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Objective:To construct a comprehensive nutritional index after treatment of nasopharyngeal carcinoma patients with intensity-modulated radiation therapy (IMRT), and to analyze its relationship with quality of life and 3-year survival period, and aimed to provide some reference for the management of nasopharyngeal carcinoma patients.Methods:This was a prospective cohort study. The clinical data of 431 nasopharyngeal carcinoma patients who admitted to Beijing Tongren Hospital Affiliated to Capital Medical University from January 2017 to December 2021 were collected using convenience sampling method. To evaluate the nutritional status of the patients, the BMI, change in body weight, hemoglobin, lymphocyte count, and albumin level and other clinical data of the patients were collected before and after intensity-modulated radiation therapy. The comprehensive nutrition index after IMRT was constructed by principal component analysis. The Chinese version of European Organization for Reasearch and Treatment of Cancer quality of life questionnare-Core 30 (EORTC QLQ-C30) and Quality of life questionnaire head and neck cancer module(QLQ-H&N35) were used to evaluate the patients′ quality of life. The best diagnostic cutoff point for predicting patient death within 3 years using ROC, and based on the determined optimal diagnostic cutoff point, all patients were divided into a low comprehensive nutritional index group and a high comprehensive nutritional index group. And analyzed the Pearson correlation between comprehensive nutritional index and quality of life.Differences in 3-year survival between the two groups were compared using the Kaplan-Meier method and Log-rank test.Results:Using the diagnostic threshold of receiver operating characteristic, all patients were divided into low comprehensive nutrition index group ( n=280) and high comprehensive nutrition index group ( n=151).The BMI, percentage of weight change, albumin, hemoglobin, and lymphocyte count of nasopharyngeal carcinoma patients before intensity-modulated radiation therapy were (23.14 ± 2.87) kg/m 2, (1.08 ± 0.14)%, (44.02 ± 4.52) g/L, (147.28 ± 15.57)g/L, (1.76 ± 0.56)×10 9/L, and higher than after intensity-modulated radiation therapy (21.14 ± 4.07) kg/m 2, (0.97 ± 0.16)%, ( 38.99 ± 5.12) g/L, (113.87 ± 18.24)g/L, (0.50 ± 0.18)×10 9/L, respectively, the difference were statistically significant ( t values were 8.34 to 44.47, all P<0.05).The comprehensive nutritional index constructed using principal component analysis was correlated with multiple dimensions of EORTC QLQ-C30) and QLQ-H&N35, with statistically significant differences ( r values were -0.169 - 0.245, all P<0.05). Kaplan-Meier curves indicated that the 3-year survival rate of the high comprehensive nutritional index group was higher than that of the low comprehensive nutritional index group, with 87.42% and 79.29% respectively, and the difference was statistically significant ( χ2=4.53, P<0.05). Conclusions:The constructed comprehensive nutritional index could reflect the comprehensive nutritional status of nasopharyngeal carcinoma patients. Nasopharyngeal carcinoma patients with a low comprehensive nutritional index score had a worse quality of life and shorter 3-year survival. Active intervention and improvement of malnutrition in nasopharyngeal carcinoma patients should be undertaken to improve patient quality of life and improve survival.
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The purpose of this study is to establish and apply a correction method for titanium alloy implant in spinal IMRT plan, a corrected CT-density table was revised from normal CT-density table to include the density of titanium alloy implant. Dose distribution after and before correction were calculated and compared to evaluate the dose deviation. Plans were also copied to a spinal cancer simulation phantom. A titanium alloy fixation system for spine was implanted in this phantom. Plans were recalculated and compared with the measurement result. The result of this study shows that the max dose of spinal cord showed significant difference after correction, and the deviation between calculation results and measurement results was reduced after correction. The method for expanding the range CT-density table, which means that the density of titanium alloy was included, can reduce the error in calculation.
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Radiotherapy, Intensity-Modulated/methods , Titanium , Radiotherapy Dosage , Alloys , Radiometry/methods , Radiotherapy Planning, Computer-Assisted/methodsABSTRACT
The cisplatin-based concurrent chemoradiotherapy (CCRT) has been accepted as a standard treatment for most locally advanced cervical cancer. Compared with radiation therapy alone, CCRT can increase tumor control and survival rates, whereas it also can increase the incidence of acute hematological toxicity, which results in the treatment interruption or delay, and may even affect clinical efficacy and prognosis of patients. Therefore, how to reduce the incidence and severity of acute hematological toxicity induced by CCRT is a hot spot of clinical research. Previous studies have demonstrated that the occurrence of hematological toxicity is associated with the volume and dose of irradiated pelvic bone marrow. With the development of modern radiotherapy technology, precise radiotherapy technologies, such as intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT), not only guaranteed the enough dose for tumor, but also realized the protection of normal tissues. This article will focus on the feasibility of bone marrow sparing during CCRT for cervical cancer, and summarize the research progress in recent years.
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Objective:To explore the feasibility of a classification prediction model for gamma pass rates (GPRs) under different intensity-modulated radiation therapy techniques for pelvic tumors using a radiomics-based machine learning approach, and compare the classification performance of four integrated tree models.Methods:With a retrospective collection of 409 plans using different IMRT techniques, the three-dimensional dose validation results were adopted based on modality measurements, with a GPR criterion of 3%/2 mm and 10% dose threshold. Then prediction were built models by extracting radiomics features based on dose documentation. Four machine learning algorithms were used, namely random forest (RF), adaptive boosting (AdaBoost), extreme gradient boosting (XGBoost), and light gradient boosting machine (LightGBM). Their classification performance was evaluated by calculating sensitivity, specificity, F1 score, and AUC value. Results:The RF, AdaBoost, XGBoost, and LightGBM models had sensitivities of 0.96, 0.82, 0.93, and 0.89, specificities of 0.38, 0.54, 0.62, and 0.62, F1 scores of 0.86, 0.81, 0.88, and 0.86, and AUC values of 0.81, 0.77, 0.85, and 0.83, respectively. XGBoost model showed the highest sensitivity, specificity, F1 score, and AUC value, outperforming the other three models. Conclusions:To build a GPR classification prediction model using a radiomics-based machine learning approach is feasible for plans using different intensity-modulated radiotherapy techniques for pelvic tumors, providing a basis for future multi-institutional collaborative research on GPR prediction.
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Objective:To investigate the efficacy and adverse reactions of moderately hypofractionated intensity modulated radiation therapy (IMRT) combined with androgen deprivation therapy (ADT) for locally advanced prostate cancer (LAPC).Methods:This study retrospectively analyzed the medical records of 40 LAPC patients who were admitted in The Second Hospital of Dalian Medical University during 2014-2020. The planning gross target volume (PGTV) dose for prostate gland and seminal vesicle gland was 64.8-70.0 Gy/25-28 f, 2.4-2.8 Gy/f and the dose of PGTVnd in 20 cases with positive pelvic lymph nodes was 60.0-64.4 Gy/25-28 f, 2.3-2.4 Gy/f. The dose of planning target volume (PTV) for the drainage area of pelvic lymph nodes was 45.0-50.4 Gy/25-28 f. The enrolled patients were treated with long-term ADT, including neoadjuvant, simultaneous, and adjuvant therapies. The efficacy and adverse reactions were evaluated. The prognostic factors affecting the biochemical failure-free survival (BFFS) were analyzed.Results:The median follow-up time was 31 months. The 2- and 3-year overall survival (OS) rates were 100% and 96.9%, respectively. The 1-, 2-, and 3-year BFFS rates were 90%, 76.8% and 72%, respectively. The 1-, 2-, and 3-year distant metastasis-free survival (DMFS) rates were 92.2%, 82.8% and 75.1%, respectively. Gleason (GS) score ( χ2=10.00, P < 0.05) and adjacent tissue invasion ( χ2=8.85, P<0.05) were prognostic factors related to BFFS for LAPC. Adjacent tissue invasion and GS 9-10 were independent poor prognostic factors. The incidence of acute urinary adverse reaction and rectal injury (grade≥2) was 7.5% and 20%, respectively. The incidence of late urinary adverse reaction and rectal injury (grade≥2) was 12.5% and 17.5%, respectively. Adverse reactions at grade 3-4 did not occur. Conclusions:The moderately hypofractionated IMRT combined with ADT is feasible for LAPC treatment, achieving satisfactory survival effects. 70 Gy/25-28 f, 2.5-2.8 Gy/f is a safe and effective moderate hypofraction scheme. Adjacent tissue invasion and GS score are prognostic factors related to BFFS for LAPC.
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Objective:By comparing the positioning errors caused by 3D printed personalized breast bracket and common headrest in intensity-modulated radiation therapy (IMRT), the fixation effect of 3D printed personalized breast bracket in IMRT was analyzed.Methods:Thirty-two breast cancer patients from January to July 2021 were randomly divided into a the 3D printed breast bracket group and common headrest group. All patients in two groups were kept in supine position, head tilted to the healthy side, the affected hand held the grip bar on the same side of the horizontal bar, the healthy hand held the opposite side of the vertical bar, and the chest and mandible were fixed with thermoplastic film. CBCT scan was performed weekly, and gray level registration was carried out according to the three registration regions of interest: breast or chest wall field, supraclavicular and inferior field, and axillary field. The positioning errors in the left and right, head and foot, abdomen and back directions were analyzed between two groups.Results:In the 3D printed breast bracket group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, head and foot, abdomen and back directions were (1.75±1.26), (1.77±1.11) and (1.70±1.08) mm, (1.75±1.25), (1.72±1.09) and (1.70±1.05) mm,(1.86±1.34), (2.14±2.13) and (1.66±1.19) mm, respectively.In the common headrest group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, the head and feet, the abdomen and back directions were (2.54±1.84), (2.73±3.62) and (2.18±2.45) mm, (3.25±2.02), (3.52±2.26) and (2.62±2.83) mm, (3.25±2.05), (4.44±2.90) and (3.10±3.18) mm, respectively.The positioning errors significantly differed between two groups (all P<0.05). Conclusions:The positioning error of 3D printed personalized breast bracket fixation is less than that of common headrest fixation. The positioning consistency of 3D printed personalized breast bracket in the three target areas of breast or chest wall field, supraclavicular and inferior field and axillary field is better than that of common headrest.
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Objective To analyze the dosimetric effect of the optimization tool, normal tissue objective (NTO), in Eclipse on the intensity modulated radiation therapy (IMRT) for postoperative patients with rectal cancer. Methods Twenty postoperative patients with rectal cancer were randomly selected. Based on the Eclipse treatment planning system, three IMRT plans were formulated for each patient, with manual NTO as the control group, and automatic NTO and no NTO as the other two groups. The dosimetric parameters of the target volume and organs at risk (OAR) and the monitor units (MU) were compared between the automatic NTO and no NTO groups and the control group under the same optimization conditions. Results Compared with the control group, the automatic NTO group showed a worse conformity index (CI) (t = 3.248, P < 0.05), a 0.6% higher Dmean of normal tissues (t = -3.678, P < 0.05), and no significant difference in the dose to OAR and the MU (P > 0.05); the no NTO group showed a worse CI (t = 16.716, P < 0.05), a better homogeneity index (t = 6.594, P < 0.05), a 3.19% higher Dmean of normal tissues (t = -8.560, P < 0.05), no significant difference in the dose to OAR except the small intestine with higher Dmax (P > 0.05), and a 3.95% increase in the MU. Conclusion From the dosimetry results of the target volume and OAR, the plans with manual NTO and automatic NTO, and without NTO can meet clinical needs, but the plan without NTO increases the hot spots outside the target volume and the MU as well as the Dmean of normal tissues. Manual NTO has no obvious advantages over automatic NTO which is recommended for the fixed-field IMRT of rectal cancer.
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Objective To compare the dosimetric differences of four fluence smoothing (FS) levels of the Monaco system in intensity-modulated radiation therapy (IMRT) after rectal cancer surgery, and to provide a reference for FS selection in clinical practice. Methods A total of 15 postoperative patients with rectal cancer admitted in 2020 were selected. Under the same optimal conditions, FS was set to Off, Low, Medium, and High for IMRT planning. The data were analyzed by SPSS 20.0 software. The dosimetric parameters of planning target volume and organs at risk (OARs), the number of Segments, the number of monitor units (MUs), the estimated total delivery time (ETDT), and the gamma pass rate were compared between the four FS levels. Results The four FS levels resulted in clinically acceptable dosimetric parameters of the planning target volume and OARs, and there was no significant difference in dose distribution between FS levels. From FS-Off to FS-High, number of Segments, number of Mus, and ETDT decreased by 15.2%, 11.8%, and 6.7%, respectively, whereas gamma pass rate increased by 1.6%. Conclusion The IMRT plans at four FS levels can meet the clinical requirements. Considering the planning quality and execution efficiency, FS-High is recommended for postoperative IMRT of patients with rectal cancer.
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Objective:To compare the efficacy and adverse events of induction chemotherapy combined with radiotherapy alone (IC+ RT) and induction chemotherapy combined with concurrent chemoradiotherapy (IC+ CCRT) for nasopharyngeal carcinoma in the era of intensity-modulated radiation therapy in this Meta-analysis.Methods:Retrospective or randomized controlled clinical studies published between 2010 and 2020 were searched from the Cochrane Library, PubMed, and Web of Science databases. The selected studies included nasopharyngeal carcinoma patients treated with IC+ CCRT or IC+ RT. STATA 12 software was used to combine the hazard ratio (HR), risk ratio (RR) and 95% confidence interval (CI), and random or fixed effect models were used for statistical analysis.Results:A total of 2483 patients from eight retrospective studies were included. The overall survival in the IC+ CCRT group was similar to that in the IC+ RT group ( HR=0.78, 95% CI: 0.58-1.04, P=0.091). However, the distant metastasis-free survival ( HR=0.56, 95% CI: 0.42-0.74, P<0.001) and progression-free survival ( HR=0.65, 95% CI: 0.54-0.77, P<0.001) were improved in the IC+ CCRT group compared with those in the IC+ RT group. In terms of adverse reactions, the acute adverse reactions in the IC+ CCRT group were increased significantly compared with those in the IC+ RT group. Conclusions:In the treatment of nasopharyngeal carcinoma, the overall survival of two treatment modes is similar, but the distant metastasis-free survival and progression-free survival in the IC+ CCRT group are better than those in the IC+ RT group, whereas the incidence of adverse reactions is also increased. IC+ CCRT may be a recommended treatment for nasopharyngeal carcinoma patients, but more research is needed.
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Objective:To evaluate the efficacy of intensity-modulated radiation therapy (IMRT) combined with chemotherapy for treating patients with T 1-2N 1M 0 nasopharyngeal carcinoma (NPC). Methods:343 patients diagnosed with T 1-2N 1M 0 NPC in Zhejiang Cancer Hospital and Sun Yat-sen University Cancer Center from January 2008 to December 2016 were recruited in this study. All patients received IMRT and divided into the radiotherapy (RT) and chemoradiotherapy (CRT) groups. Patients in the CRT group were further assigned into the concurrent chemoradiotherapy (CCRT), induction chemotherapy+ CCRT (IC+ CCRT) and CCRT+ adjuvant chemotherapy (AC) groups. Locoregional failure-free survival (LRFFS), distant metastasis-free survival (DMFS), progression-free survival (PFS), cancer-specific survival (CSS) and overall survival (OS) were estimated by Kaplan- Meier method. Multivariate prognostic analysis was performed by Cox models. Results:The median follow-up time for surviving patients (303/343) was 91(range: 49-138) months. The 5-year OS, CSS, PFS, LRFFS, and DMFS rates in the CRT group were not superior to those of the RT group (93.7%: 93.9%, 93.7%: 93.9%, 89.0%: 87.7%, 93.8%: 92.8%, 93.8%: 91.2%, all P>0.05). No significant difference was found in treatment outcomes of patients with T 1N 1 or T 2N 1 NPC between two groups (all P>0.05). In multivariable analyses, only age was an independent prognostic factor for OS, PFS, CSS and DMFS, and negative correlation was found between them. No survival benefits were achieved in the CCRT, IC+ CCRT, CCRT+ AC and RT groups, and no significant differences were found in clinical efficacy among the three combined (all P>0.05). Conclusions:IMRT alone yields comparable clinical efficacy to CRT in treating patients with T 1-2N 1M 0 NPC. However, whether CT can be eliminated in the T 1-2N 1M 0 population still needs further confirmation by prospective, randomized and controlled clinical trials.
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Objective:To explore the feasibility of the clinical implementation of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans with 6MV photon on two Elekta Linacs (Versa HD and Synergy) after beam matching.Methods:The images of 12 patients with nasopharyngeal carcinoma, central lung cancer and prostate cancer were randomly selected, and the IMRT and VMAT plans were designed. Two different dose tools of ionization chamber and three-dimensional detector ArcCheck were used to verify the individualized radiation treatment of 6MV photon beams on two Linacs and compare the differences.Results:The deviations between the doses of two Linacs (Versa HD and Synergy) measured by the ion chamber and treatment planning system were (0.32±1.32)% and (0.54±1.29)%. The differences of all plans were within the range of ±3%, and the deviations of the point dose between two Linacs were within the range of ±2% with no statistical significance (both P>0.05). The γ analysis of verification using ArcCheck showed that the passing rates of all plans under the 2mm/3% and 3mm/3% with 10% threshold conditions were over 95%, respectively. The average differences between two Linacs were 0.19%(2mm/3%) and 0.09%(3mm/3%). Conclusions:The results of performing IMRT/VMAT plans on two Linacs meet the clinical requirements and the differences between two Linacs are small. Hence, the same plans can be implemented interchangeably on different Linacs.
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Intestinal injury is an important toxic response during radiation therapy of pelvic tumors. With the widespread use of precision radiotherapy techniques such as intensity modulated radiation therapy (IMRT), the dose exposed to normal tissues and organs has been significantly reduced. However, the toxic response of the bowel still limits the increase of the dose to the target volume. Therefore, the protection of important organs at risk (OAR), such as the bowel, becomes more and more important while giving adequate irradiated dose to the target volume. Most current studies used loop to contour bowel. For patients who underwent IMRT, the meaningful dose-volume predictors of grade 2 acute intestinal adverse events using bowel loop (small loop + big bowel) delineation included V45 Gy < 50 cm 3,V50 Gy < 13 cm 3, and V55 Gy < 3 cm 3, and the corresponding predicators using bowel bag delineation were V40 Gy < 170 cm 3,V45 Gy < 100 cm 3, and V50 Gy < 33 cm 3.
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Objective To compare the dosimetric difference between the biological function based on equivalent uniform dose (EUD) and the physical function based on dose volume (DV) in the intensity modulated radiotherapy for stage Ⅲ non-small cell lung cancer. Methods Four different radiotherapy plans were designed for 15 stage Ⅲ non-small cell lung cancer patients: Group A, physical function optimization (DV + DV) was used for target area and organs at risk; GroupB, in the target region, biological function optimization conditions were added on the basis of physical function optimization, and physical function optimization of organs at risk (DV－EUD + DV) was added. Group C, biological function optimization (EUD + EUD) was used for target area and organs at risk. Group D, in the target area, physical function optimization conditions were added on the basis of biological function optimization, and biological function optimization of organs at risk (EUD－DV + DV) was added. The differences in dosimetric parameters of the four plans were compared. Results Target area: PTV: D2%, D98%, D50%, D105% and Dmax values of group C (P < 0.05) is the highest while group B and group D were relatively small (P > 0.05); The homogeneity index: the results of the group B and the group D were better than those of the other two groups (P < 0.05). conformity index: The results of the four groups were similar (P>0.05). Organ at risk: lung tissue mean dose (MLD), V5, V10, V20, V30 and heart V30, V40, Dmean dose parameters were similar (P > 0.05). Spinalcord: Group C and group D D1% were better than the other two groups (P < 0.05). There was no statistical difference in the number ofmonitor unit (MU) among the four groups (P > 0.05). Conclusion The optimization method combining physical and biological function optimization in the target area can improve the conformity of the target area on the premise of ensuring the treatment. The Spinalcord load would be significantly reduced when using biological function optimization or the combination of biological function and physical function optimization.
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Objective To compare the dose difference of intensity-modulated radiotherapy (IMRT) with different gantry angle between target volumes and surrounding normal tissues in lumbar spinal metastases therapy. Methods Ten patients with lumbar spinal metastases were enrolled in the study. Three plans with the same prescription dose of 3000 cGy/10f were designed by seven-equal beams (plan-A), five-back beams (plan-B) and seven-back beams (plan-C). All the plans were designed with the same objective function and dose limiting condition. The difference of dosimetric parameters of planning target volume (PTV), organ at risk (OAR), normal tissues, and treatment parameters in all the plans were compared with SPSS 21.0 statistical software. Results All the plans satisfied the clinical requirement. There was no significant difference in the Dmean, D2%, D98%, CI and HI of PTV between plan-A and plan-C (P >0.05), and these parameters of plan-A and plan-C were better than plan-B (P < 0.05). Compared with the other two plans, plan-B reduced the dosimetric parameters of bilateral kidney (P < 0.05), whereas plan-B increased the Dmax of spinal cord (P < 0.05). The V5 and V10 of normal tissue of plan-B were lower than the other two plans while the V15, V20 and V25 showed inverse relationship (P < 0.05). plan-B had certain advantages in shortening the monitor units and treatment time (P < 0.05).. Conclusions The seven-equal beams (plan-A) and seven-back beams (plan-C) IMRT plans can provide better target dose distribution, and reduce the Dmax of spinal cord. Five-back beams (plan-B) IMRT plan had certain advantages in protecting bilateral kidney and shortening treatment time.
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Resumen Introducción: En 2018 el cáncer de próstata presentó el segundo lugar en incidencia a nivel mundial. Con el avance en la tecnología y la aparición de la radioterapia de intensidad modulada (IMRT), se ha logrado disminuir dosis a tejido sano sin reducir la cobertura del volumen objetivo, permitiendo menor morbilidad asociada por la radioterapia y la posibilidad de escalar la dosis del tratamiento. El objetivo del estudio fue mostrar los resultados en supervivencia global y supervivencia libre de recaída bioquímica en el Instituto Nacional de Cancerología de Colombia (INC) en los paciente diagnosticados con cáncer de próstata tratados con radioterapia de intensidad modulada (IMRT). Materiales y métodos: La revisión retrospectiva incluyó 98 pacientes, mayores de 40 años con cáncer de próstata, sin evidencia de enfermedad metastásica, tratados con IMRT entre 2008 - 2015, independiente de la supresión androgénica. La dosis administrada de radioterapia varió según su riesgo basado en la clasificación D´Amico. Hallazgos: La mediana de edad fue de 68,5 años, dentro de los cuales 16 pacientes (16%) se catalogaron de bajo riesgo, 33 (34 %) de riesgo intermedio y 49 (50 %) de riesgo alto. La dosis media de radioterapia recibida fue de 75,8 Gy. La supervivencia libre de recaída bioquímica a 5 años fue del 78,6 % y la supervivencia global fue 98 %. Conclusión: En pacientes con cáncer de próstata de alto riesgo, la IMRT es una alternativa efectiva y segura, con una supervivencia global a 5 años del 98% y con un adecuado perfil dosimétrico a los órganos a riesgo.
Abstract Background: In 2018, prostate cancer ranked second in incidence worldwide. Advances in technology and the appearance of intensity-modulated radiotherapy, have made it possible to reduce doses to healthy tissue without reducing the coverage of the target volume, thus allowing lower morbidity associated with adiotherapy and the possibility of scaling the treatment dose. The aim of the study was to present the results in overall survival and biochemical relapse-free survival at the Colombian National Cancer Institute (INC) in patients diagnosed with non-metastatic prostate cáncer treated with intensity-modulated radiotherapy (IMRT). Material and methods: The retrospective review included 98 patients over 40 years of age with prostate cancer, without evidence of metastatic disease, treated with IMRT between 2008 and 2015 irrespective of androgenic suppression. The administered dose of radiotherapy varied according to their risk based on the D'Amico classification. Results: The median age was 68.5 years, and of the total of 98 patients, 16 (16%) were classified as low risk, 33 (33%) as intermediate risk, and 49 (50%) as high risk. The mean dose of radiation therapy received was 75.8 Gy. Biochemical relapse-free survival at 5 years was 78.6%, and overall survival was 98%. Conclusions: In patients with high-risk prostate cancer, IMRT is an effective and safe alternative, with an overall 5-year survival of 98%, and an adequate dosimetric profile for at-risk organs.
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Humans , Male , Prostatic Neoplasms , Radiotherapy , Radiotherapy, Intensity-Modulated , Survivorship , Recurrence , TherapeuticsABSTRACT
Head-and-neck cancer (HNC) is in close proximity to several critical structures. Intensity-modulated radiation therapy (IMRT) has the potential of generating highly conformal and concave dose distributions around complex target and is ideally suited for HNC treatment. Conventionally, the focus of IMRT for HNC patients has been on prevention of radiation-induced parotid dysfunction. In the present article, we review the potential of IMRT to reduce the risk of posttreatment aspiration and dysphagia and spare submandibular gland. We also discuss the impact of IMRT on overall survival and quality of life (QoL) for HNC patients. Small retrospective and prospective studies show that reducing dose to adjoining organs at risks is feasible and decreases the risk of posttreatment dysphagia and aspiration without compromising local control. IMRT is associated with improved QoL in several important domains including swallowing, dry mouth, sticky saliva, social eating, and opening of the mouth; however, improvement in global QoL is inconsistent. Delivery of IMRT for HNC is associated with improved survival at nasopharyngeal subsite. Small studies demonstrate improved treatment outcomes with swallowing-sparing IMRT. These results now need validation within the prospective multicenter randomized controlled trial setting
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Objective To develop and evaluate an automatic intensity-modulated radiation therapy (IMRT) program for cervical cancer based on a database of overlap volume histogram (OVH) and high-quality cervical IMRT plans for previously-treated patients.Methods A database consisting of high-quality IMRT plans and OVHs from 200 cervical cancer patients was established.OVHs of another 26 cervical cancer patients were converted into gray level images to calculate the image similarity compared with those from the database.The planning optimization function of the patients from the database with the highest image similarity was selected and inherent Pinnacle3 scripts were utilized to automatically generate IMRT plan.Finally,the dosimetric parameters,plan quality and design time were statistically compared between the automatic and manual plans.Results The target coverage,conformity index and homogeneity index did not significantly differ between two plans (all P＞0.05).The V40,V45 and mean dose for the rectum in the automatic plans were significantly decreased by 6.1％,1.3％ and 50.7 cGy than those in the manual plans (all P＜0.05).Compared with the manual plans,the mean dose for the intestine and femur in the automatic plans were significantly reduced by 31.7 cGy and 188.9 cGy (both P＜0.05),whereas the mean dose for the ilium was slightly decreased by 92.3 cGy in the automatic plans (P＞ 0.05).The plan design time was shortened by 71％ in the automatic plans.Conclusions The automatic IMRT plans based on a database of OVH and high-quality IMRT plans can not only significantly shorten the plan design time,but also reduce the irradiated dose of normal tissues without compromising the target coverage and conformity index.
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Objective To study a method for verifying the doses to PTV and OAR as well as the 2D dose distribution arising from IMRT through using radiochromic films and TLDs.Methods Totally 7 medical electronic linear accelerators from Varian,Siemens and Elekta were selected.The polystyrene phantom provided by IAEA was conducted with CT scan.After irradiation with 6 MV X-rays,the TLDs and films were returned to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.Results According to the IAEA requirements,the relative deviations between TLD-measured and TPS-planned values for PTV and OAR doses were both within ±7.0％.For PTV,the measured relative deviations for 5 accelerators were in the range of-4.0％ to 3.4％,consistent with the IAEA requirements,whereas the values for the other 2 accelerators were in the range of-7.0％ to 10.6％,not consistent with the requirements.For OAR,the values for 4 accelerators were in the range of-5.6％ to 3.3％,consistent with the IAEA requirements,whereas the values for the other 3 accelerators were in the range of-20.8％ to 11.5％,not meeting the requirements.As required by the IAEA,the 2D dose distribution 3 mm/3％ pass rate should be higher than 90％.The measured values for 5 accelerators were in the range of 91.8％ to 98.5％,consistent with the requirements,whereas the values measured for the other 2 were 45.0％ and 77.0％ respectively,not meeting the requirements.Conclusions It is feasible for using TLDs and radiochromic films to verify the doses to PTV and OAR and the 2D dose distribution in IMRT.This method should be applied to not only quality verification but also hospital internal audit to the extent possible.
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Objective To use TLDs and radiochromic films to verify the prescribed doses to both planned target volume (PTV) and organ at risk (OAR) and the 2D dose distribution in IMRT.Methods Eight accelerators of different models were selected in Henan province.The polystyrene phantom provided by IAEA was scanned using CT scanners and then the scanned images were transmitted to treatment planning system (TPS) for prescribing respectively the doses to PTV and OAR.IMRT was performed with phantom exposed to a 6 MV X-rays.The irradiated TLDs and films were delivered for measurement and estimation at Secondary Standard Dosimetry Laboratory at National Institute for Radiological Protection,Chinese Center for Disease Control and Prevention.Results According to IAEA requirements,the relative deviations of the TLD-measured and TPS-planned values were within ±7.0％ for the prescribed doses to PTV and OAR.The measured results for PTV have shown that the relative deviation of TLD-measured and TPS-planned values were within-0.3％ to 6.9％ for 8 accelerators,all consistent with the IAEA requirements.For OAR,the relative deviations of TLD-measured and TPS-planned were within-7.0％ to 0.3％ for 6 accelerators,consistent with the requirements,whereas those for other 2 accelerators were within-10.8％ to-8.4％,not up to the requirements.IAEA required that,for 2D dose distribution,the pass rate of 3 mm/3％ be ≥ 90％.The measured values for 7 accelerators were from 90.2％ to 99.9％,consistent with the requirements,whereas that for another one was 70.0％,not meeting the requirement.Conclusions The method to verify,using radiochromic film and TLD,the prescribed doses to PTV and OAR and the pass rate of 2D dose distribution is simple and reliable.It is an important step to implement quality control for IMRT and can provide effective support for medical or third-party service institution to verify clinically prescribed dose.
ABSTRACT
Objective To study a method to measure the doses to planned target volume (PTV) and organ at risk (OAR) and 2D dose distribution in IMRT by using TLD and radiochromic film for a verification purpose.Methods Totally 7 different types of medical linear accelerators were selected from seven hospitals in Hubei province.A polystyrene phantom provided by IAEA was CT scanned and then the scanned images were returned to the Treatment Planning System (TPS) for determining the prescribed doses to PTS and OAR and the corresponding MU.After the phantom was irradiated with 6 MV X-ray,the TLDs and films were transmitted to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.Results The IAEA required the relative deviations between TLD-measured and TPS-planned doses to OAR and PTV be within ±7.0％.For PTV,the measured-to-planned deviation values for 7 accelerator were within-5.4％ to 6.5％,all consistent with the IAEA requirements.For OAR,the values for 5 accelerators were within-2.2％ to 6.7％,not consistent the requirements,whereas the values for the other 2 were-8.6％ and 8.2％ respectively,beyond the required values.The IAEA required that the 2D dose distribution 3 mm/3％ pass rate be higher than 90％.The measured values for 7 accelerators were in the range of 90.3％-98.9％,all consistent with the requirements.Conclusions It is feasible scientifically and easy to operate in practice for using TLD and film to carry out dose verification in IMRT.It would be advisable to apply this method to quality verification in IMRT in medical institutions to the extent possible.