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1.
Br J Radiol ; 93(1107): 20190584, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31977241

RESUMO

OBJECTIVE: We compared the sensitivity of intensity modulated proton therapy (IMPT) and photon volumetric modulated arc therapy (VMAT) plans to setup uncertainties in locally advanced non-small cell lung cancer (NSCLC) using probabilistic scenarios. METHODS: Minimax robust (MM) and planning target volume (PTV) optimised IMPT and VMAT nominal plans were created with physical dose of 70 Gy in 35 fractions in 10 representative patients. Using population data of setup errors, a fractionated treatment course was simulated, summed (Dsum) and compared to the nominal plan. Three treatment-course simulations were done for each plan. Target robustness criteria were: dose deviation of ≤5% to clinical target volume (CTV) D98% and CTV V95% ≥ 99.9%. Voxelwise simulation repeatability was analysed using Bland-Altman plots. Acceptable limits of agreement were 2% of the prescription dose. RESULTS: All Dsum met target robustness criteria. While fraction VMAT and MM-IMPT doses were excellent, simulated fraction doses in PTV-IMPT were suboptimal. Almost all (>99%) of VMAT and MM-IMPT fraction doses met both target robustness criteria. For PTV-IMPT, only 96.9 and 80.3% of fractions met CTVD98% and V95% criteria respectively. Simulation repeatability was excellent (limits of agreement range: 0.41-1.1 Gy) with strong positive correlations. CONCLUSION: When considering the whole treatment course, setup errors do not influence robustness irrespective of planning techniques used. However, on a fraction level, VMAT and MM-IMPT plans are superior compared to PTV-IMPT plans. ADVANCES IN KNOWLEDGE: Probabilistic analysis provides a fast and practical method for evaluating VMAT and IMPT plan sensitivity against setup uncertainty. VMAT and robust-optimised IMPT plans have comparable sensitivity to setup uncertainties in conventionally fractionated treatment for NSCLC.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/radioterapia , Neoplasias Pulmonares/radioterapia , Fótons/uso terapêutico , Terapia com Prótons/métodos , Erros de Configuração em Radioterapia , Radioterapia de Intensidade Modulada/métodos , Incerteza , Carcinoma Pulmonar de Células não Pequenas/diagnóstico por imagem , Carcinoma Pulmonar de Células não Pequenas/patologia , Fracionamento da Dose de Radiação , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/patologia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
2.
Br J Radiol ; 93(1107): 20190573, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31778315

RESUMO

OBJECTIVE: Classical robust optimization (cRO) in intensity-modulated proton therapy (IMPT) considers isocenter position and particle range uncertainties; anatomical robust optimization (aRO) aims to consider additional non-rigid positioning variations. This work compares the influence of different uncertainty sources on the robustness of cRO and aRO IMPT plans for head and neck squamous cell carcinoma (HNSCC). METHODS: Two IMPT plans were optimized for 20 HNSCC patients who received weekly control CTs (cCT): cRO, using solely the planning CT, and aRO, including 2 additional cCTs. The robustness of the plans in terms of clinical target volume (CTV) coverage and organ at risk (OAR) sparing was analyzed considering stepwise the influence of (1) non-rigid anatomical variations given by the weekly cCT, (2) with fraction-wise added rigid random setup errors and (3) additional systematic proton range uncertainties. RESULTS: cRO plans presented significantly higher nominal CTV coverage but are outperformed by aRO plans when considering non-rigid anatomical variations only, as cRO and aRO plans presented a median target coverage (D98%) decrease for the low-risk/high-risk CTV of 1.8/1.1 percentage points (pp) and -0.2 pp/-0.3 pp, respectively. Setup and range uncertainties had larger influence on cRO CTV coverage, but led to similar OAR dose changes in both plans. Considering all error sources, 10/2 cRO/aRO patients missed the CTV coverage and a limited number exceeded some OAR constraints in both plans. CONCLUSION: Non-rigid anatomical variations are mainly responsible for critical target coverage loss of cRO plans, whereas the aRO approach was robust against such variations. Both plans provide similar robustness of OAR parameters. ADVANCES IN KNOWLEDGE: The influence of different uncertainty sources was quantified for robust IMPT HNSCC plans.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade Modulada/métodos , Carcinoma de Células Escamosas de Cabeça e Pescoço/radioterapia , Incerteza , Humanos , Órgãos em Risco/efeitos da radiação , Posicionamento do Paciente , Lesões por Radiação/prevenção & controle , Erros de Configuração em Radioterapia , Radioterapia de Intensidade Modulada/normas , Estudos Retrospectivos
3.
Br J Radiol ; 93(1107): 20190595, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31687833

RESUMO

OBJECTIVE: Accurate patient positioning is crucial in particle therapy due to the geometrical selectivity of particles. We report and discuss the National Center for Oncological Hadrontherapy (CNAO) experience in positioning accuracy and stability achieved with solid thermoplastic masks fixed on index base plates and assessed by daily orthogonal X-ray imaging. METHODS: Positioning data were retrospectively collected (between 2012 and 2018) and grouped according to the treated anatomical site. 19696 fractions of 1325 patients were evaluated.The study was designed to assess:(i) the number of fractions in which a single correction vector was applied(SCV);(ii) the number of fractions in which further setup verification was performed (SV);(iii) the number of fractions in which SV lead to an additional correction within (MCV<5min) or after (MCV>5min) 5 minutes from the first setup correction;(iv) the systematic (Σ) and random (σ) error components of the correction vectors applied. RESULTS: A SCV was applied in 71.5% of fractions, otherwise SV was required. In 30.6% of fractions with SV, patient position was not further revised. In the remaining fractions, MCV<5min and MCV>5min were applied mainly in extracranial and cranial sites respectively.Interfraction Σ was ≤ 1.7 mm/0.7° and σ was ≤ 1.2 mm/0.6° in cranial sites while in extracranial sites Σ was ≤ 5.5 mm/0.9° and σ was ≤4.4 mm/0.9°. Setup residuals were submillimetric in all sites. In cranial patients, maximum intrafractional Σ was 0.8 mm/0.4°. CONCLUSION: This report extensively quantifies inter- and intrafraction setup accuracy on an institutional basis and confirms the need of image guidance to fully benefit from the geometrical selectivity of particles. ADVANCES IN KNOWLEDGE: The reported analysis provides a board institutional data set on the evaluation of patient immobilization and bony anatomy alignment for several particle therapy clinical indications.


Assuntos
Imobilização/instrumentação , Máscaras , Neoplasias/radioterapia , Posicionamento do Paciente/métodos , Erros de Configuração em Radioterapia/prevenção & controle , Institutos de Câncer , Fracionamento da Dose de Radiação , Feminino , Humanos , Imobilização/métodos , Masculino , Pessoa de Meia-Idade , Neoplasias/diagnóstico por imagem , Planejamento da Radioterapia Assistida por Computador , Radioterapia Guiada por Imagem , Reprodutibilidade dos Testes , Estudos Retrospectivos , Fatores de Tempo , Tomografia Computadorizada por Raios X , Incerteza
4.
Radiat Res ; 193(2): 161-170, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31877254

RESUMO

Modern small animal irradiation platforms provide for accurate delivery of radiation under 3D image guidance. However, leveraging these improvements currently comes at the cost of lower-throughput experimentation. Herein, we characterized setup accuracy and dosimetric robustness for mock/sham irradiation of a murine xenograft flank tumor model using the X-RAD SmART+ with the vendor-supplied Monte Carlo (MC) treatment planning system (SmART ATP). The chosen beam arrangement was parallel-opposing using a 20 mm square collimator, aligned off-axis for ipsilateral lung sparing. Using a cohort of five mice imaged with cone beam computed tomography (CBCT) over five consecutive mock-irradiation fractions, we compared inter-fraction setup variability resulting from a vendor-supplied multi-purpose bed with anesthesia nose cone with a more complicated immobilization solution with an integrated bite block with nose cone and Styrofoam platform. A hypothetical "high-throughput" image-guidance scenario was investigated, wherein the day 1 stage coordinates (resulting from CBCT guidance) were applied on days 2-5. Daily inter-fraction setup errors were evaluated per specimen (days 2-5) using CBCT-derived offsets from day 1 stage coordinates. Using the CBCT images and Monte Carlo dose calculation, 3D dosimetric plan robustness was evaluated for the vendor-supplied immobilization solution, for both the high-throughput guidance scenario as well as for use of daily CBCT-based alignment. Inter-fraction setup offset magnitude was 3.6 (±1.5) mm for the vendor-supplied immobilization compared to 3.3 (±1.8) mm for the more complicated solution. For the vendor-supplied immobilization, we found that daily CBCT was needed to adequately cover the flank tumors dosimetrically, given our chosen treatment approach.


Assuntos
Transformação Celular Neoplásica , Tomografia Computadorizada de Feixe Cônico , Fracionamento da Dose de Radiação , Erros de Configuração em Radioterapia , Animais , Linhagem Celular Tumoral , Modelos Animais de Doenças , Camundongos , Método de Monte Carlo , Radioterapia Guiada por Imagem
5.
Int J Radiat Oncol Biol Phys ; 106(1): 185-193, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31580928

RESUMO

PURPOSE: Recurrent or previously irradiated head and neck cancers (HNC) are therapeutically challenging and may benefit from high-dose, highly accurate radiation techniques, such as stereotactic ablative radiation therapy (SABR). Here, we compare set-up and positioning accuracy across HNC subsites to further optimize the treatment process and planning target volume (PTV) margin recommendations for head and neck SABR. METHODS AND MATERIALS: We prospectively collected data on 405 treatment fractions across 79 patients treated with SABR for recurrent/previously irradiated HNC. First, interfractional error was determined by comparing ExacTrac x-ray to the treatment plan. Patients were then shifted and residual error was measured with repeat x-ray. Next, cone beam computed tomography (CBCT) was compared with ExacTrac for positioning agreement, and final shifts were applied. Lastly, intrafractional error was measured with x-ray before each arc. Results were stratified by treatment site into skull base, neck/parotid, and mucosal. RESULTS: Most patients (66.7%) were treated to 45 Gy in 5 fractions (range, 21-47.5 Gy in 3-5 fractions). The initial mean ± standard deviation interfractional errors were -0.2 ± 1.4 mm (anteroposterior), 0.2 ± 1.8 mm (craniocaudal), and -0.1 ± 1.7 mm (left-right). Interfractional 3-dimensional vector error was 2.48 ± 1.44, with skull base significantly lower than other sites (2.22 vs 2.77; P = .0016). All interfractional errors were corrected to within 1.3 mm and 1.8°. CBCT agreed with ExacTrac to within 3.6 mm and 3.4°. CBCT disagreements and intrafractional errors of >1 mm or >1° occurred at significantly lower rates in skull base sites (CBCT: 16.4% vs 50.0% neck, 52.0% mucosal, P < .0001; intrafractional: 22.0% vs 48.7% all others, P < .0001). Final PTVs were 1.5 mm (skull base), 2.0 mm (neck/parotid), and 1.8 mm (mucosal). CONCLUSIONS: Head and neck SABR PTV margins should be optimized by target site. PTV margins of 1.5 to 2 mm may be sufficient in the skull base, whereas 2 to 2.5 mm may be necessary for neck and mucosal targets. When using ExacTrac, skull base sites show significantly fewer uncertainties throughout the treatment process, but neck/mucosal targets may require the addition of CBCT to account for positioning errors and internal organ motion.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Recidiva Local de Neoplasia/radioterapia , Radiocirurgia/métodos , Erros de Configuração em Radioterapia , Idoso , Tomografia Computadorizada de Feixe Cônico/métodos , Fracionamento da Dose de Radiação , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Imobilização/métodos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/diagnóstico por imagem , Recidiva Local de Neoplasia/patologia , Neoplasias Parotídeas/diagnóstico por imagem , Neoplasias Parotídeas/radioterapia , Posicionamento do Paciente , Estudos Prospectivos , Melhoria de Qualidade , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem/métodos , Reirradiação/métodos , Neoplasias da Base do Crânio/diagnóstico por imagem , Neoplasias da Base do Crânio/radioterapia
7.
Cancer Radiother ; 23(8): 891-895, 2019 Dec.
Artigo em Francês | MEDLINE | ID: mdl-31615729

RESUMO

Due to high dose gradients, stereotactic body radiation therapy requires high precision in the location of the tumour. Uncertainties in the positioning can introduce serious damage on organs at risk and consequently can reduce tumour local control. A better tumour location can be achieved by controlling its position with an efficient inter and intrafraction imaging procedure. The various imaging techniques available on treatment systems are presented and performances are discussed. Finally, propositions are given in terms of imaging system according to the location treated by stereotactic body radiation therapy.


Assuntos
Neoplasias/diagnóstico por imagem , Neoplasias/radioterapia , Radiocirurgia/métodos , Radioterapia Guiada por Imagem/métodos , Neoplasias Ósseas/diagnóstico por imagem , Neoplasias Ósseas/radioterapia , Fracionamento da Dose de Radiação , Marcadores Fiduciais , Humanos , Neoplasias Renais/diagnóstico por imagem , Neoplasias Renais/radioterapia , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/radioterapia , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/radioterapia , Imagem por Ressonância Magnética , Masculino , Neoplasias Otorrinolaringológicas/diagnóstico por imagem , Neoplasias Otorrinolaringológicas/radioterapia , Neoplasias Pancreáticas/diagnóstico por imagem , Neoplasias Pancreáticas/radioterapia , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/radioterapia , Erros de Configuração em Radioterapia
8.
J Appl Clin Med Phys ; 20(9): 61-68, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31478615

RESUMO

PURPOSE: The purpose of the study was to investigate if surface guided radiotherapy (SGRT) can decrease setup deviations for tangential and locoregional breast cancer patients compared to conventional laser-based setup (LBS). MATERIALS AND METHODS: Both tangential (63 patients) and locoregional (76 patients) breast cancer patients were enrolled in this study. For LBS, the patients were positioned by aligning skin markers to the room lasers. For the surface based setup (SBS), an optical surface scanning system was used for daily setup using both single and three camera systems. To compare the two setup methods, the patient position was evaluated using verification imaging (field images or orthogonal images). RESULTS: For both tangential and locoregional treatments, SBS decreased the setup deviation significantly compared to LBS (P < 0.01). For patients receiving tangential treatment, 95% of the treatment sessions were within the clinical tolerance of ≤ 4 mm in any direction (lateral, longitudinal or vertical) using SBS, compared to 84% for LBS. Corresponding values for patients receiving locoregional treatment were 70% and 54% for SBS and LBS, respectively. No significant difference was observed comparing the setup result using a single camera system or a three camera system. CONCLUSIONS: Conventional laser-based setup can with advantage be replaced by surface based setup. Daily SGRT improves patient setup without additional imaging dose to breast cancer patients regardless if a single or three camera system was used.


Assuntos
Braquiterapia/normas , Neoplasias da Mama/radioterapia , Posicionamento do Paciente , Planejamento da Radioterapia Assistida por Computador/normas , Erros de Configuração em Radioterapia/prevenção & controle , Radioterapia Guiada por Imagem/normas , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/diagnóstico por imagem , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Pessoa de Meia-Idade , Órgãos em Risco/efeitos da radiação , Prognóstico , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Estudos Retrospectivos , Tomografia Computadorizada por Raios X/métodos
9.
Int J Radiat Oncol Biol Phys ; 105(5): 1151-1159, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31476419

RESUMO

PURPOSE: To evaluate the feasibility of fiducial markers as a surrogate for gross tumor volume (GTV) position in image-guided radiation therapy of rectal cancer. METHODS AND MATERIALS: We analyzed 35 fiducials in 19 patients with rectal cancer who received short-course radiation therapy or long-course chemoradiation therapy. Magnetic resonance imaging examinations were performed before and after the first week of radiation therapy, and daily pre- and postirradiation cone beam computed tomography scans were acquired in the first week of radiation therapy. Between the 2 magnetic resonance imaging examinations, the fiducial displacement relative to the center of gravity of the GTV (COGGTV) and the COGGTV displacement relative to bony anatomy were determined. Using the cone beam computed tomography scans, inter- and intrafraction fiducial displacement relative to bony anatomy were determined. RESULTS: The systematic error of the fiducial displacement relative to the COGGTV was 2.8, 2.4, and 4.2 mm in the left-right, anterior-posterior (AP), and craniocaudal (CC) directions, respectively. Large interfraction systematic errors of up to 8.0 mm and random errors up to 4.7 mm were found for COGGTV and fiducial displacements relative to bony anatomy, mostly in the AP and CC directions. For tumors located in the mid and upper rectum, these errors were up to 9.4 mm (systematic) and 5.6 mm (random) compared with 4.9 mm and 2.9 mm for tumors in the lower rectum. Systematic and random errors of the intrafraction fiducial displacement relative to bony anatomy were ≤2.1 mm in all directions. CONCLUSIONS: Large interfraction errors of the COGGTV and the fiducials relative to bony anatomy were found. Therefore, despite the observed fiducial displacement relative to the COGGTV, the use of fiducials as a surrogate for GTV position reduces the required margins in the AP and CC directions for a GTV boost using image-guided radiation therapy of rectal cancer. This reduction in margin may be larger in patients with tumors located in the mid and upper rectum compared with the lower rectum.


Assuntos
Marcadores Fiduciais , Ouro , Radioterapia Guiada por Imagem/instrumentação , Neoplasias Retais/diagnóstico por imagem , Neoplasias Retais/radioterapia , Carga Tumoral , Idoso , Idoso de 80 Anos ou mais , Pontos de Referência Anatômicos/diagnóstico por imagem , Quimiorradioterapia , Tomografia Computadorizada de Feixe Cônico/estatística & dados numéricos , Fracionamento da Dose de Radiação , Estudos de Viabilidade , Feminino , Humanos , Ísquio/diagnóstico por imagem , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Movimentos dos Órgãos , Sínfise Pubiana/diagnóstico por imagem , Erros de Configuração em Radioterapia , Radioterapia Guiada por Imagem/métodos , Neoplasias Retais/patologia , Fatores de Tempo
10.
Radiat Oncol ; 14(1): 139, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31387593

RESUMO

BACKGROUND: This study compared adaptive replanning and repositioning corrections based on soft-tissue matching for prostate cancer by using the magnetic resonance-guided radiation therapy (MRgRT) system. METHODS: A total of 19 patients with prostate cancer were selected retrospectively. Weekly magnetic resonance image (MRI) scans were acquired for 5 weeks for each patient to observe the anatomic changes during the treatment course. Initial intensity-modulated radiation therapy (IMRT) plans (iIMRT) were generated for each patient with 13 coplanar 60Co beams on a ViewRay™ system. Two techniques were applied: patient repositioning and replanning. For patient repositioning, one plan was created: soft-tissue (prostate) matching (Soft). The dose distribution was calculated for each MRI with the beam delivery parameters from the initial IMRT plan. The replanning technique was used to generate the Adaptive plan, which was the reoptimized plan for the weekly MRI. The dose-volumetric parameters of the planning target volume (PTV), bladder, and rectum were calculated for all plans. During the treatment course, the PTV, bladder, and rectum were evaluated for changes in volume and the effect on dosimetric parameters. The differences between the dose-volumetric parameters of the plans were examined through the Wilcoxon test. The initial plan was used as a baseline to compare the differences. RESULTS: The Adaptive plan showed better target coverage during the treatment period, but the change was not significant in the Soft plan. There were significant differences in D98%, D95%, and D2% in PTV between the Soft and Adaptive plans (p < 0.05) except for Dmean. There was no significant change in Dmax and Dmean as the treatment progressed with all plans. All indices for the Adaptive plan stayed the same compared to those of iIMRT during the treatment course. There were significant differences in D15%, D25%, D35%, and D50% in the bladder between the Soft and Adaptive plans. The Adaptive plan showed the worse dose sparing than the Soft plan for the bladder according to each dosimetric index. In contrast to the bladder, the Adaptive plan achieved better sparing than the Soft plan during the treatment course. The significant differences were only observed in D15% and D35% between the Soft and Adaptive plans (p < 0.05). CONCLUSIONS: Patient repositioning based on the target volume (Soft plan) can relatively retain the target coverage for patients and the OARs remain at a clinically tolerance level during the treatment course. The Adaptive plan did not clinically improve for the dose delivered to OARs, it kept the dose delivered to the target volume constant. However, the Adaptive plan is beneficial when the organ positions and volumes change considerable during treatment.


Assuntos
Imagem por Ressonância Magnética/métodos , Posicionamento do Paciente , Neoplasias da Próstata/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Erros de Configuração em Radioterapia/prevenção & controle , Radioterapia Guiada por Imagem/métodos , Idoso , Idoso de 80 Anos ou mais , Humanos , Masculino , Órgãos em Risco/efeitos da radiação , Prognóstico , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Estudos Retrospectivos
11.
J Appl Clin Med Phys ; 20(8): 47-55, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31294923

RESUMO

The purpose of this study is to investigate the dosimetric impact of multi-leaf collimator (MLC) positioning errors on a Varian Halcyon for both random and systematic errors, and to evaluate the effectiveness of portal dosimetry quality assurance in catching clinically significant changes caused by these errors. Both random and systematic errors were purposely added to 11 physician-approved head and neck volumetric modulated arc therapy (VMAT) treatment plans, yielding a total of 99 unique plans. Plans were then delivered on a preclinical Varian Halcyon linear accelerator and the fluence was captured by an opposed portal dosimeter. When comparing dose-volume histogram (DVH) values of plans with introduced MLC errors to known good plans, clinically significant changes to target structures quickly emerged for plans with systematic errors, while random errors caused less change. For both error types, the magnitude of clinically significant changes increased as error size increased. Portal dosimetry was able to detect all systematic errors, while random errors of ±5 mm or less were unlikely to be detected. Best detection of clinically significant errors, while minimizing false positives, was achieved by following the recommendations of AAPM TG-218. Furthermore, high- to moderate correlation was found between dose DVH metrics for normal tissues surrounding the target and portal dosimetry pass rates. Therefore, it may be concluded that portal dosimetry on the Halcyon is robust enough to detect errors in MLC positioning before they introduce clinically significant changes to VMAT treatment plans.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Aceleradores de Partículas/instrumentação , Posicionamento do Paciente , Radiometria/instrumentação , Planejamento da Radioterapia Assistida por Computador/métodos , Erros de Configuração em Radioterapia/prevenção & controle , Humanos , Órgãos em Risco/efeitos da radiação , Radiometria/métodos , Radiometria/normas , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos
12.
J Appl Clin Med Phys ; 20(6): 39-44, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31187538

RESUMO

Surface Guided Radiotherapy (SGRT) is a relatively new technique for positioning patients and for monitoring patient movement during treatment. SGRT is completely non-invasive since it uses visible light for determining the position of the patient surface. A reduction in daily imaging for patient setup is possible if the accuracy of SGRT is comparable to imaging. It allows for monitoring of intrafraction motion and the radiation beam can be held beyond a certain threshold resulting in a more accurate irradiation. The purpose of this study was to investigate setup uncertainty and the intrafraction motion in non-gated whole breast cancer radiotherapy treatment using an integrated implementation of AlignRT (OSMS) system as SGRT. In initial setup, SGRT was compared to three-point setup using tattoos on the patient and orthogonal kV imaging. For the investigation of intrafraction motion, OSMS monitored the patient with six degrees of freedom during treatment. Using three-point setup resulted in a setup root-mean-square error from the isocenter of 5.4 mm. This was improved to 4.2 mm using OSMS. For the translational directions, OSMS showed improvements in the lateral direction (P = 0.0009, Wilcoxon rank-sum), but for the longitudinal direction and rotation it was not possible to show improvements (P = 0.96 and P = 0.46, respectively). The vertical direction proved more accurate for three-point setup than OSMS (P = 0.000004). Intrafraction motion was very limited with a translational median of 1.1 mm from the isocenter. While OSMS showed marked improvements over laser and tattoo setup, the system did not prove accurate enough to replace the daily orthogonal kV images aligned to bony anatomy.


Assuntos
Neoplasias da Mama/radioterapia , Posicionamento do Paciente , Imagens de Fantasmas , Planejamento da Radioterapia Assistida por Computador/métodos , Erros de Configuração em Radioterapia/prevenção & controle , Radioterapia Guiada por Imagem/métodos , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Tomografia Computadorizada de Feixe Cônico , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imobilização , Pessoa de Meia-Idade , Movimento , Prognóstico , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Respiração
13.
Int J Radiat Oncol Biol Phys ; 105(2): 423-431, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31158426

RESUMO

PURPOSE: To investigate a Bayesian network (BN)-based method to detect errors in external beam radiation therapy physician orders. METHODS AND MATERIALS: A total of 4431 external beam radiation therapy orders from 2008 to 2017 at the authors' institution were obtained from clinical treatment management systems and divided into 3 groups: single prescription, concurrent boost, and sequential boost. Multiple BNs were developed for each group to detect errors in new orders using joint posterior probabilities of the order parameters, given disease information. Each BN was trained with a group of orders using a Bayesian learning algorithm. A procedure was developed to select the optimal BN for each treatment site in each group and to determine site-specific parameters and error detection thresholds. Potential clinical errors, created both manually and automatically, were applied to test error detection performance. RESULTS: The average true-positive rate (TPR) and false-positive rate (FPR) of error detection were 95.72% and 1.99%, respectively, for the single-prescription cohort with 9 treatment sites. For the concurrent-boost cohort, the TPR and FPR were 92.94% and 14.53%, respectively. For the sequential-boost cohort, the TPR and FPR were 100% and 9.48%, respectively, for the prescribed dose values and 100% and 4.34%, respectively, for the remaining order parameters. For the patient simulation and imaging parameters for 9 treatment sites, the TPR and FPR were 100% and 4.96%, respectively. CONCLUSIONS: The probabilistic BN method was able to perform physician order error detection at a higher accuracy than previously reported in a variety of complex prescription instances, thus warranting further development in incorporating BNs into clinical error detection tools to assist manual physician order checks.


Assuntos
Teorema de Bayes , Erros Médicos/estatística & dados numéricos , Neoplasias/radioterapia , Radiologistas/estatística & dados numéricos , Algoritmos , Estudos de Coortes , Conjuntos de Dados como Assunto , Fracionamento da Dose de Radiação , Reações Falso-Negativas , Reações Falso-Positivas , Humanos , Erros Médicos/prevenção & controle , Neoplasias/patologia , Especificidade de Órgãos , Curva ROC , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Erros de Configuração em Radioterapia , Radioterapia Guiada por Imagem , Treinamento por Simulação , Tecnologia Radiológica
14.
J Appl Clin Med Phys ; 20(7): 128-134, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31222881

RESUMO

To propose a concept for correcting the twist between the head and neck and the body frequently occurring in radiotherapy patients and to develop a prototype device for achieving this. Furthermore, the operational accuracy of this device under no load was evaluated. We devised a concept for correcting the twist of patients by adjustment of the three rotation (pitch, roll, and yaw) angles in two independent plates connected by a joint (fulcrum). The two plates (head and neck plate and body plate) rotate around the fulcrum by adjusting screws under each of them. A prototype device was created to materialize this concept. First, after all adjusting screws were set to the zero position, the rotation angle of each plate was measured by a digital goniometer. Repeatability was evaluated by performing 20 repeated measurements. Next, to confirm the rotational accuracy of each plate of the prototype device, the calculated rotation angles for 20 combinations of patterns of traveled distances of the adjusting screws were compared with those measured by the digital goniometer and cone-beam computed tomography (CT). The repeatability (standard deviation: SD) of the pitch, roll, and yaw angles of the head and neck plate was 0.04°, 0.05°, and 0.03°, and the repeatability (SD) of the body plate was 0.05°, 0.04°, and 0.04°, respectively. The mean differences ± SD between the calculated and measured pitch, roll, and yaw angles for the head and neck plate with the digital goniometer were 0.00 ± 0.06°, -0.01 ± 0.06°, and -0.04 ± 0.04°, respectively. The differences for the body plate were -0.03 ± 0.04°, 0.03 ± 0.05°, and 0.02 ± 0.05°, respectively. Results of the cone-beam CT were similar to those of the digital goniometer. The prototype device exhibited good performance regarding the rotational accuracy and repeatability under no load. The clinical implementation of this concept is expected to reduce the residual error of the patient position due to the twist.


Assuntos
Algoritmos , Tomografia Computadorizada de Feixe Cônico/métodos , Neoplasias de Cabeça e Pescoço/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Erros de Configuração em Radioterapia/prevenção & controle , Humanos , Processamento de Imagem Assistida por Computador/métodos , Órgãos em Risco/efeitos da radiação , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Rotação
15.
Radiat Oncol ; 14(1): 76, 2019 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-31072388

RESUMO

BACKGROUND: To investigate the setup uncertainties and to establish an optimal imaging schedule for the prone-positioned whole breast radiotherapy. METHODS: Twenty prone-positioned breast patients treated with tangential fields from 2015 to 2017 were retrospectively enrolled in this study. The prescription dose for the whole breast treatment was 266 cGy × 16 for all of the patients and the treatments were delivered with the SSD setup technique. At every fraction of treatment, patient was firstly set up based on the body localization tattoos. MV portal imaging was then taken to confirm the setup; if discrepancy (> 3 mm) was found between the portal images and corresponding plan images, the patient positioning was adjusted accordingly with couch movement. Based on the information acquired from the daily tattoo and portal imaging setup, three sets of data, named as weekly imaging guidance (WIG), no daily imaging guidance (NIG), and initial 3 days then weekly imaging guidance (3 + WIG) were sampled, constructed, and analyzed in reference to the benchmark of the daily imaging guidance (DIG). We compared the setup uncertainties, target coverage (D95, Dmax), V5 of the ipsilateral lung, the mean dose of heart, the mean and max dose of the left-anterior-descending coronary artery (LAD) among the 4 imaging guidance (IG) schedules. RESULTS: Relative to the daily imaging guidance (IG) benchmark, the NIG schedule led to the largest residual setup uncertainties; the uncertainties were similar for the WIG and 3 + WIG schedules. Little variations were observed for D95 of the target among NIG, DIG and WIG. The target Dmax also exhibited little changes among all the IG schedules. While V5 of the ipsilateral lung changed very little among all 4 schedules, the percent change of the mean heart dose was more pronounced; but its absolute values were still within the tolerance. However, for the left-sided breast patients, the LAD dose could be significantly impacted by the imaging schedules and could potentially exceed its tolerance criteria in some patients if NIG, WIG and 3 + WIG schedules were used. CONCLUSIONS: For left-side whole breast treatment in the prone position using the SSD treatment technique, the daily imaging guidance can ensure dosimetric coverage of the target as well as preventing critical organs, especially LAD, from receiving unacceptable levels of dose. For right-sided whole breast treatment in the prone position, the weekly imaging setup guidance appears to be the optimal choice.


Assuntos
Neoplasias da Mama/radioterapia , Suspensão da Respiração , Órgãos em Risco/efeitos da radiação , Posicionamento do Paciente , Planejamento da Radioterapia Assistida por Computador/métodos , Erros de Configuração em Radioterapia/prevenção & controle , Tomografia Computadorizada por Raios X/métodos , Neoplasias da Mama/diagnóstico por imagem , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Prognóstico , Decúbito Ventral , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Estudos Retrospectivos , Incerteza
16.
J Appl Clin Med Phys ; 20(6): 206-212, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31112364

RESUMO

We developed a new head supporting device to provide accurate correction of rotational setup during image-guided radiation therapy (IGRT), evaluating its correction performance and the efficacy of dose distribution in stereotactic radiotherapy (SRT) using a helical tomotherapy (HT) system. The accuracy of rotational motion was measured using an electronic inclinometer; we compared device angles and measurement values from 0.0° to 3.0°. The correction accuracy was investigated based on the distance between rotational centers in the device and on megavoltage computed tomography (MVCT); the correction values were compared using distances in the range of 0.0-9.0 cm using a head phantom with a rotational error of 1.5°. For an SRT with a simultaneous integrated boost plan and a rotational error of 3.0° in yaw angle using a head phantom, and for a single-isocenter SRT for multiple brain metastases in the data of three patients, dosimetric efficacy of the HT unit was evaluated for calculated dose distributions with MVCT after rotational correction. This device can correct pitch and yaw angles within 0.3° and can be corrected to within 0.5° for each rotational angle according to the result of MVCT correction regardless of the rotational center position. In the head phantom study, the device had a beneficial impact on rotational correction; D99% for the target improved by approximately 10% with rotational correction. Using patient data with the device, the mean difference based on the treatment planning data was 0.3% for D99% and -0.1% for coverage index to the target. Our rotational setup correction device has high efficacy, and can be used for IGRT.


Assuntos
Neoplasias Encefálicas/cirurgia , Cabeça/efeitos da radiação , Posicionamento do Paciente , Imagens de Fantasmas , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Erros de Configuração em Radioterapia/prevenção & controle , Cirurgia Assistida por Computador/métodos , Humanos , Órgãos em Risco/efeitos da radiação , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Estudos Retrospectivos , Rotação
17.
J Appl Clin Med Phys ; 20(6): 53-59, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31054217

RESUMO

PURPOSE: We evaluated the setup accuracy of a three-degree-of-freedom fiducial marker (3DOF-FM)-based setup compared to a soft tissue (ST)-based setup in hypofractionated intensity-modulated radiotherapy (IMRT) for prostate cancer. MATERIALS AND METHODS: We analyzed the setup accuracy for 17 consecutive prostate cancer patients with three implanted FMs who underwent hypofractionated IMRT. The 3DOF-ST-based setup using cone-beam computed tomography (CT) was performed after a six DOF-bony structure (BS)-based setup using an ExacTrac x-ray system. The 3DOF-FM-based matching using the ExacTrac x-ray system was done during the BS- and ST-based setups. We determined the mean absolute differences and the correlation between the FM- and ST-based translational shifts relative to the BS-based setup position. The rotational mean shifts detected by the ExacTrac x-ray system were also evaluated. RESULTS: The mean differences in the anterior-posterior (AP), superior-inferior (SI), and left-right (LR) dimensions were 0.69, 0.0, and 0.30 mm, respectively. The Pearson correlation coefficients for both shifts were 0.92 for AP, 0.91 for SI, and 0.68 for LR. The percentages of shift agreements within 2 mm were 85% for AP, 93% for SI, and 99% for LR. The absolute values of rotational shifts were 0.1° for AP, 0.3°, and 1.2° for LR. CONCLUSIONS: The setup accuracy of the 3DOF-FM-based setup has the potential to be interchangeable with a ST-based setup. Our data are likely to be useful in clinical practice along with the popularization of the hypofractionated IMRT in prostate cancer.


Assuntos
Tomografia Computadorizada de Feixe Cônico/métodos , Marcadores Fiduciais , Neoplasias da Próstata/patologia , Neoplasias da Próstata/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem/métodos , Radioterapia de Intensidade Modulada/métodos , Idoso , Idoso de 80 Anos ou mais , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/metabolismo , Dosagem Radioterapêutica , Erros de Configuração em Radioterapia/prevenção & controle
18.
J Med Syst ; 43(7): 194, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31114956

RESUMO

3D/3D image registration in IGRT, which aligns planning Computed Tomography (CT) image set with on board Cone Beam CT (CBCT) image set in a short time with high accuracy, is still a challenge due to its high computational cost and complex anatomical structure of medical image. In order to overcome these difficulties, a new method is proposed which contains a coarse registration and a fine registration. For the coarse registration, a supervised regression convolutional neural networks (CNNs) is used to optimize the spatial variation by minimizing the loss when combine the CT images with the CBCT images. For the fine registration, intensity-based image registration is used to calculate the accurate spatial difference of the input image pairs. A coarse registration can get a rough result with a wide capture range in less than 0.5 s. Sequentially a fine registration can get accurate results in a reasonable short time. RSD-111 T chest phantom was used to test our new method. The set-up error was calculated in less than 10s in time scale, and was reduced to sub-millimeter level in spatial scale. The average residual errors in translation and rotation are within ±0.5 mm and ± 0.2°.


Assuntos
Planejamento da Radioterapia Assistida por Computador , Erros de Configuração em Radioterapia/prevenção & controle , Radioterapia Guiada por Imagem/métodos , Algoritmos , Humanos , Imageamento Tridimensional , Imagens de Fantasmas , Tomografia Computadorizada por Raios X
19.
J Appl Clin Med Phys ; 20(4): 45-50, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30945803

RESUMO

PURPOSE: Patients undergoing external beam accelerated partial breast irradiation (APBI) receive permanent tattoos to aid with daily setup alignment and verification. With the advent of three-dimensional (3D) body surface imaging and two-dimensional (2D) x-ray imaging-based matching to surgical clips, tattoos may not be necessary to ensure setup accuracy. We compared the accuracy of conventional tattoo-based setups to a patient setup without tattoos. MATERIALS/METHODS: Twenty consecutive patients receiving APBI at our institution from July 10, 2017 to February 13, 2018 were identified. All patients received tattoos per standard of care. Ten patients underwent setup using tattoos for initial positioning followed by surface imaging and 2D matching of surgical clips. The other ten patients underwent positioning using surface imaging followed by 2D matching without reference to tattoos. Overall setup time and orthogonal x-ray-based shifts after surface imaging per fraction were recorded. Shift data were used to calculate systematic and random error. RESULTS: Among ten patients in the "no tattoo" group, the average setup time per fraction was 6.83 min vs 8.03 min in the tattoo cohort (P < 0.01). Mean 3D vector shifts for patients in the "no tattoo" group were 4.6 vs 5.9 mm in the "tattoo" cohort (P = NS). Mean systematic errors in the "no tattoo" group were: 1.2 mm (1.5 mm SD) superior/inferior, 0.5 mm (1.6 mm SD) right/left, and 2.3 mm (1.9 mm SD) anterior/posterior directions. Mean systematic errors in the "tattoo" group were: 0.8 mm (2.2 mm SD) superior/inferior, 0.3 mm (2.5 mm SD) right/left, and 1.4 mm (4.4 mm SD) anterior/posterior directions. The random errors in the "no tattoo" group ranged from 0.6 to 0.7 mm vs 1.2 to 1.7 mm in the "tattoo" group. CONCLUSIONS: Using both surface imaging and 2D matching to surgical clips provides excellent accuracy in APBI patient alignment and setup verification with reduced setup time relative to the tattoo cohort. Skin-based tattoos may no longer be warranted for patients receiving external beam APBI.


Assuntos
Neoplasias da Mama/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Erros de Configuração em Radioterapia/prevenção & controle , Tatuagem , Estudos de Viabilidade , Feminino , Humanos , Dosagem Radioterapêutica
20.
Phys Med ; 59: 37-46, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30928064

RESUMO

PURPOSE: To study the sensitivity of an Electronic Portal Imaging Device (EPID) in detecting delivery errors for VMAT lung stereotactic body radiotherapy (SBRT) using the Collapsed Arc method. METHODS: Baseline VMAT plans and plans with errors intentionally introduced were generated for 15 lung SBRT patients. Three types of errors were introduced by modifying collimator angles and multi-leaf collimator (MLC) field sizes (MLCFS) and MLC shifts by ±5, ±2, and ±1° or millimeters. A total of 103 plans were measured with EPID on an Elekta Synergy Linear Accelerator (Agility MLC) and compared to both the original treatment planning system (TPS) Collapsed Arc dose matrix and the no-error plan baseline EPID measurements. Gamma analysis was performed using the OmniPro-I'mRT (IBA Dosimetry) software and gamma criteria of 1%/1 mm, 2%/1 mm, 2%/2 mm, and 3%/3. RESULTS: When the error-introduced EPID measured dose matrices were compared to the TPS matrices, the majority of simulated errors were detected with gamma tolerance of 2%/1 mm and 1%/1 mm. When the error-introduced EPID measured dose matrices were compared to the baseline EPID measurements, all the MLCFS and MLC shift errors, and ±5°collimator errors were detected using 2%/1 mm and 1%/1 mm gamma criteria. CONCLUSION: This work demonstrates the feasibility and effectiveness of the collapsed arc technique and EPID for pre-treatment verification of lung SBRT VMAT plans. The EPID was able to detect the majority of MLC and the larger collimator errors with sensitivity to errors depending on the gamma tolerances.


Assuntos
Equipamentos e Provisões Elétricas , Neoplasias Pulmonares/diagnóstico por imagem , Planejamento da Radioterapia Assistida por Computador , Erros de Configuração em Radioterapia , Radioterapia de Intensidade Modulada/instrumentação , Humanos , Aceleradores de Partículas , Dosagem Radioterapêutica
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