Research progress on total skin irradiation using helical tomotherapy / 中华放射肿瘤学杂志

Cutaneous T-cell lymphomas are a relatively rare group of mature T-cell lymphomas mainly manifesting in the skin, and its common subtype is mycosis fungoides. Total skin electron irradiation is one of the important conventional treatment methods, but there are many disadvantages, such as uneven dose distribution, poor position repetition, and long treatment time, which affect the clinical efficacy and patient prognosis. With the emergence and gradual popularization of helical tomotherapy in recent years, more and more medical institutions are gradually expanding their applications in total skin irradiation due to their ability to treat ultra-long targets and achieve dose-sculpted distribution, aiming to further explore its good or bad, and confirm whether it can replace the traditional total skin electron irradiation. In this article, research progress on total skin irradiation using helical tomotherapy was reviewed, the development of treatment technology, clinical efficacy and current concerns and controversies were illustrated.

Evaluation the combined effect of three dose reconstruction systems on VMAT dosimetry verification of lung cancer / 中华放射肿瘤学杂志

Objective:To evaluate the combined effect of an trajectory log field based(LBF)and two commercial dose reconstruction systems on volume-modulated arc therapy(VMAT)dose verification of lung cancer.Methods:An in-house program was developed to introduce errors in trajectory log of TrueBeam to the origin plan and recalculate the dose of the error plan in treatment planning system(TPS). A total of 18 lung cancer cases treated by two-arc VMAT were selected to perform on LINAC and measured by ArcCheck simultaneously. Then, the reconstructed doses were obtained by 3DVH. The mode of reconstruction was calculated by LFB and Compass. Five of the 18 cases were performed on LINAC two times in four hours and measured by ArcCheck to evaluate the stability of the TrueBeam performance. The 18 plans were recalculated and performed on LINAC with a solid water phantom with 5 cm build-up, 4 cm back scattering thickness and a FC65-G detector in the center. The measured dose by detector was compared with the reconstructed dose by three systems.Results:TheTruebeam performance was stable. For all of the 18 cases, the point dose measured by FC65-G and reconstructed by three systems had a deviation of less than 2% to the TPS calculated. For all of the organs reconstructed by LBF and most organs reconstructed by 3DVH and Compass, the γ pass rate between them and TPS all exceeded 90% under all criteria, as well as the ArcCheck measured results. For all the organ dose difference between reconstructed and TPS, LBF system had the smallest difference, followed by the Compass system except the lung, and the 3DVH had the highest difference.Conclusions:LBF, 3DVH and Compass can reflect the VMAT dose verification results of lung cancer from different perspectives. The combined application of three systems can demonstrate the verification results in an intuitive manner, which is beneficial for subsequent analysis.

The impact factors of longitudinal dose fall-off outside the target with helical tomotherapy / 中华放射医学与防护杂志

Objective:To study the changing characteristics and impact factors of helical tomotherapy (HT)for longitudinal dose fall-off outside the target, in order to guide the plan junction or pretreatment target and implementation efficiency in clinical.Methods:Eight patients with head and neck tumors admitted to the Department of Oncology Radiotherapy of the First Affiliated Hospital of Zhengzhou University in December 2019 were retrospectively selected as the research objects. The planning target area and dose drop structure were outlined in the head and neck images with a thickness of 1 mm obtained by Siemens SOMATOM Definition AS positioning computerized tomography (CT). Different field widths (FW, 5.0 cm/2.5 cm/1.0 cm) and pitches (0.430/0.287/0.215) were assembled for planning with the same modulation factor (1.8), finest does calculation grid (0.195 cm ×0.195 cm) and other planning parameters were consistent. The plans were designed by different parameters, and the result was analyzed by univariate analysis.Results:The that different pitch curves coincided under the same field width by comparative analyzing, so pitchs had no effect on dose drop. The different field width curves were independent of each other, indicating that the field width had an effect on dose drop in the head and foot direction. The relationship between the longitudinal dose drop speed outside the target and the change of the field width was inversely correlated: the larger field widths meant the slower dose fall-off and the larger penumbra, while the smaller field widths meant the faster fall-off and the smaller penumbra. When the dose fall-off to 50% of the prescribed dose, the distance from the target was approximately equal to half the field widths, and the pitchs had not affect the rate of dose-drop, while the dose at different distances from the target boundary could be calculated by the fitting formulas. The field widths and pitchs had little effect on the CI and HI index of the target, relatively, the target area was best when the field width was 2.5 cm. The total beam-on time gradually decreased with the increase of the field widths and pitches.Conclusions:When segment target therapy needs to consider planning junction, execution efficiency, and controlling longitudinal dose fall-off and considered the execution, the optimal planned parameters such as field widths and pitches could be selected or the target at the junction regions could be adducted according to the longitudinal dose drop formula, so as to achieve the ideal dose distribution.

Impact factors of dose distribution in the abutment area duing total body irradiation with helical tomotherapy / 中华放射医学与防护杂志

Objective To investigate the optimal distance between upper and lower target volumes and their correlated planning parameters by analyzing the dose distribution in the abutment regions during total body irradiation ( TBI) using helical tomotherapy. Methods A total of 10 patients with acute leukemia and with a height around 120 cm were enrolled. All patients were scanned by a Siemens simulation computerized tomography (CT) at a slice thickness of 5 mm. A lead wire was placed 10. 0 cm above the patella as a marker of the separation boundary for the upper and lower target volumes. The delineations of target volumes and organs at risk ( OARs ) were performed in the Varian Eclipse 13. 5 workstation with targets shrunk beyond the separation boundary at different distances. After contours and CT images were transferred to HT workstation, treatment plans were designed with different field width (FW, 5. 0 cm/2. 5 cm/1. 0 cm) and pitch values (0. 430/0. 287) at a modulation factor of 1. 8. All the plans were optimized with a dose calculation grid of 0. 195 cm × 0. 195 cm and identical planning parameters. The correlation between treatment planning parameters and targets shrunk distances were investigated by analyzing the dose distributions in the abutment area. Results The study demonstrated that the dose distributions in the abutment area were influenced only by the field width parameters: when the gap distance between the upper and lower targets was 5. 0 cm, the optimal FW is 5. 0 cm;Similarly when the gap distances were 2. 0 cm and 1. 0 cm, and the optimal FW 2. 5 cm and 1. 0 cm, respectively. In another words, the dose distribution of the abutment region was optimal when the target gap distance was equal to FW. Pitch values did not affect the quality of dose distribution in the abutment region and the overall treatment time ratio. Overall treatment time was inversely related to the FW. Conclusions Consistent target distance and FW is helpful to improve the dose homogeneity in the abutment area during TBI with HT. Appropriate planning parameters is critical to balance the treatment efficacy and efficiency.

Clinical study of total marrow and lymphatic irradiation in children using helical tomotherapy / 中华放射肿瘤学杂志

Objective To evaluate the feasibility of total marrow and lymphatic irradiation (TMLI)with helical tomotherapy as a conditioning regimen before hematopoietic stem cell transplantation (HSCT).Methods Seven children with acute lymphoblastic leukemia and aplastic anemia were recruited as study subjects.The median age was 7 years old.The prescribed dose was 12 Gy/6 fractions twice daily.The exposure dose of the target and the organs at risk between helical helical tomotherapy-based TMLI regimen and total body irradiation (TBI) regimen were statistically compared,and acute toxicity grading was performed for all patients.Results Compared with the TBI regimen,the average exposure dose reduction for organs at risk after the TMLI regimen was ranged from 4.2％ to 40.6％.The average exposure dose reduction for the kidney was the largest among all organs.The acute toxicities experienced by all patients were graded and recorded including 2 cases of nausea,5 cases of vomiting,1 case of anorexia,1 case of eryhema,3 cases of diarrhea,and 1 case of oral mucositis.Only grade 1-2 toxicities were observed,and no grade 3-4 toxicities occurred.Conclusions The findings in this study confirm the feasibility of helical helical tomotherapy-based TMLI regimen.Compared with the TBI regimen,the mean duration of treatment for the TMLI regimen with an equivalent dose is not increased.The exposure dose experienced by organs at risk is reduced and the predicted incidence rate is decreased when the TMLI regimen is employed,which provides a myeloablative pretreatment strategy.However,the long-term toxicity of TMLI regime remains to be evaluated by clinical trials.

CYP3A5 promotes proliferation of pancreatic cancer cells by regulating cyclin D1 protein expression / 中华胰腺病杂志

Objective To investigate the effect of CYP3A5 on the proliferation of pancreatic cancer cells and its underlying mechanisms.Methods The protein expression of CYP3A5 in five pancreatic cancer cell lines BxPC-3,FG,MDA28,8902 and PANC1 was detected by Western blotting.The PANC1 cells with the lowest protein expression of CYP3A5 and the BxPC-3 cells with highest expression of CYP3A5 were transfected with CYP3A5 overexpression plasmid and CYP3A5 targeted-siRNA (siRNA-CYP3A5),respectively.CCK-8 and cloning formation assay were used to investigate the role of CYP3A5 overexpression and knockdown in the proliferation of pancreatic cancer cells.The changes of the protein and mRNA expression of cell cycle regulating gene cyclin E,cyclin D1 and apoptosis related gene Bcl-2 were detected by Western blotting and PCR,respectively.Results CYP3A5 protein expression in PANC1 cells increased significantly after the transfection of CYP3A5 overexpression plasmid (1.66 ± 0.14 to 1,P =0.0021),which greatly decreased in BxPC-3 cells transfected with siRNA CYP3A5 (0.18 ± 0.02 to 1,P ＜0.0001).A450 values of the CYP3A5 overexpression group and the empty plasmid group in PANC1 cells cultured for 48 and 72 h were 1.36 ±0.05 vs 1.15 ± 0.03,2.1 ± 0.09 vs 1.42 ± 0.03,respectively,which were significantly higher in CYP3A5 overexpression group than empty plasmid group,and the differences were statistically significant (P value ＜ 0.005 or 0.001).The A450 values of BxPC-3 cells in CYP3A5-siRNA transfected group and siRNA-NC transfected group were 0.62 ±0.01 vs 0.77 ± 0.03、0.83 ± 0.01 vs 1.18 ± 0.02,respectively,which in The CYP3A5-siRNA transfection group was significantly lower than that of siRNA-NC transfection group,and the difference was statistically significant (P ＜ 0.05 or ＜ 0.001).The clone formation rate of PANC1 cells in the overexpression group was (19.33 ± 0.58)％,which was significantly higher than that in the empty plasmid group (9.67±0.63) ％,and the clone formation rate in CYP3A5-siRNA group was (8.5± 0.8)％,which was significantly lower than that of group siRNA-NC (16± 0.6)％,and the differences were statistically significant (P ＜0.01).The protein expression of cyclin D1 in CYP3A5 overexpression PANC1 cells was 2.00 ± 0.11,which was obviously higher than 1.00 in empty plasmid group (P ＜0.01).The protein expression of cyclin D1 in siRNA CYP3A5 BxPC cells was 0.45 ±0.04,which was obviously lower than 1.00 in siRNA NC group,and the difference was statistically significant (P＜0.01).However,CYP3A5 overexpression or inhibition did not influence the relative expression of cyclin D1 mRNA and cyclin E,Bcl-2 pretein expression.Conclusions CYP3A5 can promote the proliferation of pancreatic cancer cells by up-regulating cyclin D1 protein expression.

A study of the distance between the upper and lower targets in subsection total body irradiation by helical tomotherapy / 中华放射肿瘤学杂志

Objective To investigate the optimal distance between the upper and lower targets in the subsection total body irradiation(TBI)using helical tomotherapy,and to analyze the dose distribution of abutment regions. Methods A total of 8 patients with acute leukemia with a height of about 120 cm were involved in the study. All patients were scanned from the calvarium to the toe by computerized tomography (CT,Siemens)with a thickness of 5 mm,and a lead wire was placed at a point 10 cm above the patella as a marker of the boundary between the upper and lower targets. The delineation of target volumes and organs at risk(OAR)was performed in the Varian Eclipse 10.0 doctor workstation. The different distances between the lead wires and the boundary of the two targets were delineated, and images were transferred to the HT workstation to design the radiotherapy planning,including Jaw width(5 cm),modulation factor(1.8),and pitch(0.43). The plans were superimposed together, and then the dose distribution in abutment regions with different target gaps was analyzed to find the optimal distance. Results When the target gap was 5 cm, the dose distribution in abutment regions was satisfactory. However,the dose was obviously insufficient when the gap was more than 5 cm;the doses in abutment regions significantly exceeded the prescribed doses when the gap was less than 5 cm. Conclusions In the subsection TBI using HT, different parameters were designed,including Jaw width(5 cm), modulation factor(1.8), pitch(0.43), and slice thickness(5 mm). The upper and lower borders of the targets should be 2.5 cm away from the lead wire,that is,a gap of 5 cm,thus avoiding the dose-related hot or cold spots in the target convergence and ensuring a safer and more accurate radiotherapy.

Effect of different needle sizes and aspiration techniques on sample quantity / 中华消化内镜杂志

Objective To investigate the effect of needle sizes and aspiration techniques on sample quantity. Methods Aspiration was performed on porcine liver in vitro for 10 times with three different sizes of needles(19 G, 22 G and 25 G) and four different aspiration techniques[non?negative pressure(NP), 10 ml NP,20 ml NP and slow?pull], 20 mm in depth. A total of six aspirations were performed with each needle by the same aspiration technique. All the obtained specimens were fixed in formalin with the cell block method. The samples were evacuated according to our grading criteria. Results The mean±standard deviation(SD) score for 19 G,22 G, 25 G were 5?71±0?69,4?63±1?24, 3?79±1?84 respectively. The mean±SD score for methods non?NP,10 ml NP,20 ml NP and slow?pull were 4?72±1?53,4?56±1?46,4?72±1?50,4?83±1?76 respectively. The multi?analysis of variance results showed that there were statistical differences between different needles size( F=12?00,P<0?001) with 19 G being the best,followed by 22 G and the least specimen obtained by 25 G needle. There were no statistical differences among aspiration techniques ( F=0?128, P=0?943).The analysis showed that the thicker the needle was,the better sample quality was 19 G yielded to the highest quantity of specimens. The most specimens could be obtained with 19 G needle and non?NP, 22 G needle and 20 ml NP and 25 G needle and slow?pull. Conclusion In clinic, aspiration technique should be selected according to different aspiration needles. 19 G is superior to others, with non?NP method. For 22 G needle, 20 ml NP is preferred and for 25 G needle,slow?pull is preferred.