Feasibility Study of Beam Angle Optimization Based on Scripts in Automated-planning for Liver Cancer / 中国医疗器械杂志

OBJECTIVE@#To study the feasibility and potential benefits of beam angle optimization (BAO) to automated planning in liver cancer.@*METHODS@#An approach of beam angle sampling is proposed to implement BAO along with the module Auto-planning in treatment planning system (TPS) Pinnacle. An in-house developed plan quality metric (PQM) is taken as the preferred evaluating method during the sampling. The process is driven automatically by in-house made Pinnacle scripts both in sampling and scoring. In addition, dosimetry analysis and physician's opinion are also performed as the supplementary and compared with the result of PQM.@*RESULTS@#It is revealed by the numerical analysis of PQM scores that only 15% patients whose superior trials evaluated by PQM are also the initial trials. Gantry optimization can bring benefit to plan quality along with auto-planning in liver cancer. Similar results are provided by both dose comparison and physician's opinion.@*CONCLUSIONS@#It is possible to introduce a full automated approach of beam angle optimization to automated planning process. The advantages of this procedure can be observed both in numerical analysis and physician's opinion.

Progress in Development of Dose Verification System Software KylinRay-Dose4D / 中国医疗器械杂志

Advanced radiotherapy technology enables the dose to more accurately conform to the tumor target area of the patient, providing accurate treatment for the patient, but the gradient of the patient's radiation dose at the tumor edge is getting larger, which putting forward higher requirements for radiotherapy dose verification. The dose verification system software KylinRay-Dose4D can verify the patient's pre-treatment plan and the in vivo/on-line dose during the patient's treatment, providing important reference for the physicist to modify the radiotherapy plan and ensuring that the patient receives accurate treatment. This study introduces the overall design and key technologies of KylinRay-Dose4D, and tests the pre-treatment plan dose checking calculation and 2D/3D dose verification through clinical cases. The test results showed that the 2D/3D gamma pass rate (3 mm/3%) of KylinRay-Dose4D reconstructed dose compared with TPS plan dose and measured dose is larger than 95%, which indicating that the reconstructed dose of KylinRay-Dose4D meets the requirement of clinical application.

Dosimetric Impact of Titanium Alloy Implant in Spinal IMRT Plan / 中国医疗器械杂志

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.

Study on the sensitivity of a volumetric modulated arc therapy plan verification equipment on multi-leaf collimator opening and closing errors and its gamma pass rate limit / 生物医学工程学杂志

To investigate the γ pass rate limit of plan verification equipment for volumetric modulated arc therapy (VMAT) plan verification and its sensitivity on the opening and closing errors of multi-leaf collimator (MLC), 50 cases of nasopharyngeal carcinoma VMAT plan with clockwise and counterclockwise full arcs were randomly selected. Eight kinds of MLC opening and closing errors were introduced in 10 cases of them, and 80 plans with errors were generated. Firstly, the plan verification was conducted in the form of field-by-field measurement and true composite measurement. The γ analysis with the criteria of 3% dose difference, distance to agreement of 2 mm, 10% dose threshold, and absolute dose global normalized conditions were performed for these fields. Then gradient analysis was used to investigate the sensitivity of field-by-field measurement and true composite measurement on MLC opening and closing errors, and the receiver operating characteristic curve (ROC) was used to investigate the optimal threshold of γ pass rate for identifying errors. Tolerance limits and action limits for γ pass rates were calculated using statistical process control (SPC) method for another 40 cases. The error identification ability using the tolerance limit calculated by SPC method and the universal tolerance limit (95%) were compared with using the optimal threshold of ROC. The results show that for the true composite measurement, the clockwise arc and the counterclockwise arc, the descent gradients of the γ passing rate with per millimeter MLC opening error are 10.61%, 7.62% and 6.66%, respectively, and the descent gradients with per millimeter MLC closing error are 9.75%, 7.36% and 6.37%, respectively. The optimal thresholds obtained by the ROC method are 99.35%, 97.95% and 98.25%, respectively, and the tolerance limits obtained by the SPC method are 98.98%, 97.74% and 98.62%, respectively. The tolerance limit calculated by SPC method is close to the optimal threshold of ROC, both of which could identify all errors of ±2 mm, while the universal tolerance limit can only partially identify them, indicating that the universal tolerance limit is not sensitive on some large errors. Therefore, considering the factors such as ease of use and accuracy, it is suggested to use the true composite measurement in clinical practice, and to formulate tolerance limits and action limits suitable for the actual process of the institution based on the SPC method. In conclusion, it is expected that the results of this study can provide some references for institutions to optimize the radiotherapy plan verification process, set appropriate pass rate limit, and promote the standardization of plan verification.

Analysis of risk factors of radiation-induced toxicity in limited-stage small cell lung cancer treated with hypofractionated intensity-modulated radiotherapy / 中华肿瘤杂志

Objective: To compare the incidence of radiation-related toxicities between conventional and hypofractionated intensity-modulated radiation therapy (IMRT) for limited-stage small cell lung cancer (SCLC), and to explore the risk factors of hypofractionated radiotherapy-induced toxicities. Methods: Data were retrospectively collected from consecutive limited-stage SCLC patients treated with definitive concurrent chemoradiotherapy in Cancer Hospital of Chinese Academy of Medical Sciences from March 2016 to April 2022. The enrolled patients were divided into two groups according to radiation fractionated regimens. Common Terminology Criteria for Adverse Events (CTCAE, version 5.0) was used to evaluate the grade of radiation esophagus injuries and lung injuries. Logistic regression analyses were used to identify factors associated with radiation-related toxicities in the hypofractionated radiotherapy group. Results: Among 211 enrolled patients, 108 cases underwent conventional IMRT and 103 patients received hypofractionated IMRT. The cumulative incidences of acute esophagitis grade ≥2 [38.9% (42/108) vs 35.0% (36/103), P=0.895] and grade ≥ 3 [1.9% (2/108) vs 5.8% (6/103), P=0.132] were similar between conventional and hypofractionated IMRT group. Late esophagus injuries grade ≥2 occurred in one patient in either group. No differences in the cumulative incidence of acute pneumonitis grade ≥2[12.0% (13/108) vs 5.8% (6/103), P=0.172] and late lung injuries grade ≥2[5.6% (6/108) vs 10.7% (11/103), P=0.277] were observed. There was no grade ≥3 lung injuries occurred in either group. Using multiple regression analysis, mean esophageal dose ≥13 Gy (OR=3.33, 95% CI: 1.23-9.01, P=0.018) and the overlapping volume between planning target volume (PTV) and esophageal ≥8 cm(3)(OR=3.99, 95% CI: 1.24-12.79, P=0.020) were identified as the independent risk factors associated with acute esophagitis grade ≥2 in the hypofractionated radiotherapy group. Acute pneumonitis grade ≥2 was correlated with presence of chronic obstructive pulmonary disease (COPD, P=0.025). Late lung injuries grade ≥2 was correlated with tumor location(P=0.036). Conclusions: Hypofractionated IMRT are tolerated with manageable toxicities for limited-stage SCLC patients treated with IMRT. Mean esophageal dose and the overlapping volume between PTV and esophageal are independently predictive factors of acute esophagitis grade ≥2, and COPD and tumor location are valuable factors of lung injuries for limited-stage SCLC patients receiving hyofractionated radiotherapy. Prospective studies are needed to confirm these results.

Comparação Dosimétrica entre Técnicas de Planejamento de Radioterapia para Câncer de Mama Esquerda / Dosimetry Comparison of Radiotherapy Planning Techniques for Left Breast Cancer / Comparación Dosimétrica entre Técnicas de Planificación de Radioterapia para el Cáncer de Mama Izquierdo

Introdução: A radioterapia é utilizada no tratamento do câncer de mama. No planejamento radioterápico, há formas de desenvolver o plano de tratamento, como a radioterapia 3D conformacional (3D-CRT), a radioterapia de intensidade modulada (IMRT) e a arcoterapia volumétrica modulada (VMAT). Objetivo: Comparar as doses nos órgãos de risco e no volume-alvo de tratamento com as diferentes técnicas de planejamento: 3D-CRT, IMRT, VMAT e VMAT modificada para o tratamento do câncer de mama em um phantom antropomórfico. Método: O plano de tratamento foi realizado no sistema Eclipse™ v.15.6 da Varian a partir de imagens de tomografia computadorizada adquiridas de phantom. A dose de prescrição estabelecida foi de 45 Gy em 25 frações de 1,8 Gy/dia. Resultados: Sobre a cobertura do volume do alvo planejado (PTV), as técnicas 3D-CRT (FILTRO e field-in-field ­ FIF) demonstram cobertura inferior comparada aos planos de IMRT e VMAT. Já o plano 3D-CRT-FIF apresenta maior homogeneidade comparado ao 3D-CRT-FILTRO. Para o pulmão contralateral, os planos de 3D-CRT (FIF, FILTRO) obtiveram restrições melhores em relação aos demais planos. Sobre a exposição cardíaca, os planos 3D-CRT (FIF, FILTRO) apresentaram maiores benefícios do que as técnicas IMRT, VMAT e VMAT modificada. Conclusão: As técnicas convencionais 3D-CRT (FIF, FILTRO) apresentaram menores doses nos órgãos de risco. Contudo, as técnicas IMRT e VMAT obtiveram melhor homogeneidade e conformidade da dose distribuída no PTV ao comparar as técnicas convencionais.

Introduction: Radiotherapy is utilized to treat breast cancer. For radiotherapy planning, there are several ways to develop the treatment plan, such as 3D conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). Objective: To compare the doses to risk organs and treatment target volume with different planning techniques, 3D-CRT, IMRT, VMAT and modified VMAT for the treatment of breast cancer in an anthropomorphic phantom. Method: The treatment plan was performed in the Eclipse™ v.15.6 system by Varian from CT images acquired from phantom. The established prescription dose was 45 Gy in 25 fractions of 1.8Gy/day. Results: For the planning target volume (PTV) coverage, 3D-CRT techniques (FILTER and field-in-field ­ FIF) showed inferior coverage compared to IMRT and VMAT plans. The 3D-CRT-FIF plan, on the other hand, shows greater homogeneity when compared to 3D-CRT-FILTER. For the contralateral lung, the 3D-CRT plans (FIF, FILTER) have better restrictions when compared with the other plans. On cardiac exposure, the 3D-CRT (FIF, FILTER) plans showed greater benefits when compared with IMRT, VMAT and Modified VMAT techniques. Conclusion: Conventional 3D-CRT techniques (FIF, FILTER) showed lower doses in organs at risk. However, IMRT and VMAT techniques obtained better homogeneity and conformity of the dose delivered to the PTV when compared to conventional techniques

Introducción: La radioterapia se utiliza en el tratamiento del cáncer de mama. En la planificación de la radioterapia, existen formas de desarrollar el plan de tratamiento, como la radioterapia conformacional 3D (3D-CRT), la radioterapia de intensidad modulada (IMRT) y la arcoterapia volumétrica modulada (VMAT). Objetivo: Comparar las dosis en órganos de riesgo y en el volumen blanco de tratamiento con diferentes técnicas de planificación: 3D-CRT, IMRT, VMAT y VMAT modificada para el tratamiento del cáncer de mama en un fantoma antropomórfico. Método: El plan de tratamiento se realizó en el sistema Eclipse™ v.15.6 de Varian a partir de imágenes de TC adquiridas del fantoma. La dosis de prescripción establecida fue de 45 Gy en 25 fracciones de 1,8Gy/día. Resultados: En cuanto a la cobertura del volumen blanco de planificación (VBP), las técnicas 3D-CRT (filtro - FILTRO y field-in-field ­ FIF) demostraron una cobertura inferior en comparación con los planes IMRT y VMAT. El plan 3D-RCT-FIF mostró mayor homogeneidad en comparación con el 3D-RCT-FILTRO. Para el pulmón contralateral, los planes 3D-CRT (FIF, FILTER) obtuvieron mejores restricciones en comparación con los otros planes. En la exposición cardiaca, los planes 3D-CRT (FIF, FILTER) mostraron mayores beneficios en comparación con las técnicas IMRT, VMAT y VMAT modificada. Conclusión: Las técnicas convencionales de 3D-CRT (FIF, FILTER) mostraron dosis más bajas en los órganos de riesgo. Sin embargo, las técnicas IMRT y VMAT obtuvieron una mejor homogeneidad y conformidad de la dosis distribuida en el VBP en comparación con las técnicas convencionales.

Leak and Scattering Assessment by Optically Stimulated Luminescence Dosimetry in a Helical Linear Accelerator / Valoración de Fuga y Dispersión por medio de Dosimetría de Luminiscencia Estimulada Ópticamente (OSL) en un Acelerador Lineal Helicoidal

Radiation absorbed doses to organs outside the radiation therapy treatment beam can be significant and therefore of clinical interest. Two sets of out-of-beam measurements were performed measuring the leak dose and the scattered dose, at 5 points within the accelerator components (accelerator tube and collimator) and at 21 points on the equipment and surroundings based on a positioning scheme. For this purpose, 52 Optically Stimulated Luminescence (OSL) dosimeters were used in a latest generation helical linear accelerator. Of the 200 cGy fired at a cheese-like phantom, 0.332% of the out-of-beam dose contribution was found to come from the leak and 0.784% was transformed into scattering. For these dose values, estimates of the risk of second tumors in long-term survivors indicate a reduced probability of acquiring a second secondary radiation malignancy, based on information from the 1990 BEIR Committee report.

La dosis absorbida de radiación a órganos fuera del haz de tratamiento de radioterapia puede ser significativa y, por lo tanto, de interés clínico. Se realizaron dos sets de mediciones fuera del haz para determinar la dosis de fuga y la dosis dispersa, en 5 puntos dentro de los componentes del acelerador (tubo de aceleración y colimador) y 21 puntos en el equipo y alrededores basado en un esquema de posicionamiento. Para este fin se utilizaron 52 dosímetros de luminiscencia estimulada ópticamente (OSL, Optically Stimulated Luminescence), en un acelerador lineal helicoidal de última generación. De los 200 cGy disparados a un maniquí tipo queso, se encontró que el 0.332% de la contribución de dosis fuera del haz provenía de la fuga y 0.784% se transforma en dispersión. Para estos valores de dosis, las estimaciones del riesgo de segundos tumores en los supervivientes a largo plazo indican una reducida probabilidad de contraer una segunda malignidad por radiación secundaria, según la información del informe del Comité BEIR de 1990.

Corrigendum to Hemoglobin patterns and anemia in intensity-modulated radiotherapy versus three-dimensional conformal radiotherapy among patients with breast cancer

@#We published in May 10, 2022 a retrospective cohort study comparing the post-radiotherapy (post-RT) hemoglobin levels between patients with breast cancer who underwent intensity-modulated radiotherapy (IMRT) and those who underwent three-dimensional conformal radiotherapy (3D-CRT) in the Radiation Oncology Section of the Department of Radiological and Imaging Sciences of Southern Philippines Medical Center (ROS DORIS-SPMC) from October 2018 to March 2019. It came to our knowledge that the IMRT planning that was done on the patients included in our study was different from the IMRT planning that is currently being done since late 2020. Prior to late 2020, ROS DORIS-SPMC had been implementing forward-planned IMRT, wherein the weight of the multileaf collimator (MLC) segment was preselected at fixed values. In late 2020, ROS DORIS-SPMC started implementing inverse-planned IMRT, wherein the appropriate weights of the MLC segments are determined by an inverse optimization algorithm that creates a more uniform dose distribution throughout the target. Inverse-planned IMRT improves the dose homogeneity within the entire 3D-breast volume, while forward-planned IMRT mainly improves the dose distribution on the inframammary fold.1 Compared to 3D-CRT, however, forward-planned IMRT improves target homogeneity, albeit to a lesser degree than the homogeneity produced by the inverse technique.2 In the original article, we also stated that, for both IMRT and 3D-CRT, each dose fraction is given weekly within a span of 7 to 8 months. We recently confirmed that, among patients with breast cancer, each dose fraction of IMRT or 3D-CRT is given daily within a span of 33 days—28 days for conventional dose and 5 days for boost dose. In this corrigendum, we specify that the IMRT protocol used among the patients in our study was forward-planned IMRT, with all dose fractions given daily for 33 consecutive workdays, excluding weekends and holidays. We also describe here the original statements that we changed or removed because they have become irrelevant in light of the corrections. The table below shows the list of corrections.

Impact of multi-leaf collimator positioning accuracy on quality control of volumetric modulation arc therapy plan for cervical cancer treated with Elekta linear accelerator / 南方医科大学学报

OBJECTIVE@#To investigate the influence of positioning accuracy of the multi-leaf collimators (MLC) on the passing rate of the plan dose verification for volumetric modulation arc therapy (VMAT) of cervical cancer using an Elekta linear accelerator.@*METHODS@#The dose distributions were measured using Sun Nuclear's Mapcheck and Arccheck semiconductors matrix before and after MLC calibration in30 cervical cancer patients undergoing VMAT. Dosimetric comparisons were performed with 2D and 3D gamma passing rates of 3%, 3 mm and 2%, and 2 mm. The 3D gamma distribution was reconstructed with respect to the patient's anatomy using 3DVH software to evaluate the possible influence of MLC positioning accuracy.@*RESULTS@#Before and after MLC calibration, the gamma passing rates of Mapcheck were (88.80±1.81)% and (99.25 ± 0.53)% under 3% and 3 mm standard, respectively, with an average increase of 10.45%. The corresponding gamma passing rates of Arccheck were (87.61±1.98)% and (98.13±0.99)%, respectively, with an average increase of 10.52%. The gamma passing rates of 3DVH were (89.87±2.28)% and (98.3±1.15)%, respectively, with an average increase of 8.43%.@*CONCLUSION@#The MLC positioning accuracy is one of the main factors influencing dosimetric accuracy of VMAT for cervical cancer. The application of Autocal software facilitates MLC calibration and improves the accuracy and safety of VMAT delivery for cervical cancer.

Study on Automatic Plan Method for Radiotherapy after Breast-conserving Surgery Based on TiGRT System / 中国医疗器械杂志

To study an automatic plan(AP) method for radiotherapy after breast-conserving surgery based on TiGRT system and and compare with manual plan (MP). The dosimetry parameters of 10 patients and the evaluation of scoring table were analyzed, it was found that the targets dose of AP were better than that of MP, but there was no statistical difference except for CI, The V5, V20 and V30 of affected lungs and whole lungs in AP were lower than all that in MP, the Dmean of hearts was slightly higher than that of MP, but the difference was not statistically significant, the MU of AP was increase by 16.1% compared with MP, the score of AP evaluation was increase by 6.1% compared with MP. So the AP could be programmed and automated while ensuring the quality of the plan, and can be used to design the plans for radiotherapy after breast-conserving surgery.

Dosimetric effect of patient arm position on Cyberknife radiosurgery for spinal tumors / 北京大学学报(医学版)

OBJECTIVE@#To assess the potential dosimetric effects of arms movement in patients with Cyberknife spine tumors.@*METHODS@#In the study, 12 patients with thoracic and lumbar tumors were retrospectively selected respectively. The contour of the patient's arms was sketched and the CT density was modified to be equivalent to air in order to simulate the extreme case when the arm was completely removed from the radiation fields. The dose of simulated plan was re-calculated with the original beam parameters and compared with the original plan. The changes of V100, D95, and D90, conformity index (CI) and heterogeneity index (HI) in planning target volume (PTV), as well as Dmax, D1cc and D2cc in the spinal cord, stomach, esophagus, and intestines were analyzed by comparing with the original plans.@*RESULTS@#Compared with the original treatment plan, V100, D95, D90 and CI of PTV for the simulated plan was increased by 0.86%, 2.02%, 1.97% and 0.80% respectively, the difference was statistically significant (P < 0.05). Dmax, D1cc and D2cc of spinal cord was increased by 2.35%, 0.59% and 1.49% on average, compared with the original plan, the difference was statistically significant (P < 0.05). The difference was statistically significant only in average D2cc of stomach, which was increased by 1.70%, compared with the original plan (P < 0.05). There was no significant difference in dose change of eso-phagus and intestine between the original and simulated plans.@*CONCLUSION@#This study analyzed the most extreme arm position in spinal tumor of radiation therapy based on Cyberknife. It was found that the change of arm position had little effect on dosimetry. In addition, with the change of arm position, the dose in PTV and organ at risk (OAR) increased, but the increase was relatively small. Therefore, in some special cases where the patient really can't keep the arm position consistent during treatment, reasonable adjustment can be accepted. However, in order to ensure accurate radiotherapy, patient position should be as stable and consistent as possible.

Hypofractionated radiotherapy recommendations for localized prostate cancer in Brasil

SUMMARY OBJECTIVE: Several prospective randomized trials have shown that hypofractionation has the same efficacy and safety as the conventional fractionation in the treatment of localized prostate cancer. There are many benefits of hypofractionation, including a more convenient schedule for the patients and better use of resources, which is especially important in low- and middle-income countries like Brasil. Based on these data, the Brazilian Society of Radiotherapy (Sociedade Brasileira de Radioterapia) organized this consensus to guide and support the use of hypofractionated radiotherapy for localized prostate cancer in Brasil. METHODS: The relevant literature regarding moderate hypofractionation (mHypo) and ultra-hypofractionation (uHypo) was reviewed and discussed by a group of experts from public and private centers of different parts of Brasil. Several key questions concerning clinical indications, outcomes and technological requirements for hypofractionation were discussed and voted. For each question, consensus was reached if there was an agreement of at least 75% of the panel members. RESULTS: The recommendations are described in this article. CONCLUSION: This initiative will assist Brazilian radiation oncologists and medical physicists to safely treat localized prostate cancer patients with hypofractionation.

Radioterapia definitiva en el carcinoma adenoide quístico de la tráquea. A propósito de un caso / Definitive radiotherapy in adenoid cystic carcinoma of the trachea. A case report

Los carcinomas adenoides quísticos son tumores extremadamente raros, para los cuales la cirugía es el pilar terapéutico; sin embargo, el abordaje quirúrgico puede estar contraindicado en función del tamaño tumoral, el compromiso de estructuras adyacentes o enfermedades concurrentes. En estos casos, la radioterapia externa definitiva puede ofrecer un adecuado control tumoral y alivio de síntomas. El presente reporte de caso describe un paciente con un tumor irregular que rodea la circunferencia de la tráquea, el cual genera disminución de la luz traqueal, en quién se decidió realizar una reducción de volumen de la lesión tumoral con argón plasma, seguido de colocación de un stent en Y (traqueal, bronquial izquierdo y bronquial derecho) y, posteriormente, realizar un tratamiento definitivo con radioterapia externa con técnica de intensidad modulada a dosis de 60 Gy en fraccionamiento de 2 Gy. Tres meses después del tratamiento, el paciente se presenta sin evidencia radiológica de adenopatías en la base del cuello o axila, con un stent endotraqueal permeable, sin estenosis y con una disminución del volumen tumoral, por lo que fue posible el retiro del stent.

Adenoid cystic carcinomas are extremely rare tumors, for which surgery is the mainstay of therapy; however, the surgical approach may be contradictory depending on tumor size, involvement of adjacent structures or concurrent diseases. In these cases, definitive external beam radiation therapy can offer adequate tumor control and symptom relief. The present case report describes a patient with an irregular tumor that surrounds the circumference of the trachea, causing a decrease in the tracheal lumen, in whom it was decided to perform a volume reduction of tumor with argon plasma, followed by placement of a Y-stent (tracheal, left bronchial and right bronchial), and subsequent definitive treatment with external radiotherapy with intensity modulated technique at doses of 60 Gy in 2 Gy fractionation. Three months after treatment, the patient presents without radiological evidence of lymphadenopathy at the base of the neck or axilla, with a patent endotracheal stent, with no stenosis and a decrease in tumor volume, for which the removal of the Stent was feasilble.

Effect of tumor and normal lung volumes on the lung volume-dose parameters of IMRT in non-small-cell lung cancer

OBJECTIVES: To explore the effect of tumor and normal lung volumes on lung volume-dose parameters in patients with non-small-cell lung cancer (NSCLC) who had undergone intensity-modulated radiation therapy (IMRT). METHODS: The clinical data of 208 patients with NSCLC who underwent radical IMRT between June 2014 and June 2018 were retrospectively analyzed. A regression model curve was used to evaluate the effect of tumor and normal lung volumes on normal lung relative volumes receiving greater than 5 and 20 Gy (V5, V20), on mean lung dose (MLD), and on absolute volumes spared from greater than 5 and 20 Gy (AVS5, AVS20). RESULTS: The V5, V20, and MLD of the bilateral lung were fitted to a quadratic equation curve with the change in tumor volume, which increased initially and then decreased when the tumor volume increased. The V5, V20, and MLD of the lung reached their apex when the tumor volumes were 288.07, 341.69, and 326.83 cm3, respectively. AVS5 and AVS20 decreased in a logarithmic curve with an increase in tumor volume. The V5, V20, and MLD of the small normal lung volume group were all significantly higher than those of the large normal lung volume group (p<0.001, p=0.004, p=0.002). However, the AVS5 and AVS20 of the small normal lung volume group were all significantly lower than those of the large normal lung volume group (p<0.001). CONCLUSION: The effects of tumor volume and normal lung volume on dose-volume parameters should be considered. AVS5 is an important supplementary dose limitation parameter for patients whose tumor volume exceeds a certain boundary value (approximately 300 cm3).

Research on Individualized Phantom Based on 3D Printing for Radiotherapy Dose Verification / 中国医疗器械杂志

Dose verification is carried out on the individualized three-dimensional phantom based on 3D printing technology, which simulates the anatomical structure of human body, contour shape, tumor anatomical structure and other dangerous organs to the greatest extent, and produces a reasonable and effective dose validation phantom. According to the need to obtain effective patient data, import Mimics software to reconstruct the parts of the body and its surrounding tissues and organs that need to be measured, and make them into three-dimensional shell components. The 3D printing is used to assemble and fill the equivalent tissue, and then the body phantom is made. The phantom was scanned by CT and the data was transmitted to TPS system. The previously completed treatment plan was transplanted to the phantom. The phantom was placed according to the patient's location information, irradiated and measured data. The three-dimensional shell assembly is completely reconstructed according to the patient's data, and the contour difference is not significant. The shell is filled with tissue radiation equivalent material whose CT value is the same as the average CT value of the shell volume. The CT image data show that the radiation equivalence of the phantom is similar to the actual tissue of the patient, and the equivalent dose distribution conforms to the conventional treatment range. It can provide a reliable means of dose verification for the accurate design of intensity modulated radiation therapy.

Dosimetric verification of stereotactic body radiotherapy treatment plan via ArcCHECK-3DVH system / 中南大学学报(医学版)

OBJECTIVES@#To study the feasibility of ArcCHECK-3DVH system in dosimetric verification for stereotactic body radiaotherapy (SBRT) with flattening filter free (FFF) model.@*METHODS@#SBRT treatment plans for 57 patients were introduced into ArcCHECK phantom and recalculated. The calculated dose distribution of treatment planning system and the measured dose distribution of ArcCHECK phantom were compared by γ analysis. Then the 3 dimensional dose distribution of target and organs at risk was reconstructed by 3DVH software. The reconstructed dose and calculated dose with treatment planning system (TPS) were compared, and the dose volume γ pass rate and deviation of dose volume parameters to the target and organs at risk were quantitatively valuated.@*RESULTS@#Based on the threshold criteria (3%, 3 mm, 10%), namely the deviation of measuring points between the planned value and the measured value was less than 3%, and the proportion of points with similar values in the plane or sphere with the center of the point and the radius of 3 mm was 10%, the relative and absolute dose pass rates of SBRT treatment plans in ArcCHECK system via γ analysis were greater than 95%. Based on the stricter threshold criteria (2%, 2 mm, 10%), the relative and absolute dose pass rates of SBRT treatment plan in ArcCHECK system via γ analysis were about 93%. In 3DVH dose verification, the γ pass rate of target and organs at risk was exceed 97%, and the deviations in 3DVH of the target and organs at risk were less than ±5%.@*CONCLUSIONS@#The ArcCHECK-3DVH system in dose verification can provide more comprehensive dose distribution information to reasonably evaluate the SBRT plan, with more significance for guiding clinical treatment.

Application of Statistical Process Control in Evaluation of Performance for Beam-matched Medical Electron Linacs / 中国医疗器械杂志

Clinically, beam matching can greatly improve the flexibility and efficiency of treating patients between different medical electron linacs. However, in addition to the regular quality assurance (QA) test of the machine performance of linacs, there is still a lack of comprehensive evaluation of the clinical radiotherapy performance of beam-matched linacs. In this paper, the performance of volumetric modulated arc therapy (VMAT) between three closely matched linacs was evaluated by statistical process control (SPC) technology. It was found that the average and median γ passing rates of the VMAT QA processes of the three linacs had little difference, but the process capability levels were at three different levels. The results show that SPC technology can effectively evaluate the performance of beam matching for medical electron linacs, improve the patient-specific VMAT QA processes, and guide clinical decision-making.

Short-term effect of intensity-modulated radiotherapy for children with high-risk neuroblastoma: an analysis of 24 cases / 中国当代儿科杂志

OBJECTIVE@#To study the efficacy and safety of intensity-modulated radiotherapy (IMRT) in children with high-risk neuroblastoma (NB).@*METHODS@#A retrospective analysis was performed on the medical data of 24 children with high-risk NB who were diagnosed and treated with IMRT in the Department of Hematology and Oncology, Hunan Provincial People's Hospital, from April 2018 to December 2020. The medical data included age, radiotherapy dose, times of radiotherapy, laboratory examination results, adverse reactions, and survival.@*RESULTS@#All 24 children (14 boys and 10 girls) received IMRT, with a mean age of (65±23) months and a median age of 59 months. The primary tumor was located in the abdomen in 23 children and 1 child had primary tumor in the mediastinum. The median age was 41.5 months at the time of radiotherapy. The radiation dose of radiotherapy ranged from 14.4 to 36.0 Gy, with a mean dose of (22±3) Gy and a daily dose of 1.8-2.0 Gy. The radiotherapy was performed for a total number of 8-20 times, with a mean number of 11.9 times. Among these children, 6 received radiotherapy for the residual or metastatic lesion. Of all the 23 children, 3 experienced cough, 2 experienced diarrhea, and 1 experienced vomiting during radiotherapy. At 2 weeks after radiotherapy, serum creatinine ranged from 2.3 to 70.1 μmol/L and alanine aminotransferase ranged from 9.1 to 65.3 μ/L. Ten children experienced grade Ⅲ bone marrow suppression and 2 experienced grade Ⅳ bone marrow suppression 1 to 2 weeks after radiotherapy. Four children experienced grade Ⅲ bone marrow suppression and 1 experienced grade Ⅳ bone marrow suppression 3 to 4 weeks after radiotherapy. During a median follow-up time of 13.5 months, 23 children (96%) achieved stable disease and 1 died. Up to the follow-up date, second malignant tumor or abnormal organ function was not observed.@*CONCLUSIONS@#IMRT can improve the local control rate of NB. IMRT appears to be safe in the treatment of children with NB.

Supervivencia global y supervivencia libre de recaída bioquímica en pacientes con cáncer de próstata tratados con radioterapia de intensidad modulada (IMRT) en el Instituto Nacional de Cancerología / Global survival and biochemical relapse-free survival in patients with prostate cancer treated with intensity modulated radiotherapy (IMRT) at the National Cancer Institute

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.