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1.
Anticancer Res ; 41(10): 5131-5135, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34593464

RESUMO

BACKGROUND/AIM: Image-guided intensity-modulated radiotherapy (IG-IMRT) is increasingly being used to treat patients with head and neck malignancies. This analysis compared conventional radiotherapy (CRT) and IMRT outcomes for head and neck aggressive extranodal non-Hodgkin lymphomas (EN-NHL). PATIENTS AND METHODS: Forty-eight patients who underwent irradiation between 2005 and 2019 were identified. RESULTS: The median follow-up was 42 months. Patients treated with IMRT experienced higher overall responde rate than patients who received 3DCRT (85% vs. 73%, p=0.4). There was non-significant longer survival following IMRT compared with 3DCRT in terms of 5-year OS (p=0.16). Complete responders after primary treatments had a significantly higher 5-year progression-free (p<0.001) and overall survival (p=0.003) in comparison with those without a complete response. Regarding toxicities, IMRT was associated with less acute and chronic adverse events. CONCLUSION: IG-IMRT following systemic therapy seems to be associated with a favorable survival and toxicity profile in patients with EN-NHL.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Linfoma não Hodgkin/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem/mortalidade , Radioterapia de Intensidade Modulada/mortalidade , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Linfoma não Hodgkin/patologia , Masculino , Pessoa de Meia-Idade , Prognóstico , Dosagem Radioterapêutica , Estudos Retrospectivos , Taxa de Sobrevida
2.
J Appl Clin Med Phys ; 22(10): 210-221, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34529332

RESUMO

PURPOSE: This provides a benchmark of dosimetric benefit and clinical cost of cone-beam CT-based online adaptive radiotherapy (ART) technology for cervical and rectal cancer patients. METHODS: An emulator of a CBCT-based online ART system was used to simulate more than 300 treatments for 13 cervical and 15 rectal cancer patients. CBCT images were used to generate adaptive replans. To measure clinical resource cost, the six phases of the workflow were timed. To evaluate the dosimetric benefit, changes in dosimetric values were assessed. These included minimum dose (Dmin) and volume receiving 95% of prescription (V95%) for the planning target volume (PTV) and the clinical target volume (CTV), and maximum 2 cc's (D2cc) of the bladder, bowel, rectum, and sigmoid colon. RESULTS: The average duration of the workflow was 24.4 and 9.2 min for cervical and rectal cancer patients, respectively. A large proportion of time was dedicated to editing target contours (13.1 and 2.7 min, respectively). For cervical cancer patients, the replan changed the Dmin to the PTVs and CTVs for each fraction 0.25 and 0.25 Gy, respectively. The replan changed the V95% by 9.2 and 7.9%. The D2cc to the bladder, bowel, rectum, and sigmoid colon for each fraction changed -0.02, -0.08, -0.07, and -0.04 Gy, respectively. For rectal cancer patients, the replan changed the Dmin to the PTVs and CTVs for each fraction of 0.20 and 0.24 Gy, respectively. The replan changed the V95% by 4.1 and 1.5%. The D2cc to the bladder and bowel for each fraction changed 0.02 and -0.02 Gy, respectively. CONCLUSIONS: Dosimetric benefits can be achieved with CBCT-based online ART that is amenable to conventional appointment slots. The clinical significance of these benefits remains to be determined. Managing contours was the primary factor affecting the total duration and is imperative for safe and effective adaptive radiotherapy.


Assuntos
Radioterapia Guiada por Imagem , Radioterapia de Intensidade Modulada , Tomografia Computadorizada de Feixe Cônico Espiral , Neoplasias do Colo do Útero , Feminino , Humanos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Reto/diagnóstico por imagem , Neoplasias do Colo do Útero/diagnóstico por imagem , Neoplasias do Colo do Útero/radioterapia
3.
Phys Med ; 89: 243-249, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34428608

RESUMO

PURPOSE: To assess the effectiveness of SGRT in clinical applications through statistical process control (SPC). METHODS: Taking the patients' positioning through optical surface imaging (OSI) as a process, the average level of process execution was defined as the process mean. Setup errors detected by cone-beam computed tomography (CBCT) and OSI were extracted for head-and-neck cancer (HNC) and breast cancer patients. These data were used to construct individual and exponentially weighted moving average (EWMA) control charts to analyze outlier fractions and small process shifts from the process mean. Using the control charts and process capability indices derived from this process, the patient positioning-related OSI performance and setup error were analyzed for each patient. RESULTS: Outlier fractions and small shifts from the process mean that are indicative of setup errors were found to be widely prevalent, with the outliers randomly distributed between fractions. A systematic error of up to 1.6 mm between the OSI and CBCT results was observed in all directions, indicating a significantly degraded OSI performance. Adjusting this systematic error for each patient using setup errors of the first five fractions could effectively mitigate these effects. Process capability analysis following adjustment for systematic error indicated that OSI performance was acceptable (process capability index Cpk = 1.0) for HNC patients but unacceptable (Cpk < 0.75) for breast cancer patients. CONCLUSION: SPC is a powerful tool for detecting the outlier fractions and process changes. Our application of SPC to patient-specific evaluations validated the suitability of OSI in clinical applications involving patient positioning.


Assuntos
Neoplasias da Mama , Neoplasias de Cabeça e Pescoço , Radioterapia Guiada por Imagem , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/radioterapia , Tomografia Computadorizada de Feixe Cônico , Feminino , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Posicionamento do Paciente , Planejamento da Radioterapia Assistida por Computador , Erros de Configuração em Radioterapia
4.
J Appl Clin Med Phys ; 22(9): 252-261, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34409766

RESUMO

PURPOSE: Demonstrate a novel phantom design using a remote camera imaging method capable of concurrently measuring the position of the x-ray isocenter and the magnetic resonance imaging (MRI) isocenter on an MR-linac. METHODS: A conical frustum with distinct geometric features was machined out of plastic. The phantom was submerged in a small water tank, and aligned using room lasers on a MRIdian MR-linac (ViewRay Inc., Cleveland, OH). The phantom physical isocenter was visualized in the MR images and related to the DICOM coordinate isocenter. To view the x-ray isocenter, an intensified CMOS camera system (DoseOptics LLC., Hanover, NH) was placed at the foot of the treatment couch, and centered such that the optical axis of the camera was coincident with the central axis of the treatment bore. Two or four 8.3mm x 24.1cm beams irradiated the phantom from cardinal directions, producing an optical ring on the conical surface of the phantom. The diameter of the ring, measured at the peak intensity, was compared to the known diameter at the position of irradiation to determine the Z-direction offset of the beam. A star-shot method was employed on the front face of the frustum to determine X-Y alignment of the MV beam. Known shifts were applied to the phantom to establish the sensitivity of the method. RESULTS: Couch translations, demonstrative of possible isocenter misalignments, on the order of 1mm were detectable for both the radiotherapy and MRI isocenters. Data acquired on the MR-linac demonstrated an average error of 0.28mm(N=10, R2 =0.997, σ=0.37mm) in established Z displacement, and 0.10mm(N=5, σ=0.34mm) in XY directions of the radiotherapy isocenter. CONCLUSIONS: The phantom was capable of measuring both the MRI and radiotherapy treatment isocenters. This method has the potential to be of use in MR-linac commissioning, and could be streamlined to be valuable in daily constancy checks of isocenter coincidence.


Assuntos
Aceleradores de Partículas , Radioterapia Guiada por Imagem , Humanos , Imageamento por Ressonância Magnética , Imagens de Fantasmas , Planejamento da Radioterapia Assistida por Computador
5.
Cancer Radiother ; 25(6-7): 607-616, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34389243

RESUMO

Deep-learning (DL)-based auto-contouring solutions have recently been proposed as a convincing alternative to decrease workload of target volumes and organs-at-risk (OAR) delineation in radiotherapy planning and improve inter-observer consistency. However, there is minimal literature of clinical implementations of such algorithms in a clinical routine. In this paper we first present an update of the state-of-the-art of DL-based solutions. We then summarize recent recommendations proposed by the European society for radiotherapy and oncology (ESTRO) to be followed before any clinical implementation of artificial intelligence-based solutions in clinic. The last section describes the methodology carried out by three French radiation oncology departments to deploy CE-marked commercial solutions. Based on the information collected, a majority of OAR are retained by the centers among those proposed by the manufacturers, validating the usefulness of DL-based models to decrease clinicians' workload. Target volumes, with the exception of lymph node areas in breast, head and neck and pelvic regions, whole breast, breast wall, prostate and seminal vesicles, are not available in the three commercial solutions at this time. No implemented workflows are currently available to continuously improve the models, but these can be adapted/retrained in some solutions during the commissioning phase to best fit local practices. In reported experiences, automatic workflows were implemented to limit human interactions and make the workflow more fluid. Recommendations published by the ESTRO group will be of importance for guiding physicists in the clinical implementation of patient specific and regular quality assurances.


Assuntos
Aprendizado Profundo , Neoplasias/diagnóstico por imagem , Órgãos em Risco/diagnóstico por imagem , Radioterapia (Especialidade)/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Europa (Continente) , Humanos , Neoplasias/radioterapia , Guias de Prática Clínica como Assunto , Radioterapia Guiada por Imagem/métodos , Sociedades Médicas , Carga de Trabalho
6.
J Appl Clin Med Phys ; 22(9): 215-226, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34406710

RESUMO

BACKGROUND AND PURPOSE: When treating lung tumors with stereotactic body radiation therapy (SBRT), patient immobilization is of outmost importance. In this study, the intra-fractional shifts of the patient (based on bony anatomy) and the tumor (based on the visible target volume) are quantified, and the associated impact on the delivered dose is estimated for a frameless immobilization approach in combination with surface guided radiation therapy (SGRT) monitoring. METHODS: Cone beam computed tomographies (CBCT) were collected in free breathing prior and after each treatment for 25 patients with lung tumors, in total 137 fractions. The CBCT collected after each treatment was registered to the CBCT collected before each treatment with focus on bony anatomy to determine the shift of the patient, and with focus on the visible target volume to determine the shift of the tumor. Rigid registrations with 6 degrees of freedom were used. The patients were positioned in frameless immobilizations with their position and respiration continuously monitored by a commercial SGRT system. The patients were breathing freely within a preset gating window during treatment delivery. The beam was automatically interrupted if isocenter shifts >4 mm or breathing amplitudes outside the gating window were detected by the SGRT system. The time between the acquisition of the CBCTs was registered for each fraction to examine correlations between treatment time and patient shift. The impact of the observed shifts on the dose to organs at risk (OAR) and the gross tumor volume (GTV) was assessed. RESULTS: The shift of the patient in the CBCTs was ≤2 mm for 132/137 fractions in the vertical (vrt) and lateral (lat) directions, and 134/137 fractions in the longitudinal (lng) direction and ≤4 mm in 134/137 (vrt) and 137/137 (lat, lng) of the fractions. The shift of the tumor was ≤2 mm in 116/137 (vrt), 123/137 (lat) and 115/137 (lng) fractions and ≤4 mm in 136/137 (vrt), 137/137 (lat), and 135/137 (lng) fractions. The maximal observed shift in the evaluated CBCT data was 4.6 mm for the patient and 7.2 mm for the tumor. Rotations were ≤3.3ᵒ for all fractions and the mean/standard deviation were 0.2/1.0ᵒ (roll), 0.1/0.8ᵒ (yaw), and 0.3/1.0ᵒ (pitch). The SGRT system interrupted the beam due to intra-fractional isocenter shifts >4 mm for 21% of the fractions, but the patients always returned within tolerance without the need of repositioning. The maximal observed isocenter shift by the SGRT system during the beam holds was 8 mm. For the respiration monitoring, the beam was interrupted at least one time for 54% of the fractions. The visual tumor was within the planned internal target volume (ITV) for 136/137 fractions in the evaluated CBCT data collected at the end of each fraction. For the fraction where the tumor was outside the ITV, the D98% for the GTV decreased with 0.4 Gy. For the OARs, the difference between planned and estimated dose from the CBCT data (D2% or Dmean ) was ≤2.6% of the prescribed PTV dose. No correlation was found between treatment time and the magnitude of the patient shift. CONCLUSIONS: Using SGRT for motion management and respiration monitoring in combination with a frameless immobilization is a feasible approach for lung SBRT.


Assuntos
Neoplasias Pulmonares , Radiocirurgia , Radioterapia Guiada por Imagem , Tomografia Computadorizada de Feixe Cônico , Humanos , Pulmão , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/cirurgia , Movimento , Planejamento da Radioterapia Assistida por Computador
7.
Comput Med Imaging Graph ; 91: 101953, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34242852

RESUMO

Magnetic Resonance Imaging (MRI) guided Radiation Therapy is a hot topic in the current studies of radiotherapy planning, which requires using MRI to generate synthetic Computed Tomography (sCT). Despite recent progress in image-to-image translation, it remains challenging to apply such techniques to generate high-quality medical images. This paper proposes a novel framework named Multi-Cycle GAN, which uses the Pseudo-Cycle Consistent module to control the consistency of generation and the domain control module to provide additional identical constraints. Besides, we design a new generator named Z-Net to improve the accuracy of anatomy details. Extensive experiments show that Multi-Cycle GAN outperforms state-of-the-art CT synthesis methods such as Cycle GAN, which improves MAE to 0.0416, ME to 0.0340, PSNR to 39.1053.


Assuntos
Processamento de Imagem Assistida por Computador , Radioterapia Guiada por Imagem , Imageamento por Ressonância Magnética , Planejamento da Radioterapia Assistida por Computador , Tomografia Computadorizada por Raios X
8.
J Med Imaging Radiat Oncol ; 65(5): 596-611, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34288501

RESUMO

During radiotherapy, the organs and tumour move as a result of the dynamic nature of the body; this is known as intrafraction motion. Intrafraction motion can result in tumour underdose and healthy tissue overdose, thereby reducing the effectiveness of the treatment while increasing toxicity to the patients. There is a growing appreciation of intrafraction target motion management by the radiation oncology community. Real-time image-guided radiation therapy (IGRT) can track the target and account for the motion, improving the radiation dose to the tumour and reducing the dose to healthy tissue. Recently, artificial intelligence (AI)-based approaches have been applied to motion management and have shown great potential. In this review, four main categories of motion management using AI are summarised: marker-based tracking, markerless tracking, full anatomy monitoring and motion prediction. Marker-based and markerless tracking approaches focus on tracking the individual target throughout the treatment. Full anatomy algorithms monitor for intrafraction changes in the full anatomy within the field of view. Motion prediction algorithms can be used to account for the latencies due to the time for the system to localise, process and act.


Assuntos
Movimento (Física) , Radioterapia (Especialidade) , Inteligência Artificial , Humanos , Planejamento da Radioterapia Assistida por Computador , Radioterapia Guiada por Imagem , Radioterapia de Intensidade Modulada
9.
Med Phys ; 48(8): 4523-4531, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34231224

RESUMO

The past decade has seen the increasing integration of magnetic resonance (MR) imaging into radiation therapy (RT). This growth can be contributed to multiple factors, including hardware and software advances that have allowed the acquisition of high-resolution volumetric data of RT patients in their treatment position (also known as MR simulation) and the development of methods to image and quantify tissue function and response to therapy. More recently, the advent of MR-guided radiation therapy (MRgRT) - achieved through the integration of MR imaging systems and linear accelerators - has further accelerated this trend. As MR imaging in RT techniques and technologies, such as MRgRT, gain regulatory approval worldwide, these systems will begin to propagate beyond tertiary care academic medical centers and into more community-based health systems and hospitals, creating new opportunities to provide advanced treatment options to a broader patient population. Accompanying these opportunities are unique challenges related to their adaptation, adoption, and use including modification of hardware and software to meet the unique and distinct demands of MR imaging in RT, the need for standardization of imaging techniques and protocols, education of the broader RT community (particularly in regards to MR safety) as well as the need to continue and support research, and development in this space. In response to this, an ad hoc committee of the American Association of Physicists in Medicine (AAPM) was formed to identify the unmet needs, roadblocks, and opportunities within this space. The purpose of this document is to report on the major findings and recommendations identified. Importantly, the provided recommendations represent the consensus opinions of the committee's membership, which were submitted in the committee's report to the AAPM Board of Directors. In addition, AAPM ad hoc committee reports differ from AAPM task group reports in that ad hoc committee reports are neither reviewed nor ultimately approved by the committee's parent groups, including at the council and executive committee level. Thus, the recommendations given in this summary should not be construed as being endorsed by or official recommendations from the AAPM.


Assuntos
Imageamento por Ressonância Magnética , Radioterapia Guiada por Imagem , Humanos , Aceleradores de Partículas , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Estados Unidos
10.
Radiologe ; 61(9): 839-845, 2021 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-34297139

RESUMO

BACKGROUND: Hybrid devices of MR-scanners and linear accelerators (MR-Linacs) represent a new and promising extension of radiotherapeutic options for prostate cancer. The potential advantage of magnetic resonance imaging (MRI) over computed tomography (CT) for soft tissue contrast is well-known and leads to more consistent and smaller target volumes and improved normal tissue sparing. OBJECTIVES: This article presents an overview of clinical experience, indications, advantages and challenges of utilizing a 1.5 T MR-Linac in the setting of radiotherapy of prostate cancer. RESULTS: All current indications for radiotherapy of prostate cancer can be treated with an MR-Linac. The advantages include daily MR-based imaging in treatment position and daily adaption of the treatment plan on current anatomy (adaptive radiotherapy). Additionally, functional MRI sequences might be exploited to enhance treatment individualization and response assessment. Ultimately treatment on an MR-Linac might further increase the therapeutic window. The limitations of using MR-Linac include treatment complexity and the duration of each session. CONCLUSIONS: MR-Linacs expand the spectrum of radiotherapeutic options for prostate cancer. Increased precision can be reached with daily MRI-based target volume definition and plan adaption. Clinical studies are necessary to identify patient groups who would benefit most from radiotherapy on a MR-Linac.


Assuntos
Neoplasias da Próstata , Radioterapia Guiada por Imagem , Humanos , Imageamento por Ressonância Magnética , Masculino , Aceleradores de Partículas , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/radioterapia , Planejamento da Radioterapia Assistida por Computador
11.
Cancer Radiother ; 25(6-7): 554-564, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34272182

RESUMO

In the current spectrum of cancer treatments, despite high costs, a lack of robust evidence based on clinical outcomes or technical and radiobiological uncertainties, particle therapy and in particular proton therapy (PT) is rapidly growing. Despite proton therapy being more than fifty years old (first proposed by Wilson in 1946) and more than 220,000 patients having been treated with in 2020, many technological challenges remain and numerous new technical developments that must be integrated into existing systems. This article presents an overview of on-going technical developments and innovations that we felt were most important today, as well as those that have the potential to significantly shape the future of proton therapy. Indeed, efforts have been done continuously to improve the efficiency of a PT system, in terms of cost, technology and delivery technics, and a number of different developments pursued in the accelerator field will first be presented. Significant developments are also underway in terms of transport and spatial resolution achievable with pencil beam scanning, or conformation of the dose to the target: we will therefore discuss beam focusing and collimation issues which are important parameters for the development of these techniques, as well as proton arc therapy. State of the art and alternative approaches to adaptive PT and the future of adaptive PT will finally be reviewed. Through these overviews, we will finally see how advances in these different areas will allow the potential for robust dose shaping in proton therapy to be maximised, probably foreshadowing a future era of maturity for the PT technique.


Assuntos
Previsões , Neoplasias/radioterapia , Terapia com Prótons/tendências , Institutos de Câncer , Ciclotrons , Humanos , Análise de Ativação de Nêutrons , Tratamentos com Preservação do Órgão/instrumentação , Tratamentos com Preservação do Órgão/métodos , Órgãos em Risco , Terapia com Prótons/economia , Terapia com Prótons/instrumentação , Terapia com Prótons/métodos , Garantia da Qualidade dos Cuidados de Saúde , Radioterapia Guiada por Imagem/tendências , Síncrotrons
12.
Bull Cancer ; 108(9): 868-876, 2021 Sep.
Artigo em Francês | MEDLINE | ID: mdl-34246458

RESUMO

Radiation therapy is a standard treatment for limbs soft tissue sarcomas. Preoperative versus postoperative radiotherapy has been a controversial topic for years. With preoperative irradiation, the treatment volume is more limited, the delivered dose possibly lower and the tumor volume easier to delimit. Only one randomized trial compared these two irradiation sequences. The results in terms of local control and survival were equivalent but the risk of acute postoperative complications was higher if irradiation was administered before surgery. However, in the latest update of this trial, patients who received adjuvant irradiation exhibited more severe late toxicity than those treated preoperatively. In addition, with modern irradiation techniques such as conformal with image-guided intensity modulated radiotherapy and flap coverage techniques, the incidence of complications after preoperative irradiation were lower than historically published rates. Locally advanced proximal sarcomas and the failure of other neoadjuvant treatments are nowadays classical indications for preoperative irradiation. As with other neoadjuvant treatments, induction radiotherapy must be personalized according to the histological subtype, the tumor site and the benefit/risk ratio, which is best appreciated by a multidisciplinary surgical and oncological team in a specialized center in the management of soft-tissue sarcomas.


Assuntos
Neoplasias de Tecidos Moles/radioterapia , Doença Aguda , Quimiorradioterapia , Extremidades , Humanos , Terapia Neoadjuvante/métodos , Cuidados Pós-Operatórios , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/prevenção & controle , Cuidados Pré-Operatórios/efeitos adversos , Terapia com Prótons , Dosagem Radioterapêutica , Radioterapia Adjuvante/efeitos adversos , Radioterapia Adjuvante/métodos , Radioterapia Conformacional , Radioterapia Guiada por Imagem , Radioterapia de Intensidade Modulada , Neoplasias de Tecidos Moles/patologia , Neoplasias de Tecidos Moles/terapia , Carga Tumoral
13.
J Appl Clin Med Phys ; 22(9): 73-81, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34272810

RESUMO

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education, and professional practice of medical physics. The AAPM has more than 8000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized.


Assuntos
Radioterapia (Especialidade) , Radioterapia Guiada por Imagem , Física Médica , Humanos , Sociedades , Estados Unidos , Raios X
14.
J Appl Clin Med Phys ; 22(8): 45-59, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34275176

RESUMO

PURPOSE: To develop and implement an acceptance procedure for the new Elekta Unity 1.5 T MRI-linac. METHODS: Tests were adopted and, where necessary adapted, from AAPM TG106 and TG142, IEC 60976 and NCS 9 and NCS 22 guidelines. Adaptations were necessary because of the atypical maximum field size (57.4 × 22 cm), FFF beam, the non-rotating collimator, the absence of a light field, the presence of the 1.5 T magnetic field, restricted access to equipment within the bore, fixed vertical and lateral table position, and the need for MR image to MV treatment alignment. The performance specifications were set for stereotactic body radiotherapy (SBRT). RESULTS: The new procedure was performed similarly to that of a conventional kilovoltage x-ray (kV) image guided radiation therapy (IGRT) linac. Results were acquired for the first Unity system. CONCLUSIONS: A comprehensive set of tests was developed, described and implemented for the MRI-linac. The MRI-linac met safety requirements for patients and operators. The system delivered radiation very accurately with, for example a gantry rotation locus of isocenter of radius 0.38 mm and an average MLC absolute positional error of 0.29 mm, consistent with use for SBRT. Specifications for clinical introduction were met.


Assuntos
Planejamento da Radioterapia Assistida por Computador , Radioterapia Guiada por Imagem , Humanos , Imageamento por Ressonância Magnética , Aceleradores de Partículas , Imagens de Fantasmas , Dosagem Radioterapêutica
15.
J Appl Clin Med Phys ; 22(8): 168-174, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34302421

RESUMO

The purpose of this study is to validate a previously developed algorithm for alerting clinicians when to consider re-CT simulation due to changes in the patient's anatomy during radiation therapy of head and neck cancer. Cone beam computed tomography (CBCT) data were collected prospectively for 77 patients. Each CBCT was mathematically compared to a reference CBCT using the gamma index. We defined the match quality parameter (MQP) as an indicator of CBCT image similarity, where a negative MQP value indicates a poorer CBCT match than the match between the first two CBCT acquired during treatment. If three consecutive MQP values were below a chosen threshold, an "alert" is triggered to indicate action required, for example, possible re-CT simulation. The timing of image review requests made by the radiation therapists and any re-CT/re-plan decisions were documented for each patient's treatment course. The MQP for each patient (including any re-plans) was calculated in a manner that was blinded from the clinical process. The MQP as a function of fraction number was compared to actual clinical decisions in the treatment progress to evaluate alert system performance. There was a total of 93 plans (including re-plans) with 34 positives (action required) and 59 negatives (no action required). The sensitivity of the alert system was 0.76 and the false positive rate was 0.37. Only 1 case out of the 34 positive cases would have been missed by both the alert system and our clinical process. Despite the false negatives and false positives, analysis of the timing of alert triggers showed that the alert system could have resulted in seven fewer clinical misses. The alert system has the potential to be a valuable tool to complement human judgment and to provide a quality assurance safeguard to help improve the delivery of radiation treatment of head and neck cancer.


Assuntos
Neoplasias de Cabeça e Pescoço , Radioterapia Guiada por Imagem , Tomografia Computadorizada de Feixe Cônico , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador
16.
Br J Radiol ; 94(1124): 20210068, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-34282947

RESUMO

OBJECTIVES: A simple, robust method, for optimising cone-beam CT (CBCT) dose and image quality for pelvis treatment, based on patient-specific attenuation. METHODS: Methods were investigated for grouping patients into four imaging categories (small [S], medium [M], large [L], extra large [XL]), based on planning-CT CTDIvol, and phantoms constructed to represent each group. CBCTs with varying kV, mA and ms honed in on the best settings, with a bladder noise of 25 HU. A patient pilot study clinically verified the new imaging settings. RESULTS: The planning CTDIvol is a reliable method for grouping patients. Phantom measurements from the S, M and L groups show doses significantly reduced (19-83% reduction), whilst the XL group required an increase of 39%. Phantom TLD measurements showed the number of scans needed to increase rectal organ at risk (OAR) dose by 1 Gy was 143 (S group) and 50 (M group). Images were qualitatively assessed as sufficient by clinicians. CONCLUSION: Patient-specific CBCT modes are in use clinically with dose reductions across all modes except Pelvis XL, keeping doses ALARP and images optimal. Consideration of OAR doses controls the number of CBCTs allowed to ensure adherence to OAR tolerance. Reporting CBCT doses in "scans per Gray" allows clinicians to make informed decisions regarding the imaging schedule and concomitant doses. ADVANCES IN KNOWLEDGE: Patient grouping at planning CT, using CTDIvol, allows for CBCT imaging protocols to be selected based on patient specific attenuation. Reporting OAR doses in terms of "scans per Gray" allows translation of imaging dose risk to the Oncologist.


Assuntos
Tomografia Computadorizada de Feixe Cônico , Neoplasias Pélvicas/radioterapia , Dosagem Radioterapêutica , Radioterapia Guiada por Imagem , Feminino , Humanos , Masculino , Imagens de Fantasmas , Projetos Piloto , Doses de Radiação , Estudos Retrospectivos
18.
Medicine (Baltimore) ; 100(28): e26659, 2021 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-34260572

RESUMO

RATIONALE: Tenosynovial giant cell tumor (TGCT) is a neoplastic, inflammatory disease with a benign but aggressive course that often presents as localized (TGCT-L) and diffuse (TGCT-D) forms based on the growth pattern and clinical behavior. For TGCT-L, simple excision of the diseased synovial tissue is the preferred treatment option, while for TGCT-D, adequate synovectomy is usually tricky but is essential. However, approximately 44% of TGCT-D cases will relapse after surgery alone. Thus, the optimal treatment strategy in patients with TGCT-D is evolving, and standalone surgical resection can no longer be regarded as the only treatment. The previous studies have shown that postoperative adjuvant radiotherapy can reduce recurrence in TGCT, especially in patients with incomplete synovectomy. PATIENT CONCERNS: In the first case, a 54-year-old male presented with recurrent pain and swelling of the right knee with a protracted disease course (≥10 years). The other patient is a 64-year-old male who developed swelling, pain, abnormal bending, and limited movement of the left knee without obvious inducement. DIAGNOSES: Clinical and imaging examinations can provide a definitive diagnosis, and pathology is the gold standard. TGCT-D was confirmed by postoperative pathology. After the operation, the patients underwent an MRI re-examination and showed that the lesions of the knee were not completely resected. INTERVENTIONS: Arthroscopic synovectomy was performed on the patients, and postoperative pathology was confirmed as TGCT-D. Because of incomplete synovectomy, the 2 cases received image-guided, intensity-modulated radiotherapy (IG-IMRT) after the operation. OUTCOMES: The follow-up time was 1 year, no evidence of disease progression was found in MRI. No obvious adverse effects associated with radiotherapy were detected during the follow-up period. LESSONS: These cases and reviews illustrate the necessity of radiotherapy for TGCT-D and that IG-IMRT is a safe and effective method for treating TGCT-D of the knee.


Assuntos
Tumor de Células Gigantes de Bainha Tendinosa/radioterapia , Articulação do Joelho/patologia , Radioterapia Guiada por Imagem/métodos , Tumor de Células Gigantes de Bainha Tendinosa/diagnóstico por imagem , Tumor de Células Gigantes de Bainha Tendinosa/patologia , Tumor de Células Gigantes de Bainha Tendinosa/cirurgia , Humanos , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/cirurgia , Espectroscopia de Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Sinovectomia
20.
Med Phys ; 48(9): 5531-5539, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34173976

RESUMO

PURPOSE: We evaluated the correlation between stomach volume change and interfractional baseline shifts of the diaphragm in image-guided radiotherapy (IGRT) for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty-four patients with HCC underwent ten fractions of IGRT, and a total of 240 cone beam computed tomography (CBCT) and on-board imager (OBI) kV image sets were acquired. These image sets were retrospectively analyzed. Baseline shifts of the diaphragm relative to bone and stomach volume change ratios were evaluated using four-dimensional simulation CT, kV image, and CBCT images. Associations between baseline shifts and patient physiologic factors were investigated. RESULTS: The average baseline shift of the diaphragm in the superior-inferior (SI) direction was 1.5 mm (standard deviation 4.6 mm), which was higher than the shift in other directions (0.7, 2.0 mm and 0.9, 2.6 mm in right-left (RL) and anterior-posterior (AP) directions, respectively). Interfractional baseline shifts of the diaphragm in the SI and AP directions were positively correlated with the stomach volume change ratio (Pearson's r: 0.416 and 0.302, p-value: <0.001 and <0.001, respectively). CONCLUSIONS: The interfractional baseline shifts of the diaphragm in the SI and AP directions correlated well with stomach volume changes. Efforts to maintain a constant stomach volume before the simulation and each treatment, such as fasting, may reduce interfractional baseline shifts of liver tumors.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Radioterapia Guiada por Imagem , Carcinoma Hepatocelular/diagnóstico por imagem , Carcinoma Hepatocelular/radioterapia , Tomografia Computadorizada de Feixe Cônico , Diafragma/diagnóstico por imagem , Humanos , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/radioterapia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Estudos Retrospectivos , Estômago/diagnóstico por imagem
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