RESUMO
Therapeutical strategies in breast cancer are continuously updating. Recent researches assessed the possibility of irradiating only the surgical bed in selected patients (Partial Breast Irradiation, PBI). In 2014 we designed a study to evaluate toxicity and cosmesis of APBI using Volumetric Modulated Arc Therapy-Rapid Arc compared with hypofractionated whole breast irradiation (WBI). We present here the 5-years updated data. HYPAB was a single-institution randomized trial that recruited 172 patients from 2015 to 2018. Patients underwent conserving surgery and were randomized to either adjuvant WBI (40.5Gy/15 fractions with simultaneous boost to 48 Gy to tumoral bed) or APBI (30Gy/5 fractions), both delivered with VMAT-RA technique. Clinical evaluation was performed during the first visit, once a week during radiotherapy and during follow up. Cosmesis was assessed using the Harvard Scale for Breast Cosmesis. At the time of the analysis 161 patients were eligible, 53% in the WBI and 47% in the APBI group, with a median follow-up of 67 months. Most common late skin toxicities were G1 fibrosis (32%) and oedema (28%) and were higher in the WBI group; no G3 toxicities were observed. Cosmesis was rated poor in only 6 cases. 147 patients had no evidence of disease at the last follow-up, and no patients died of the disease. Mature results confirm the safety and efficacy of APBI in selected early stage breast cancer patients. Late toxicity is improved in the APBI arm at the cost of a slight increase in local relapse. Further studies are ongoing to better elucidate the use of APBI as a de-escalation approach.
Assuntos
Neoplasias da Mama , Feminino , Humanos , Neoplasias da Mama/radioterapia , Neoplasias da Mama/cirurgia , Pós-Menopausa , Mastectomia Segmentar , Recidiva Local de Neoplasia/epidemiologia , Recidiva Local de Neoplasia/prevenção & controle , Recidiva Local de Neoplasia/cirurgia , Mama/efeitos da radiaçãoRESUMO
PURPOSE: to report toxicity and cosmetic outcome with a median follow-up of 6 years of a phase II trial of hypofractionated radiotherapy with volumetric modulated arc therapy (VMAT) and simultaneous integrated boost (SIB) for early-stage breast cancer after conservative surgery. MATERIALS AND METHODS: From August 2010 to September 2014, patients requiring adjuvant radiotherapy for early-stage breast cancer were treated according to a phase I-II protocol with SIB to 40.5 and 48 Gy to the breast and the boost region, respectively, with VMAT technique. The primary endpoint evaluated the treatment feasibility regarding adherence to required dose constraints for target, heart and lungs. Acute and late toxicity, local and distant control were secondary endpoints. RESULTS: 450 patients were included in the trial and analysed after a median follow-up of 6 years. Acute toxicity was already presented in a previous paper. Regarding late toxicity, 93% of patients had no skin alteration at five years, while 5.3% and 1.3% did record G1 and G2 residual toxicity, respectively. Cosmetic outcome was scored good or excellent in almost all cases (97.2%), fair only in 2.3% of patients. Residual tenderness in the irradiated breast was reported by 10% of patients. Cosmesis and breast pain improved during follow-up. Two cases of G2 pneumonitis and two cases of ischemic cardiopathy were registered during follow-up. Five cases presented local recurrence in the homolateral breast, four patients had a new primary cancer in the contralateral breast, while distant metastasis developed in 7 patients. CONCLUSION: After more than six years, hypofractionated VMAT with SIB for adjuvant radiotherapy in early-stage breast cancer patients remains a safe and effective approach. Mature data on skin toxicity and cosmetic outcome are encouraging. However, longer follow-up is required to evaluate local control, cardiac toxicity and secondary carcinogenesis.
Assuntos
Neoplasias da Mama , Radioterapia de Intensidade Modulada , Mama , Neoplasias da Mama/radioterapia , Neoplasias da Mama/cirurgia , Feminino , Humanos , Mastectomia Segmentar , Hipofracionamento da Dose de Radiação , Radioterapia Adjuvante/efeitos adversos , Radioterapia de Intensidade Modulada/efeitos adversosRESUMO
BACKGROUND: Many dose calculation algorithms for radiotherapy planning need to be configured for each clinical beam using pre-defined measurements. An optimization process adjusts the physical parameters able to estimate the energy released in the medium in any geometrical condition. This work investigates the impact of measured input data quality on the configuration of the type "c" Acuros-XB dose calculation algorithm in the Eclipse (Varian Medical Systems) treatment planning system. METHODS: Different datasets were acquired with the BeamScan water phantom (PTW) to configure 6 MV beams, for both flattened (6X) and flattening filter free mode (6FFF) for a Varian TrueBeam: (i) a correct dataset measured using a Semiflex-3D ion chamber, (ii) a set in missing lateral scatter conditions (MLS), (iii) a set with incorrect effective point of measurement (EPoM), (iv) sets acquired with PinPoint-3D chamber, DiodeP, microDiamond detectors. The Acuros-XB dose calculation algorithm (version 15.6) was configured using the reference dataset, the sets measured with the different detectors, with intentional errors, and using the representative beam data (RBD) made available by the vendor. The physical parameters obtained from each optimization process (spectrum, mean radial energy, electron contamination), were analyzed and compared. Calculated data were finally compared against the input and reference measurements. RESULTS: Concerning the physical parameters, the configurations presenting the largest differences were the MLS conditions (mean radial energy) and the incorrect EPoM (electron contamination). The calculation doses relative to the input data present low accuracy, with mean differences > 2% in some conditions. The PinPoint-3D ion chamber presented lower accuracy for the 6FFF beam. Regarding the RBD, calculations compared well with the input data used for the configuration, but not with the reference data. CONCLUSION: The MLS conditions and the incorrect setting of the EPoM lead to erroneous configurations and should be avoided. The choice of an appropriate detector is important. Whenever the representative beam data is used, a careful check under more clinical geometrical conditions is advised.
Assuntos
Neoplasias/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Algoritmos , Elétrons , Humanos , Dosagem Radioterapêutica , Espalhamento de RadiaçãoRESUMO
INTRODUCTION: The use of flattening filter free (FFF) beams generated by standard linear accelerators is increasing in the clinical practice. The radiation intensity peaked toward the beam central axis is properly managed in the optimization process of treatment planning through intensity modulation. Specific FFF parameters for profile analysis, as unflatness and slope for FFF beams, based on the renormalization factor concept has been introduced for quality assurance purposes. Recently, Halcyon, an O-ring based linear accelerator equipped with a 6 MV FFF beam only has been introduced by Varian. METHODS: Renormalization factors and related fit parameters according to Fogliata et al. ["Definition of parameters for quality assurance of FFF photon beams in radiation therapy," Med. Phys. 39, 6455-6464 (2012)] have been evaluated for the 6 MV FFF beam generated by Halcyon units. The Halcyon representative beam data provided by Varian were used. Dose fall-off at the field edges was matched with an unflattened beam generated by a 6 MV from a TrueBeam linac. Consistency of the results was evaluated against measurements on a clinical Halcyon unit, as well as a TrueBeam 6 MV FFF for comparison. RESULTS: The five parameters in the analytical equation for estimating the renormalization factor were determined with an R2 of 0.997. The comparison of the unflatness parameters between the Halcyon representative and hospital beam data was consistent within a range of 0.6%. Consistently with the computed parameters, the Halcyon profiles resulted in a less pronounced peak than TrueBeam. CONCLUSION: Renormalization factors and related fit parameters from the 6 MV FFF beam generated by the Varian Halcyon unit are provided.
Assuntos
Aceleradores de Partículas , Fótons , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por ComputadorRESUMO
PURPOSE: To ascertain the dosimetric performance of a new delivery system (the Halcyon system, H) equipped with dual-layer stacked multi-leaf collimator (MLC) for risk-adapted targets in cervix uteri cancer patients compared to another ring-based system in clinical operation (Helical Tomotherapy, HT). METHODS: Twenty patients were retrospectively included in a treatment planning study (10 with positive lymph nodes and 10 without). The dose prescription (45Gy to the primary tumour volume and a simultaneously integrated boost up to 55Gy for the positive patients) and the clinical planning objectives were defined consistently as recommended by an ongoing multicentric clinical trial. Halcyon plans were optimised for the volumetric modulated arc therapy. The plan comparison was performed employing the quantitative analysis of the dose-volume histograms. RESULTS: The coverage of the primary and nodal target volumes was comparable for both techniques and both subsets of patients. The primary planning target volume (PTV) receiving at least 95% of the prescription isodose ranged from 97.2 ± 1.1% (node-negative) to 99.1 ± 1.2% (node-positive) for H and from 96.5 ± 1.9% (node-negative) to 98.3 ± 0.9% (node-positive) for HT. The uncertainty is expressed at one standard deviation from the cohort of patient per each group. For the nodal clinical target volumes, the dose received by 98% of the planning target volume ranged 55.5 ± 0.1 to 56.0 ± 0.8Gy for H and HT, respectively. The only significant and potentially relevant differences were observed for the bowels. In this case, V40Gy resulted 226.3 ± 35.9 and 186.9 ± 115.9 cm3 for the node-positive and node-negative patients respectively for Halcyon. The corresponding findings for HT were: 258.9 ± 60.5 and 224.9 ± 102.2 cm3. On the contrary, V15Gy resulted 1279.7 ± 296.5 and 1557.2 ± 359.9 cm3 for HT and H respectively for node-positive and 1010.8 ± 320.9 versus 1203.8 ± 332.8 cm3 for node-negative. CONCLUSION: This retrospective treatment planning study, based on the dose constraints derived from the Embrace II study protocol, suggested the essential equivalence between Halcyon based and Helical Tomotherapy based plans for the intensity-modulated rotational treatment of cervix uteri cancer. Different levels of sparing were observed for the bowels with H better protecting in the high-dose region and HT in the mid-low dose regions. The clinical impact of these differences should be further addressed.
Assuntos
Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Neoplasias do Colo do Útero/radioterapia , Colo do Útero/efeitos da radiação , Feminino , Humanos , Órgãos em Risco/efeitos da radiação , Lesões por Radiação/etiologia , Lesões por Radiação/prevenção & controle , Radiometria , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/instrumentação , Radioterapia de Intensidade Modulada/instrumentação , Neoplasias do Colo do Útero/patologiaRESUMO
AIMS: To investigate the role of intensity-modulated proton therapy (IMPT) for regional nodal irradiation in patients with breast carcinoma in comparison with volumetric-modulated arc therapy (VMAT). MATERIALS AND METHODS: A cohort of 20 patients (10 in the breast-conserving surgery group and 10 post-mastectomy patients with tissue expander implants) was investigated. Proton plans were also computed using robust optimisation methods. Plan quality was assessed by means of dose-volume histograms and scored with conventional metrics. Estimates of the risk of secondary cancer induction (excess absolute risk, EAR) were carried out, taking into account fractionation, repopulation and repair. RESULTS: Concerning target coverage, the data proved a substantial equivalence of VMAT and IMPT: for example, coverage for the 50 Gy target, expressed in terms of V98%, was 47.8 ± 0.4, 47.6 ± 0.4, 47.3 ± 0.8, consistent with the objective of 47.5 Gy, for post-mastectomy patients for the three groups of patients. Also, the conformality of the dose distributions was similar for the two techniques, about 1.1, without statistically significant differences. Organ at risk planning aims were achieved for all structures for both techniques. The mean dose to the ipsilateral lung was 10.8 ± 1.1, 6.2 ± 0.8, 7.2 ± 1.0; for the contralateral lung was 3.2 ± 0.7, 0.3 ± 0.2, 0.4 ± 0.2; for the contralateral breast was: 3.1 ± 0.7, 0.3 ± 0.3 and 0.3 ± 0.3, whereas it was 3.9 ± 0.9, 0.4 ± 0.3 and 0.5 ± 0.5, respectively, for the heart for VMAT, IMPT and robust IMPT plans over the whole group of patients. Robust optimisation affected the near-to-maximum dose values for contralateral lung and breast, the mean dose for the heart and ipsilateral lung, with a deterioration ranging from 20 to 40% of the nominal value of IMPT plans (e.g. from 8.1 ± 6.4 to 11.4 ± 8.8 for the heart compared with 16.2 ± 5.2 for the VMAT plans). The numerical values of EAR per 10 000 patient-years were about one order of magnitude higher for VMAT than for IMPT for contralateral structures: 11.66 ± 2.01, 0.89 ± 0.80, 0.98 ± 0.77 for the contralateral breast and the three groups of plans, respectively; 14.31 ± 2.75, 1.42 ± 0.80, 1.78 ± 0.87 for the contralateral lung; and 34.86 ± 2.64, 18.85 ± 2.15, 20.98 ± 2.35 for the ipsilateral lung. CONCLUSION: IMPT with or without robust optimisation seems to be a potentially promising approach for the radiation treatment of breast cancer when nodal volumes should be irradiated. This was measured in terms of dosimetric advantage and predicted clinical benefit. In fact, the significant reduction in estimated EAR could add further clinical value to the dosimetric sparing of the organs at risk achievable with IMPT.
Assuntos
Neoplasias da Mama/radioterapia , Terapia com Prótons/métodos , Neoplasias da Mama/patologia , Feminino , Humanos , Planejamento da Radioterapia Assistida por Computador/métodosRESUMO
PURPOSE: To determine if the performance of a knowledge based RapidPlan (RP) planning model could be improved with an iterative learning process, i.e. if plans generated by an RP model could be used as new input to re-train the model and achieve better performance. METHODS: Clinical VMAT plans from 83 patients presenting with head and neck cancer were selected to train an RP model, CL-1. With this model, new plans on the same patients were generated, and subsequently used as input to train a novel model, CL-2. Both models were validated on a cohort of 20 patients and dosimetric results compared. Another set of 83 plans was realised on the same patients with different planning criteria, by using a simple template with no attempt to manually improve the plan quality. Those plans were employed to train another model, TP-1. The differences between the plans generated by CL-1 and TP-1 for the validation cohort of patients were compared with respect to the differences between the original plans used to build the two models. RESULTS: The CL-2 model presented an improvement relative to CL-1, with higher R2 values and better regression plots. The mean doses to parallel organs decreased with CL-2, while D1% to serial organs increased (but not significantly). The different models CL-1 and TP-1 were able to yield plans according to each original strategy. CONCLUSION: A refined RP model allowed the generation of plans with improved quality, mostly for parallel organs at risk and, possibly, also the intrinsic model quality.
Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Humanos , Órgãos em Risco , Melhoria de Qualidade , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/efeitos adversosRESUMO
BACKGROUND: Linac output as a function of field sizes has a phantom and a head scatter component. This last term can be measured in-air with appropriate build-up ensuring a complete electron equilibrium and the absence of the contaminant electrons. Equilibrium conditions could be achieved using a build-up cap or a mini-phantom. Monte Carlo simulations in a virtual phantom mimicking a mini-phantom were analysed with the aim of better understanding the setup conditions for measuring the collimator scatter factor that is the head scatter component of the linac output factors. METHODS: Beams of 6 and 15 MV from a TrueBeam, with size from 4 × 4 to 40 × 40 cm2 were simulated in cylindrical acrylic phantoms 20 cm long, of different diameters, from 0.5 to 4 cm, with the cylinder axis coincident with the beam central axis. The PRIMO package, based on PENELOPE Monte Carlo code, was used. The phase-space files for a Varian TrueBeam linac, provided by the linac vendor, were used for the linac head simulation. Depth dose curves were analysed, and collimator scatter factors estimated at different depth in the different phantom conditions. Additionally, in-air measurements using acyrilic and brass build-up caps, as well as acrylic mini-phantom were acquired for 6 and 18 MV beams from a Varian Clinac DHX. RESULTS: The depth dose curves along the cylinders were compared, showing, in each phantom, very similar curves for all analysed field sizes, proving the correctness in estimating the collimator scatter factor in the mini-phantom, provided to position the detector to a sufficient depth to exclude electron contamination. The results were confirmed by the measurements, where the acrylic build-up cap showed to be inadequate to properly estimate the collimator scatter factors, while the mini-phantom and the brass caps gave reasonable measurements. CONCLUSION: A better understanding of the beam characteristics inside a virtual mini-phantom through the analysis of depth dose curves, showed the critical points of using the acrylic build-up cap, and suggested the use of the mini-phantom for the collimator scatter factor measurements in the medium-large field size range.
Assuntos
Aceleradores de Partículas/instrumentação , Imagens de Fantasmas , Espalhamento de Radiação , Ar , Elétrons , Método de Monte Carlo , RadiometriaRESUMO
BACKGROUND: Monte Carlo simulations were run to estimate the dose variations generated by thedifference arising from the chemical composition of the tissues. METHODS: CT datasets of five breast cancer patients were selected. Mammary gland was delineated as clinical target volume CTV, as well as CTV_lob and CTV_fat, being the lobular and fat fractions of the entire mammary gland. Patients were planned for volumetric modulated arc therapy technique, optimized in the Varian Eclipse treatment planning system. CT, structures and plans were imported in PRIMO, based on Monte Carlo code Penelope, to run three simulations: AdiMus, where the adipose and muscle tissues were automatically assigned to fat and lobular fractions of the breast; Adi and Mus, where adipose and muscle, respectively were assigned to the whole mammary gland. The specific tissue density was kept identical from the CT dataset. Differences in mean doses in the CTV_lob and CTV_fat structures were evaluated for the different tissue assignments. Differences generated by the tissue composition and estimated by Acuros dose calculations in Eclipse were also analysed. RESULTS: From Monte Carlo simulations, the dose in the lobular fraction of the breast, when adipose tissue is assigned in place of muscle, is overestimated by 1.25 ± 0.45%; the dose in the fat fraction of the breast with muscle tissue assignment is underestimated by 1.14 ± 0.51%. Acuros showed an overestimation of 0.98 ± 0.06% and an underestimation of 0.21 ± 0.14% in the lobular and fat portions, respectively. Reason of this dissimilarity resides in the fact that the two calculations, Monte Carlo and Acuros, differently manage the range of CT numbers and the material assignments, having Acuros an overlapping range, where two tissues are both present in defined proportions. CONCLUSION: Although not clinically significant, the dose deposition difference in the lobular and connective fat fraction of the breast tissue lead to an improved knowledge of the possible dose distribution and homogeneity in the breast radiation treatment.
Assuntos
Tecido Adiposo/efeitos da radiação , Algoritmos , Osso e Ossos/efeitos da radiação , Neoplasias da Mama/radioterapia , Pulmão/efeitos da radiação , Músculo Esquelético/efeitos da radiação , Planejamento da Radioterapia Assistida por Computador/métodos , Neoplasias da Mama/patologia , Feminino , Humanos , Método de Monte Carlo , Órgãos em Risco/efeitos da radiação , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodosRESUMO
BACKGROUND: To evaluate a knowledge based planning model for RapidPlan (RP) generated for advanced head and neck cancer (HNC) patient treatments, as well its ability to possibly improve the clinical plan quality. The stability of the model was assessed also for a different beam geometry, different dose fractionation and different management of bilateral structures (parotids). METHODS: Dosimetric and geometric data from plans of 83 patients presenting HNC were selected for the model training. All the plans used volumetric modulated arc therapy (VMAT, RapidArc) to treat two targets at dose levels of 69.96 and 54.45 Gy in 33 fractions with simultaneous integrated boost. Two models were generated, the first separating the ipsi- and contra-lateral parotids, while the second associating the two parotids to a single structure for training. The optimization objectives were adjusted to the final model to better translate the institutional planning and dosimetric strategies and trade-offs. The models were validated on 20 HNC patients, comparing the RP generated plans and the clinical plans. RP generated plans were also compared between the clinical beam arrangement and a simpler geometry, as well as for a different fractionation scheme. RESULTS: RP improved significantly the clinical plan quality, with a reduction of 2 Gy, 5 Gy, and 10 Gy of the mean parotid, oral cavity and laryngeal doses, respectively. A simpler beam geometry was deteriorating the plan quality, but in a small amount, keeping a significant improvement relative to the clinical plan. The two models, with one or two parotid structures, showed very similar results. NTCP evaluations indicated the possibility of improving (NTCP decreasing of about 7%) the toxicity profile when using the RP solution. CONCLUSIONS: The HNC RP model showed improved plan quality and planning stability for beam geometry and fractionation. An adequate choice of the objectives in the model is necessary for the trade-offs strategies.
Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Modelos Teóricos , Garantia da Qualidade dos Cuidados de Saúde/normas , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Humanos , Órgãos em Risco/efeitos da radiação , Dosagem RadioterapêuticaRESUMO
PURPOSE: The optimal treatment for unfavourable intermediate/high-risk prostate cancer is still debated. In the present study, the pattern of toxicity and early clinical outcome of patients with localized prostate cancer was analyzed. METHODS: A cohort of 90 patients treated on pelvic lymph nodes from 2010 to 2015 was selected. All patients were treated with Volumetric Modulated Arc Therapy (VMAT), and Simultaneous integrated boost (SIB) in 28 fractions; the prostate, the seminal vesicle and the pelvic lymph node received total doses of 74.2, 65.5, and 51.8 Gy, respectively. End points were the detection of acute and late toxicities graded according to the Common Toxicity Criteria CTCAE version 3, evaluating the rectal, genito-urinary and gastro-intestinal toxicity. Correlation of OARs dose parameters and related toxicities was explored. Preliminary overall survival and Progression-free survival (PFS) were evaluated. RESULTS: With a median follow-up of 25 months, no interruptions for treatment-related toxicity were recorded. Univariate analysis among dosimetric data and acute toxicities showed no correlations. Regarding late toxicity: the dose received by a rectal volume of 90 cm3 was found to be significant for toxicity prediction (p = 0.024). PFS was 90.6% and 60.2% at 2 and 4 years, respectively. PFS correlates with age (p = 0.011) and Gleason score (p = 0.011). Stratifying the PSA nadir in quartiles, its value was significant (p = 0.016) in predicting PFS, showing a reduction of PFS of 2 months for each PSA-nadir increase of 0.1 ng/ml. CONCLUSION: HRT with VMAT and SIB on the whole pelvis in unfavourable prostate cancer patients is effective with a mild pattern of toxicity.
Assuntos
Adenocarcinoma/radioterapia , Neoplasias da Próstata/radioterapia , Radioterapia de Intensidade Modulada/métodos , Idoso , Idoso de 80 Anos ou mais , Intervalo Livre de Doença , Fracionamento da Dose de Radiação , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Pelve , Radiometria , Planejamento da Radioterapia Assistida por Computador , Estudos RetrospectivosRESUMO
OBJECTIVE: To evaluate the efficacy and the feasibility of SBRT for selected patients with isolated local recurrence of pancreatic cancer after radical surgery. METHODS: A retrospective analysis was performed on patients treated with SBRT for isolated local recurrence from resected pancreatic adenocarcinoma, after multidisciplinary board evaluation. Prescription dose was 45 Gy in 6 fractions for all patients. Primary end-point was freedom from local progression (FFLP). Secondary end-points were overall survival (OS), progression free survival (PFS) and toxicity. Local control was defined according to RECIST criteria. Acute and late toxicity was scored according to the NCI Common Terminology Criteria for Adverse Events (CTCAE) v4.0. RESULTS: Between January 2011 and February 2015, 31 patients with isolated local recurrence of resected pancreatic cancer were treated with SBRT. Pancreato-duodenectomy (PD) was performed on 24 patients and distal pancreatectomy (DP) in 7 cases, all with radical resection (R0). Median local recurrence disease free interval (DFI) was 14 months. Median follow-up was 12 months. FFLP was 91% and 82% at 1 and 2-years, respectively. Median PFS was 9 months. Median OS was 18 months. At univariate analysis, OS was correlated with a DFI>18 months. No cases of acute G3 toxicity or greater occurred. CONCLUSIONS: SBRT seems to be an effective and safe therapeutic option for isolated local recurrence of pancreatic cancer after surgery. Encouraging local control rate, very low toxicity profile and effective pain control suggest the crucial role of SBRT in the treatment of these long-survivors selected patients.
Assuntos
Adenocarcinoma/radioterapia , Recidiva Local de Neoplasia/radioterapia , Pancreatectomia , Neoplasias Pancreáticas/radioterapia , Pancreaticoduodenectomia , Radiocirurgia , Adenocarcinoma/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Quimioterapia Adjuvante , Intervalo Livre de Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Terapia Neoadjuvante , Recidiva Local de Neoplasia/diagnóstico por imagem , Neoplasias Pancreáticas/diagnóstico por imagem , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Radioterapia Adjuvante , Estudos Retrospectivos , Taxa de Sobrevida , Tomografia Computadorizada por Raios XRESUMO
PURPOSE: To assess the efficacy of stereotactic body radiotherapy in patients with unresectable locally advanced pancreatic cancer. MATERIALS AND METHODS: All patients received a prescription dose of 45 Gy in 6 fractions. Primary end point was freedom from local progression. Secondary end points were overall survival, progression-free survival, and toxicity. Actuarial survival analysis and univariate or multivariate analysis were investigated. RESULTS: Forty-five patients were enrolled in a phase 2 trial. Median follow-up was 13.5 months. Freedom from local progression was 90% at 2 years. On univariate ( P < .03) and multivariate analyses ( P < .001), lesion size was statistically significant for freedom from local progression. Median progression-free survival and overall survival were 8 and 13 months, respectively. On multivariate analysis, tumor size ( P < .001) and freedom from local progression ( P < .002) were significantly correlated with overall survival. Thirty-two (71%) patients with locally advanced pancreatic cancer received chemotherapy before stereotactic body radiotherapy. Median overall survival from diagnosis was 19 months. Multivariate analysis showed that freedom from local progression ( P < .035), tumor diameter ( P < .002), and computed tomography before stereotactic body radiotherapy ( P < .001) were significantly correlated with overall survival from diagnosis. CONCLUSION: Stereotactic body radiotherapy is a safe and effective treatment for patients with locally advanced pancreatic cancer with no G3 toxicity or greater and could be a promising therapeutic option in multimodality treatment regimen.
Assuntos
Adenocarcinoma/radioterapia , Recidiva Local de Neoplasia/radioterapia , Neoplasias Pancreáticas/radioterapia , Radiocirurgia/métodos , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/patologia , Adenocarcinoma/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Terapia Combinada , Desoxicitidina/administração & dosagem , Progressão da Doença , Intervalo Livre de Doença , Fracionamento da Dose de Radiação , Feminino , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/patologia , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/patologia , Neoplasias Pancreáticas/cirurgia , Neoplasias PancreáticasRESUMO
PURPOSE: To investigate the correlation between total monitor units (MU), dosimetric findings, and pre-treatment quality assurance for volumetric modulated arc therapy (VMAT) by RapidArc (RA). METHODS AND MATERIALS: Ten patients with breast cancer were considered. Dose prescriptions were: 48 Gy and 40.5 Gy in 15 fractions to, respectively, PTV(Boost) and PTVWholeBreast. A reference plan was optimized and four more plans using the "MU Objective", a tool for total MU controlling, were prepared imposing ± 20 and ± 50% total MU for inducing different complexities. Plan objectives were: D95% > 95% for both PTVs, and D2% < 107% for PTV(Boost); mean dose < 9.5 Gy and V20 Gy < 10% for ipsilateral lung; V18 Gy < 5% for heart; mean dose <3 Gy for controlateral breast; furthermore V5 Gy, V10 Gy, V20 Gy, and V30 Gy to body were minimized. Plans were evaluated in terms of technical parameters, dosimetric plan objectives findings and pre-treatment quality assurance (QA). RESULTS: Concerning PTVs, there were no significant differences for target coverage (D95%); mean doses for ipsilateral lung and controlateral breast, and V18 Gy for heart decreased with MUs increasing, reaching a plateau with reference plan. Body volume receiving low dose (V5-10 Gy) was minimized for reference plans. All plans had GAI (3 mm, 3%) > 95%. CONCLUSIONS: The data suggest that the best plan is the reference one, where the "MU Objective" tool was not used during optimisation. Nevertheless, it is advisable to use the "MU Objective" tool for re-planning when low GAI is found to increase its value. In this case, attention should be paid to OARs dose limits, since their values may be increased.
Assuntos
Neoplasias da Mama/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Humanos , Órgãos em Risco/efeitos da radiação , Controle de Qualidade , Radiometria , Radioterapia de Intensidade Modulada/efeitos adversos , Estudos RetrospectivosRESUMO
PURPOSE: To demonstrate the feasibility of portal dosimetry with an amorphous silicon mega voltage imager for flattening filter free (FFF) photon beams by means of the GLAaS methodology and to validate it for pretreatment quality assurance of volumetric modulated arc therapy (RapidArc). METHODS: The GLAaS algorithm, developed for flattened beams, was applied to FFF beams of nominal energy of 6 and 10 MV generated by a Varian TrueBeam (TB). The amorphous silicon electronic portal imager [named mega voltage imager (MVI) on TB] was used to generate integrated images that were converted into matrices of absorbed dose to water. To enable GLAaS use under the increased dose-per-pulse and dose-rate conditions of the FFF beams, new operational source-detector-distance (SDD) was identified to solve detector saturation issues. Empirical corrections were defined to account for the shape of the profiles of the FFF beams to expand the original methodology of beam profile and arm backscattering correction. GLAaS for FFF beams was validated on pretreatment verification of RapidArc plans for three different TB linacs. In addition, the first pretreatment results from clinical experience on 74 arcs were reported in terms of γ analysis. RESULTS: MVI saturates at 100 cm SDD for FFF beams but this can be avoided if images are acquired at 150 cm for all nominal dose rates of FFF beams. Rotational stability of the gantry-imager system was tested and resulted in a minimal apparent imager displacement during rotation of 0.2 ± 0.2 mm at SDD = 150 cm. The accuracy of this approach was tested with three different Varian TrueBeam linacs from different institutes. Data were stratified per energy and machine and showed no dependence with beam quality and MLC model. The results from clinical pretreatment quality assurance, provided a gamma agreement index (GAI) in the field area for six and ten FFF beams of (99.8 ± 0.3)% and (99.5 ± 0.6)% with distance to agreement and dose difference criteria set to 3 mm/3% with 2 mm/2% thresholds, GAI resulted (95.7.0 ± 2.3)% and (97.2 ± 2.1)%. CONCLUSIONS: The GLAaS methodology, introduced in clinical practice for conventional flattened photon beams for machine, IMRT, and RapidArc quality assurance, was successfully adapted for FFF beams of Varian TrueBeam Linac. The detector saturation effects could be eliminated if the portal images acquired at 150 cm for all nominal dose rates of FFF beams.
Assuntos
Radiometria/métodos , Radioterapia de Intensidade Modulada/métodos , Silício/química , Algoritmos , Calibragem , Desenho de Equipamento , Humanos , Aceleradores de Partículas , Fótons , Controle de Qualidade , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Reprodutibilidade dos Testes , Espalhamento de RadiaçãoRESUMO
PURPOSE: The accuracy of photon dose calculation algorithms in out-of-field regions is often neglected, despite its importance for organs at risk and peripheral dose evaluation. The present work has assessed this for the anisotropic analytical algorithm (AAA) and the Acuros-XB algorithms implemented in the Eclipse treatment planning system. Specifically, the regions shielded by the jaw, or the MLC, or both MLC and jaw for flattened and unflattened beams have been studied. METHODS: The accuracy in out-of-field dose under different conditions was studied for two different algorithms. Measured depth doses out of the field, for different field sizes and various distances from the beam edge were compared with the corresponding AAA and Acuros-XB calculations in water. Four volumetric modulated arc therapy plans (in the RapidArc form) were optimized in a water equivalent phantom, PTW Octavius, to obtain a region always shielded by the MLC (or MLC and jaw) during the delivery. Doses to different points located in the shielded region and in a target-like structure were measured with an ion chamber, and results were compared with the AAA and Acuros-XB calculations. Photon beams of 6 and 10 MV, flattened and unflattened were used for the tests. RESULTS: Good agreement between calculated and measured depth doses was found using both algorithms for all points measured at depth greater than 3 cm. The mean dose differences (± 1SD) were -8% ± 16%, -3% ± 15%, -16% ± 18%, and -9% ± 16% for measurements vs AAA calculations and -10% ± 14%, -5% ± 12%, -19% ± 17%, and -13% ± 14% for Acuros-XB, for 6X, 6 flattening-filter free (FFF), 10X, and 10FFF beams, respectively. The same figures for dose differences relative to the open beam central axis dose were: -0.1% ± 0.3%, 0.0% ± 0.4%, -0.3% ± 0.3%, and -0.1% ± 0.3% for AAA and -0.2% ± 0.4%, -0.1% ± 0.4%, -0.5% ± 0.5%, and -0.3% ± 0.4% for Acuros-XB. Buildup dose was overestimated with AAA, while Acuros-XB gave results more consistent with measurements. From RapidArc plan analysis the average difference between calculation and measurement in the shielded region was -0.3% ± 0.4% and -2.5% ± 1.2% for AAA and Acuros-XB, respectively, relative to the mean target dose value (1.6% ± 2.3%, -12.7% ± 4.0% if relative to each local value). These values were compared with the corresponding differences in the target structure: -0.7% ± 2.3% for AAA, and -0.5% ± 2.3% for Acuros-XB. CONCLUSIONS: The two algorithms analyzed showed encouraging results in predicting out-of-field region dose for clinical use.
Assuntos
Fótons/uso terapêutico , Proteção Radiológica/métodos , Radiometria/métodos , Algoritmos , Anisotropia , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade ModuladaRESUMO
OBJECTIVE: To evaluate the use of volumetric-modulated arc therapy [VMAT, RapidArc® (RA); Varian Medical Systems, Palo Alto, CA] for the treatment of cutaneous Kaposi's sarcoma (KS) of lower extremities with adequate target coverage and high bone sparing, and to compare VMAT with electron beam therapy. METHODS: 10 patients were planned with either RA or electron beams. The dose was prescribed to 30 Gy, 10 fractions, to mean the planning target volume (PTV), and significant maximum dose to bone was limited to 30 Gy. Plans were designed for 6-MV photon beams for RA and 6 MeV for electrons. Dose distributions were computed with AcurosXB® (Varian Medical Systems) for photons and with a Monte Carlo algorithm for electrons. RESULTS: V(90%) was 97.3±1.2 for RA plans and 78.2±2.6 for electrons; similarly, V(107%) was 2.5±2.2 and 37.7±3.4, respectively. RA met coverage criteria. Concerning bone sparing, D(2%) was 29.6±1.1 for RA and 31.0±2.4 for electrons. Although acceptable for bone involvement, pronounced target coverage violations were obtained for electron plans. Monitor units were similar for electrons and RA, although for the latter they increased when superior bone sparing was imposed. Delivery times were 12.1±4.0 min for electrons and 4.8±1.3 min for the most modulated RA plans. CONCLUSION: High plan quality was shown for KS in the lower extremities using VMAT, and this might simplify their management in comparison with the more conventional usage of electrons, particularly in institutes with limited staff resources and heavy workloads. ADVANCES IN KNOWLEDGE: VMAT is also dosimetrically extremely advantageous in a typology of treatments where electron beam therapy is mainly considered to be effective owing to the limited penetration of the beams.
Assuntos
Elétrons/uso terapêutico , Radioterapia de Intensidade Modulada/métodos , Sarcoma de Kaposi/radioterapia , Neoplasias Cutâneas/radioterapia , Ossos do Pé/efeitos da radiação , Humanos , Ossos da Perna/efeitos da radiação , Tratamentos com Preservação do Órgão/métodos , Planejamento de Assistência ao Paciente , Dosagem RadioterapêuticaRESUMO
PURPOSE: The aim of this article is to report the dosimetric and clinical findings in the treatment of primary hepatocellular carcinoma (HCC) with volumetric modulated arc therapy (VMAT, RapidArc). METHODS AND MATERIALS: A total of 138 patients were investigated. Dose prescription ranged from 45-66 Gy. Most patients (88.4 %) presented AJCC stage III or IV and 83 % were N0-M0. All were classified as Barcelona Clinic Liver Cancer (BCLC) stage A-C. All patients were treated using 10 MV photons with single or multiple, coplanar or non-coplanar arcs, and cone-down technique in case of early response of tumors. RESULTS: The patients' median age was 66 years (range 27-87 years), 83 % were treated with 60 Gy (12 % at 45 Gy, 6 % at 66 Gy), 62 % with cone-down, 98 % with multiple arcs. The mean initial planning target volume (PTV) was 777 ± 632 cm(3); the mean final PTV (after the cone-down) was 583 ± 548 cm(3). High target coverage was achieved. The final PTV was V98% > 98 %. Kidneys received on average 5 and 8 Gy (left and right), while the maximum dose to the spinal cord was 22 Gy; mean doses to esophagus and stomach were 23 Gy and 15 Gy, respectively. The average volume of healthy liver receiving more than 30 Gy was 294 ± 145 cm(3). Overall survival at 12 months was 45 %; median survival was 10.3 months (95 % confidence interval 7.2-13.3 months). Actuarial local control at 6 months was 95 % and 93.7 % at 12 months. The median follow-up was 9 months and a maximum of 28 months. CONCLUSION: This study showed from the dosimetric point of view the feasibility and technical appropriateness of RapidArc for the treatment of HCC. Clinical results were positive and might suggest, with appropriate care, to consider RapidArc as an additional therapeutic opportunity for these patients.
Assuntos
Carcinoma Hepatocelular/radioterapia , Neoplasias Hepáticas/radioterapia , Radioterapia de Intensidade Modulada/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma Hepatocelular/mortalidade , Carcinoma Hepatocelular/patologia , Intervalo Livre de Doença , Estudos de Viabilidade , Feminino , Seguimentos , Humanos , Fígado/efeitos da radiação , Neoplasias Hepáticas/mortalidade , Neoplasias Hepáticas/patologia , Masculino , Pessoa de Meia-Idade , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodosRESUMO
PURPOSE: Complex radiotherapy fields delivered using a tertiary multileaf collimator (MLC) often feature small open segments surrounded by large areas of the beam only shielded by the MLC. The aim of this study was to test the ability of two modern dose calculation algorithms to accurately calculate the dose in these fields which would be common, for example, in volumetric modulated arc treatment (VMAT) and study the impact of variations in dosimetric leaf gap (DLG), focal spot size, and MLC transmission in the beam models. METHODS: Nine test fields with small fields (0.6-3 cm side length) surrounded by large MLC shielded areas (secondary collimator 12 × 12 cm(2)) were created using a 6 MV beam from a Varian Clinac iX linear accelerator with 120 leaf MLC. Measurements of output factors and profiles were performed using a diamond detector (PTW) and compared to two dose calculations algorithms anisotropic analytical algorithm [(AAA) and Acuros XB] implemented on a commercial radiotherapy treatment planning system (Varian Eclipse 10). RESULTS: Both calculation algorithms predicted output factors within 1% for field sizes larger than 1 × 1 cm(2). For smaller fields AAA tended to underestimate the dose. Profiles were predicted well for all fields except for problems of Acuros XB to model the secondary penumbra between MLC shielded fields and the secondary collimator. A focal spot size of 1 mm or less, DLG 1.4 mm and MLC transmission of 1.4% provided a generally good model for our experimental setup. CONCLUSIONS: AAA and Acuros XB were found to predict the dose under small MLC defined field segments well. While DLG and focal spot affect mostly the penumbra, the choice of correct MLC transmission will be essential to model treatments such as VMAT accurately.
Assuntos
Modelos Teóricos , Proteção Radiológica/instrumentação , Radiometria/instrumentação , Radiometria/métodos , Radioterapia Conformacional/instrumentação , Radioterapia Conformacional/métodos , Simulação por Computador , Desenho Assistido por Computador , Dosagem Radioterapêutica , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
PURPOSE: In the present study, the acute toxicity profiles for prostate patients treated with simultaneous integrated boost (SIB) with volumetric modulated arcs in a hypofractionated regime are reported. PATIENTS AND METHODS: A total of 70 patients treated with RapidArc between May 2010 and September 2011 were retrospectively evaluated. Patients were stratified into low (36%), intermediate (49%), and high-risk (16%) groups. Target volumes (expanded to define the planning volumes (PTV)) were clinical target volume (CTV) 1: prostate; CTV2: CTV1 + seminal vesicles; CTV3: CTV2 + pelvic nodes. Low-risk patients received 71.4 Gy to PTV1; intermediate-risk 74.2 Gy to PTV1 and 61.6 or 65.5 Gy to PTV2; high-risk 74.2 Gy to PTV1, 61.6 or 65.5 Gy to PTV2, and 51.8 Gy to PTV3. All treatments were in 28 fractions. The median follow-up was 11 months (range 3.5-23 months). The acute rectal, gastrointestinal (GI) and genitourinary (GU) toxicities were scored according to EORTC/RTOG scales. RESULTS: Acute toxicities were recorded for the GU [G0 = 31/70 (44%), G1 = 22/70 (31%); G2 = 16/70 (23%); G3 = 1/70 (1%)], the rectum [G0 = 46/70 (66%); G1 = 12/70 (17%); G2 = 12/70 (17%); no G3], and the GI [G0 = 54/69 (77%); G1 = 11/69 (16%); G2 = 4/69 (6%); no G3]. Median time to rectal, GU, and GI toxicities were 27, 30, and 33 days, respectively. Only the GI toxicity correlated with stage and pelvic irradiation. Univariate analysis presented significant correlations between GI toxicity and intestinal irradiation (V(50 Gy) and V(60 Gy)). In the multivariate analysis, the only significant dosimetric variable was V(50 Gy) for the intestinal cavity. CONCLUSION: Moderate hypofractionation with SIB and RapidArc was shown to be safe, with acceptable acute toxicity. Longer follow-up is needed to assess late toxicity and clinical outcome.