Dosimetric Comparative Analysis of Volumetric Modulated Arc Therapy and Intensity-Modulated Radiation Therapy in Cervical Cancer

Objective:To carry out dosimetric comparison between volumetric modulated arc therapy(VMAT)and intensity-modulated radiation therapy(IMRT)in cervical cancer.Methods:50 postoperative cervical cancer patients were included in this study.The patients were admitted for treatment from January 2021 to January 2022.VMAT and IMRT plans were designed for each patient to analyze the dose distribution in the target area of the two treatment techniques.Results:Comparing the monitor unit for single treatment(638.21±116.21 MU)and time of single treatment(143.21±23.14 s)in the observation group and the monitor unit for single treatment(932.14±74.11 MU)and time of single treatment(223.14±17.26 s)in the control group,there was significant difference(P<0.05);there was also significant difference(P<0.05)between the normal tissue(bladder and rectum)of the observation group and that(bladder and rectum)of the control group.Conclusion:VMAT is more effective in cervical cancer,and it has a certain protective effect on normal tissues in patients and can reduce the radiation dose.

Treatment outcomes for different subgroups of nasopharyngeal carcinoma patients treated with intensity-modulated radiation therapy

Although many studies have investigated intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC),sample sizes in the reported studies are usually small and different in outcomes in different T and N subgroups are seldom analyzed.Herein,we evaluated the outcomes of NPC patients treated with IMRT and further explored treatment strategy to improve such outcome.We collected clinical data of 865 NPC patients treated with IMRT alone or in combination with chemotherapy,and classified all cases into the following prognostic categories according to different TNM stages:early stage group (T1-2N0-1M0),advanced local disease group (T3-4N0-1M0),advanced nodal disease group (T1-2N2-3M0),and advanced locoregional disease group (T3-4N2-3M0).The 5-year overall survival (OS),local relapse-free survival (LRFS),and distant metastases-free survival (DMFS) were 83.0%,90.4%,and 84.0%,respectively.The early disease group had the lowest treatment failure rate,with a 5-year OS of 95.6%.The advanced local disease group and advanced nodal disease group had similar failure pattern and treatment outcomes as well as similar hazard ratios for death (4.230 and 4.625,respectively).The advanced locoregional disease group had the highest incidence of relapse and death,with a 5-year DMFS and OS of 62.3% and 62.2%,respectively,and a hazard ratio for death of 10.402.Comparing with IMRT alone,IMRT in combination with chemotherapy provided no significant benefit to locoregionally advanced NPC.Our results suggest that the decision of treatment strategy for NPC patients should consider combinations of T and N stages,and that IMRT alone for early stage NPC patients can produce satisfactory results.However,for advanced local,nodal,and locoregional disease groups,a combination of chemotherapy and radiotherapy is recommended.

Intensity modulated radiation therapy with simultaneous integrated boost based dose escalation on neoadjuvant chemoradiation therapy for locally advanced distal esophageal adenocarcinoma

AIM:To evaluate impact of radiation therapy dose escalation through intensity modulated radiation therapy with simultaneous integrated boost(IMRT-SIB).METHODS:We retrospectively reviewed the patients who underwent four-dimensional-based IMRT-SIBbased neoadjuvant chemoradiation protocol.During the concurrent chemoradiation therapy,radiation therapy was through IMRT-SIB delivered in 28 consecutive daily fractions with total radiation doses of 56 Gy to tumor and 5040 Gy dose-painted to clinical tumor volume,with a regimen at the discretion of the treating medical oncologist.This was followed by surgical tumor resection.We analyzed pathological completion response(p CR) rates its relationship with overall survival and event-freesurvival.RESULTS:Seventeen patients underwent dose escalation with the IMRT-SIB protocol between 2007 and 2014 and their records were available for analysis.Among the IMRT-SIB-treated patients,the toxicity appeared mild,the most common side effects were grade 1-3 esophagitis(46%) and pneumonitis(11.7%).There were no cardiac events.The Ro resection rate was 94%(n = 16),the p CR rate was 47%(n = 8),and the postoperative morbidity was zero.There was one mediastinal failure found,one patient had local failure at the anastomosis site,and the majority of failures were distant in the lung or bone.The 3-year diseasefree survival and overall survival rates were 41%(n = 7) and 53%(n = 9),respectively.CONCLUSION:The dose escalation through IMRT-SIB in the chemoradiation regimen seems responsible for down-staging the distal esophageal with well-tolerated complications.

Leakage-Penumbra effect in intensity modulated radiation therapy step-and-shoot dose delivery

AIM: To study the leakage-penumbra(LP) effect with a proposed correction method for the step-and-shoot intensity modulated radiation therapy(IMRT).METHODS: Leakage-penumbra dose profiles from 10 randomly selected prostate IMRT plans were studied. The IMRT plans were delivered by a Varian 21 EX linear accelerator equipped with a 120-leaf multileaf collimator(MLC). For each treatment plan created by the Pinnacle3 treatment planning system,a 3-dimensional LP dose distribution generated by 5 coplanar photon beams,starting from 0o with equal separation of 72 o,was investigated. For each photon beam used in the stepand-shoot IMRT plans,the first beam segment was set to have the largest area in the MLC leaf-sequencing,and was equal to the planning target volume(PTV). The overshoot effect(OSE) and the segment positional errors were measured using a solid water phantom with Kodak(TL and X-OMAT V) radiographic films. Film dosimetric analysis and calibration were carried out using a film scanner(Vidar VXR-16). The LP dose profiles were determined by eliminating the OSE and segment positional errors with specific individual irradiations. RESULTS: A non-uniformly distributed leaf LP dose ranging from 3% to 5% of the beam dose was measured in clinical IMRT beams. An overdose at the gap between neighboring segments,represented as dose peaks of up to 10% of the total BP,was measured. The LP effect increased the dose to the PTV and surrounding critical tissues. In addition,the effectdepends on the number of beams and segments for each beam. Segment positional error was less than the maximum tolerance of 1 mm under a dose rate of 600 monitor units per minute in the treatment plans. The OSE varying with the dose rate was observed in all photon beams,and the effect increased from 1 to 1.3 Gy per treatment of the rectal intersection. As the dosimetric impacts from the LP effect and OSE may increase the rectal post-radiation effects,a correction of LP was proposed and demonstrated for the central beam profile for one of the planned beams. CONCLUSION: We concluded that the measured dosimetric impact of the LP dose inaccuracy from photon beam segment in step-and-shoot IMRT can be corrected.

Dosimetric Improvements Utilising Intensity Modulated Radiation Therapy for Patients with Glioblastoma Multiforme

Aims: The EORTC-NCI study investigating the addition of temozolomide trial to standard radiation therapy has demonstrated improved duration of survival in patients with Glioblastoma multiforme (GBM). With longer survival duration, there is the potential for latent RT morbidity, not previously seen in historical patients. This study evaluates the potential dosimetric advantages of utilising IMRT over 3D-conformal RT in such patients. Methods: 10 consecutive patients with GBM formally screened for a clinical study over a two-month period were planned and treated with IMRT utilising daily on-board imaging (OBI). The EORTC protocol dosimetric criteria and constraints were used in target delineation and planning. For each patient, a 3DCRT plan was also produced. Endpoints for dosimetric evaluation analysed related to tumour dose: mean PTV60 dose (mPTV60Dose), Conformity Index (CI);and normal tissue dose: mean normal brain dose (mBrainDose) and V40 Brain (Brainv40). IGRT endpoints were the median isocentre shifts required in 3 axes measured in one direction. The variation between the IMRT and 3DCRT dosimetric endpoints was examined using Wilcoxon analysis. Results: The 10 patients had tumours located in temporal (3), parietal (3), occipital (2) and callosal (2) regions. The median PTV and normal brain volumes were 308.1 cm3 and 1077.5 cm3 respectively. The IMRT dosimetry was significantly improved in all endpoints specifically CI (p = 0.002), mPTV60Dose (p = 0.004), mBrainDose (p = 0.002) and Brainv40 (p = 0.019). OBI directed isocentre measurements in the patient group were available for 230 treatments. The median shifts (and 95% C.I.s) were 0.1 cm vertical (0.1 - 0.2), 0.1 cm longitudinal (0.1 - 0.2) and 0.2 cm lateral (0.2 - 0.2). At a minimum follow-up of 2 years’ post diagnosis, the median survival of the group is 18.0 months (95% CI: 13.4 - 22.6 months). Conclusion: IMRT for GBM produces significant dosimetric advantages in relation to planning target volume and normal tissue dose compared with 3D conformal plans. The data also confirm the accuracy of IMRT technique for CNS with IGRT delivery utilising OBI demonstrating minimal deviation from planned to treated isocentre.

A prospective trial of volumetric intensity-modulated arc therapy vs conventional intensity modulated radiation therapy in advanced head and neck cancer

AIM: To prospectively compare volumetric intensitymodulated arc therapy(VMAT) and conventional intensity-modulated radiation therapy(IMRT) in coverage of planning target volumes and avoidance of multiple organs at risk(OARs) in patients undergoing definitive chemoradiotherapy for advanced(stage Ⅲ or Ⅳ)squamous cell cancer of the head and neck. METHODS: Computed tomography scans of 20 patients with advanced tumors of the larynx, naso-, oroand hypopharynx were prospectively planned using IMRT(7 field) and VMAT using two arcs. Calculated doses to planning target volume(PTV) and OAR were compared between IMRT and VMAT plans. Dose-volume histograms(DVH) were utilized to obtain calculated doses to PTV and OAR, including parotids, cochlea,spinal cord, brainstem, anterior tongue, pituitary and brachial plexus. DVH's for all structures were compared between IMRT and VMAT plans. In addition the planswere compared for dose conformity and homogeneity. The final treatment plan was chosen by the treating radiation oncologist. RESULTS: VMAT was chosen as the ultimate plan in 18 of 20 patients(90%) because the plans were thought to be otherwise clinically equivalent. The IMRT plan was chosen in 2 of 20 patients because the VMAT plan produced concentric irradiation of the cord which was not overcome even with an avoidance structure. For all patients, VMAT plans had a lower number of average monitor units on average(MU = 542.85) than IMRT plans(MU = 1612.58)(P < 0.001). Using the conformity index(CI), defined as the 95% isodose volume divided by the PTV, the IMRT plan was more conformal with a lower conformity index(CI = 1.61) than the VMAT plan(CI = 2.00)(P = 0.003). Dose homogeneity, as measured by average standard deviation of dose distribution over the PTV, was not different with VMAT(1.45 Gy) or IMRT(1.73 Gy)(P = 0.069). There were no differences in sparing organs at risk.CONCLUSION: In this prospective study, VMAT plans were chosen over IMRT 90% of the time. Compared to IMRT, VMAT plans used only one third of the MUs, had shorter treatment times, and similar sparing of OAR. Overall, VMAT provided similar dose homogeneity but less conformity in PTV irradiation compared to IMRT. This difference in conformity was not clinically significant.

Dose Perturbations of Gold Fiducial Markers in the Prostate Cancer Intensity Modulated Proton Radiation Therapy (IMPT)

The objective of this study is to investigate the dose perturbations introduced by the implanted gold fiducial markers in the prostate cancer intensity modulated proton therapy (IMPT) and the impacts of different plan designs on the pertur-bations. Five proton plans: a single lateral field 3D-modulation (3D-mod) plan, 2 fields laterally opposing 3D-mod plan, 6-, 9-, and 18-field distal edge tracking (DET) plans were designed on the CT images of a prostate patient. The dose distributions were first generated for the plans free of fiducial markers with 78 Gy prescribed to 95% of the PTV. To derive the dose perturbations of the gold fiducial markers, three cylindrical shaped gold fiducial markers (3 mm long and 1 mm in diameter) were artificially inserted into the prostate, and the dose distributions were re-computed. Monte Carlo method was used for dose computation. It was found that the gold fiducial markers perturbed the dose distribu-tions, especially along the beam paths. The markers caused a shadowing effect reducing the doses in the areas beyond the markers. Overall, due to the presence of the fiducial markers, D99% of prostate were reduced by 2.96 Gy, 4.21 Gy, 0.16 Gy, 0.34 Gy, 0.15 Gy for the plans of single field 3D-mod, 2-field parallel opposed 3D-mod, 6-, 9-, and 18-field DET respectively. Our study showed these dose perturbation effects decreased with the increase of number of beam angles. Up to 6 beam angles may be required to reduce the dose perturbations from the gold fiducial markers to a clini- cally acceptable level in IMPT.

Three-dimensional conformal intensity-modulated radiation therapy of left femur foci does not damage the sciatic nerve

During radiotherapy to kill femoral hydatid tapeworms, the sciatic nerve surrounding the focus can be easily damaged by the treatment. Thus, it is very important to evaluate the effects of ra- diotherapy on the surrounding nervous tissue. In the present study, we used three-dimensional, conformal, intensity-modulated radiation therapy to treat bilateral femoral hydatid disease in Meriones meridiani. The focus of the hydatid disease on the left femur was subiected to radio- therapy （40 Gy） for 14 days, and the right femur received sham irradiation. Hematoxylin-eosin staining, electron microscopy, and terminal deoxynucleotidyl transferase-dUTP nick end labeling assays on the left femurs showed that the left sciatic nerve cell structure was normal, with no ob- vious apoptosis after radiation. Trypan blue staining demonstrated that the overall protoscolex structure in bone parasitized with Echinococcus granulosus disappeared in the left femur of the animals after treatment. The mortality of the protoscolex was higher in the left side than in the right side. The succinate dehydrogenase activity in the protoscolex in bone parasitized with Echi- nococcus granulosus was lower in the left femur than in the right femur. These results suggest that three-dimensional conformal intensity-modulated radiation therapy achieves good therapeutic effects on the secondary bone in hydatid disease in Meriones meridiani without damaging the morphology or function of the sciatic nerve.

Comparison of efficacy and safety between late-course and simultaneous integrated dose-increasing intensity-modulated radiation therapy for cervical cancer complicated with pelvic lymph node metastasis

Objective This study aimed to compare and analyze the clinical efficacy and safety of late-course and simultaneous integrated dose-increasing intensity-modulated radiation therapy(IMRT) for cervical cancer complicated with pelvic lymph node metastasis. Methods Sixty patients with cervical cancer complicated with pelvic lymph node metastasis who were admitted to our hospital from January 2013 to January 2015 were enrolled. The patients were randomly divided into the late-course dose-increasing IMRT group and the simultaneous integrated dose-increasing IMRT group, with 30 cases included in each group, respectively. All patients were concurrently treated with cisplatin. After treatment, the clinical outcomes of the two groups were compared. Results The remission rate of symptoms in the simultaneous integrated dose-increasing IMRT group was significantly higher than that in the late-course dose-increasing IMRT group(P < 0.05). The follow-up results showed that the overall survival time, progression-free survival time, and distant metastasis time of patients in the simultaneous integrated dose-increasing IMRT group were significantly longer than those in the late-course dose-increasing IMRT group(P < 0.05). The recurrent rate of lymph nodes in the radiation field in the simultaneous integrated dose-increasing IMRT group was significantly lower(P < 0.05) than in the late-course dose-increasing IMRT group. There was no significant difference in the incidence of cervical and vaginal recurrence and distant metastasis between the two groups(P > 0.05). The radiation doses of Dmax in the small intestine, D1 cc(the minimum dose to the 1 cc receiving the highest dose) in the bladder, and Dmax in the rectum in the simultaneous integrated dose-increasing IMRT group were significantly lower(P < 0.05) than in the late-course dose-increasing IMRT group. There was no significant difference in intestinal D2 cc(the minimum dose to the 2 cc receiving the highest dose) between the two groups(P > 0.05). The incidence of bone marrow suppression in the simultaneous integrated dose-increasing IMRT group was significantly lower(P < 0.05) than in the late-course dose-increasing IMRT group.Conclusion The application of simultaneous integrated dose-increasing IMRT in the treatment of cervical cancer patients complicated with pelvic lymph node metastasis can significantly control tumor progression, improve the long-term survival time, and postpone distant metastasis time with high safety.

Effect of intensity modulated radiation therapy combined with paclitaxel+ endostar chemotherapy on serum malignant molecule levels in patients with locally advanced non-small cell lung cancer

Objective: To discuss the effect of intensity modulated radiation therapy combined with paclitaxel + endostar chemotherapy on serum malignant molecule levels in patients with locally advanced non-small cell lung cancer. Methods: Patients with locally advanced NSCLC who were treated in the hospital between February 2015 and January 2017 were collected and divided into control group (n=59) and research group (n=59) by random number table. Control group received the routine paclitaxel + endostar chemotherapy after the operation, and research group underwent intensity modulated radiation therapy combined with paclitaxel +endostar chemotherapy after the operation. The differences in serum levels of NSCLC-related tumor markers and angiogenesis indexes were compared between the two groups before and after treatment. Results: Before treatment, the differences in serum levels of NSCLC-related tumor markers and angiogenesis indexes were not statistically significant between the two groups. After treatment, serum TK1, CYFRA21-1, Pro-GRP, CEA, CA125 and SCC-Ag levels of research group were lower than those of control group;serum EGFR, COX-2, VEGF, HIF-1 and MMP-2 levels of research group were lower than those of control group. Conclusion:Postoperative intensity modulated radiation therapy combined with paclitaxel + endostar chemotherapy can effectively reduce the serum malignant molecule levels and optimize the illness in patients with local advanced NSCLC.

Bilateral diffuse grade 5 radiation pneumonitis after intensity modulated radiation therapy for localized lung cancer

We are reporting a case of fatal radiation pneumonitis that developed six months following chemoradiation for limited stage small cell lung cancer.The patient was a 67-year-old man with a past medical history of Hashimoto's thyroiditis and remote suspicion for CREST,neither of which were active in the years leading up to treatment.He received 6600 cG y delivered in 200 cG y daily fractions via intensity modulated radiation therapy with concurrent cisplatin/etoposide followed by additional chemotherapy with dosereduced cisplatin/etoposide and carboplatin/etoposide and then received prophylactic cranial irradiation.The subsequent months were notable for progressively worsening episodes of respiratory compromise despite administration of prolonged steroids and he ultimately expired.Imaging demonstrated bilateral interstitial and airspace opacities.Autopsy findings were consistent with pneumonitis secondary to chemoradiation as well as lymphangitic spread of small cell carcinoma.The process was diffuse bilaterally although his radiation was delivered focally to the right lung and mediastinum.

Verification of Dosimetric and Positional Accuracy of Dynamic Tumor Tracking Intensity Modulated Radiation Therapy

Purpose: We performed both, dosimetric and positional accuracy verification of dynamic tumor tracking (DTT) intensity modulated radiation therapy (IMRT), with the Vero4DRT system using a moving phantom (QUASAR respiratory motion platform;QUASAR phantom) and system log files. Methods: The QUASAR phantom was placed on a treatment couch. Measurement of the point dose and dose distribution was performed for conventional IMRT, with the QUASAR phantom static and moving;for DTT IMRT, this was performed with the phantom moving for pyramid shaped, prostate, paranasal sinus, and pancreas targets. The QUASAR phantom was driven by a sinusoidal signal in the superior-inferior direction. Furthermore, predicted positional errors induced by the Vero4DRT system and mechanical positional errors of the gimbal head, were calculated using the system log files. Results and Conclusion: For DTT IMRT, the dose at the evaluation point was within 3% compared with the verification plan, and the dose distribution in the passing rates of γ was 97.9%, with the criteria of 3% dose and 3 mm distance to agreement. The position error calculated from the log files was within 2 mm, suggesting the feasibility of employing DTT IMRT with high accuracy using the Vero4DRT system.

Clinical study on concurrent and sequential therapy of intensity modulated radiation therapy (IMRT) combined with NP regimen chemotherapy in the treatment of middle and advanced non-small cell lung cancer

Objective: To evaluate the clinical effects of concurrent and sequential therapy for middle and advanced stage non-small cell lung cancer (NSCLC) useing IMRT combined with NP regimen chemotherapy. Methods: Eighty patients with middle and advanced stage NSCLC were randomized into two groups. Forty patients were underwent sequential therapy and other 40 patients were underwent concurrent therapy. IMRT was used in radiotherapy and NP regimen of vinorelbine+cispatin (NP) was used in chemotherapy. Results: (1) The overall response (CR+PR) rate was 75% in concurrent group and 45% in sequential group (P<0.05); (2) The treatment courses were 84 days and 140 days for concurrent group and sequential group respectively (P<0.05); (3) One-year survival rate in concurrent group was 72.4% and 52.3% in sequential group respectively; (4) The toxic effects can be tolerable by all of patients. Conclusion: The concurrent chemo-radiotherapy has better overall re- sponse, one-year survival rate and shorter treatment course than the sequential chemo-radiotherapy, so it is a better method for the treatment of middle and advanced stage NSCLC, but the long term survival rate will be studied.

Prostate specific antigen bounce after intensity-modulated radiation therapy in an Asian population

Objective:Serum prostate specific antigen(PSA)is commonly used to evaluate treatment response after definitive radiation therapy(RT).However,PSA levels can temporarily rise without a clear reason,termed“PSA bounce”,and often engender great anxiety for both patients and physicians.The present study aimed to determine the prevalence and factors that predict“PSA bounce”after intensity-modulated radiation therapy(IMRT),and the relevance to biochemical failure and cancer recurrence in an Asian population.Methods:We retrospectively reviewed 206 patients who received IMRT for prostate cancer from 2004 to 2012 in the National Cancer Centre Singapore.These patients were followed up with regular PSA monitoring.We defined“PSA bounce”as a rise of 0.1 ng/mL,followed by two consecutive falls.Patients with biochemical failure(PSA nadir t 2 ng/mL)were further evaluated for cancer recurrence.Results:Sixty-one patients(29.6%)experienced“PSA bounce”,at a median time of 16 months and lasted for 12 months.Age remained the most consistent predictor of the incidence,duration and extent of“PSA bounce”.Other contributory factors included baseline PSA,Gleason score and PSA nadir.Hormonal therapy and prostate volume did not affect this phenomenon.Sixteen patients(7.8%)developed biochemical recurrence,at median time of 32 months,of which 11 were confirmed to have metastatic disease.The median follow-up time was 71 months.

Intensity Modulated Proton Therapy for Re-Irradiation of Bulky Loco-Regional Recurrent Breast Cancer: A Case Report

Patients with recurrent breast cancer to chest wall, who had previous irradiation, are difficult to manage and have limited options. Several reports described the use of photon therapy, hyperthermia, and brachytherapy. This is a case report of a 72-year-old female with Stage IIIA (pT3N1M0) invasive ductal carcinoma of the right breast status post modified radical mastectomy. The patient developed recurrence to the chest wall and one internal mammary lymph node one year later. She received 3-D conformal photon radiation therapy for this recurrence. Two years later, she had progression of the recurrence at the right chest wall and axillary and internal mammary lymph nodes. She was treated with intensity modulated proton therapy (IMPT) for a total of 6600 cGy in 33 fractions. However, four months later, she was found to have biopsy-proven isolated metastatic disease at her right bicep, which was again treated with IMPT for a dose of 6000 cGy in 20 fractions. Proton beam therapy was used in this case to spare dose to the brachial plexus, heart and lung while optimally irradiating the recurrent tumors. At last follow up, the patient is alive and has been disease free for 39 months. This report describes the technique and dosimetry for this unique case, which also reviewed recent series of re-irradiation using proton beam.

Local definitive intensity-modulated radiation therapy recommended for patients initially diagnosed with nasopharyngeal carcinoma with distant metastasis after an effective systemic chemotherapy

Objective The aim of the study was to propose a hypothesis that local definitive intensity-modulated radiation therapy(IMRT) should be recommended for initially diagnosed metastatic nasopharyngeal carcinoma(NPC) and demonstrate its feasibility.Methods Recently published papers on local definitive radiotherapy for initially diagnosed metastatic NPC were reviewed to propose a hypothesis.Results Several studies revealed the survival benefits of adding local definitive radiotherapy to the systemic chemotherapy in patients initially diagnosed with metastatic NPC.Conclusion We suggested that local definitive IMRT should be recommended in patients initially diagnosed with NPC with distant metastasis after an effective systemic chemotherapy, which may possibly prolong their survival time and potentially treat the disease.

Effects of intensity modulated radiation therapy + local hyperthermia on the cancer cell apoptosis and invasion in liver cancer lesion

Objective: To investigate the effects of intensity modulated radiation therapy + local hyperthermia on the cancer cell apoptosis and invasion in liver cancer lesion. Methods:A total of 94 patients with middle-advanced primary liver cancer who were diagnosed and treated in this hospital between November 2015 and February 2017 were divided into control group (n=47) and experimental group (n=47) by random number table method. Control group received intensity modulated radiation therapy and experimental group received intensity modulated radiation therapy + local hyperthermia. Both groups accepted peritoneal lesion biopsy before and after treatment, and the expression of apoptosis and invasion genes in specimen tissue were detected by fluorescence quantitative PCR. Results: There was no statistically significant difference in apoptosis and invasion gene expression between the two groups of patients before treatment. After treatment, apoptosis genes Fas, caspase-3, Bax and p53 mRNA expression in lesion tissue of experimental group were higher than those of control group whereas FasL and Bcl-2 mRNA expression were lower than those of control group;invasion genes Cofilin-1, Bmi-1, STAT3 and SOX18 mRNA expression in lesion tissue of experimental group were lower than those of control group whereas Tip30 and TP53IP1 mRNA expression were higher than those of control group. Conclusion: intensity modulated radiation therapy + local hyperthermia can effectively promote cancer cell apoptosis and inhibit its invasion activity in patients with middle and advanced primary liver cancer.

The Impact of Variation in Bladder Volume on the Doses of Target and Organ-at-Risk in Intensity-Modulated Radiation Therapy for Localized Prostate Cancer

Intensity-modulated radiation therapy (IMRT) has become the mainstay of treatment for localized prostate cancer. In IMRT, minimizing differences between the conditions used during planning CT and daily treatment is important to prevent adverse events in normal tissues. In the present study, we evaluated the impact of variation in bladder volume on the doses to various organs. A total of 35 patients underwent definitive radiotherapy at Saitama Medical Center. A Light Speed RT16 (GE Healthcare) was used for planning and to obtain examination CT images. Such images were acquired after 4 - 6 days of planning CT image acquisition. The IMRT plans were optimized using the planning CT data to satisfy the dose constraints set by our in-house protocols for the PTV and the OARs. The dose distributions were then re-calculated using the same IMRT beams, and checked on examination CT images. It was clear that bladder volume affected the doses to certain organs. We focused on the prostate, bladder, rectum, small bowel, and large bowel. Regression coefficients were calculated for variables that correlated strongly with bladder volume (p < 0.05). We found that variation in bladder volume [cm3] predicted deviations in the bladder V70Gy, V50Gy, and V30Gy [%];the maximum dose to the small bowel [cGy];and the maximum dose to the large bowel [cGy]. The regression coefficients were -0.065, -0.125, -0.180, -10.22, and -9.831, respectively. We evaluated the impacts of such variation on organ doses. These may be helpful when checking a patient’s bladder volume before daily IMRT for localized prostate cancer.

Unraveling the efficacy network: A network meta-analysis of adjuvant external beam radiation therapy methods after hepatectomy

BACKGROUND Primary liver cancer is a malignant tumor with a high recurrence rate that significantly affects patient prognosis.Postoperative adjuvant external radiation therapy(RT)has been shown to effectively prevent recurrence after liver cancer resection.However,there are multiple RT techniques available,and the differ-ential effects of these techniques in preventing postoperative liver cancer re-currence require further investigation.AIM To assess the advantages and disadvantages of various adjuvant external RT methods after liver resection based on overall survival(OS)and disease-free survival(DFS)and to determine the optimal strategy.METHODS This study involved network meta-analyses and followed the PRISMA guidelines.The data of qualified studies published before July 10,2023,were collected from PubMed,Embase,the Web of Science,and the Cochrane Library.We included relevant studies on postoperative external beam RT after liver resection that had OS and DFS as the primary endpoints.The magnitudes of the effects were determined using risk ratios with 95%confidential intervals.The results were analyzed using R software and STATA software.RESULTS A total of 12 studies,including 1265 patients with hepatocellular carcinoma(HCC)after liver resection,were included in this study.There was no significant heterogeneity in the direct paired comparisons,and there were no significant differences in the inclusion or exclusion criteria,intervention measures,or outcome indicators,meeting the assumptions of heterogeneity and transitivity.OS analysis revealed that patients who underwent stereotactic body radiotherapy(SBRT)after resection had longer OS than those who underwent intensity modulated radiotherapy(IMRT)or 3-dimensional conformal RT(3D-CRT).DFS analysis revealed that patients who underwent 3D-CRT after resection had the longest DFS.Patients who underwent IMRT after resection had longer OS than those who underwent 3D-CRT and longer DFS than those who underwent SBRT.CONCLUSION HCC patients who undergo liver cancer resection must consider distinct advantages and disadvantages when choosing between SBRT and 3D-CRT.IMRT,a RT technique that is associated with longer OS than 3D-CRT and longer DFS than SBRT,may be a preferred option.

The Impact of Small Field’s Off-Set on Output Factor in Intensity Modulated Radiation Treatment

In intensity modulated radiation treatment (IMRT) planning, the use of asymmetrically collimated fields that are placed on central axis or its off-set is mostly required. Output is the main topic discussed today for extremely small and/or severe irregularly shaped fields. The air scatter data are involved directly or indirectly in obtaining the output. Despite the fact that extensive data have been published in many studies to provide a guide on the magnitude of output factor for clinical accelerators, there are very few data reviewed about output factor in-air or phantom for off-set fields. This study was aimed to investigate the impact of these conditions for small fields. This study was conducted in Elekta Synergy linear accelerator which produces 6 MV X-ray energy. The in-air output factor (Sc) has been measured by CC04 ion chamber with brass-alloy “build-up” cap and Dose-1 electrometer, and the total output (Scp) measurements were carried on at dose maximum depth in phantom by the same chamber and Thermoluminescence dosimeter (TLD) for 1 - 10 cm2 fields. The all measurements at center of isocenter and off-set fields at three directions (X2, Y1, Diagonal) were done. By decreasing field size from 10 to 2 cm2 at isocenter, the Sc value using CC04 was decreased to 5.4% and Scp using CC04 and TLD to 14.5% and 11% respectively. By increasing off-set value, the Sc and Scp values were increased in all directions comparing to central fields. The maximum increase was obtained in Y1 direction for Sc and Scp. TLD results for Scp is slightly higher than CC04. The dosimetric properties of small fields and their off-set should be evaluated and modelled appropriately in the treatment planning system to ensure accurate dose calculation in Intensity Modulated Radiation Treatment.