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1.
Magn Reson Med ; 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34652819

RESUMO

PURPOSE: To design and manufacture a pelvis phantom for magnetic resonance (MR)-guided prostate interventions, such as MRGB (MR-guided biopsy) or brachytherapy seed placement. METHODS: The phantom was designed to mimic the human pelvis incorporating bones, bladder, prostate with four lesions, urethra, arteries, veins, and six lymph nodes embedded in ballistic gelatin. A hollow rectum enables transrectal access to the prostate. To demonstrate the feasibility of the phantom for minimal invasive MRI-guided interventions, a targeted inbore MRGB was performed. The needle probe was rectally inserted and guided using an MRI-compatible remote controlled manipulator (RCM). RESULTS: The presented pelvis phantom has realistic imaging properties for MR imaging (MRI), computed tomography (CT) and ultrasound (US). In the targeted inbore MRGB, a prostate lesion was successfully hit with an accuracy of 3.5 mm. The experiment demonstrates that the limited size of the rectum represents a realistic impairment for needle placements. CONCLUSION: The phantom provides a valuable platform for evaluating the performance of MRGB systems. Interventionalists can use the phantom to learn how to deal with challenging situations, without risking harm to patients.

2.
Z Med Phys ; 2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34373188

RESUMO

PURPOSE: Robotic systems to assist needle placements for low-dose rate brachytherapy enable conformal dose planning only restricted to path planning around risk structures. We report a treatment planning system (TPS) combining multiple direction needle-path planning with inverse dose optimization algorithms. METHODS: We investigated in a path planning algorithm to efficiently locate needle injection points reaching the target volume without puncturing risk structures. A candidate needle domain with all combinations of trajectories is used for the optimization process. We report a modular algorithm for inverse radiation plan optimization. The initial plan with V100>99% is generated by the "greedy optimizer". The "remove-seed algorithm" reduces the number of seeds in the high dose regions. The "depth-optimizer" varies the insertion depth of the needles. The "coverage-optimizer" locates under-dosed areas in the target volume and supports them with an additional amount of seeds. The dose calculation algorithm is benchmarked on an image set of a phantom with a liver metastasis (prescription dose Dpr=100Gy) and is re-planned in a commercial CE-marked TPS to compare the calculated dose grids using a global gamma analysis. The inverse optimizer is benchmarked by calculating 10 plans on the same phantom to investigate the stability and statistical variability of the dose parameters. RESULTS: The path planning algorithm efficiently removes 72.5% of all considered injection points. The candidate needle domain consists of combinations of 1971 tip points and 827 injection points. The global gamma analysis with gamma 1%=2.9Gy, 1mm showed a pass rate of 98.5%. The dose parameters were V100=99.1±0.3%, V150=76.4±2.5%, V200=44.5±5.5% and D90=125.9±3.6Gy and 10.7±1.3 needles with 34.0±0.8 seeds were used. The median of the TPS total running time was 4.4minutes. CONCLUSIONS: The TPS generates treatment plans with acceptable dose coverage in a reasonable amount of time. The gamma analysis shows good accordance to the commercial TPS. The TPS allows taking full advantage of robotic navigation tools to enable a new precise and safe method of minimally invasive low-dose-rate brachytherapy.

3.
Radiologe ; 61(9): 829-838, 2021 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-34251481

RESUMO

CLINICAL/METHODOLOGICAL ISSUE: Multiparametric magnetic resonance imaging (mpMRI) of the prostate plays a crucial role in the diagnosis and local staging of primary prostate cancer. STANDARD RADIOLOGICAL METHODS: Image-guided biopsy techniques such as MRI-ultrasound fusion not only allow guidance for targeted tissue sampling of index lesions for diagnostic confirmation, but also improve the detection of clinically significant prostate cancer. METHODOLOGICAL INNOVATIONS: Minimally invasive, focal therapies of localized prostate cancer complement the treatment spectrum, especially for low- and intermediate-risk patients. PERFORMANCE: In patients of low and intermediate risk, MR-guided, minimally invasive therapies could enable local tumor control, improved functional outcomes and possible subsequent therapy escalation. Further study results related to multimodal approaches and the application of artificial intelligence (AI) by machine and deep learning algorithms will help to leverage the full potential of focal therapies for prostate cancer in the upcoming era of precision medicine. ACHIEVEMENTS: Completion of ongoing randomized trials comparing each minimally invasive therapy approach with established whole-gland procedures is needed before minimally invasive therapies can be implemented into existing treatment guidelines. PRACTICAL RECOMMENDATIONS: This review article highlights minimally invasive therapies of prostate cancer and the key role of mpMRI for planning and conducting these therapies.


Assuntos
Inteligência Artificial , Neoplasias da Próstata , Humanos , Biópsia Guiada por Imagem , Imageamento por Ressonância Magnética , Masculino , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/cirurgia
4.
BMC Cancer ; 19(1): 430, 2019 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-31072314

RESUMO

BACKGROUND: The spine is the most frequent location of bone metastases. Local treatment aims at palliation of pain and, given the increased likelihood of long-term cancer survival, at local control. Kyphoplasty and intraoperative radiotherapy (Kypho-IORT) provided instantaneous pain relief in 70% of patients at the first day after the intervention and resulted in local control rates of > 93% at 1 year in a recently conducted phase I/II trial. To assess its clinical value, we designed a phase III trial which tests Kypho-IORT against the most widespread standard-of-care, external beam radiotherapy (EBRT), in patients with painful vertebral metastases. METHODS: This phase III study includes patients ≥50 years of age with up to 4 vertebral metastases and a pain score of at least 3/10 points on the visual/numeric analogy scale (VAS). Patients randomized into the experimental arm (A) will undergo Kypho-IORT (Kyphoplasty plus IORT with 8 Gy prescribed to 13 mm depth). Patients randomized into the control arm (B) will receive EBRT with either 30 Gy in 10 fractions or 8 Gy as a single dose. The primary end point is pain reduction defined as at least - 3 points on the VAS compared to baseline at day 1. Assuming that 40% of patients in the Kypho-IORT arm and 5% of patients in the control arm will achieve this reduction and 20% will drop out, a total of 54 patients will have to be included to reach a power of 0.817 with a two-sided alpha of 0.05. Secondary endpoints are evaluation of the percentage of patients with a pain reduction of at least 3 points at 2 and 6 weeks, local tumor control, frequency of re-intervention, secondary fractures/sintering, complication rates, skin toxicity/wound healing, progression-free survival (PFS), overall survival (OS) and quality of life. DISCUSSION: This trial will generate level 1 evidence on the clinical value of a one-stop procedure which may provide instantaneous pain relief, long-term control and shortened intervals to further adjuvant (systemic) therapies in patients with spinal metastases. TRIAL REGISTRATION: Registered with ClinicalTrials.gov, number: NCT02773966 (Registration date: 05/16/2016).


Assuntos
Dor do Câncer/terapia , Cuidados Intraoperatórios/métodos , Cifoplastia/métodos , Manejo da Dor/métodos , Neoplasias da Coluna Vertebral/terapia , Dor do Câncer/diagnóstico , Dor do Câncer/etiologia , Ensaios Clínicos Fase III como Assunto , Terapia Combinada/métodos , Fracionamento da Dose de Radiação , Humanos , Pessoa de Meia-Idade , Medição da Dor , Intervalo Livre de Progressão , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Neoplasias da Coluna Vertebral/complicações , Neoplasias da Coluna Vertebral/mortalidade , Neoplasias da Coluna Vertebral/secundário , Coluna Vertebral/efeitos da radiação , Coluna Vertebral/cirurgia
5.
Strahlenther Onkol ; 195(7): 640-647, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30796496

RESUMO

PURPOSE: Partial breast irradiation using intraoperative radiotherapy (IORT) after breast-conserving surgery could be sufficient for a selected group of breast cancer patients. We report the results of a cohort of patients from a single center treated as part of the randomized phase-3 TARGIT-A trial. METHODS: Patients (≥50 years) with cT1 cN0 cM0 and invasive ductal histology on biopsy were randomized between IORT with 20 Gy (arm-A) or postoperative whole-breast RT (WBRT) up to 56 Gy in 2 Gy fractions (arm-B). Postoperatively, patients in arm-A with multifocality, lymphovascular invasion, nodal invasion, extensive intraductal component, invasive lobular carcinoma, or resection margins <1 cm received additional postoperative WBRT. RESULTS: Between 2002 and 2012, 184 patients were randomized, of whom 90 in arm-A and 90 in arm-B were evaluated. Median follow-up was 8.5 years. The 5­year overall survival was 94.4% in arm-A and 93.3% in arm-B (p = 0.73). Two local recurrences were observed: one at 70.3 months in an arm-A patient who received IORT + WBRT and another at 4.5 months in an arm-B patient who refused all forms of adjuvant treatment, thus resulting in a 5-year local recurrence of 0% in arm-A and 1.1% in arm-B. The 5­year in-breast recurrence (outside of the index quadrant) was 0% in arm-A and 1.2% in arm-B. Salvage mastectomy was performed successfully in all patients with relapse. CONCLUSION: Long-term follow-up of this single-center cohort consolidates the earlier reports of low local recurrence rates after single-dose IORT. Our results are in line with non-inferiority of risk-adapted IORT for selected patients with early breast cancer.


Assuntos
Neoplasias da Mama/radioterapia , Neoplasias da Mama/cirurgia , Carcinoma Ductal de Mama/radioterapia , Carcinoma Ductal de Mama/cirurgia , Mastectomia Segmentar , Terapia Neoadjuvante , Neoplasias da Mama/mortalidade , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/mortalidade , Carcinoma Ductal de Mama/patologia , Estudos de Coortes , Terapia Combinada , Seguimentos , Humanos , Período Intraoperatório , Pessoa de Meia-Idade , Invasividade Neoplásica , Estadiamento de Neoplasias , Taxa de Sobrevida
6.
Neurosurgery ; 84(1): 41-49, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29528443

RESUMO

BACKGROUND: The median time to recurrence of glioblastoma (GB) following multimodal treatment is ∼7 mo. Nearly all cancers recur locally, suggesting that augmenting local treatments may improve outcomes. OBJECTIVE: To investigate whether intraoperative radiotherapy (IORT) to the resection cavity is safe and effective. METHODS: INTRAGO was a phase I/II trial to evaluate the safety and tolerability of IORT with 20 to 40 Gy of low-energy photons in addition to standard radiochemotherapy (ClinicalTrials.gov ID, NCT02685605). The primary endpoint was safety as per occurrence of dose-limiting toxicities. Secondary endpoints were progression-free survival (PFS) and overall survival (OS). We also performed an exploratory analysis of the local PFS (L-PFS), defined as recurrence within 1 cm of the treated margin. RESULTS: Fifteen patients were treated at 3 dose levels. Of these, 13 underwent incomplete resection, 6 had unresected satellites, and 3 did not receive per-protocol treatment (PPT). The MGMT promoter was unmethylated in 10 patients. The median follow-up was 13.8 mo. The majority of grade 3 to 5 adverse events were deemed unrelated to IORT. Five cases of radionecrosis were observed, 2 were classified as grade 3 events. Other grade 3 events judged related to radiotherapy (external-beam radiotherapy and/or IORT) were wound dehiscence (n = 1), CSF leakage (n = 1), cyst formation (n = 1). No IORT-related deaths occurred. The median PFS was 11.2 mo (95% confidence interval [CI]: 5.4-17.0) for all patients and 11.3 mo (95% CI: 10.9-11.6) for those receiving PPT. The median L-PFS was 14.3 mo (95% CI: 8.4-20.2) for all patients and 17.8 mo (95% CI: 9.7-25.9) for those receiving PPT. The median OS was 16.2 mo (95% CI: 11.1-21.4) for all patients and 17.8 mo (95% CI: 13.9-21.7) for those receiving PPT. CONCLUSION: These data suggest that IORT is associated with manageable toxicity. Considering the limitations of a 15-patient phase I/II trial, further studies aimed at assessing an outcome benefit are warranted.


Assuntos
Neoplasias Encefálicas/radioterapia , Glioblastoma/radioterapia , Cuidados Intraoperatórios , Radioterapia/métodos , Idoso , Quimiorradioterapia , Terapia Combinada , Relação Dose-Resposta à Radiação , Determinação de Ponto Final , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Radioterapia/efeitos adversos , Resultado do Tratamento
7.
Int J Med Robot ; 14(3): e1899, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29484802

RESUMO

OBJECTIVE: Intraoperative radiotherapy (IORT) after surgical resection using a low-kV-X-ray source is a proven method used in cancer treatment. However, the shape and size of the targeted surface area are limited to the size of the available applicators. This can lead to nonconformal and therefore suboptimal treatment for many patients. METHODS: A system is proposed comprising an X-ray source with an applicator for surface irradiation mounted on a robotic arm. This is controlled by an algorithm designed for planning the required continuous path, enabling irradiation of any desired shape with a controlled dose distribution. RESULTS: The system is shown to be capable of irradiating areas composed of rectangles on a flat surface with a homogeneity index of less than 7% inside the targeted area. CONCLUSION: The presented results demonstrate the potential of the proposed setup to eliminate the current limitations, leading to better treatment of patients.


Assuntos
Neoplasias/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Algoritmos , Calibragem , Humanos , Robótica , Raios X
8.
J Neurosurg Sci ; 62(2): 214-220, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26771176

RESUMO

Patients diagnosed with glioblastoma multiforme receiving stereotactic biopsy only either due to tumor localization or impaired clinical status face a devastating prognosis with very short survival times. One strategy to provide an initial cytoreductive and palliative therapy at the time of the stereotactic biopsy is interstitial irradiation through the pre-defined trajectory of the biopsy channel. We designed a novel treatment planning system and evaluated the treatment potential of a fixed-source and a stepping-source algorithm for interstitial radiosurgery on non-spherical glioblastoma in direct adjacency to risk structures. Using both setups, we show that radiation doses delivered to 100% of the gross tumor volume shifts from sub-therapeutic (10-12 Gy) to sterilizing single doses (25-30 Gy) when using the stepping source algorithm due to improved sparing of organs-at-risk. Specifically, the maximum doses at the brain stem were 100% of the PTV dose when a fixed central source and 38% when a stepping-source algorithm was used. We also demonstrated precision of intracranial target points and stability of superficial and deep trajectories using both a phantom and a body donor study. Our setup now for the first time provides a basis for a clinical proof-of-concept trial and may widen palliation options for patients with limited life expectancy that should not undergo time-consuming therapies.


Assuntos
Neoplasias Encefálicas/radioterapia , Glioblastoma/radioterapia , Radioterapia/métodos , Técnicas Estereotáxicas , Neoplasias Encefálicas/patologia , Glioblastoma/patologia , Humanos
9.
Spine J ; 18(5): 776-781, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-28962909

RESUMO

BACKGROUND CONTEXT: Spinal metastases occur in 30%-50% of patients with systemic cancer. The primary goals of palliation are pain control and prevention of local recurrence. PURPOSE: This study aimed to test the safety and efficacy of a combined modality approach consisting of kyphoplasty and intraoperative radiotherapy (Kypho-IORT). STUDY DESIGN/SETTING: Kyphoplasty and intraoperative radiotherapy was a prospective, single-center phase I/II trial. Patients were enrolled in a classical 3+3 scheme within the initial phase I, where Kypho-IORT was applied using a needle-shaped 50 kV X-ray source at three radiation dose levels (8 Gy in 8-mm, 8 Gy in 11-mm, and 8 Gy in 13-mm depth). Thereafter, cohort expansion was performed as phase II of the trial. The trial is registered with clinicaltrials.gov, number NCT01280032. PATIENT SAMPLE: Patients aged 50 years and older with a Karnofsky Performance Status of at least 60% and with one to three painful vertebral metastases confined to the vertebral body were eligible to participate. OUTCOME MEASURES: The primary end point was safety as per the occurrence of dose-limiting toxicities. The secondary end points were pain reduction, local progression-free survival (L-PFS), and overall survival (OS). METHODS: Pain was measured using the visual analog scale (VAS) and local control was assessed in serial computed tomography or magnetic resonance imaging scans. RESULTS: None of the nine patients enrolled in the phase I showed dose-limiting toxicities at any level and thus, 52 patients were subsequently enrolled into a phase II, where Kypho-IORT was performed at various dose levels. The median pain score significantly dropped from 5 preoperatively to 2 at the first postoperative day (p<.001). Of 43 patients who reported a pre-interventional pain level of 3 or more, 30 (69.8%) reported a reduction of ≥3 points on the first postoperative day. A persistent pain reduction beyond the first postoperative day of ≥3 points was seen in 34 (79.1%) patients. The 3, 6, and 12 month L-PFS was excellent with 97.5%, 93.8%, and 93.8%. The 3, 6, and 12 months OS was 76.9%, 64.0%, and 48.4%. CONCLUSION: Kyphoplasty and intraoperative radiotherapy is safe and immediately provided sustained pain relief with excellent local control rates in patients with painful vertebral metastases.


Assuntos
Cifoplastia/métodos , Recidiva Local de Neoplasia/prevenção & controle , Complicações Pós-Operatórias/epidemiologia , Radioterapia/métodos , Neoplasias da Coluna Vertebral/cirurgia , Idoso , Terapia Combinada , Feminino , Humanos , Cifoplastia/efeitos adversos , Masculino , Pessoa de Meia-Idade , Manejo da Dor/efeitos adversos , Manejo da Dor/métodos , Radioterapia/efeitos adversos , Neoplasias da Coluna Vertebral/radioterapia , Neoplasias da Coluna Vertebral/secundário
10.
Phys Med ; 37: 82-87, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28535919

RESUMO

BACKGROUND: To the present date, IORT has been eye and hand guided without treatment planning and tissue heterogeneity correction. This limits the precision of the application and the precise documentation of the location and the deposited dose in the tissue. Here we present a set-up where we use image guidance by intraoperative cone beam computed tomography (CBCT) for precise online Monte Carlo treatment planning including tissue heterogeneity correction. MATERIALS AND METHODS: An IORT was performed during balloon kyphoplasty using a dedicated Needle Applicator. An intraoperative CBCT was registered with a pre-op CT. Treatment planning was performed in Radiance using a hybrid Monte Carlo algorithm simulating dose in homogeneous (MCwater) and heterogeneous medium (MChet). Dose distributions on CBCT and pre-op CT were compared with each other. Spinal cord and the metastasis doses were evaluated. RESULTS: The MCwater calculations showed a spherical dose distribution as expected. The minimum target dose for the MChet simulations on pre-op CT was increased by 40% while the maximum spinal cord dose was decreased by 35%. Due to the artefacts on the CBCT the comparison between MChet simulations on CBCT and pre-op CT showed differences up to 50% in dose. CONCLUSIONS: igIORT and online treatment planning improves the accuracy of IORT. However, the current set-up is limited by CT artefacts. Fusing an intraoperative CBCT with a pre-op CT allows the combination of an accurate dose calculation with the knowledge of the correct source/applicator position. This method can be also used for pre-operative treatment planning followed by image guided surgery.


Assuntos
Planejamento da Radioterapia Assistida por Computador , Radioterapia Guiada por Imagem , Algoritmos , Artefatos , Tomografia Computadorizada de Feixe Cônico , Humanos , Método de Monte Carlo
11.
BMC Cancer ; 14: 992, 2014 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-25535398

RESUMO

BACKGROUND: Glioblastoma multiforme (GBM) is the most frequent primary malignant brain tumor in adults. Despite multimodal therapies, almost all GBM recur within a narrow margin around the initial resected lesion. Thus, novel therapeutic intensification strategies must target both, the population of dispersed tumor cells around the cavity and the postoperative microenvironment. Intraoperative radiotherapy (IORT) is a pragmatic and effective approach to sterilize the margins from persistent tumor cells, abrogate post-injury proliferative stimuli and to bridge the therapeutic gap between surgery and radiochemotherapy. Therefore, we have set up INTRAGO, a phase I/II dose-escalation study to evaluate the safety and tolerability of IORT added to standard therapy in newly diagnosed GBM. In contrast to previous approaches, the study involves the application of isotropic low-energy (kV) x-rays delivered by spherical applicators, providing optimal irradiation properties to the resection cavity. METHODS/DESIGN: INTRAGO includes patients aged 50 years or older with a Karnofsky performance status of at least 50% and a histologically confirmed (frozen sections) supratentorial GBM. Safety and tolerability (i.e., the maximum tolerated dose, MTD) will be assessed using a classical 3 + 3 dose-escalation design. Dose-limiting toxicities (DLT) are wound healing deficits or infections requiring surgical intervention, IORT-related cerebral bleeding or ischemia, symptomatic brain necrosis requiring surgical intervention and early termination of external beam radiotherapy (before the envisaged dose of 60 Gy) due to radiotoxicity. Secondary end points are progression-free and overall survival. TRIAL REGISTRATION: The study is registered with clinicaltrials.gov, number: NCT02104882 (Registration Date: 03/26/2014).


Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/cirurgia , Protocolos Clínicos , Glioblastoma/diagnóstico por imagem , Glioblastoma/cirurgia , Cuidados Intraoperatórios , Terapia Combinada , Humanos , Radiografia , Dosagem Radioterapêutica
12.
J Appl Clin Med Phys ; 15(1): 4502, 2014 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-24423847

RESUMO

The use of IORT as a treatment modality for patients with close or positive margins has increased over the past decade. For situations where a flat area (up to 6 cm in diameter) has to be treated intraoperatively, new applicators for superficial treatment with a miniature X-ray source (INTRABEAM system) were developed. Here we report our evaluation of the dosimetric characteristics of these new applicators and their first clinical use. Each of these flat and surface applicators consists of a radiation protective metal tube and a flattening filter, which converts the spherical dose distribution of the X-ray source into a flat one. The homogeneity of each dose distribution and depth-dose measurements were evaluated using film dosimetry in a solid water phantom and a soft X-ray ionization chamber in a water tank. The first patient was treated with 5 Gy delivered in 5 mm using a 4 cm FLAT applicator over 21 minutes. The flat applicators show the maximum homogeneity, with a uniformity ratio of 1.02-1.08 in certain depths. In 1 mm depth surface applicators show a uniformity ratio of 1.15-1.28. They also show a higher dose rate and a steeper dose gradient compared to the flat applicators. The results of this investigation demonstrated that the flat and surface applicators have unique dosimetric characteristics that need to be considered during the treatment planning stages. This work also showed that it is possible to perform a superficial localized IORT which provides new application possibilities for use of the INTRABEAM system.


Assuntos
Neoplasias da Mama/radioterapia , Carcinoma Ductal de Mama/radioterapia , Mastectomia , Idoso , Neoplasias da Mama/patologia , Neoplasias da Mama/cirurgia , Carcinoma Ductal de Mama/patologia , Carcinoma Ductal de Mama/cirurgia , Terapia Combinada , Feminino , Humanos , Período Intraoperatório , Imageamento por Ressonância Magnética , Prognóstico , Dosagem Radioterapêutica , Raios X
13.
Radiother Oncol ; 110(3): 471-6, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24444525

RESUMO

PURPOSE: Second cancer risk after breast conserving therapy is becoming more important due to improved long term survival rates. In this study, we estimate the risks for developing a solid second cancer after radiotherapy of breast cancer using the concept of organ equivalent dose (OED). MATERIALS AND METHODS: Computer-tomography scans of 10 representative breast cancer patients were selected for this study. Three-dimensional conformal radiotherapy (3D-CRT), tangential intensity modulated radiotherapy (t-IMRT), multibeam intensity modulated radiotherapy (m-IMRT), and volumetric modulated arc therapy (VMAT) were planned to deliver a total dose of 50 Gy in 2 Gy fractions. Differential dose volume histograms (dDVHs) were created and the OEDs calculated. Second cancer risks of ipsilateral, contralateral lung and contralateral breast cancer were estimated using linear, linear-exponential and plateau models for second cancer risk. RESULTS: Compared to 3D-CRT, cumulative excess absolute risks (EAR) for t-IMRT, m-IMRT and VMAT were increased by 2 ± 15%, 131 ± 85%, 123 ± 66% for the linear-exponential risk model, 9 ± 22%, 82 ± 96%, 71 ± 82% for the linear and 3 ± 14%, 123 ± 78%, 113 ± 61% for the plateau model, respectively. CONCLUSION: Second cancer risk after 3D-CRT or t-IMRT is lower than for m-IMRT or VMAT by about 34% for the linear model and 50% for the linear-exponential and plateau models, respectively.


Assuntos
Neoplasias da Mama/radioterapia , Neoplasias Induzidas por Radiação , Segunda Neoplasia Primária/etiologia , Radioterapia Conformacional/efeitos adversos , Radioterapia de Intensidade Modulada/efeitos adversos , Idoso , Feminino , Humanos , Pessoa de Meia-Idade , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Risco
15.
Z Med Phys ; 24(3): 243-51, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24238628

RESUMO

BACKGROUND: Intraoperative radiotherapy (IORT) using the INTRABEAM(®) system promises a flexible use regarding radiation protection compared to other approaches such as electron treatment or HDR brachytherapy with (192)Ir or (60)Co. In this study we compared dose rate measurements of breast- and Kypho-IORT with C-arm fluoroscopy which is needed to estimate radiation protection areas. MATERIALS AND METHODS: C-arm fluoroscopy, breast- and Kypho-IORTs were performed using phantoms (silicon breast or bucket of water). Dose rates were measured at the phantom's surface, at 30 cm, 100 cm and 200 cm distance. Those measurements were confirmed during 10 Kypho-IORT and 10 breast-IORT patient treatments. RESULTS: The measured dose rates were in the same magnitude for all three paradigms and ranges from 20 µSv/h during a simulated breast-IORT at two meter distance up to 64 mSv/h directly at the surface of a simulated Kypho-IORT. Those measurements result in a circle of controlled area (yearly doses >6 mSv) for each paradigm of about 4 m±2 m. DISCUSSION/CONCLUSIONS: All three paradigms show comparable dose rates which implies that the radiation protection is straight forward and confirms the flexible use of the INTRABEAM(®) system.


Assuntos
Fluoroscopia/instrumentação , Proteção Radiológica/instrumentação , Radiografia Intervencionista/instrumentação , Radioterapia Guiada por Imagem/instrumentação , Radioterapia/instrumentação , Cirurgia Assistida por Computador/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Dosagem Radioterapêutica
16.
Z Med Phys ; 22(3): 197-204, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22739321

RESUMO

PURPOSE: To generate and validate a source model of a miniature X-ray generator (INTRABEAM, Carl Zeiss Surgical, Oberkochen, Germany) for endovaginal TARGeted Intra-operative radioTherapy (TARGIT) brachytherapy a Geant4-based Monte Carlo (MC) tool was developed. The model was used to calculate the accurate relative dose distribution for the source combined with a cylindrical applicator which was developed for endovaginal treatment. METHODS AND MATERIALS: Geometries with given materials of the X-ray source and applicator were implemented in a Geant4-based dose calculation framework. To reduce the calculation time, phase space files for a set of circular electron beam foci and different beam radii were precalculated. Different beam radii had to be considered because the exact electron beam path on the target is not known in advance. To estimate the electron beam radius distribution of the system, a least squares minimization between the EBT film measured relative dose distribution and the simulation was performed. RESULTS: Relative dose distributions were calculated and compared with Gafchromic EBT film measurements to validate the MC method. In a region of interest around the source, the 2%/2mm gamma criterion matched with 98%. Profiles showed excellent agreement between measurement and simulation. The calculation time to simulate an entire treatment was twelve minutes. CONCLUSIONS: The method was able to predict the radius and width of the trajectory where the electrons impact on the target. This enables the complete simulation. The developed method allows calculating relative dose distributions for endovaginal TARGIT brachytherapy matching measured relative dose distributions within clinically acceptable limits.


Assuntos
Braquiterapia/instrumentação , Modelos Biológicos , Modelos Estatísticos , Próteses e Implantes , Radiometria/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Vagina , Simulação por Computador , Feminino , Humanos , Método de Monte Carlo , Dosagem Radioterapêutica , Espalhamento de Radiação , Software
17.
Radiat Oncol ; 6: 174, 2011 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-22176703

RESUMO

BACKGROUND: Radiation induced secondary cancers are a rare but severe late effect after breast conserving therapy. Intraoperative radiotherapy (IORT) is increasingly used during breast conserving surgery. The purpose of this analysis was to estimate secondary cancer risks after IORT compared to other modalities of breast radiotherapy (APBI - accelerated partial breast irradiation, EBRT - external beam radiotherapy). METHODS: Computer-tomography scans of an anthropomorphic phantom were acquired with an INTRABEAM IORT applicator (diameter 4 cm) in the outer quadrant of the breast and transferred via DICOM to the treatment planning system. Ipsilateral breast, contralateral breast, ipsilateral lung, contralateral lung, spine and heart were contoured. An INTRABEAM source (50 kV) was defined with the tip of the drift tube at the center of the spherical applicator. A dose of 20 Gy at 0 mm depth from the applicator surface was prescribed for IORT and 34 Gy (5 days × 2 × 3.4 Gy) at 10 mm depth for APBI. For EBRT a total dose of 50 Gy in 2 Gy fractions was planned using two tangential fields with wedges. The mean and maximal doses, DVHs and volumes receiving more than 0.1 Gy and 4 Gy of organs at risk (OAR) were calculated and compared. The life time risk for secondary cancers was estimated according to NCRP report 116. RESULTS: IORT delivered the lowest maximal doses to contralateral breast (< 0.3 Gy), ipsilateral (1.8 Gy) and contralateral lung (< 0.3 Gy), heart (1 Gy) and spine (< 0.3 Gy). In comparison, maximal doses for APBI were 2-5 times higher. EBRT delivered a maximal dose of 10.4 Gy to the contralateral breast and 53 Gy to the ipsilateral lung. OAR volumes receiving more than 4 Gy were 0% for IORT, < 2% for APBI and up to 10% for EBRT (ipsilateral lung). The estimated risk for secondary cancer in the respective OAR is considerably lower after IORT and/or APBI as compared to EBRT. CONCLUSIONS: The calculations for maximal doses and volumes of OAR suggest that the risk of secondary cancer induction after IORT is lower than compared to APBI and EBRT.


Assuntos
Neoplasias da Mama/radioterapia , Neoplasias Induzidas por Radiação/prevenção & controle , Radioterapia/efeitos adversos , Radioterapia/métodos , Neoplasias da Mama/cirurgia , Feminino , Humanos , Período Intraoperatório , Mastectomia Segmentar , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Fatores de Risco
18.
Int J Radiat Oncol Biol Phys ; 81(4): 1114-9, 2011 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-20934272

RESUMO

PURPOSE: Approximately 30% of patients with cancer receive bone metastases, of which 50% are in the spine. Approximately 20% present with unstable lesions requiring surgical intervention, followed by fractionated radiotherapy over 2-4 weeks to prevent early regrowth. Because of the limited survival time of patients with metastatic cancer, novel treatment concepts shortening the overall treatment time or hospitalization are desirable. In this study, we established a novel approach for intraoperative radiotherapy during kyphoplasty (Kypho-IORT), a method that combines stabilizing surgery and radiotherapy within one visit, after estimating the percentage of eligible patients for this treatment. METHODS AND MATERIALS: To estimate the percentage of eligible patients, 53 planning CTs (897 vertebrae) of patients with spinal metastases were evaluated. The number of infiltrated vertebrae were counted and classified in groups eligible or not eligible for Kypho-IORT. The Kypho-IORT was performed in a donated body during a standard balloon kyphoplasty using the INTRABEAM system and specially designed applicators. A single dose of 10 Gy (in 10 mm) was delivered over 4 min to the vertebra. This was verified using two ionization chambers and a Monte Carlo simulation. RESULTS: The estimation of eligible patients resulted in 34% of the evaluated patients, and thus 34% of patients with instable spinal metastases are suitable for Kypho-IORT. This study shows also that, using the approach presented here, it is possible to perform an IORT during kyphoplasty with an additional 15 min operation time. The measurement in the donated body resulted in a maximum dose of 3.8 Gy in the spinal cord. However, the Monte Carlo depth dose simulation in bone tissue showed 68% less dose to the prescription depth. CONCLUSION: We present for the first time a system using an x-ray source that can be used for single-dose IORT during kyphoplasty. The described Kypho-IORT can decrease the overall treatment time for up to 34% of patients who usually receive radiotherapy for spinal metastases.


Assuntos
Cifoplastia , Neoplasias da Coluna Vertebral/radioterapia , Idoso , Idoso de 80 Anos ou mais , Braquiterapia/instrumentação , Braquiterapia/métodos , Feminino , Humanos , Período Intraoperatório , Masculino , Método de Monte Carlo , Seleção de Pacientes , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Fraturas da Coluna Vertebral/cirurgia , Neoplasias da Coluna Vertebral/secundário , Fatores de Tempo
19.
Strahlenther Onkol ; 186(5): 280-8, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20437018

RESUMO

BACKGROUND AND PURPOSE: Volumetric modulated arc therapy (VMAT) has the potential to deliver dose distributions comparable to the established intensity-modulated radiotherapy techniques for a multitude of target paradigms. Prior to implementing VMAT into their clinical routine in December 2008, the authors evaluated the dose calculation/delivery accuracy of 24 sample VMAT plans (prostate and anal cancer target paradigms) with film and ionization dosimetry. After the start of the clinical program, in vivo measurements with a rectal probe were performed. MATERIAL AND METHODS: The VMAT plans were generated by the treatment-planning system (TPS) ERGO++ (Elekta, Crawley, UK) and transferred to a phantom. Film dosimetry was performed with Kodak EDR2 films, and evaluated with dose profiles and gamma-index analysis. Appropriate ionization chambers were used for absolute dose measurements in the phantom and for in vivo measurements. The ionization chamber was used with localization of the measurement volume based on positioning cone-beam computed tomography. RESULTS: Plans were transferred from ERGO++ to the record and verify (R&V) system/linear accelerator (linac). The absolute dose deviations recorded with the ionization chamber were 1.74% +/- 1.62% across both indications. The gamma-index analysis of the film dosimetry showed no deviation > 3%/3 mm in the high-dose region. On in vivo measurements, a deviation between calculation and measurement of 2.09% +/- 2.4% was recorded, when the chamber was successfully positioned in the high-dose region. CONCLUSION: VMAT plans can be planned and treated reproducibly in high quality after the commissioning of the complete delivery chain consisting of TPS, R&V system and linac. The results of the individual plan verification meet the commonly accepted requirements. The first in vivo measurements confirm the reproducible precision of the delivered dose during clinical treatments.


Assuntos
Radioterapia de Intensidade Modulada/métodos , Dosimetria Fotográfica , Humanos , Masculino , Aceleradores de Partículas , Imagens de Fantasmas , Neoplasias da Próstata/radioterapia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos
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