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.

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.

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.

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.

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.

Effect of Tegafur Gimeracil Oteracil Potassium Capsule + Kangai injection + intensity-modulated radiation therapy on the cellular malignant biological processes in advanced cervical cancer lesion

Objective:To study the effect of Tegafur Gimeracil Oteracil Potassium Capsule + Kangai injection + intensity-modulated radiation therapy on the cellular malignant biological processes in advanced cervical cancer lesion.Methods: Patients who were diagnosed with advanced cervical cancer in the Second People Hospital of Banan District Chongqing between April 2015 and March 2017 were selected and divided into two groups, group A received Tegafur Gimeracil Oteracil Potassium Capsule + Kangai injection + intensity-modulated radiation therapy, and group B received cisplatin + intensity-modulated radiation therapy. Serum contents of tumor markers, tumor invasion molecules and tumor proliferation molecules of two groups of patients were detected before treatment as well as 2 weeks and 4 weeks after treatment.Results: Serum E-cad, STMN1, Fas and p53 levels of both groups of patients 2 weeks and 4 weeks after treatment were significantly higher than those before treatment while TSGF, TK1, SCC-Ag, CA125, OPN, MMP9, NGAL, CyclinE, CyclinD1 and PCNA levels were significantly lower than those before treatment, and serum E-cad, STMN1, Fas and p53 levels of group A 2 weeks and 4 weeks after treatment were significantly higher than those of group B while TSGF, TK1, SCC-Ag, CA125, OPN, MMP9, NGAL, CyclinE, CyclinD1 and PCNA levels were significantly lower than those of group B.Conclusion: Tegafur Gimeracil Oteracil Potassium Capsule + Kangai injection + intensity-modulated radiation therapy for advanced cervical cancer can induce cancer cell apoptosis and inhibit cancer cell proliferation and invasion.

Long-term outcomes of a phase Ⅱ randomized controlled trial comparing intensity-modulated radiotherapy with or without weekly cisplatin for the treatment of locally recurrent nasopharyngeal carcinoma

Background:Salvage treatment for locally recurrent nasopharyngeal carcinoma(NPC) is complicated and relatively limited.Radiotherapy,combined with effective concomitant chemotherapy,may improve clinical treatment outcomes.We conducted a phase Ⅱ randomized controlled trial to evaluate the efficacy of intensity-modulated radiotherapy with concomitant weekly cisplatin on locally recurrent NPC.Methods:Between April 2002 and January 2008,69 patients diagnosed with non-metastatic locally recurrent NPC were randomly assigned to either concomitant chemoradiotherapy group(n = 34) or radiotherapy alone group(n = 35).All patients received intensity-modulated radiotherapy.The radiotherapy dose for both groups was 60 Gy in 27 fractions for 37 days(range 23-53 days).The concomitant chemotherapy schedule was cisplatin 30 mg/m^2 by intravenous infusion weekly during radiotherapy.Results:The median follow-up period of all patients was 35 months(range 2-112 months).Between concomitant chemoradiotherapy and radiotherapy groups,there was only significant difference in the 3-year and 5-year overall survival(OS) rates(68.7%vs.42.2%,P = 0.016 and 41.8%vs.27.5%,P = 0.049,respectively).Subgroup analysis showed that concomitant chemoradiotherapy significantly improved the 5-year OS rate especially for patients in stage rT3-4(33.0%vs.13.2%,P = 0.009),stages Ⅲ-Ⅳ(34.3%vs.13.2%,P = 0.006),recurrence interval >30 months(49.0%vs.20.6%,P = 0.017),and tumor volume >26 cm^3(37.6%vs.0%,P = 0.006).Conclusion:Compared with radiotherapy alone,concomitant chemoradiotherapy can improve OS of the patients with locally recurrent NPC,especially those with advanced T category(rT3-4) and stage(lll-IV) diseases,recurrence intervals >30 months,and tumor volume >26 cm^3.

Long-term Therapeutic Outcome and Prognostic Factors of Patients with Nasopharyngeal Carcinoma Receiving Intensity-modulated Radiotherapy: An Analysis of 608 Patients from Low-endemic Regions of China

Objective To evaluate the long-term outcome and prognostic factors of patients with nasopharyngeal carcinoma(NPC)from low-endemic regions of China who received definitive intensity-modulated radiation therapy(IMRT).Methods The clinical data from 608 patients with newly-diagnosed non-metastatic NPC who have received initial treatment at our cancer center from January,2008 to December,2013 were retrospectively reviewed.All patients received definitive IMRT,and 87.7%received platinum-based chemotherapy.Results The median follow-up duration was 51 months(follow-up rate,98.5%;range,10–106 months)for the entire cohort.The 5-year overall survival rate was 79.7%.The 5-year local relapse-free survival rate,regional relapse-free survival rate,distant metastasis-free survival rate and progression-free survival rate were 92.4%,93.3%,79.2%and 74.3%,respectively.A total of 153 patients had experienced treatment failure,with distant metastasis as the primary cause in 77.1%(118/153).Patients with T4 or N3 diseases had a significantly poorer prognosis than other subcategories.Stage T4 and N3 were closely associated with distant metastasis,with the metastatic rate of 29.3%and 45.5%,respectively.Conclusion IMRT provides patients with non-metastatic NPC with satisfactory long-term survival.Both T stage and N stage are important prognostic factors for NPC patients.Patients with T4 or N3 diseases have significantly increased distant metastatic rates and poor survival time.

Intensity-modulated Radiotherapy for Sinonasal Teratocarcinosarcoma

Surgical excision and postoperative radiotherapy are widely accepted therapeutic modalities for sinonasal teratocarcinosarcoma （SNTCS）. Previous studies have shown that intensity-modulated radiation therapy （IMRT） is safe and effective for the treatment of some sinonasal malignancies. We hypothesize that use of IMRT for SNTCS may result in clinical benefits. We report here two cases of SNTCS that were treated by IMRT. One patient was given extensive IMRT involving elective neck irradiation. Follow-up examinations revealed no recurrence and metastasis 3.5 years after IMRT. Another patient simultaneously suffered from multiple systematical diseases and was administered involved-field radiotherapy. He was found to have a marginal recurrence during the follow up and eventually died 8 months after disease diagnosis. It was suggested in this study that appropriate use of IMRT for the treatment of SNTCS may achieve excellent local control.

The Effect of Absorbed Dose to Organs at Risk Following Craniospinal Irradiation Using Different Radiotherapy Techniques

Introduction: In medulloblastoma patients craniospinal irradiation is an important element the treatment. Our study aimed to evaluate the effect of absorbed dose to organs at risk using the hybrid intensity-modulated radiation therapy (IMRT) versus three-dimensional conformal radiotherapy (3DCRT) for craniospinal irradiation (CSI) in average risk medulloblastoma patients. Materials and Methods: In this study, thirteen medulloblastoma patients were included. The prescribed total dose to the planning target volume (PTV) was 23, 40 Gy in 13 fractions. Two radiotherapy techniques, three dimensional conformal radiotherapy (3DCRT) and hybrid intensity modulated radiotherapy (IMRT) were used to treat these patients. The coverage of the Target was evaluated using the D mean, D95%, D2%, D98% and V95%. Other parameters were also compared such as Integral dose (ID), Homogeneity index (HI) and doses to the organs at risk (OARs). Results: There was no significant difference in the mean dose received by the PTV-Brain or the dose received by 95% and 98% of PTV volume using the two techniques. For PTV-Spine, the percentage volume receiving 95% of the total dose increased significantly in the hybrid IMRT technique compared to the conformal technique. So, hybrid IMRT plan achieved the best coverage for PTV spine. Lower dose for OAR was delivered by 3DCRT, except the heart and thyroid, hybrid IMRT achieved better sparing. All plans resulted in the same dose homogeneity index (DHI) for PTV-Brain. For PTV-Spine, hybrid IMRT technique achieved better dose homogeneity compared to 3DCRT technique (1.09 vs. 1.12;p > 0.05). Conclusions: hybrid IMRT technique can be realized on conformal technique because it achieved better dose coverage for the (PTV) and organ at risk (OAR). 3DCRT reduced mean dose to most OARS, except the heart and thyroid. Therefore, the hybrid IMRT technique may be a CSI treatment alternative to 3DCRT.

Evaluation of endocrine therapy combined with intensity modulated radiation therapy in patients with advanced prostate cancer

Objective The aim of this study was to study the effect of endocrine therapy combined with intensity-modulated radiation therapy in patients with advanced prostate cancer.Methods The clinical data of 231 patients with advanced prostate cancer treated with radiotherapy in our hospital from May 2010 to March 2018 were collected.A total of 135 patients were treated with endocrine therapy combined with intensity-modulated radiotherapy,and 96 patients were treated with intensity-modulated radiotherapy only because of drug allergy,serious adverse reactions,and economic reasons.Two months after the end of the treatment,the short-term curative effect was evaluated using imaging reexamination.The total prostate-specific antigen(TPSA)and free prostate-specific antigen(FPSA)were detected before and 2 months after the end of the treatment.All patients were followed up for at least 3 years,and the metastasis-free survival rate and cumulative survival rate of the two groups were calculated.Results The remission rates(RRs)of the observation and control groups were 64.45%and 46.87%,respectively;the difference was not statistically significant(P>0.05);however,the efficacy distribution of the endocrine therapy combined with intensity-modulated radiotherapy group was significantly better than that of the intensity-modulated radiotherapy group(P<0.05).There was no significant difference in clinical efficacy between the two groups in different TNM stages and Gleason grades.After treatment,the levels of TPSA and FPSA were significantly decreased compared with those before treatment;however,the decrease in the endocrine therapy combined with the intensity-modulated radiation therapy(IMRT)group was significantly higher than that in the IMRT group(P<0.05).Although there were no significant differences in the 1-year and 3-year cumulative survival rates between the two groups,the 1-year and 3-year metastasis-free survival rates of the endocrine therapy combined with the IMRT group were 60%and 38.17%,respectively,which were significantly higher than those of the IMRT group(37.5%and 20.83%,P<0.05).Conclusion Endocrine therapy combined with IMRT significantly improved the clinical efficacy of advanced prostate cancer,reduced PSA(prostate specific antigen)levels,and improved the metastasis-free survival rates.

Efficacy and safety of berberine in the prophylactic treatment of acute radiation proctitis in postoperative patients with cervical cancer:a randomized controlled study

Objective The aiom of this study was to study the efficacy and safety of berberine as a prophylactic treatment of acute radiation proctitis in postoperative patients with cervical cancer.Methods A total of 120 postoperative patients with cervical cancer were enrolled between July 2016 and October 2019,and randomly divided into a treatment group(berberine 300 mg three times a day,n=60)and a control group(receiving vitamin C tablets,100 mg three times a day;n=60)using the random number table method.All patients received pelvic intensity-modulated radiation therapy(IMRT)and concurrent sensitizing chemotherapy weekly.The difference in the percentage of irradiation volume to the rectum and small intestine as well as the incidence,onset time,severity,and duration of acute radiation proctitis and cystitis during radiotherapy were compared between the two groups.The completion rate,completion time,number of chemotherapy sessions,and quality of life during radiotherapy were also compared.Results There were no statistical differences in age,FIGO stage,pathological type,complications,highrisk factors,and rectum and small intestine irradiation dose distribution(V20,V30,V40,and V50)between the two groups(P>0.05).No acute radiation proctitis of grade 3 or above occurred in the two groups.There was no significant difference in the incidence of acute radiation cystitis,grade 2 acute radiation proctitis,completion rate of IMRT,and frequency of sensitization chemotherapy between the two groups.After prophylactic treatment with berberine,the incidence of grade 1 acute radiation proctitis,occurrence of grade 1 radiation proctitis,and completion time of radiotherapy in the treatment group were significantly lower than those in the control group(P<0.05).The SF-36 score of the treatment group after radiotherapy was 67.53±4.21,which was significantly better than that of the control group(64.90±6.32;P<0.05).The incidence of grade 3-4 neutropenia in the treatment group was 10%and lower than that in the control group(31.7%,P=0.003).No adverse reactions related to berberine were observed.Conclusion Prophylactic prescription with oral berberine can reduce the incidence,onset time,and duration of grade 1 acute radiation proctitis,and improve the quality of life of postoperative patients with cervical cancer receiving concurrent chemoradiotherapy.

Effect of Medical Qigong Therapy on Distress,Fatigue,and Quality of Life in Head and Neck Cancer Patients Undergoing Intensity-Modulated Radiation Therapy:A Single Arm Clinical Trial

Background:Cancer of Head and Neck(HNC)is the 2 nd common cancer in India leading to around 8%of the global cancer mortality.Intensity-modulated radiation therapy(IMRT)is advanced method minimizing exposure of radiation to adjacent normal structures but is associated with higher fatigue indirectly elevating distress levels.Medical Qigong(MQ),a meditative mind therapy has numerous health benefits.The purpose of the current study was to investigate effect of MQ therapy on distress,fatigue,and quality of life in HNC patients undergoing IMRT.Materials and Methods:This experimental study was conducted on 16 Hospitalized HNC subjects undergoing IMRT aged 18–65 years.All the subjects performed Qigong Walk Cycle for 5 weekdays for 4 weeks from initiation of IMRT.Scores of Brief Fatigue Inventory(BFI),6 min walk distance(6 MWD),Functional Assessment of Cancer Therapy-Head and Neck(FACT-HN)were documented at the baseline and at end of 4 th week and compared.Results:IBM SPSS Statistics version 23.0;Indian version of Windows was used for statistical analysis.The 16 HNC subjects majorly rural residents(62.5%)of mean age group 47.68±10.25 years with tobacco chewing as prevalent habit(94%)with maximum cases recorded in stage III of the disease.The pre and post test score comparison of serum cortisol,BFI and 6 MWD found high statistical significance with P=0.001 while that of the total and all components of FACT HN was found to be significant with P≤0.05.Conclusion:MQ therapy was effective in managing the levels of distress and fatigue thereby improving quality of life of all HNC subjects.

Comparison of Volumetric and Dosimetric Variations in Nasopharyngeal Carcinoma during Intensity-modulated Radiation Therapy with and without Neoadjuvant Chemotherapy

Objective Patients with nasopharyngeal carcinoma(NPC)undergoing intensity-modulated radiation therapy(IMRT)may experience significant volumetric and dosimetric variations throughout the treatment course.However,neoadjuvant chemotherapy may reduce the extent of these variations.This study was carried out to evaluate volumetric and dosimetric changes in target volumes and organs at risk(OARs)during IMRT in patients with locally advanced NPC who received concurrent chemoradiotherapy(CCRT)alone or in combination with neoadjuvant chemotherapy(NACT).Methods 35 NPC patients were recruited for this study and divided into the NACT(n=15)and CCRT(n=20)groups.Computed tomography(CT)scans were performed before neoadjuvant chemotherapy,before IMRT,before the 24 th fraction of IMRT,and after treatment.The original plan(plan 0)was based on CT images collected before IMRT.Hybrid plan 1(plan 1)and hybrid plan 2(plan 2)were generated by applying the beam configurations of plan0 to the CT scans collected before the 24 th fraction of IMRT and after treatment.Volumetric and dosimetric variations were assessed by comparing the results of plan 0 with those of plan 1 and plan 2.Results In the NACT group,compared with that in plan 0,the primary gross tumor volume(GTVnx)decreased by 33.2%±18.4%and 50.5%±12.6%in plan1 and plan 2,respectively.In the CCRT group,the corresponding reduction rates in plan 1 and plan 2 were 49.4%±8.0%and 77.8%±28.1%,respectively.The volume decrease rates in the NACT group were less than those in the CCRT group(P<0.001).In the NACT group,compared with that of plan0,the dose to 95%of the volume(D95)for the planning target volume of the primary tumor(PTVnx)decreased by 1.0%±0.7%and 0.6%±0.6%in plan 1 and plan 2,respectively.In the CCRT group,the corresponding decrease rates in plan 1 and plan 2 were 4.2%±3.8%and 6.1%±6.3%,respectively.The decrease rate of D95 for PTVnx in the NACT group was less than that in the CCRT group(P<0.001).Similar results among the plans were found in terms of D99,Dmean,V93 for PTVnxand PTVnd,and Dmeanfor the parotid glands.Conclusion Neoadjuvant chemotherapy reduces the extent of volumetric and dosimetric variations in target volumes and OARs during IMRT and,thus,helps achieve better target volume coverage,protects adjacent important structures,and minimizes unnecessary replanning during radiotherapy.

Precision radiotherapy for brain tumors A 10-year bibliometric analysis

OBJECTIVE： Precision radiotherapy plays an important role in the management of brain tumors. This study aimed to identify global research trends in precision radiotherapy for brain tumors using a bibliometric analysis of the Web of Science. DATA RETRIEVAL： We performed a bibliometric analysis of data retrievals for precision radiotherapy for brain tumors containing the key words cerebral tumor, brain tumor, intensity-modulated radiotherapy, stereotactic body radiation therapy, stereotactic ablative radiotherapy, imaging-guided radiotherapy, dose-guided radiotherapy, stereotactic brachytherapy, and stereotactic radiotherapy using the Web of Science. SELECTION CRITERIA： Inclusion criteria： （a） peer-reviewed articles on precision radiotherapy for brain tumors which were published and indexed in the Web of Science; （b） type of articles： original research articles and reviews; （c） year of publication： 2002-2011. Exclusion criteria： （a） articles that required manual searching or telephone access; （b） Corrected papers or book chapters. MAIN OUTCOME MEASURES： （1） Annual publication output; （2） distribution according to country; （3） distribution according to institution; （4） top cited publications; （5） distribution according to journals; and （6） comparison of study results on precision radiotherapy for brain tumors. RESULTS： The stereotactic radiotherapy, intensity-modulated radiotherapy, and imaging-guided radiotherapy are three major methods of precision radiotherapy for brain tumors. There were 260 research articles addressing precision radiotherapy for brain tumors found within the Web of Science. The USA published the most papers on precision radiotherapy for brain tumors, followed by Germany and France. European Synchrotron Radiation Facility, German Cancer Research Center and Heidelberg University were the most prolific research institutes for publications on precision radiotherapy for brain tumors. Among the top 13 research institutes publishing in this field, seven are in the USA, three are in Germany, two are in France, and there is one institute in India. Research interests including urology and nephrology, clinical neurology, as well as rehabilitation are involved in precision radiotherapy for brain tumors studies. CONCLUSION： Precision radiotherapy for brain tumors remains a highly active area of research and development.

Implementation of Constant Dose Rate and Constant Angular Spacing Intensity-modulated Arc Therapy for Cervical Cancer by Using a Conventional Linear Accelerator

Background： Volumetric-modulated arc therapy （VMAT） can only be implemented on the new generation linacs such as the Varian Trilogy（R） and Elekta Synergy（R）.This prevents most existing linacs from delivering VMAT.The purpose of this study was to investigate the feasibility of using a conventional linear accelerator delivering constant dose rate and constant angular spacing intensity-modulated arc therapy （CDR-CAS-IMAT） for treating cervical cancer.Methods： Twenty patients with cervical cancer previously treated with intensity-modulated radiation therapy （IMRT） using Varian Clinical 23EX were retreated using CDR-CAS-IMAT.The planning target volume （PTV） was set as 50.4 Gy in 28 fractions.Plans were evaluated based on the ability to meet the dose volume histogram.The homogeneity index （HI）, target volume conformity index （CI）, the dose to organs at risk, radiation delivery time, and monitor units （MUs） were also compared.The paired t-test was used to analyze the two data sets.All statistical analyses were performed using SPSS 19.0 software.Results： Compared to the IMRT group, the CDR-CAS-IMAT group showed better PTV CI （0.85 ＆#177; 0.03 vs.0.81 ＆#177; 0.03, P =0.001）, clinical target volume CI （0.46 ＆#177; 0.05 vs.0.43 ＆#177; 0.05, P =0.001）, HI （0.09＆#177;0.02 vs.0.11 ＆#177; 0.02, P =0.005） and D95 （5196.33 ＆#177; 28.24 cGy vs.5162.63 ＆#177; 31.12 cGy, P =0.000）, and cord D2 （3743.8 ＆#177; 118.7 cGy vs.3806.2 ＆#177; 98.7 cGy, P =0.017） and rectum V40 （41.9 ＆#177; 6.1% vs.44.2 ＆#177; 4.8%, P =0.026）.Treatment time （422.7 ＆#177; 46.7 s vs.84.6 ＆#177; 7.8 s, P =0.000） and the total plan Mus （927.4 ＆#177; 79.1 vs.787.5 ＆#177; 78.5, P =0.000） decreased by a factor of 0.8 and 0.15, respectively.The IMRT group plans were superior to the CDR-CAS-IMAT group plans considering decreasing bladder V50 （17.4 ＆#177; 4.5% vs.16.6 ＆#177; 4.2%, P =0.049）, bowel V30 （39.6 ＆#177; 6.5% vs.36.6 ＆#177; 7.5%, P =0.008）, and low-dose irradiation volume;there were no significant differences in other statistical indexes.Conclusions： Patients with cervical cancer treated with CDR-CAS-IMAT using Varian Clinical 23EX can get equivalent or superior dose distribution compared to those treated with IMRT.CDR-CAS-IMAT has a less treatment time and MU, which can reduce the uncertainty factor and patient discomfort in treatment.

The Dosimetric Effects of Different Beam Energy on Physical Dose Distributions in IMRT Based on Analysis of Physical Indices

This work aimed at evaluating the effect of 6- and 10-MV photon energies on intensity-modulated radiation therapy (IMRT) treatment plan outcome in different selected diagnostic cases. For such purpose, 19 patients, with different types of non CNS solid tumers, were selected. Clinical step-and-shoot IMRT treatment plans were designed for delivery on a Siemens Oncor accelerator with 82 leafs;multi-leaf collimators (MLCs). To ensure that the similarity or difference among the plans is due to energy alone, the same optimization constraints were applied for both energy plans. All the parameters like beam angles, number of beams, were kept constant to achieve the same clinical objectives. The Comparative evaluation was based on dose-volumetric analysis of both energy IMRT plans. Both qualitative and quantitative methods were used. Several physical indices for Planning Target Volume (PTV), the relevant Organs at Risk (OARs) as mean dose (Dmean), maximum dose (Dmax), 95% dose (D95), integral dose, total number of segments, and the number of MU were applied. Homogeneity index and conformation number were two other evaluation parameters that were considered in this study. Collectively, the use of 6 MV photons was dosimetrically comparable with 10 MV photons in terms of target coverage, homogeneity, conformity, and OAR savings. While 10-MV plans showed a significant reduction in the number of MUs that varied between 4.2% and 16.6% (P-value = 0.0001) for the different cases compared to 6-MV. The percentage volumes of each patient receiving 2 Gy and 5 Gy were compared for the two energies. The general trend was that 6-MV plans had the highest percentage volume, (P-value = 0.0001, P-value = 0.006) respectively. 10-MV beams actually decreased the integral dose (from average 183.27 ± 152.38 Gy-Kg to 178.08 ± 147.71 Gy-Kg, P-value = 0.004) compared with 6-MV. In general, comparison of the above parameters showed statistically significant differences between 6-MV and 10-MV groups. Based on the present results, the 10-MV is the optimal energy for IMRT, regardless of the concerns about a potential risk of radiation-induced malignancies. It is recommended that the choice to treat at 10 MV be taken as a risk vs. benefit as the clinical significance remains to be determined on case by case basis.

Study on the effect of PET/CT-guided nasopharyngeal carcinoma target delineation on the dose received by endangered organs

Objective:To compare the differences of radiation-induced doses between 18F-FDG-PET/CT and CT/MRI-guided target delineation in nasopharyngeal carcinoma in intensity-modulated radiotherapy.Methods:A total of 31 patients with locally advanced nasopharyngeal carcinoma receiving treatment in our hospital from December 2016 to December 2017 were studied in this research,and 18F-FDG-PET/CT and CT/MRI were used to guide the target delineation to develop an intensity-modulated radiotherapy plan(experimental group and control group).The dose differences between GTV and endangered organs in the two groups were compared.Results:Comparison of primary tumor volume:PET/CT was smaller than CT/MRI,and volumes of T3 and T4 were significantly different(P<0.001).Comparison of the two delineation plans,in terms of PGTV in Dmin,Dmean,and D95,the data of experimental group was smaller than that of the control group;in Dmax,the PGTV of the experimental group was larger than that of the control group with P<0.001 considered as a significant difference.In Dmin and Dmax,doses of experimental groups of the spinal cord were lower than those of the control group,showing a significant difference(P=0.022,0.042);In Dmean,there was no difference between the two groups.In Dmax doses of an experimental group of the brainstem and parotid gland were significantly smaller than the control group(P=0.001,0.047)while there was no difference between Dmin and Dmean.There was no difference between the two groups of Dmin,Dmean,and Dmax in the doses received by chiasm and temporal lobe.Conclusion:PET/CT guided target delineation is applied in the simultaneous dose adjustment of intensity-modulated radiation therapy in patients with advanced nasopharyngeal carcinoma.In primary lesion targets shown by MRI/CT,the tumor tissue of PET/CT concentration zone was given a higher dose with relatively smaller average dose and minimum dose in the overall tumor target area.Statistics also showed that the doses received by the spinal cord,brain stem,and parotid gland were reduced with no effect on the optic chiasm and temporal lobe.In the future,more studies should probe into the long-term effects of dose changes on lesion control and endangered organs.

New frontiers in proton therapy:applications in cancers

Proton therapy offers dominant advantages over photon therapy due to the unique depth-dose characteristics of proton,which can cause a dramatic reduction in normal tissue doses both distal and proximal to the tumor target volume.In turn,this feature may allow dose escalation to the tumor target volume while sparing the tumor-neighboring susceptible organs at risk,which has the potential to reduce treatment toxicity and improve local control rate,quality of life and survival.Some dosimetric studies in various cancers have demonstrated the advantages over photon therapy in dose distributions.Further,it has been observed that proton therapy confers to substantial clinical advantage over photon therapy in head and neck,breast,hepatocellular,and non-small cell lung cancers.As such,proton therapy is regarded as the standard modality of radiotherapy in many pediatric cancers from the technical point of view.However,due to the limited clinical evidence,there have been concerns about the high cost of proton therapy from an economic point of view.Considering the treatment expenses for late radiation-induced toxicities,cost-effective analysis in many studies have shown that proton therapy is the most cost-effective option for brain,head and neck and selected breast cancers.Additional studies are warranted to better unveil the cost-effective values of proton therapy and to develop newer ways for better protection of normal tissues.This review aims at reviewing the recent studies on proton therapy to explore its benefits and cost-effectiveness in cancers.We strongly believe that proton therapy will be a common radiotherapy modality for most types of solid cancers in the future.

甲状腺癌的放射治疗

甲状腺癌约占全身恶性肿瘤的1%[1],主要包括3种病理类型：分化型甲状腺癌（differentiated thyroid cancer,DTC）、髓样癌（medullary thyroid carcinoma,MTC）和间变癌/未分化癌（anaplastic thyroid carcinoma, ATC/undifferentiated carcinoma）.