RESUMO
This work presents the dosimetric characteristics of Total Body Irradiation (TBI) delivered using a dedicated Co-60 TBI unit. We demonstrate the ability to deliver a uniform dose to the entire patient without the need for a beam spoiler or patient-specific compensation. Full dose distributions are calculated using an in-house Monte Carlo treatment planning system, and cumulative dose distributions are created by deforming the dose distributions within two different patient orientations. Sample dose distributions and profiles are provided to illustrate the plan characteristics, and dose and DVH statistics are provided for a heterogeneous cohort of patients. The patient cohort includes adult and pediatric patients with a range of 132-198 cm in length and 16.5-37.5 cm in anterior-posterior thickness. With the exception of the lungs, a uniform dose of 12 Gy is delivered to the patient with nearly the entire volume receiving a dose within 10% of the prescription dose. Mean lung doses (MLDs) are maintained below the estimated threshold for radiation pneumonitis, with MLDs ranging from 7.3 to 9.3 Gy (estimated equivalent dose in 2 Gy fractions (EQD2 ) of 6.2-8.5 Gy). Dose uniformity is demonstrated across five anatomical locations within the patient for which mean doses are all within 3.1% of the prescription dose. In-vivo dosimetry demonstrates excellent agreement between measured and calculated doses, with 78% of measurements within ±5% of the calculated dose and 99% within ±10%. These results demonstrate a state-of-the-art TBI planning and delivery system using a dedicated TBI unit and hybrid in-house and commercial planning techniques which provide comprehensive dosimetric data for TBI treatment plans that are accurately verified using in-vivo dosimetry.
Assuntos
Planejamento da Radioterapia Assistida por Computador , Irradiação Corporal Total , Adulto , Humanos , Criança , Irradiação Corporal Total/métodos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioisótopos de Cobalto/uso terapêutico , Radiometria/métodosRESUMO
Due to the limited height of commercial prone breast boards, large or pendulous breasts may contact the base layer of the board during simulation and throughout the course of treatment. Our clinic has historically identified and marked this region of contact to ensure reproducible setup. However, this situation may result in unwanted hotspots where the breast rests atop the board due to electron scatter. In this study, we performed in-vivo dosimetric measurements to evaluate the surface dose in regions of contact with the immobilization device. The average dose and hotspot were identified and evaluated to determine whether plan modifications were necessary to avoid excess skin toxicity at the skin/breast board interface. The film method results were validated against a commissioned in vivo OSLD dosimetry system. Radiochromic film measurements agreed with OSLD readings (n = 18) overall within 1%, σ = 6.4%, with one deviation of >10%. Pertinent information for the physician includes the average, maximum, and minimum doses received at the film interface. Future readings will not require OSLD verification. Physicians now have access to additional spatial data to correlate skin toxicity with doses delivered at the skin/breast board interface. This new technique is now an established procedure at our clinic, and can inform future efforts to model enhanced methods to calculate the dosimetric effects from the prone breast board in the treatment planning system.
Assuntos
Neoplasias da Mama , Radiometria , Mama , Neoplasias da Mama/radioterapia , Simulação por Computador , Feminino , Humanos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , PeleRESUMO
The use of kilovoltage cone-beam computed tomography (kV-CBCT) or megavoltage computed tomography (MVCT) for image guidance prior to lung stereotactic body radiation therapy (SBRT) is common clinical practice. We demonstrate that under equivalent respiratory conditions, image guidance using both kV-CBCT and MVCT may result in the inadequate estimation of the range of target motion under free-breathing (FB) conditions when standard low-density window and levels are used. Two spherical targets within a respiratory motion phantom were imaged using both long-exhale (LE) and sinusoidal respiratory traces. MVCT and kV-CBCT images were acquired and evaluated for peak-to-peak amplitudes of 10 or 20 mm in the cranial-caudal direction, and with 2, 4 or 5 s periods. All images were visually inspected for artifacts and conformity to the ITV for each amplitude, period, trace-type, and target size. All LE respiratory traces required a lower threshold HU window for MVCT and kV-CBCT compared to sinusoidal traces to obtain 100% volume conformity compared with the theoretical ITV (ITVT ). Excess volume was less than 2% for all kV-CBCT contours regardless of trace-type, breathing period, or amplitude, while the maximum excess volume for MVCT was 48%. Adjusting window and level to maximize conformity with the ITVT is necessary to reduce registration uncertainty to less than 5 mm. To fully capture target motion with either MVCT or kV-CBCT, substantial changes in HU levels up to -600 HU are required which may not be feasible clinically depending on the target's location and surrounding tissue contrast. This registration method, utilizing a substantially decreased window and level compared to standard low-density settings, was retrospectively compared to the automated registration algorithm for five lung SBRT patients exposed to pre-treatment kV-CBCT image guidance. Differences in registrations in the super-inferior (SI) direction greater than the commonly used ITV to PTV margin of 5 mm were encountered for several cases. In conclusion, pre-treatment image guidance for lung SBRT targets using MVCT or kV-CBCT is unlikely to capture the full extent of target motion as defined by the ITVT and additional caution is warranted to avoid registration errors for small targets and patients with LE respiratory traces.
Assuntos
Neoplasias Pulmonares , Tomografia Computadorizada de Feixe Cônico Espiral , Tomografia Computadorizada de Feixe Cônico , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Imagens de Fantasmas , Estudos RetrospectivosRESUMO
INTRODUCTION: Image registration and delineation of organs at risk (OARs) are key components of three-dimensional conformal (3DCRT) and intensity-modulated radiotherapy (IMRT) treatment planning. This study hypothesized that image registration and OAR delineation are often performed by medical physicists and/or dosimetrists and are not routinely reviewed by treating physicians. METHODS: An anonymous, internet-based survey of medical physicists and dosimetrists was distributed via the MEDPHYS and MEDDOS listserv groups. Participants were asked to characterize standard practices for completion and review of OAR contouring, target volume contouring, and image registration at their institution along with their personal training in these areas and level of comfort performing these tasks. Likert-type scales are reported as Median [Interquartile range] with scores ranging from 1 = "Extremely/All of the time" to 5 = "Not at all/Never." RESULTS: Two hundred and ninety-seven individuals responded to the survey. Overall, respondents indicated significantly less frequent physician review (3 [2-4] vs 2 [1-3]), and less confidence in the thoroughness of physician review (3 [2-4] vs 2 [1-3], P < 0.01) of OAR contours compared to image registration. Only 19% (95% CI 14-24%) of respondents reported a formal process by which OAR volumes are reviewed by physicians in their clinic. The presence of a formal review process was also associated with significantly higher perceived thoroughness of review of OAR volumes compared to clinics with no formal review process (2 [2-3] vs 3 [2-4], P < 0.01). CONCLUSION: Despite the critical role of OAR delineation and image registration in the 3DCRT and IMRT treatment planning process, physician review of these tasks is not always optimal. Radiotherapy clinics should consider implementation of formal processes to promote adequate physician review of OARs and image registrations to ensure the quality and safety of radiotherapy treatment plans.
Assuntos
Médicos , Radioterapia Conformacional , Radioterapia de Intensidade Modulada , Humanos , Órgãos em Risco , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por ComputadorRESUMO
BACKGROUND: Although tri-modality therapy is an acceptable standard of care in patients with locally advanced esophageal cancer, data regarding patterns of failure is lacking. We report bi-institutional patterns of failure experience treating patients using tri-modality therapy. MATERIALS AND METHODS: We retrospectively reviewed patients who underwent chemoradiation followed by esophagectomy between 2006 and 2011 at two NCI-designated cancer centers. First failure sites were categorized as local, regional nodal, or distant. Statistical analysis was performed using Fisher's exact test, non-parametric Wilcoxon rank-sum test, and multiple logistic regression. Kaplan-Meier curves were generated for relapse-free survival (RFS) and overall survival. RESULTS: A total of 132 patients met the inclusion criteria with a median age of 62 (range 36-80) and median follow-up of 28 months (range 4-128). There were a total of six (4.5%) local, 13 (10%) regional nodal, and 32 (23.5%) distant failures. Local failure was correlated with fewer lymph nodes (LN) assessed (p = 0.01) and close/positive margins (p < 0.01). Regional nodal failure was correlated with fewer LN assessed (p < 0.01) and larger pretreatment tumor size (p = 0.04). Patients with ≤13 LN evaluated had an inferior locoregional RFS versus patients with >13 LN evaluated (p = 0.003). Distant recurrence was correlated with higher pathologic nodal stage (p < 0.001), ulceration (p = 0.017), perineural invasion (p = 0.029), residual disease (p = 0.004), and higher post-treatment PET SUV max (p = 0.049). Patients with a pathologic complete response (OR 0.19, 95% CI 0.05-0.68) were less likely to experience distant recurrence. CONCLUSION: Tumor and treatment factors may predict for failure in patients undergoing tri-modality therapy for locally advanced esophageal cancer. Further data is needed to identify patterns of failure in these patients.
Assuntos
Adenocarcinoma/terapia , Carcinoma de Células Escamosas/terapia , Neoplasias Esofágicas/terapia , Recidiva Local de Neoplasia/terapia , Neoplasia Residual/terapia , Adenocarcinoma/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma de Células Escamosas/patologia , Quimiorradioterapia , Terapia Combinada , Neoplasias Esofágicas/patologia , Esofagectomia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Recidiva Local de Neoplasia/patologia , Estadiamento de Neoplasias , Neoplasia Residual/patologia , Estudos Retrospectivos , Taxa de Sobrevida , Falha de TratamentoAssuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Comunicação Interdisciplinar , Linfonodos/patologia , Órgãos em Risco/efeitos da radiação , Planejamento da Radioterapia Assistida por Computador/estatística & dados numéricos , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Estadiamento de Neoplasias , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada , Medição de RiscoAssuntos
Carcinoma Pulmonar de Células não Pequenas/radioterapia , Neoplasias Pulmonares/radioterapia , Neoplasias/imunologia , Neoplasias/radioterapia , Radioterapia (Especialidade)/métodos , Radiocirurgia/métodos , Carcinoma Pulmonar de Células não Pequenas/imunologia , Ensaios Clínicos como Assunto , Terapia Combinada , Humanos , Sistema Imunitário , Imunoterapia/métodos , Inflamação , Comunicação Interdisciplinar , Neoplasias Pulmonares/imunologia , Metástase NeoplásicaAssuntos
Radioterapia com Íons Pesados/métodos , Neoplasias/radioterapia , Radioterapia (Especialidade)/métodos , Radioterapia (Especialidade)/organização & administração , Radioterapia/métodos , Ensaios Clínicos como Assunto , Comportamento Cooperativo , Arquitetura de Instituições de Saúde , Humanos , Comunicação Interdisciplinar , Desenvolvimento de Programas , Radiobiologia , Resultado do Tratamento , Estados UnidosAssuntos
Carcinoma Pulmonar de Células não Pequenas/cirurgia , Neoplasias Pulmonares/cirurgia , Padrões de Prática Médica/normas , Radiocirurgia/normas , Carcinoma Pulmonar de Células não Pequenas/patologia , Humanos , Neoplasias Pulmonares/patologia , Estadiamento de Neoplasias , Radioterapia ConformacionalAssuntos
Neoplasias/radioterapia , Radioterapia (Especialidade)/instrumentação , Radioterapia (Especialidade)/métodos , Radioterapia/instrumentação , Radioterapia/métodos , Ensaios Clínicos como Assunto , Difusão de Inovações , Desenho de Equipamento , Humanos , Comunicação Interdisciplinar , National Institutes of Health (U.S.) , Neoplasias/diagnóstico por imagem , Inovação Organizacional , Radioterapia (Especialidade)/tendências , Radioterapia/tendências , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia Conformacional , Radioterapia de Intensidade Modulada , Tecnologia Radiológica/tendências , Estados UnidosRESUMO
PURPOSE: Limiting cardiac radiation dose is important for minimizing long-term cardiac toxicity in patients with left-sided early-stage breast cancer. METHODS AND MATERIALS: Prospectively collected dosimetric data were analyzed for patients undergoing moderately hypofractionated radiation therapy to the left breast within the Michigan Radiation Oncology Quality Consortium from 2016 to 2022. The mean heart dose (MHD) goal was progressively tightened from ≤2 Gy in 2016 to MHD ≤ 1.2 Gy in 2018. In 2021, a planning target volume (PTV) coverage goal was added, and the goal MHD was reduced to ≤1 Gy. Multivariate logistic regression models were developed to assess for covariates associated with meeting the MHD goals in 2016 to 2020 and the combined MHD/PTV coverage goal in 2021 to 2022. RESULTS: In total, 4165 patients were analyzed with a median age of 64 years. Overall average cardiac metric compliance was 91.7%. Utilization of motion management increased from 41.8% in 2016 to 2020 to 46.5% in 2021 to 2022. Similarly, use of prone positioning increased from 12.2% to 22.2% in these periods. On multivariate analysis in the 2016 to 2020 cohort, treatment with motion management (odds ratio [OR], 5.20; 95% CI, 3.59-7.54; P < .0001) or prone positioning (OR, 3.21; 95% CI, 1.85-5.57; P < .0001) was associated with meeting the MHD goal, while receipt of boost (OR, 0.25; 95% CI, 0.17-0.39; P < .0001) and omission of hormone therapy (OR, 0.65; 95% CI, 0.49-0.88; P = .0047) were associated with not meeting the MHD goal. From 2021 to 2022, treatment with motion management (OR, 1.89; 95% CI, 1.12-3.21; P = .018) or prone positioning (OR, 3.71; 95% CI, 1.73-7.95; P = .0008) was associated with meeting the combined MHD/PTV goal, while larger breast volume (≥1440 cc; OR, 0.34; 95% CI, 0.13-0.91; P = .031) was associated with not meeting the combined goal. CONCLUSIONS: In our statewide consortium, high rates of compliance with aggressive targets for limiting cardiac dose were achievable without sacrificing target coverage.
Assuntos
Neoplasias da Mama , Neoplasias Unilaterais da Mama , Humanos , Pessoa de Meia-Idade , Feminino , Dosagem Radioterapêutica , Neoplasias Unilaterais da Mama/radioterapia , Redução da Medicação , Neoplasias da Mama/radioterapia , Coração , Planejamento da Radioterapia Assistida por Computador/métodosRESUMO
INTRODUCTION: Treatment for inoperable stage II to III non-small cell lung cancer (NSCLC) involves chemo-radiotherapy (CRT). However, some patients transition to hospice or die early during their treatment course. We present a model to prognosticate early poor outcomes in NSCLC patients treated with curative-intent CRT. METHODS AND MATERIALS: Across a statewide consortium, data was prospectively collected on stage II to III NSCLC patients who received CRT between 2012 and 2019. Early poor outcomes included hospice enrollment or death within 3 months of completing CRT. Logistic regression models were used to assess predictors in prognostic models. LASSO regression with multiple imputation were used to build a final multivariate model, accounting for missing covariates. RESULTS: Of the 2267 included patients, 128 experienced early poor outcomes. Mean age was 71 years and 59% received concurrent chemotherapy. The best predictive model, created parsimoniously from statistically significant univariate predictors, included age, ECOG, planning target volume (PTV), mean heart dose, pretreatment lack of energy, and cough. The estimated area under the ROC curve for this multivariable model was 0.71, with a negative predictive value of 95%, specificity of 97%, positive predictive value of 23%, and sensitivity of 16% at a predicted risk threshold of 20%. CONCLUSIONS: This multivariate model identified a combination of clinical variables and patient reported factors that may identify individuals with inoperable NSCLC undergoing curative intent chemo-radiotherapy who are at higher risk for early poor outcomes.