, 33.6 to 126.1 and 353.2 to 924.8 Bq kg(-1) with averages of 15.5, 70.3 and 802.9 Bq kg(-1), respectively. All Raeq values were lower than the limit of 370 Bq kg(-1). The mean value of D was higher than the world population-weighted average of 84 nGy h(-1), while the mean AED and ELCR values were below the internationally accepted values. Conclusions: The use of sand in construction of dwellings is considered to be safe for inhabitants.
Background: We used a MapCHECK software-based dimensional dose distribution comparison method capable of evaluating point-to-point geometrical dose differences in volume to determine whether doses obtained from an enhanced computed tomography (CT)-based treatment plan, which better defines the target regions and organs at risk, differs from doses obtained from plain CT and then evaluated the feasibility of treatment planning via enhanced CT. Materials and Methods: Forty-three randomly selected patients underwent plain and subsequent enhanced CT with the same settings. Treatment plans developed for the two scans were idenitcal in terms of planning parameters (e.g., isocentre, gantry angle, segments) and monitor units (MU) used for dose calculation. Horizontal and vertical dose distribution planes across the same isocentre were selected from two types of plan; a two-dimensional dose distribution analysis was used to determine the Distance-To-Agree (DTA) pass ratios of corresponding dose distribution planes. Results: Obtained doses at the head and neck (H&N) and pelvic sites did not differ greatly between enhanced and plain CT. However, enhanced CT significantly influenced doses to the lower thoracic oesophagus. A corrected pass ratio that was achieved by non-pass points in lower isodose areas excluded from the statistical analysis had better clinical outcome. Conclusion: Radiation plans with multi-fields and multi-angles can reduce the influence of enhanced CT on torso cases and may even negate its influence on H&N cases. Enhanced CT can be directly used for planning unless the target region contains the lower oesophagus and its surrounding blood vessel whose high density requires correction.
Background: Radiotherapy is an effective and important therapeutic method for breast cancer, but at the same time it has a radiation-induced bystander effect on normal tissue around the tumor. Repair of double-strand breaks (DSBs) by normal cells can reduce the extent of damage caused by this effect. Caveolin-1 (Cav-1) is an important regulatory molecule in cell signal transduction. However, the response of normal human mammary epithelial cells following low dose radiation (LDR)-induced DSBs and the role of Cav-1 in the repair of the DSBs are not clear. The present study examined the DNA damage repair mechanism triggered by LDR in human mammary epithelial cells. Materials and Methods: Human mammary epithelial (MCF10A) and Cav-1 haplo-insufficiency (MCF10A-ST1) cells were irradiated with LDR gamma rays and the effect of this radiation on cell proliferation was determined by cytometric method. Western blot analysis was then used to measure the expression levels of different proteins associated with cell proliferation and DNA repair. Results: LDR enhanced the radiation responsiveness of MCF10A cells in a dose- and time-dependent manner. At a dose of 100 cGy, LDR increased the expression levels of several proteins involved in DNA repair pathways, such as ATM, p53, DNA-PKcs and also activated Cav-1-mediated cell proliferation and survival pathways, such as the MAPK and AKT pathways. The expression of the various DNA repair related proteins was changed after down-regulating the Cav-1 expression. Conclusion: LDR could increase the radiation responsiveness of human mammary epithelial cells through activating the DNA repair pathways, including both HR and NHEJ pathways, as well as triggering the cell proliferation and survival pathways, both of which required Cav-1.
Background: The activity concentrations of natural radionuclides in soil around a coal-fired thermal power plant of northwest China were investigated for assessing the radioactivity level. Materials and Methods: Soil samples were collected around the coal-fired thermal power plant and their radioactivity levels were determined using gamma ray spectrometry. Radiation hazards were assessed by radium equivalent activity (Raeq), air absorbed dose rate (D) and annual effective dose equivalent (AEDE). ResultsThe activity concentrations of Ra-226, Th-232 and K-40 ranged from 24.7 to 89.8, 38.4 to 122.3 and 206.7 to 573.8 Bq kg(-1) with an average of 49.7, 63.5 and 396.3 Bq kg(-1), respectively. The mean Raeq value was less than the recommended limit, while the mean values of D and AEDE were slightly higher than the corresponding world average. Conclusion: The coal-fired thermal power plant enhanced the natural radiation of surrounding soil environment.
Background: This study evaluated whether IMRT using fewer beams and segments could reduce delivery time without compromising plan quality in gastric cancer adjuvant radiotherapy. Materials and Methods: Fifteen patients with advanced gastric cancer who underwent D2, R0 surgery were included in this study. IMRT plans for each patient were designed as 7 equal beams with 40 segments, 5 beams with 25 segments and 4 beams with 20 segments. The dosimetric parameters were compared for the planned target volume (PTV). The dose of normal organs at risk (OARs) was also assessed. The monitor units and treatment times of the different IMRT plans were calculated. Results: The 20-segment IMRT plan significantly reduced the PTV maximum dose compared to the 40-segment IMRT plan. The 20-segment IMRT plan improved left kidney and liver dose sparing in V20 and V30 as well as the 40-segment IMRT plan did and provided better protection for the V20 (13.86 +/- 7.78) of the right kidney, the V30 (9.25 +/- 4.04) of the left kidney, the D mean (19.68 +/-.47) of liver and D max (38.79 +/- 3.57) of the spinal cord. Irradiation times in the 20-segment and 25-segment plans decreased by 2.5 and 1.9 min, respectively, compared to the 40-segment IMRT plan. Conclusion: IMRT using fewer beams and segments reduced delivery time without compromising plan quality in gastric cancer adjuvant radiotherapy. Fewer segments IMRT plans lowered the monitor units and the treatment time.
Background: To evaluate computed tomography (CT) and magnetic resonance imaging (MRI) fusion images for delineating gross tumor volume (GTV) in three-dimensional conformal radiotherapy (3D-CRT) of nasophanrygeal carcinoma (NPC), and compare treatment outcomes between CT- and CT+MRI-based targets. Materials and Methods: A total of 120 NPC patients treated with 3D-CRT were included, in which, 60 each were treated with CT-based and 60 with CT+MRI fusion targets. We explored the clinical application of CT+MRI fusion targets and compared the 1-, 3-, and 5-year survival and relapse rates between both targets. Results: The clinical characteristics and treatment factors were well balanced. The differences in public volume using CT alone in the CT+MRI (Group A) and the CT arm (Group B) were not significant (33.6 +/- 2.18 vs. 34.3 +/- 2.98, P > 0.05). The public volumes of GTV in the two arms were 49.48 +/- 2.46 cm(3) and 33.6 +/- 2.18 cm(3) respectively (P < 0.05). CT+MR fusion images did not influence the one-, three-, and 5-year survival rates (100% vs. 98.3%, 85.0% vs. 81.2%, and 73.3% vs. 68.3%, respectively). The three- and 5-year out-of-field progression was reduced in the CT+MRI arm. However, only the difference in 3-year out-of-field relapse rate was significant (3.3% vs. 13.3%; P < 0.05). The incidence of acute toxicities was similar between groups. Conclusion: The variability in GTV delineation in NPC was ascribed to intermodality and not interobserver variability. CT+MR fusion images likely reduced the 3-year out-of-field relapse rate.