International Journal of Cancer Therapy and Oncology
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Assessment and performance evaluation of photon optimizer (PO) vs. dose volume optimizer (DVO) for IMRT and progressive resolution optimizer (PRO) for RapidArc planning using a virtual phantom
Get PDFPurpose: The purpose of the study was to present the quantitative and qualitative evaluation of newly incorporated photon optimizer (PO) versus previously was used independent dose volume optimizer (DVO) for intensity modulated radiation therapy (IMRT) and progressive resolution optimizer (PRO) for Rapid-arc/ volumetric modulated arc therapy (VMAT) in version 13.5 of Eclipse treatment planning system (ETPS).Methods: We accomplished this study with the help of cylindrical virtual phantom created in the ETPS. Six individual phantoms study sets (PSS) were generated and different material density value was assigned in order to evaluate the behavior optimizers in the presence of tissue heterogeneity. Several independent plans were generated for IMRT and Rapid-arc by changing optimizer module PO, DVO, and PRO for 6 MV, 15 MV flattened beam and 6 MV-flattening filter free (FFF) beam.Results: The self-governing evaluations of PO versus DVO for IMRT plan and PO versus PRO for Rapid-arc/VMAT plans were performed. We estimated and compared various distinct parameters such as maximum dose, minimum dose, mean dose, conformity index (CI), quality index (QI), homogeneity index (HI), integral plan monitor unit (MU) and dose volume histogram (DVH). The percentages of the average variation over all PSS and beam energy between PO versus DVO optimized plan quality parameters such as planning target volume (PTV) maximum, minimum, mean doses, CI, QI and HI were 0.23%, 1.67%, 0.09%, 20.4%, 0.77% and 0.52% , respectively, whereas for PO versus PRO were 1.18%, 3.38%, 0.19%, 8.11%, 2.78%, and 1.28%, respectively.Conclusion: The results presented in this study showed that PO generates plans with better quality in shorter time compared to DVO and PRO for both IMRT and Rapid-arc/VMAT, respectively
Radiation protection and secondary cancer prevention using biological radioprotectors in radiotherapy
Get PDFRadiotherapy is the feasible treatment approach for many malignant diseases and cancers. New radiotherapy techniques such as ion therapy, stereotactic radiosurgery and intensity modulated radiation therapy deliver higher low dose radiation to large volume of normal tissues and are in debating as more secondary cancers inducers. A secondary cancer after radiotherapy is an important issue that reduces treatment efficiency and should be decreased. Radioprotective compounds are of importance in clinical radiation therapy for saving normal tissues. In the present study, we are so interest to introduce, suggest and review the application of biological radioprotectors in radiotherapy. We propose probiotics, prebiotics, gas, vitamin and nanoparticle producing microorganisms as new biological systems based radioprotectors to protect normal tissues. Also, we reviewed the main biological pathways, molecules and also radioadaptive response that act as radioprotectors. In this review we tried to address the secondary cancer induction by radiotherapy and also main biological radiation protection approaches, although there is a wealth of data in this subject.
Advantage of using deep inspiration breath hold with active breathing control and image-guided radiation therapy for patients treated with lung cancers
Get PDFPurpose: The aim of this study was to evaluate the irradiated volume and doses to the target, heart, left lung, right lung and spinal cord, the number of segments and treatment time by using moderated deep inspiration breath hold (mDIBH) with active breathing control (ABC) and image-guided radiotherapy (IGRT) for patients treated with lung cancers.Methods: The suitability of this technique for lung patient treated with ABC was investigated and the solutions to achieve better treatments were discussed. Eleven lung cancer patients (3 left-sided and 8 right sided lesions) with stages I-III underwent standard free breath (FB) and ABC computed tomography (CT) scans in the treatment supine position. This can be achieved by applying respiratory manoeuvres, such as mDIBH, during which the threshold volume utilized is defined as 75-80% of the maximum aspiratory capacity. Five to seven, 6-MV photon beams with optimized gantry angles were designed according to the tumor location to conform to the PTV while sparing as much heart, spinal cord, and contra lateral lung as possible. For eleven patients, treatment planning using mDIBH CT data with intensity modulated radiation therapy (IMRT) was then reoptimized on the free breathing data set for comparison. The studied parameters of the plans for each patient were evaluated based on the average of the minimum, mean, and maximum difference in dose, the range of difference, and the p-value using two-tailed paired t test assuming equal variance.Results: The average volume of the planning target volume (PTV) in 11 patients increased to 1.32% in ABC compared to FB. The average volume of heart in 11 patients decreased to 2.9% in ABC compared to free breathing IMRT. In the case of lungs, the volume increased to 27.5% and 25.85% for left and right lungs, respectively. The range of mean difference in dose to the PTV in 11 patients was -54 cGy to 230 cGy with ABC technique when compared with free breathing. The range of mean dose difference of heart in 11 patients observed were -88 cGy to 66 cGy (p < 0.0410) between ABC and FB. The range of maximum dose difference to the spinal cord in 11 patients were -1592 cGy to 190 cGy (p < 0.041) with ABC technique when compared with FB IMRT. Monitor units (MUs) were -22.9% less in ABC compared to FB. Segments were more in ABC compared to FB for about 16.39% on an average. The average of minimum, mean and maximum difference in dose to the right lung and left lung were less in ABC compared with FB.Conclusion: In most of the cases, IGRT with ABC significantly reduces the mean dose to heart, right lung, left lung, and spinal cord compared with FB. Discrepancy observed in few cases made the statistical data inconsistent. Depending on anatomy and arbitrary phase of the breathing cycle, the results may vary and for better outcome of the results optimum treatment procedures need to follow.
Study the effects of radon inhalation on biomechanical properties of blood in rats
Get PDFPurpose: To investigate the effect of inhalation radon gas (Rn) on the biomechanical properties of red blood cell of rats. Methods: 20 young healthy adult male albino rats were divided into equally 4 groups. The first group (0) served as control group, while the other three groups (I, II and III) were exposed to Rn gas inside a chamber for 3, 5 and 7 weeks. The biomechanical properties of red blood cell of rats was performed by determine the rheological properties of blood and the osmotic fragility of red blood cells (RBCs). Results: The Rn doses received by every group of rats were found to 34.84, 58.07 and 81.30 mSv for 3, 5 and 7 weeks respectively (based on 12 exposure hours per week). The obtained results indicate that the viscosity, consistency index, yield stress and aggregation index increase with Rn doses. The osmotic fragility curves of irradiated groups shift toward lower values of NaCl concentration. The dispersion of hemolysis (S) increased, at the same time an average osmotic fragility (H50%) decreased. Conclusion: The results indicates that the exposure to radon alters the mechanical properties of red blood cells membrane (permeability and elasticity) reflecting a change in its physiological properties. This mean that low levels of Rn gas are harmful to biological systems and the degree of damage was dose-dependent
Downregulation of transient receptor potential cation channel, subfamily C, member 1 (TRPC1) is associated with drug resistance and high histologic grade in ovarian cancer
No full textPurpose: Ovarian cancer (OC) drug resistance, believed to result in treatment failure and death in more than 90% of patients with metastatic OC, is due to a myriad of contributing factors. However, no matter what mechanisms, dysregulation of critical genes essentially play important roles. Transient receptor potential cation channel, subfamily C, member 1 (TRPC1) contributes to various physiological functions, and is involved in the regulation of cancer development. However, the overall studies of TRPC1 with cancer are limited, the study with drug resistance or OC is rare, and the research on TRPC1 with drug resistance in OC has never been reported. In this study, we aimed to explain the associations of TRPC1 with drug resistance in OC.Methods: The expression of TRPC1 was determined by the microarrays retrieved from Oncomine (https://www.oncomine.org/resource/login.html) and GEO Profiles (http://www.ncbi.nlm.nih.gov/geoprofiles/), and further confirmed by RT-qPCR. The clinical data of 341 OC patients with TRPC1 mRNA expression data in TCGA cohort was retrieved from cBioPortal (http://cbioportal.org). Comprehensive bioinformatics analyses including protein/gene interaction, protein-small molecule/chemical interaction, biological process annotation, microRNA-mRNA interaction and pathway enrichment analysis of microRNAs were performed to clarify the drug resistant-related functions of TRPC1. The data was analyzed by SPSS 20.0 software. P-values of <0.05 were considered to indicate statistically significant differences.Results: The mRNA expressions of TRPC1 were downregulated by 3.955-fold, 3.681-fold and 3.260-fold in ovarian cancers according to the Welsh Ovarian covering 28 cases of ovarian serous surface papillary carcinoma and 4 cases of ovaries, the Bonome Ovarian covering 185 cases of ovarian carcinomas and 10 cases of ovarian surface epitheliums, and the Yoshihara Ovarian covering 38 cases of ovarian serous adenocarcinomas and 10 cases of peritoneum, respectively, which all were retrieved from the Oncomine. Consistent with the expression in OC tissues, the TRPC1 was downregulated by at least 3-fold in OC cells compared with the expression in normal ovarian surface epithelial cells in accordance with microarray data (GDS3592) retrieved from GEO Profiles. The mRNA expression of TRPC1 were also significantly downregulated in A2780 epithelial OC cells with acquired platinum resistance and carboplatin-resistant OC tissues compared with the expression in their sensitive counterparts according to microarray data (GDS3754 and GDS1381). This result is confirmed by RT-qPCR measurement indicated that the TRPC1 is downregulated in cisplatin-resistant SKOV3 cells and carboplatin resistant A2780 cells, by at least 2-fold changes. Protein/gene interaction indicated that TRPC1 interacted with 21 proteins/genes and 14 of them were associated with drug resistance in OC. Protein-small molecule/chemical interaction indicated that there were 7 chemicals had interactions with TRPC1, and 6 of them were associated with drug resistance or involved in chemotreatment in ovarian and other cancers. Annotation of TRPC1, OC and drug resistance suggested that the TRPC1 might perform drug resistance-related functions in OC through 17 biological processes which involved in the cell cycle, gene expression, and in particular the cell growth and death. mRNA-microRNA interaction indicated that among the top 11 pathways enriched from top 38 microRNAs targeted TRPC1, 8 of them were involved in the regulation of drug resistance in OC, and among the top 10 microRNAs targeted TRPC1, 8 of them were implicated in the drug resistance in ovarian and other cancers. All these results provided a strong possibility that TRPC1 might contribute to drug resistance in OC. Besides, on the basis of the analysis of TRPC1 mRNA with histologic grade of 341 OC patients in TCGA cohort, we revealed that the expression of TRPC1 in OC patients was differed significantly between grade 2 (moderately-differentiated) and grade 3 (poorly-differentiated) (p = 0.006), and low expression of TRPC1 was correlated with high tumor grade.Conclusion: Downregulation of TRPC1 is potentially associated with drug resistance and high histologic grade in OC. This study would pave the way for further investigation of the drug resistance-related functions of TRPC1.-----------------------------------------Cite this article as: Liu X, Zhang J, Li L, Yin F. Downregulation of transient receptor potential cation channel, subfamily C, member 1 (TRPC1) is associated with drug resistance and high histologic grade in ovarian cancer. Int J Cancer Ther Oncol 2015; 3(4):3409.[This abstract was presented at the BIT’s 8th Annual World Cancer Congress, which was held from May 15-17, 2015 in Beijing, China.
A quantitative method to implement and to assess the single isocenter technique for breast cancer radiation therapy
Get PDFPurpose: We propose a process of quality assurance to validate and implement the single isocenter technique for breast cancer radiotherapy. We evaluated the dosimetric and temporal gains using the single isocenter technique compared to classic source to skin distance (SSD) technique. Methods: 6 patients of breast cancer localization were studied. For each patient 2 treatment plans were generated. In plan 1 the dose was calculated using SSD technique. In plan 2 the dose was calculated using single isocenter technique. To implement the plan 2 a dosimetric analysis including monitor units (MU), isodose curves, cumulative and differential dose volume histograms cDVH, dDVH respectively, coverage index, conformity index for planning target volume were used. The measurements using a PMMA phantom consist of measuring point dose by an ionization chamber and 2D dose distributions using 2D diodes arrays. Wilcoxon signed rank and Spearman’s tests were used to calculate p-value and correlation coefficient, respectively.Results: The single isocenter technique reduced the MU by average on -30.1 ± 13.6%, (p = 0.03). We observed an improvement with statistical significance between the two techniques for the mean dose, minimum dose and volume receiving 95% of the prescribed dose without over-dosage. The analysis for dDVH showed that the dose distribution in the target volume calculated in the single isocenter technique is more homogeneous than the SSD technique. Wilcoxon test showed that the two treatment plans had the same quality (p > 0.05). The difference between calculated and measured dose was within 2.4 ± 3.3% for absolute point dose and the percentage of points passing gamma criteria was on average 99.8 ± 0.2%. Conclusion: This method provides a quantitative evaluation and comparison of the two irradiation techniques for breast cancer and the consequences of the technical change on dose calculation
Clinically evaluating directional dependence of 2D seven29 ion-chamber array with different IMRT plans
Get PDFPurpose: This study aims to clinically evaluate the directional dependence of a 2D seven29 ion-chamber array with different intensity-modulated radiotherapy (IMRT) plans. Methods: Twenty-five patients who had already been treated with IMRT plans were selected for the study. Verification plans were created in an Eclipse treatment planning system (TPS) for each treatment plan. The verification plans were executed twice for each patient. The first IMRT plan used a true gantry angle (plan-related approach), and the second plan used a 0° gantry angle (field-related approach). Measurements were performed using a Varian Clinac 2100 iX linear accelerator. The fluence was measured for all the delivered plans and analyzed using Verisoft software. A comparison of the fluence was performed between IMRT with a static gantry (0° gantry angle) and real gantry angles. Results: The results indicate that the Gamma average was 98.8 % for IMRT with a 0° gantry angle and 96.616% for IMRT with a true gantry angle. Average percent difference of normalized doses for IMRT delivered with zero degree gantry angle and IMRT with actual gantry angles is 0.15 and 0.88 respectively. Conclusion: The ion chamber of the 2D array used in IMRT verification has angular dependence, reducing the verification accuracy when the 2D array is used for measuring the actual beams of the treatment plan
Role of laparoscopic surgery in cancer of stomach: Our early experience
Get PDFPurpose: To study the clinical outcome and scope of laparoscopic management in patients of cancer stomach. Methods: This is a prospective study of our first 25 patients of cancer stomach managed laparoscopically. Following procedures were undertaken: 1) Gastric resection in resectable cases; 2) Palliative bypass; 3) Tumor/ nodal/ peritoneal/ any other/ biopsy in cases of unresectable tumors. Results: Growth was resectable in 10 (40%) patients, and unresectable in 15 (60%) patients. Diagnostic laparoscopy had sensitivity of 100%, while other modalities of investigation were not totally useful in 1/3 to ½ of cases. Laparoscopic gastrojejunostomy was done in 5 (20%) patients, laparoscopy assisted distal partial gastrectomy was performed in 8 (32%) patients while totally laparoscopic gastrectomy was possible in 1 (4%) patient. Long term follow up was observed. Conclusion: In cancer stomach laparoscopy is a safe, effective, and cost effective means of directing appropriate therapy especially in patients requiring diagnostic, staging and palliative procedures
Influence of collimator rotation on dose distribution and delivery in intensity modulated radiation therapy for parotid cancer
Get PDFPurpose: To evaluate the influence of collimator rotation in IMRT planning with respect to the target coverage and dose to critical structures. In addition, the delivery efficiency of desired fluence with collimator rotation is assessed.Methods: The computed tomography (CT) datasets of 5 patients with parotid cancer were employed for this study. Dynamic IMRT plans were generated with a dose prescription of 60 Gy in 30 fractions. IMRT plans were generated with five unilateral fields using 6MV X-rays. Four different plans were generated for each patient by keeping the collimator angle at 0, 30, 60, and 90 degree. All plans were analyzed using dose volume histogram. Conformity index (CI) and heterogeneity index (HI) were calculated. The total monitor units (MU) required to deliver one fraction were noted and compared. To verify the delivery efficiency; the measured fluence on IBA I’mRT MatriXX ionization chamber array detector was compared with the TPS dose plan with 2D gamma evaluation.Results: There is not much difference in the PTV Dmax and Dmean with respect to the different collimator angles. The PTV coverage is best at collimator angle of 0 degree. A slight reduction in CI was observed with plans at other collimator angles as compared to 0 degree. The HI values were almost similar for plans with collimator angle 0, 30, and 60 degree. The plan with 90 degree collimator showed a slightly higher heterogeneity for the PTV. A slight reduction in the average Dmax to spinal cord was observed for the plan with collimator angle 30 degree as compared to other angles whereas maximum value of Dmax to spinal cord was at collimator angle 60 degree. No clinically relevant difference was observed among the plans with respect to brainstem and mandible Dmax. An increase in average of oral cavity Dmax and Dmean was observed for collimator angle 60 and 90 degree as compared to collimator angle 0 and 30 degree. Not much difference was observed with respect to Dmax and Dmean for contralateral parotid and cochlea with plans at different collimator angles. A decrease in MU required to deliver a fraction was observed for the plan with collimator angle 30 degree as compared to other angles. The plan with 90 degree collimator required maximum MU. The 2D γ index evaluation of planned and delivered fluence showed almost similar results for plans with different collimator angles.Conclusion: An individual case-specific collimator rotation may aid in achieving the desired dose distribution and relative sparing of critical structures in IMRT.
Concurrent pelvic radiation with weekly low-dose cisplatin and gemcitabine as primary treatment of locally advanced cervical cancer: A phase II study
Get PDFPurpose: This study was done to evaluate response, compliance and survival of weekly low dose cisplatin (20 mg/m2) and gemcitabine (125 mg/m2) concurrently with pelvic radiation as primary treatment of stage IIB-IIIB cervical cancer.Methods: External radiation consisted of 50 Gy/25 fractions using 6-10 MV photon followed by 600 cGy boost to parametrium if it was still felt thickened. Then, intracavitary radiotherapy to deliver 60 Gy at point A. Chemotherapy consisted of gemcitabine at a dose of 125 mg/ m2 was given by i.v infusion over 30 minutes immediately after cisplatin 20 mg/ m2 weekly for 5 weeks during EBRT. Forty–five eligible patients received the treatment protocol. Results: Toxicity was tolerable and manageable. No grade 4 toxicity while grade 3 was recorded in hematologic one only. In order of frequency; diarrhea, nausea and vomiting, and anemia (50%, 40%, 35.5%) were most common adverse events. Overall clinical response rate was 93.4% with pathological complete response of 62.2%. After median follow-up of 20 months, 2-year survival and progression-free survival rates were 90.5% and 81% respectively. Conclusion: Weekly combination of low- dose cisplatin and gemcitabine given concurrently with pelvic radiotherapy in primary treatment of locally advanced cervical cancer resulted in a high response rate with a good compliance. Further exploration is needed for the use of this approach prior to incorporating it into routine clinical care through phase III clinical trial