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1.
Anticancer Res ; 41(4): 2101-2110, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33813420

RESUMO

BACKGROUND/AIM: To evaluate if topical support therapy during static-intensity modulated radiotherapy (sIMRT) course is able to equal the characteristic minimum risk for radiation proctitis of Image-guided volumetric modulated arc therapy (IG-VMAT) treatment among localized prostate cancer patients. PATIENTS AND METHODS: Rectal toxicity data of the above patients were retrospectively collected throughout three different clinical periods at our Radiotherapy Deparment: from October 2011 to December 2012, prostate cancer patients were treated with sIMRT and in advance supported by means of daily topical corticosteroids; from January 2013 to November 2016, topical corticosteroids were replaced by daily hyaluronic acid enemas; from December 2016 to May 2018 eligible patients were treated with newly introduced IG-VMAT supported by only on-demand topical corticosteroids. RESULTS: Among 359 eligible patients, IG-VMAT was proven generally more effective than sIMRT supported by topical medications in terms of proctitis reduction, although without clinical and practical relevance. CONCLUSION: Topical medications might have a role in radiation proctitis prevention.


Assuntos
Anti-Inflamatórios/administração & dosagem , Proctite/prevenção & controle , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/radioterapia , Radioterapia de Intensidade Modulada , Administração Tópica , Idoso , Idoso de 80 Anos ou mais , Beclometasona/administração & dosagem , Enema/métodos , Humanos , Ácido Hialurônico/administração & dosagem , Itália , Masculino , Pessoa de Meia-Idade , Tratamentos com Preservação do Órgão/métodos , Proctite/etiologia , Neoplasias da Próstata/patologia , Hipofracionamento da Dose de Radiação , Lesões por Radiação/prevenção & controle , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem/efeitos adversos , Radioterapia Guiada por Imagem/métodos , Radioterapia de Intensidade Modulada/efeitos adversos , Radioterapia de Intensidade Modulada/métodos , Estudos Retrospectivos
2.
Zhongguo Yi Liao Qi Xie Za Zhi ; 45(2): 163-166, 2021 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-33825375

RESUMO

In order to adapt to different target shapes and protect the surrounding normal tissues, the design of two-dimensional electron beam radiotherapy planning requires additional lead blocks. But the Pinnacle treatment planning system can not directly shape the lead block conformity to the size of the beam field given by the doctor. Every time, physicists need to manually drag the lead block to form the required beam field. When meeting a two-dimensional electron beam treatment planning with the same field parameters as before, physicists need to rearrange the field for dose calculation, which greatly reduces the design efficiency of the two-dimensional electron beam treatment planning. In this study, we independently developed a two-dimensional electron beam radiotherapy planning system based on Qt Creator. The system can quickly design a two-dimensional electron beam radiotherapy plan, which reduces the repeated work of physicists.


Assuntos
Elétrons , Planejamento da Radioterapia Assistida por Computador , Dosagem Radioterapêutica
3.
Zhongguo Yi Liao Qi Xie Za Zhi ; 45(2): 231-236, 2021 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-33825389

RESUMO

Accurate CT simulation is the key link of precision radiotherapy, and the performance of the localization couch of CT simulator directly affects the accuracy of radiotherapy. With the rapid development of precision radiotherapy, conventional large aperture radiotherapy special CT simulator is difficult to meet the needs of precision radiotherapy localization, so most radiotherapy centers choose high-end diagnostic CT machines equipped with a flat tabletop for radiotherapy localization. In clinical work, the performance testing of the CT simulator localization couch is easy to be ignored. In addition, there are some problems such as insufficient precision in transforming the cradle-shaped couch top of diagnostic CT into a special flat couch top for radiotherapy. This paper provided an in-depth description of the improved design and performance test of the localization couch of the first special GE Revolution CT simulator for radiotherapy introduced by West China Hospital of Sichuan University. After the improvement, all the acceptance tests of the localization couch are in line with the standard, and the performance meets the high-precision radiotherapy localization needs of patients with different body weight in the center.


Assuntos
Planejamento da Radioterapia Assistida por Computador , Tomografia Computadorizada por Raios X , China , Simulação por Computador , Humanos , Imagens de Fantasmas
4.
Magy Onkol ; 65(1): 6-13, 2021 Mar 17.
Artigo em Húngaro | MEDLINE | ID: mdl-33730111

RESUMO

Our aim was to present different treatment strategies (non-gated [NG], respiratory-gated [RG] and deep inspiration breath-hold [DIBH] technique) of linac-based stereotaxic ablative radiotherapy (SABR) for pancreatic cancer in terms of use of marker, abdominal compression, image quality, and time efficiency. From October 2016 to October 2020 14 patients were treated with VMAT-based SABR (NG: 6/14, 8/14 RG RT including 3/8 DIBH SABR). Treatment verification consisted of 3D/4D CBCTs. For intrafractional tumor visualization (11/14) different type of fiducials were used. The average treatment time was the shortest with NG RT, followed by DIBH and RG RT. However, the best image quality was achieved with DIBH technique. The Krippendorff's agreement test among three independent RTTs showed that DIBH CBCT (Cone Beam CT) can produce sufficient image quality for OARs and can be used to reliably determine OARs position related to safety zone (PRV). Overall, marker-based DIBH SABR with intrafractional tumor visualization appears to be the best technique on linac at present.


Assuntos
Neoplasias Pancreáticas , Radiocirurgia , Suspensão da Respiração , Humanos , Neoplasias Pancreáticas/diagnóstico por imagem , Neoplasias Pancreáticas/radioterapia , Neoplasias Pancreáticas/cirurgia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador
5.
Magy Onkol ; 65(1): 14-22, 2021 Mar 17.
Artigo em Húngaro | MEDLINE | ID: mdl-33730112

RESUMO

In treatment planning of small-sized lung tumors treated with stereotactic body radiotherapy (SBRT) in Eclipse treatment planning system with the Normal tissue objective (NTO) tool sharp dose gradients beyond the target volume can be achived. NTO has 5 variable parameters, so it is difficult to know which settings are optimal. The purpose of this study was to characterize the effects of changing NTO parameters on lung SBRT dose distributions. Ten lung SBRT cases were replanned using different NTO parameters. Dose calculation was performed using AAA and AXB algorithms as well. Differences between AAA and AXB plans were statistically significant. Plans were evaluated based on plan quality metrics. According to this analysis the fall-off of 0.15 and the priority of 500 have satisfied our institutional criteria best. Using NTO during planning is recommended in clinical practice.


Assuntos
Neoplasias Pulmonares , Radiocirurgia , Radioterapia de Intensidade Modulada , Algoritmos , Humanos , Pulmão , Neoplasias Pulmonares/radioterapia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador
6.
Magy Onkol ; 65(1): 23-29, 2021 Mar 17.
Artigo em Húngaro | MEDLINE | ID: mdl-33730113

RESUMO

The aim of the study was to compare the different stereotactic treatment plans and dose calculation algorithms for small targets with film dosimetry in anthropomorphic phantom. Treatment plans were prepared for multiple targets with single setup isocenter. Plans for three different irradiation techniques were generated using conformal arc with four non-coplanar arcs, RapidArc with two coplanar full arcs and RapidArc with four non-coplanar arcs in the Varian Eclipse v13.7.16 TPS. Conformal arc and RapidArc plans were calculated using AAA, Acuros XBDm and XBDw algorithms. Conformity index, gradient index and dose maximum were calculated for all PTVs. All measurements were made on the Varian TrueBeam linear accelerator. Comparison between computed and measured dose distributions was performed with gamma evaluation criteria of 3%, 3 mm; 3%, 1 mm and 2%, 2 mm. According to our results, the Eclipse AAA and AXB algorithms provide accurate dose distributions for homogeneous cranial irradiation.


Assuntos
Neoplasias Encefálicas , Radiocirurgia , Radioterapia de Intensidade Modulada , Algoritmos , Neoplasias Encefálicas/radioterapia , Humanos , Aceleradores de Partículas , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador
7.
Magy Onkol ; 65(1): 30-37, 2021 Mar 17.
Artigo em Húngaro | MEDLINE | ID: mdl-33730114

RESUMO

Flattening filter free mode (FFF) has been introduced in radiotherapy during the past decades, however, not much has been reported on its radiobiological effect. The purpose of our study was to compare the radiobiological effects of flattening filter and flattening filter free photon beams on chromosomal aberrations in peripheral blood lymphocytes. In our study the blood of the same healthy donor was irradiated with linear accelerator using both conventional flattening filter (FF) and FFF photon beams at dose rate of 3.57-23.08 Gy/min, using 6 or 10 MV. The dose-response calibration curves for dicentric + ring chromosomes induced by irradiation were fitted with linear-quadratic model. CABAS (Chromosomal Aberration Calculation Software) was used to prepare the curves. The coefficients and equations of the curves were calculated and compared with the results of other authors. We found significant differences in the number of aberrations at different irradiation parameters. Based on our results, FFF mode has a 10-20% higher biological effect than FF mode. These results can be used during radiotherapy or to estimate the biological doses in case of an accidental exposure to radiation.


Assuntos
Aceleradores de Partículas , Fótons , Humanos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Software
8.
Br J Radiol ; 94(1120): 20201397, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33684308

RESUMO

The efficiency of radiotherapy treatment regimes varies from tumour to tumour and from patient to patient but it is generally highly influenced by the tumour microenvironment (TME). The TME can be described as a heterogeneous composition of biological, biophysical, biomechanical and biochemical milieus that influence the tumour survival and its' response to treatment. Preclinical research faces challenges in the replication of these in vivo milieus for predictable treatment response studies. 2D cell culture is a traditional, simplistic and cost-effective approach to culture cells in vitro, however, the nature of the system fails to recapitulate important features of the TME such as structure, cell-cell and cell-matrix interactions. At the same time, the traditional use of animals (Xenografts) in cancer research allows realistic in vivo architecture, however foreign physiology, limited heterogeneity and reduced tumour mutation rates impairs relevance to humans. Furthermore, animal research is very time consuming and costly. Tissue engineering is advancing as a promising biomimetic approach, producing 3D models that capture structural, biophysical, biochemical and biomechanical features, therefore, facilitating more realistic treatment response studies for further clinical application. However, currently, the application of 3D models for radiation response studies is an understudied area of research, especially for pancreatic ductal adenocarcinoma (PDAC), a cancer with a notoriously complex microenvironment. At the same time, specific novel and/or more enhanced radiotherapy tumour-targeting techniques such as MRI-guided radiotherapy and proton therapy are emerging to more effectively target pancreatic cancer cells. However, these emerging technologies may have different biological effectiveness as compared to established photon-based radiotherapy. For example, for MRI-guided radiotherapy, the novel use of static magnetic fields (SMF) during radiation delivery is understudied and not fully understood. Thus, reliable biomimetic platforms to test new radiation delivery strategies are required to more accurately predict in vivo responses. Here, we aim to collate current 3D models for radiation response studies of PDAC, identifying the state of the art and outlines knowledge gaps. Overall, this review paper highlights the need for further research on the use of 3D models for pre-clinical radiotherapy screening including (i) 3D (re)-modeling of the PDAC hypoxic TME to allow for late effects of ionising radiation (ii) the screening of novel radiotherapy approaches and their combinations as well as (iii) a universally accepted 3D-model image quantification method for evaluating TME components in situ that would facilitate accurate post-treatment(s) quantitative comparisons.


Assuntos
Modelos Biológicos , Neoplasias Pancreáticas/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos
9.
Anticancer Res ; 41(3): 1529-1538, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33788746

RESUMO

BACKGROUND/AIM: This study aimed to analyze the dosimetric gain of the deep-inspiration-breath-hold (DIBH) technique over the free-breathing (FB) one in left breast cancer (LBC) 3D-conformal-radiotherapy (3D-CRT), and simultaneously investigate the anatomical parameters related to heart RT-exposure. PATIENTS AND METHODS: Treatment plans were generated in both DIBH and FB scenarios for 116 LBC patients monitored by the Varian RPM™ respiratory gating system for delivery of conventional or moderately hypofractionated schedules (±sequential boost). For comparison, we considered cardiac and ipsilateral lung doses and volumes. RESULTS: A significant reduction of cardiac and pulmonary doses using DIBH technique was achieved compared to FB plans. Larger clinical target volumes generally need longer distance between medial and lateral entrances of tangent fields at body surface, thus conditioning a worse heart RT-exposure. CONCLUSION: The DIBH technique reduces cardiac and pulmonary doses for LBC patients. Through easily detectable anatomical parameters, it is possible to predict which patients benefit most from DIBH-RT.


Assuntos
Neoplasias da Mama/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Conformacional/métodos , Adulto , Idoso , Suspensão da Respiração , Feminino , Coração/efeitos da radiação , Humanos , Pulmão/efeitos da radiação , Pessoa de Meia-Idade , Órgãos em Risco , Hipofracionamento da Dose de Radiação , Dosagem Radioterapêutica , Radioterapia Conformacional/efeitos adversos
10.
Br J Radiol ; 94(1119): 20201031, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33529057

RESUMO

OBJECTIVE: To study dosimetric impact of random spot positioning errors on the clinical pencil beam scanning proton therapy plans. METHODS AND MATERIALS: IMPT plans of 10 patients who underwent proton therapy for tumors in brain or pelvic regions representing small and large volumes, respectively, were included in the study. Spot positioning errors of 1 mm, -1 mm or ±1 mm were introduced in these clinical plans by modifying the geometrical co-ordinates of proton spots using a script in the MATLAB programming environment. Positioning errors were simulated to certain numbers of (20%, 40%, 60%, 80%) randomly chosen spots in each layer of these treatment plans. Treatment plans with simulated errors were then imported back to the Raystation (Version 7) treatment planning system and the resultant dose distribution was calculated using Monte-Carlo dose calculation algorithm.Dosimetric plan evaluation parameters for target and critical organs of nominal treatment plans delivered for clinical treatments were compared with that of positioning error simulated treatment plans. For targets, D95% and D2% were used for the analysis. Dose received by optic nerve, chiasm, brainstem, rectum, sigmoid, and bowel were analyzed using relevant plan evaluation parameters depending on the critical structure. In case of intracranial lesions, the dose received by 0.03 cm3 volume (D0.03 cm3) was analyzed for optic nerve, chiasm and brainstem. In rectum, the volume of it receiving a dose of 65 Gy(RBE) (V65) and 40 Gy(RBE) (V40) were compared between the nominal and error introduced plans. Similarly, V65 and V63 were analyzed for Sigmoid and V50 and V15 were analyzed for bowel. RESULTS: The maximum dose variation in PTV D95% (1.88 %) was observed in a brain plan in which the target volume was the smallest (2.7 cm3) among all 10 plans included in the study. This variation in D95% drops down to 0.3% for a sacral chordoma plan in which the PTV volume is significantly higher at 672 cm3. The maximum difference in OARs in terms of absolute dose (D0.03 cm3) was found in left optic nerve (9.81%) and the minimum difference was observed in brainstem (2.48%). Overall, the magnitude of dose errors in chordoma plans were less significant in comparison to brain plans. CONCLUSION: The dosimetric impact of different error scenarios in spot positioning becomes more prominent for treatment plans involving smaller target volume compared to plans involving larger target volumes. ADVANCES IN KNOWLEDGE: Provides information on the dosimetric impact of various possible spot positioning errors and its dependence on the tumor volume in intensity modulated proton therapy.


Assuntos
Neoplasias Encefálicas/radioterapia , Neoplasias Pélvicas/radioterapia , Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Humanos , Método de Monte Carlo , Dosagem Radioterapêutica , Reprodutibilidade dos Testes
11.
Br J Radiol ; 94(1119): 20200433, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33586999

RESUMO

OBJECTIVE: We aim to test the hypothesis that neurovascular bundle (NVB) displacement by rectal hydrogel spacer combined with NVB delineation as an organ at risk (OAR) is a feasible method for NVB-sparing stereotactic body radiotherapy. METHODS: Thirty-five men with low- and intermediate-risk prostate cancer who underwent rectal hydrogel spacer placement and pre-, post-spacer prostate MRI studies were treated with prostate SBRT (36.25 Gy in five fractions). A prostate radiologist contoured the NVB on both the pre- and post-spacer T2W MRI sequences that were then registered to the CT simulation scan for NVB-sparing radiation treatment planning. Three SBRT treatment plans were developed for each patient: (1) no NVB sparing, (2) NVB-sparing using pre-spacer MRI, and (3) NVB-sparing using post-spacer MRI. NVB dose constraints include maximum dose 36.25 Gy (100%), V34.4 Gy (95% of dose) <60%, V32Gy <70%, V28Gy <90%. RESULTS: Rectal hydrogel spacer placement shifted NVB contours an average of 3.1 ± 3.4 mm away from the prostate, resulting in a 10% decrease in NVB V34.4 Gy in non-NVB-sparing plans (p < 0.01). NVB-sparing treatment planning reduced the NVB V34.4 by 16% without the spacer (p < 0.01) and 25% with spacer (p < 0.001). NVB-sparing did not compromise PTV coverage and OAR endpoints. CONCLUSIONS: NVB-sparing SBRT with rectal hydrogel spacer significantly reduces the volume of NVB treated with high-dose radiation. Rectal spacer contributes to this effect through a dosimetrically meaningful displacement of the NVB that may significantly reduce RiED. These results suggest that NVB-sparing SBRT warrants further clinical evaluation. ADVANCES IN KNOWLEDGE: This is a feasibility study showing that the periprostatic NVBs can be spared high doses of radiation during prostate SBRT using a hydrogel spacer and nerve-sparing treatment planning.


Assuntos
Disfunção Erétil/prevenção & controle , Hidrogéis/uso terapêutico , Neoplasias da Próstata/radioterapia , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Idoso , Estudos de Viabilidade , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Órgãos em Risco/diagnóstico por imagem , Próstata/diagnóstico por imagem , Neoplasias da Próstata/diagnóstico por imagem , Dosagem Radioterapêutica , Reto/diagnóstico por imagem , Estudos Retrospectivos
12.
Cancer Radiother ; 25(2): 200-205, 2021 Apr.
Artigo em Francês | MEDLINE | ID: mdl-33546996

RESUMO

It is proposed to delineate the anatomo-clinical target volumes of primary tumor (CTV-P) in ethmoid cancers treated with post-operative radiotherapy. This concept is based on the use of radioanatomy and the natural history of cancer. It is supported by the repositioning of the planning scanner with preoperative imaging for the replacement of the initial GTV and the creation of margins around it extended to the microscopic risk zones according to the anatomical concept. This article does not discuss the indications of external radiotherapy but specifies the volumes to be delineated if radiotherapy is considered.


Assuntos
Osso Etmoide , Planejamento da Radioterapia Assistida por Computador/métodos , Neoplasias Cranianas/radioterapia , Osso Etmoide/anatomia & histologia , Osso Etmoide/diagnóstico por imagem , Humanos , Imagem por Ressonância Magnética , Cuidados Pós-Operatórios/métodos , Neoplasias Cranianas/diagnóstico por imagem , Neoplasias Cranianas/cirurgia , Tomografia Computadorizada por Raios X
14.
Zhongguo Yi Liao Qi Xie Za Zhi ; 45(1): 109-113, 2021 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-33522189

RESUMO

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.


Assuntos
Elétrons , Aceleradores de Partículas , Garantia da Qualidade dos Cuidados de Saúde , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade Modulada
15.
Artigo em Japonês | MEDLINE | ID: mdl-33473076

RESUMO

PURPOSE: Knowledge-based planning (KBP) has disadvantages of high monitor unit (MU) and complex multi-leaf collimator (MLC) motion. We investigated the optimal aperture shape controller (ASC) level for the KBP to reduce these factors in volumetric modulated arc therapy (VMAT) for prostate cancer. METHODS: The KBP model was created based on 51 clinical plans (CPs) of patients who underwent the VMAT for prostate cancer. Another 10 CPs were selected randomly, and the KBPs with/without ASC, changed stepwise from very low (KBP-VL) to very high (KBP-VH), were performed with a single auto-optimization. The parameters of dose-volume histograms (DVHs) and MLC performance metrics were evaluated. We obtained the modulation complexity score for VMAT (MCSv), closed leaf score (CLS), small aperture score (SAS), leaf travel (LT), and total MU. RESULTS: The ASC did not affect the DVH parameters negatively. The following comparisons of MLC performance were obtained (KBP vs. KBP-VL vs. KBP-VH, respectively): 0.25 vs. 0.27 vs. 0.30 (MCSv), 0.19 vs. 0.18 vs. 0.16 (CLS), 0.50 vs. 0.45 vs. 0.40 (SAS10 mm), 0.73 vs. 0.68 vs. 0.63 (SAS20 mm), 768.35 mm vs. 671.50 mm vs. 551.32 mm (LT), and 672.87 vs. 642.36 vs. 607.59 (MU). There were significant differences between KBP and KBP-VH for MCSv and LT (p<0.05). CONCLUSIONS: The KBP using an ASC set to the very high level could reduce the complexity of MLC motion significantly more without deterioration of the DVH parameters compared with the KBP in VMAT for prostate cancer.


Assuntos
Neoplasias da Próstata , Radioterapia de Intensidade Modulada , Humanos , Bases de Conhecimento , Masculino , Neoplasias da Próstata/radioterapia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador
16.
Medicine (Baltimore) ; 100(1): e24266, 2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33429836

RESUMO

BACKGROUND: Intensity-modulated radiotherapy (IMRT) is a widely used irradiation technique in rectal cancer patients. We aimed to compare 4 different IMRT plans with 3-dimensional conformal radiotherapy (3D-CRT) considering organs at risk (OARs) in patients with rectal carcinoma. METHODS: This retrospective study included 27 rectal cancer patients who were irradiated preoperatively between January 2016 and December 2018. Five different plans (4-field 3D-CRT in 2 phases, 7-field IMRT in 2 phases, 9-field IMRT in 2 phases, 7-field simultaneous integrated boost [SIB] IMRT, and 9-field SIB IMRT) were generated for each patient. Comparison of 5 different plans according to bladder and bilateral femoral head mean doses, bladder V40, bilateral femoral head V40, and small bowel V35 values were evaluated. RESULTS: Most of the OAR parameters significantly favored IMRT plans compared to the 3D-CRT plan. The largest difference was observed in bladder V40 values (reduction of V40 value up to 51.2% reduction) in favor of IMRT. In addition, SIB plans showed significantly better reduction in OARs than phase plans except for small bowel V35 values. CONCLUSIONS: IMRT plans reduced almost all the OARs doses compared with the 3D-CRT plan in rectal cancer patients. Furthermore, SIB plans demonstrated lower OAR doses than the phase plans. IMRT techniques, especially SIB plans, reduce OAR doses and provide safer doses for the treatment of rectal carcinoma.


Assuntos
Adenocarcinoma/radioterapia , Neoplasias Retais/radioterapia , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Órgãos em Risco/efeitos da radiação , Período Pré-Operatório , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade Modulada , Estudos Retrospectivos
17.
Br J Radiol ; 94(1119): 20201354, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33481637

RESUMO

OBJECTIVES: This multicentric study was carried out to investigate the impact of small field output factors (OFs) inaccuracies on the calculated dose in volumetric arctherapy (VMAT) radiosurgery brain plans. METHODS: Nine centres, realised the same five VMAT plans with common planning rules and their specific clinical equipment Linac/treatment planning system commissioned with their OFs measured values (OFbaseline). In order to simulate OFs errors, two new OFs sets were generated for each centre by changing only the OFs values of the smallest field sizes (from 3.2 × 3.2 cm2 to 1 × 1 cm2) with well-defined amounts (positive and negative). Consequently, two virtual machines for each centre were recommissioned using the new OFs and the percentage dose differences ΔD (%) between the baseline plans and the same plans recalculated using the incremented (OFup) and decremented (OFdown) values were evaluated. The ΔD (%) were analysed in terms of planning target volume (PTV) coverage and organs at risk (OARs) sparing at selected dose/volume points. RESULTS: The plans recalculated with OFdown sets resulted in higher variation of doses than baseline within 1.6 and 3.4% to PTVs and OARs respectively; while the plans with OFup sets resulted in lower variation within 1.3% to both PTVs and OARs. Our analysis highlights that OFs variations affect calculated dose depending on the algorithm and on the delivery mode (field jaw/MLC-defined). The Monte Carlo (MC) algorithm resulted significantly more sensitive to OFs variations than all of the other algorithms. CONCLUSION: The aim of our study was to evaluate how small fields OFs inaccuracies can affect the dose calculation in VMAT brain radiosurgery treatments plans. It was observed that simulated OFs errors, return dosimetric calculation accuracies within the 3% between concurrent plans analysed in terms of percentage dose differences at selected dose/volume points of the PTV coverage and OARs sparing. ADVANCES IN KNOWLEDGE: First multicentre study involving different Planning/Linacs about undetectable errors in commissioning output factor for small fields.


Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/radioterapia , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Tomografia Computadorizada por Raios X/métodos , Encéfalo/diagnóstico por imagem , Simulação por Computador , Humanos , Dosagem Radioterapêutica , Reprodutibilidade dos Testes , Incerteza
18.
Cancer Radiother ; 25(2): 161-168, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33454191

RESUMO

PURPOSE: The aims of this study were: determination of the CTV to PTV margins for prostate and pelvic lymph nodes. Investigation of the impact of registration modality (pelvic bones or prostate) on the CTV to PTV margins of pelvic lymph nodes. Investigation of the variations of bladder and rectum over the treatment course. Investigation of the impact of bladder and rectum variations on prostate position. PATIENTS AND METHODS: This study included 15 patients treated for prostate adenocarcinoma. Daily kilo voltage images and weekly CBCT scans were performed to assess prostate displacements and common and external iliac vessels motion. These data was used to calculate the CTV to PTV margins using Van Herk equation in the setting of a daily bone registration. We also compared the CTV to PTV margins of pelvic lymph nodes according to registration method; based on pelvic bone or prostate. We delineated bladder and rectum on all CBCT scans to assess their variations over treatment course at 4 anatomic levels [1.5cm above pubic bone (PB), superior edge, mid- and inferior edge of PB]. RESULTS: Using Van Herk equation, the prostate CTV to PTV margins (bone registration) were 8.03mm, 5.42mm and 8.73mm in AP, ML and SI direction with more than 97% of prostate displacements were less than 5mm. The CTV to PTV margins ranged from 3.12mm to 3.25mm for external iliac vessels and from 3.12mm to 4.18mm for common iliac vessels. Compared to registration based on prostate alignment, bone registration resulted in an important reduction of the CTV to PTV margins up to 54.3% for external iliac vessels and up to 39.6% for common iliac vessels. There was no significant variation of the mean bladder volume over the treatment course. There was a significant variation of the mean rectal volume before and after the third week of treatment. After the third week, the mean rectal volume seemed to be stable. The uni- and multivariate analysis identified the anterior wall of rectum as independent factor acting on prostate motion in AP direction at 2 levels (superior edge of, mid PB). The right rectal wall influenced the prostate motion in ML direction at inferior edge of PB. The bladder volume tends toward significance as factor acting on prostate motion in AP direction. CONCLUSIONS: We recommend CTV to PTV margins of 8mm, 6mm and 9mm in AP, ML and SI directions for prostate. And, we suggest 4mm and 5mm for external and common iliac vessels respectively. We also prefer registration based on bony landmarks to minimize bowel irradiation. More CBCT scans should be performed during the first 3weeks and especially the first week to check rectum volume.


Assuntos
Adenocarcinoma/radioterapia , Linfonodos/diagnóstico por imagem , Próstata/diagnóstico por imagem , Neoplasias da Próstata/radioterapia , Reto/diagnóstico por imagem , Bexiga Urinária/diagnóstico por imagem , Adenocarcinoma/diagnóstico por imagem , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/patologia , Algoritmos , Análise de Variância , Antagonistas de Androgênios/uso terapêutico , Humanos , Artéria Ilíaca/diagnóstico por imagem , Veia Ilíaca/diagnóstico por imagem , Linfonodos/anatomia & histologia , Irradiação Linfática/métodos , Masculino , Movimentos dos Órgãos , Órgãos em Risco/anatomia & histologia , Órgãos em Risco/diagnóstico por imagem , Ossos Pélvicos/anatomia & histologia , Ossos Pélvicos/diagnóstico por imagem , Pelve , Estudos Prospectivos , Próstata/anatomia & histologia , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/patologia , Planejamento da Radioterapia Assistida por Computador/métodos , Erros de Configuração em Radioterapia , Radioterapia Conformacional , Radioterapia Guiada por Imagem , Reto/anatomia & histologia , Estatísticas não Paramétricas , Tomografia Computadorizada por Raios X , Carga Tumoral , Bexiga Urinária/anatomia & histologia
19.
Zhonghua Zhong Liu Za Zhi ; 43(1): 155-159, 2021 Jan 23.
Artigo em Chinês | MEDLINE | ID: mdl-33472330

RESUMO

Objective: To investigate the effect of six degree of freedom (6-DOF) bed combined with cone beam computed tomography (CBCT) in the on-line correction of setup errors in patients with primary rectal cancer. Methods: The clinicopathological data of 17 patients with primary rectal cancer in Department of Radiotherapy, Third Hospital of Peking University from July 2013 to January 2014 were collected. There were 14 males and 3 females, a median age of 65 years. The difference of CBCT and 6-DOF bed combined with CBCT online correction of patients with positioning error were retrospectively analyzed. Results: Before position correction, the first CBCT verification of setup errors in the three translation directions including X (left and right), Y (in and out) and Z (up and down) directions were (0.06±0.25) cm, (0.13±0.40) cm and (-0.28±0.31) cm, respectively. The setup errors of RX (rotation pitch), RY(rolling) and RZ (left and right rotation) directions were (0.62±1.15)°, (-0.19±0.99)°, and (-0.34 ± 0.84)°, respectively . After correction of IGRT combined with six freedom of bed, the setup errors of translation X, Y and Z were (0.01±0.09) cm, (-0.01±0.05) cm and (-0.03±0.08) cm, respectively, and the setup errors of rotation RX, RY and RZ directions were (-0.16±0.40)°, (0.36±0.31)°and (-0.01±0.25)°, respectively. There were significant differences in translation direction (X, Y and Z direction) and rotation direction (Rx, RY and RZ) before and after 6-DOF bed combined with CBCT correction (all P<0.05). In the translation direction, the higher frequency range of Z-direction error value was 0.20-0.79 cm. In the rotation direction, the frequency range of error in Rx direction was 0.20°-2.99°. There was no significant difference between bone mode and gray scale model registration (P>0.05). With the progress of radiotherapy, the setup errors of X, Z, Rx, RY and RZ directions increased except Y direction. Conclusions: In radiotherapy, six freedom bed combined with CBCT is helpful to correct the setup errors of patients with primary rectal cancer. Six freedom bed may be used to correct the setup errors of patients with primary rectal cancer online. Image-guided radiation therapy (IGRT) is recommended for bone pattern registration in patients with rectal cancer.


Assuntos
Radioterapia Guiada por Imagem , Neoplasias Retais , Idoso , Tomografia Computadorizada de Feixe Cônico , Feminino , Humanos , Planejamento da Radioterapia Assistida por Computador , Erros de Configuração em Radioterapia , Neoplasias Retais/diagnóstico por imagem , Neoplasias Retais/radioterapia , Estudos Retrospectivos
20.
Phys Med Biol ; 65(24): 24TR05, 2021 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-33438582

RESUMO

In the late 1980s, a new technique was proposed that would revolutionize radiotherapy. Now referred to as intensity-modulated radiotherapy, it is at the core of state-of-the-art photon beam delivery techniques, such as helical tomotherapy and volumetric modulated arc therapy. Despite over two decades of clinical application, there are still no established guidelines on the calibration of dynamic modulated photon beams. In 2008, the IAEA-AAPM work group on nonstandard photon beam dosimetry published a formalism to support the development of a new generation of protocols applicable to nonstandard beam reference dosimetry (Alfonso et al 2008 Med. Phys. 35 5179-86). The recent IAEA Code of Practice TRS-483 was published as a result of this initiative and addresses exclusively small static beams. But the plan-class specific reference calibration route proposed by Alfonso et al (2008 Med. Phys. 35 5179-86) is a change of paradigm that is yet to be implemented in radiotherapy clinics. The main goals of this paper are to provide a literature review on the dosimetry of nonstandard photon beams, including dynamic deliveries, and to discuss anticipated benefits and challenges in a future implementation of the IAEA-AAPM formalism on dynamic photon beams.


Assuntos
Fótons/uso terapêutico , Radiometria/normas , Radioterapia de Intensidade Modulada , Calibragem , Humanos , Planejamento da Radioterapia Assistida por Computador , Padrões de Referência
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