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BACKGROUND/AIM: There are only a few studies on dosimetry with ultrahigh-dose-rate (uHDR) scanned carbon-ion beams. This study investigated the characteristics of four types of ionization chambers for the uHDR beam. MATERIALS AND METHODS: We employed a newly developed large-plane parallel chamber to monitor a 208.3-MeV/u uHDR scanned carbon-ion beam with a 110-Gy/s average dose rate. The ionization chambers used were the Advanced Markus chamber (AMC), PinPoint 3D chamber (PPC), Farmer chamber (FC), and large-plane parallel chamber (StingRay). The AMC and StingRay surfaces and the PPC and FC geometric centers were aligned to the radiation isocenter using treatment room lasers. Using the voltage range stated in the instruction manuals, we obtained the saturation curves of the chambers. From these curves, we obtained the ion recombination correction factors using the two-voltage and three-voltage linear methods. The dose linearity was evaluated using five measurement points, and the chamber repeatability was verified by conducting repeated measurements for different dose values. RESULTS: Although all chambers, except for AMC, reached saturation when specified voltages were applied, they exhibited excellent linearity for different dose values. The ion recombination correction factors of the AMC obtained using the aforementioned linear methods were nearly 1. Additionally, all chambers exhibited excellent repeatability. Although the standard deviation of the PPC for the lowest dose was ~1.5%, those of all the other chambers were <1.0%. CONCLUSION: All ionization chambers can be used for measuring the relative dose, and absolute dose can be conveniently measured using the AMC with an uHDR carbon-ion scanned beam.
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Radioterapia com Íons Pesados , Radiometria , Dosagem Radioterapêutica , Radiometria/métodos , Radiometria/instrumentação , Radioterapia com Íons Pesados/métodos , Radioterapia com Íons Pesados/instrumentação , Carbono/química , HumanosRESUMO
BACKGROUND/AIM: Despite the established antitumor effectiveness and synergistic interactions of melatonin with photon irradiation, its role in carbon-ion radiotherapy remains uncertain. This study aimed to elucidate the mechanisms and potential clinical advantages of combining exogenous melatonin therapy with carbon-ion radiotherapy. MATERIALS AND METHODS: The investigation assessed the impact of combining exogenous melatonin with photon or carbon-ion irradiation on cell-cycle modulation and DNA-repair capability using the melanoma cell line B16F10. RNA sequencing and bioinformatics analysis were conducted to explore mechanisms and evaluate potential clinical benefits, with validation performed on the osteosarcoma cell line LM8. RESULTS: Pre-treatment with melatonin reduced the survival fraction of B16F10 and LM8 cells upon exposure to photon and carbon-ion radiation. Mechanistically, melatonin was found to inhibit G2/M arrest, preserve DNA damage, and suppress key genes involved in DNA double-strand break repair after 8 Gy carbon-ion radiation. Furthermore, RNA sequencing and bioinformatics analysis revealed favorable changes in genes associated with survival and metastasis, highlighting potential clinical significance. LM8 cells treated with melatonin exhibited increased radiosensitivity and suppression of DNA-repair proteins. CONCLUSION: The combination of exogenous melatonin not only heightened radiosensitivity and modulated hallmark tumor gene sets in vitro but also markedly suppressed the efficiency of DNA double-strand break-repair pathway, thus enhancing the cytotoxicity of carbon-ion radiotherapy.
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Reparo do DNA , Radioterapia com Íons Pesados , Melatonina , Tolerância a Radiação , Radiossensibilizantes , Melatonina/farmacologia , Linhagem Celular Tumoral , Tolerância a Radiação/efeitos dos fármacos , Camundongos , Animais , Humanos , Reparo do DNA/efeitos dos fármacos , Reparo do DNA/efeitos da radiação , Radiossensibilizantes/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Melanoma Experimental/radioterapia , Melanoma Experimental/tratamento farmacológico , Melanoma Experimental/patologia , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Quebras de DNA de Cadeia Dupla/efeitos da radiaçãoRESUMO
We sought to identify potential evidence-practice gaps in palliative radiotherapy using quality indicators (QIs), previously developed using a modified Delphi method. Seven QIs were used to assess the quality of radiotherapy for bone metastases (BoM) and brain metastases (BrM). Compliance rate was calculated as the percentage of patients for whom recommended medical care was conducted. Random effects models were used to estimate the pooled compliance rates. Of the 39 invited radiation oncologists, 29 (74%) from 29 centers participated in the survey; 13 (45%) were academic and 16 (55%) were non-academic hospitals. For the QIs, except for BoM-4, the pooled compliance rates were higher than 80%; however, for at least some of the centers, the compliance rate was lower than these pooled rates. For BoM-4 regarding steroid use concurrent with radiotherapy for malignant spinal cord compression, the pooled compliance rate was as low as 32%. For BoM-1 regarding the choice of radiation schedule, the compliance rate was higher in academic hospitals than in non-academic hospitals (P = 0.021). For BrM-3 regarding the initiation of radiotherapy without delay, the compliance rate was lower in academic hospitals than in non-academic hospitals (P = 0.016). In conclusion, overall, compliance rates were high; however, for many QIs, practice remains to be improved in at least some centers. Steroids are infrequently used concurrently with radiotherapy for malignant spinal cord compression.
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Cuidados Paliativos , Indicadores de Qualidade em Assistência à Saúde , Humanos , Inquéritos e Questionários , Neoplasias Encefálicas/radioterapia , Neoplasias Ósseas/radioterapia , Neoplasias Ósseas/secundário , Radioterapia , Fidelidade a DiretrizesRESUMO
The current monochromatic beam mode (i.e., uHDR irradiation mode) of the scanned carbon-ion beam lacks a dedicated dose monitor, making the beam control challenging. We developed and characterized a dedicated dose monitor for uHDR-scanned carbon-ion beams. Furthermore, a simple measurable dose rate (dose rate per spot (DRspot)) was suggested by using the developed dose monitor and experimentally validating quantities relevant to the uHDR scanned carbon-ion beam. A large plane-parallel ionization chamber (IC) with a smaller electrode spacing was used to reduce uHDR recombination effects, and a dedicated operational amplifier was manufactured for the uHDR-scanned carbon-ion beam. The dose linearity of the IC was within ± 1% in the range of 1.8-12.3 Gy. The spatial inhomogeneity of the dose response of the IC was ± 0.38% inside the ± 40-mm detector area, and a systematic deviation of approximately 2% was measured at the edge of the detector. uHDR irradiation with beam scanning was tested and verified for different doses at the corresponding dose rates (in terms of both the average dose rate and DRspot). We confirmed that the dose monitor can highlight the characteristics (i.e., dose, dose rate, and dose profile) of uHDR-scanned carbon-ion beams at several dose levels in the monochromatic beam mode.
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The purpose of the study is to investigate the variation in Hounsfield unit (HU) values calculated using dual-energy computed tomography (DECT) scanners. A tissue characterization phantom inserting 16 reference materials were scanned three times using DECT scanners [dual-layer CT (DLCT), dual-source CT (DSCT), and fast kilovoltage switching CT (FKSCT)] changing scanning conditions. The single-energy CT images (120 or 140 kVp), and virtual monochromatic images at 70 keV (VMI70) and 140 keV (VMI140) were reconstructed, and the HU values of each reference material were measured. The difference in HU values was larger when the phantom was scanned using the half dose with wrapping with rubber (strong beam-hardening effect) compared with the full dose without the rubber (reference condition), and the difference was larger as the electron density increased. For SECT, the difference in HU values against the reference condition measured by the DSCT (3.2 ± 5.0 HU) was significantly smaller (p < 0.05) than that using DLCT with 120 kVp (22.4 ± 23.8 HU), DLCT with 140 kVp (11.4 ± 12.8 HU), and FKSCT (13.4 ± 14.3 HU). The respective difference in HU values in the VMI70 and VMI140 measured using the DSCT (10.8 ± 17.1 and 3.5 ± 4.1 HU) and FKSCT (11.5 ± 21.8 and 5.5 ± 10.4 HU) were significantly smaller than those measured using the DLCT120 (23.1 ± 27.5 and 12.4 ± 9.4 HU) and DLCT140 (22.3 ± 28.6 and 13.1 ± 11.4 HU). The HU values and the susceptibility to beam-hardening effects varied widely depending on the DECT scanners.
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Imagens de Fantasmas , Tomografia Computadorizada por Raios X , Tomografia Computadorizada por Raios X/métodos , Processamento de Imagem Assistida por Computador/métodos , Doses de RadiaçãoRESUMO
To investigate the geometric accuracy of the radiation focal point (RFP) and cone-beam computed tomography (CBCT) over long-term periods for the ICON Leksell Gamma Knife radiosurgery system. This phantom study utilized the ICON quality assurance tool plus, and the phantom was manually set on the patient position system before the implementation of treatment for patients. The deviation of the RFP position from the unit center point (UCP) and the positions of the four ball bearings (BBs) in the CBCT from the reference position were automatically analyzed. During 544 days, a total of 269 analyses were performed on different days. The mean ± standard deviation (SD) of the deviation between measured RFP and UCP was 0.01 ± 0.03, 0.01 ± 0.03, and -0.01 ± 0.01 mm in the X, Y, and Z directions, respectively. The deviations with offset values after the cobalt-60 source replacement (0.00 ± 0.03, -0.01 ± 0.01, and -0.01 ± 0.01 mm in the X, Y, and Z directions, respectively) were significantly (p = 0.001) smaller than those before the replacement (0.02 ± 0.03, 0.02 ± 0.01, and -0.02 ± 0.01 mm in the X, Y, and Z directions, respectively). The overall mean ± SD of four BBs was -0.03 ± 0.03, -0.01 ± 0.05, and 0.01 ± 0.03 mm in the X, Y, and Z directions, respectively. Geometric positional accuracy was ensured to be within 0.1 mm on most days over a long-term period of more than 500 days.
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Tomografia Computadorizada de Feixe Cônico , Imagens de Fantasmas , Radiocirurgia , Radiocirurgia/instrumentação , Garantia da Qualidade dos Cuidados de Saúde , Humanos , Controle de Qualidade , Fatores de TempoRESUMO
Purpose: Radiation therapy is widely used to treat head and neck squamous cell carcinoma (HNSCC). This study evaluated the association between circulating plasma programmed death-ligand 1 (PD-L1) and the outcomes of patients with HNSCC after radiation therapy. Methods and Materials: In this retrospective observational study, plasma samples of 76 patients with HNSCC who underwent radiation therapy from June 2019 to August 2021 were analyzed. These plasma samples were obtained before radiation therapy. The median follow-up was 32.5 months. Total and exosomal PD-L1 was measured by enzyme-linked immunosorbent assay and retrospectively analyzed for association with overall survival (OS), progression-free survival (PFS), and local control (LC). Prognostic factors among patients' characteristics and circulating PD-L1 in plasma were evaluated by univariate (log-rank test) and multivariate (Cox proportional hazards model) analyses. Results: The median concentration of total PD-L1 in plasma was 115.1 pg/mL (95% CI, 114.7-137.9 pg/mL), and the median concentration of exosomal PD-L1 was 2.8 pg/mL (95% CI, 6.0-13.0 pg/mL). Univariate and multivariate analyses showed exosomal PD-L1 as a prognostic factor for PFS and LC. Patients with high exosomal PD-L1 in plasma had poor PFS and LC compared with those with low exosomal PD-L1, indicating that 1-year PFS was 79.2% versus 33.3% (P < .001) and 1-year LC was 87.3% versus 50.0% (P < .001) in patients with high and low exosomal PD-L1, respectively. However, exosomal PD-L1 in plasma had no significant effect on OS. Total PD-L1 in plasma did not correlate with PFS, LC, and OS. Conclusions: The pretreatment circulating exosomal PD-L1 in plasma of patients with HNSCC was a prognostic factor after radiation therapy.
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BACKGROUND/AIM: Radiotherapy (RT) outcomes are generally reported based on stage, patient background, and concomitant chemotherapy. This study aimed to investigate the effects of the prescribed dose to gross tumor volume (GTV) and the calculation algorithm on local control in definitive RT for head and neck (H&N) cancers using follow-up images after RT. PATIENTS AND METHODS: This study included 154 patients with H&N cancers treated by Volumetric Modulated Arc Therapy at the Kobe City Medical Center General Hospital. Patients were classified into those receiving definitive RT (70 Gy of irradiation) and those not receiving it. Follow-up images were used to categorize the patients into the responders and non-responders groups. In the non-responders group, follow-up images were imported into the treatment planning system, and the contours of the residual or recurrent areas (local failure) were extracted and fused with computed tomography-simulated images for treatment planning. Dose evaluation parameters included maximum dose, dose administered to 1% of the volume, dose administered to 50% of the volume, dose administered to 99% of the volume (D99%), and minimum dose (Dmin) administered to the GTV. The doses to the GTV were compared between responders and non-responders. RESULTS: D99% exhibited significant differences between local failure and responders and between local failure and non-responders. Dmin showed significant differences between responders and non-responders and between responders and local failure. CONCLUSION: This study emphasizes the importance of verifying dose distribution in all slices of treatment planning, highlighting the need for precise assessment of the dose to the GTV in head and neck cancers.
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Neoplasias de Cabeça e Pescoço , Radioterapia Conformacional , Radioterapia de Intensidade Modulada , Humanos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Neoplasias de Cabeça e Pescoço/radioterapia , Radioterapia Conformacional/métodos , Radioterapia de Intensidade Modulada/métodosRESUMO
PURPOSE: To explore the potential of quantitative parameters of the hydrogel spacer distribution as predictors for separating the rectum from the planning target volume (PTV) in linear-accelerator-based stereotactic body radiotherapy (SBRT) for prostate cancer. METHODS: Fifty-five patients underwent insertion of a hydrogel spacer and were divided into groups 1 and 2 of the PTV separated from and overlapping with the rectum, respectively. Prescribed doses of 36.25-45 Gy in five fractions were delivered to the PTV. The spacer cover ratio (SCR) and hydrogel-implant quality score (HIQS) were calculated. RESULTS: Dosimetric and quantitative parameters of the hydrogel spacer distribution were compared between the two groups. For PTV, D99% in group 1 (n = 29) was significantly higher than that in group 2 (n = 26), and Dmax, D0.03cc, D1cc, and D10% for the rectum were significantly lower in group 1 than in group 2. The SCR for prostate (89.5 ± 12.2%) in group 1 was significantly higher (p < 0.05) than that in group 2 (74.7 ± 10.3%). In contrast, the HIQS values did not show a significant difference between the groups. An area under the curve of 0.822 (95% confidence interval, 0.708-0.936) for the SCR was obtained with a cutoff of 93.6%, sensitivity of 62.1%, and specificity of 100%. CONCLUSIONS: The SCR seems promising to predict the separation of the rectum from the PTV in linear-accelerator-based SBRT for prostate cancer.
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Órgãos em Risco , Neoplasias da Próstata , Radiocirurgia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade Modulada , Humanos , Neoplasias da Próstata/radioterapia , Neoplasias da Próstata/cirurgia , Masculino , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Órgãos em Risco/efeitos da radiação , Idoso , Aceleradores de Partículas/instrumentação , Hidrogéis/química , Pessoa de Meia-Idade , Prognóstico , Radiometria/métodos , Idoso de 80 Anos ou maisRESUMO
In linear accelerator-based stereotactic irradiation (STI) for brain metastasis, cone-beam computed tomography (CBCT) image quality is essential for ensuring precise patient setup and tumor localization. However, CBCT images may be degraded by the deviation of the CBCT isocenter from the brain center. This study aims to investigate the effects of the distance from the brain center to the CBCT isocenter (DBI) on the image quality in STI. An anthropomorphic phantom was scanned with varying DBI in right, anterior, superior, and inferior directions. Thirty patients undergoing STI were prospectively recruited. Objective metrics, utilizing regions of interest included contrast-to-noise ratio (CNR) at the centrum semiovale, lateral ventricle, and basal ganglia levels, gray and white matter noise at the basal ganglia level, artifact index (AI), and nonuniformity (NU). Two radiation oncologists assessed subjective metrics. In this phantom study, objective measures indicated a degradation in image quality for non-zero DBI. In this patient study, there were significant correlations between the CNR at the centrum semiovale and lateral ventricle levels (rs = - 0.79 and - 0.77, respectively), gray matter noise (rs = 0.52), AI (rs = 0.72), and NU (rs = 0.91) and DBI. However, no significant correlations were observed between the CNR at the basal ganglia level, white matter noise, and subjective metrics and DBI (rs < ± 0.3). Our results demonstrate the effects of DBI on contrast, noise, artifacts in the posterior fossa, and uniformity of CBCT images in STI. Aligning the CBCT isocenter with the brain center can aid in improving image quality.
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Encéfalo , Tomografia Computadorizada de Feixe Cônico , Imagens de Fantasmas , Radiocirurgia , Humanos , Encéfalo/diagnóstico por imagem , Masculino , Feminino , Pessoa de Meia-Idade , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/radioterapia , Idoso , Razão Sinal-Ruído , Processamento de Imagem Assistida por Computador , Adulto , ArtefatosRESUMO
PURPOSE: The geometric distortion related to magnetic resonance (MR) imaging in a diagnostic radiology (MRDR) and radiotherapy (MRRT) setup is evaluated, and the dosimetric impact of MR distortion on fractionated stereotactic radiotherapy (FSRT) in patients with brain metastases is simulated. MATERIALS AND METHODS: An anthropomorphic skull phantom was scanned using a 1.5T MR scanner, and the magnitude of MR distortion was calculated with (MRDR-DC and MRRT-DC) and without (MRDR-nDC and MRRT-nDC) distortion-correction algorithms. Automated noncoplanar volumetric modulated arc therapy (HyperArc, HA; Varian Medical Systems, Palo Alto, CA, USA) plans were generated for 53 patients with 186 brain metastases. The MR distortion at each gross tumor volume (GTV) was calculated using the distance between the center of the GTV and the MR image isocenter (MIC) and the quadratic regression curve derived from the phantom study (MRRT-DC and MRRT-nDC). Subsequently, the radiation isocenter of the HA plans was shifted according to the MR distortion at each GTV (HADC and HAnDC). RESULTS: The median MR distortions were approximately 0.1â¯mm when the distance from the MIC was <â¯30â¯mm, whereas the median distortion varied widely when the distance was >â¯60â¯mm (0.23, 0.47, 0.37, and 0.57â¯mm in MRDR-DC, MRDR-nDC, MRRT-DC, and MRRT-nDC, respectively). The dose to the 98% of the GTV volume (D98%) decreased as the distance from the MIC increased. In the HADC plans, the relative dose difference of D98% was less than 5% when the GTV was located within 70â¯mm from the MIC, whereas the underdose of GTV exceeded 5% when it was 48â¯mm (-26.5% at maximum) away from the MIC in the HAnDC plans. CONCLUSION: Use of a distortion-correction algorithm in the studied MR diagnoses is essential, and the dosimetric impact of MR distortion is not negligible, particularly for tumors located far away from the MIC.
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Neoplasias Encefálicas , Radiocirurgia , Humanos , Planejamento da Radioterapia Assistida por Computador/métodos , Radiocirurgia/métodos , Algoritmos , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/secundário , Imageamento por Ressonância Magnética/métodos , Dosagem RadioterapêuticaRESUMO
BACKGROUND/AIM: Radiation therapy is pivotal in cancer treatment; however, its efficacy is limited by challenges such as tumor recurrence. This study delves into the role of exosomes, which are molecular cargo-bearing vesicles, in influencing cell proliferation, radioresistance, and consequent post-irradiation tumor recurrence. Given the significance of exosomes from irradiated malignancies in diagnostics and therapy, it is vital to delineate their functional dynamics, especially in breast and cervical cancer cell lines, where the impact of irradiation on exosome behavior remains enigmatic. MATERIALS AND METHODS: Using MDA-MB-231 and HeLa cell lines, exosomes were isolated from the culture supernatant via ultracentrifugation. The bicinchoninic acid assay was used to measure exosome quantities in irradiated and non-irradiated cells. Radiosensitivity was assessed using colony formation assays, while the role of the MAPK/Erk signaling pathway in recipient cell proliferation and radioresistance was probed using western blotting. RESULTS: Irradiated cells, in both MDA-MB-231 and HeLa lines, produced significantly more exosomes than their non-irradiated counterparts. Co-culturing irradiated cells with exosomes led to increased cell survival post-irradiation and enhanced cell proliferation in both cell lines. Western blotting indicated elevated p-Erk expression in such cells, underscoring the influence of the MAPK/Erk pathway in radioresistance and proliferation. CONCLUSION: The study establishes a potential nexus between exosome secretion and tumor resurgence following radiotherapy. The spotlight falls on the MAPK/ERK signaling conduit as a key influencer. This new knowledge provides an innovative strategy for counteracting cancer recurrence after radiotherapy, emphasizing the importance of understanding the multifaceted roles of exosomes in this context.
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Exossomos , Sistema de Sinalização das MAP Quinases , Humanos , Células HeLa , Exossomos/metabolismo , Recidiva Local de Neoplasia/patologia , Proliferação de Células , Linhagem Celular TumoralRESUMO
BACKGROUND: Fatigue during radiation therapy in women with breast cancer can decrease quality of life (QOL), yet it is often underestimated and needs to be evaluated objectively. This longitudinal study aimed to evaluate fatigue and QOL of women with breast cancer undergoing radiotherapy with a simple autonomic function measurement. METHODS: Women with breast cancer who underwent postoperative radiotherapy in eight cancer care hospitals in Chubu and Kinki regions in Japan were recruited between October 2021 and June 2022. The women underwent a self-administered questionnaire that included the Cancer Fatigue Scale (CFS) and the Short Form-8 Health Survey (SF-8) and an autonomic nervous function measurement using a simple, non-invasive device before (T0, baseline), mid (T1), and at the end (T2) of treatment. RESULTS: The 57 women showed similar trends, with CFS scores and log LF/HF ratio being the highest at T0 and significantly decreasing at T1 (both p < 0.05). The log LF/HF trends differed between those with high and low baseline log LF/HF values. Women with mental component summary (MCS) score improvement (T0 to T2) had the highest log LF/HF ratio at T0 and had significantly lower log LF/HF values at T1 and T2 than at T0 (p < 0.01 and p < 0.05, respectively). The change of (â¿) MCS from T0 to T1 was negatively correlated with â¿log LF/HF from T0 to T1 (r = - 0.36, p < 0.01). CONCLUSIONS: Measurement of autonomic nerve function with a simple device is useful for objective fatigue assessment during radiotherapy. Psychological support is important as improvement in mental health helps improve autonomic nerve function and, in turn, fatigue.
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Neoplasias da Mama , Qualidade de Vida , Humanos , Feminino , Estudos Prospectivos , Neoplasias da Mama/radioterapia , Estudos Longitudinais , Fadiga/etiologiaRESUMO
To explore predictors of the histopathological response to preoperative chemoradiotherapy (CRT) in patients with pancreatic cancer (PC) using dual-energy computed tomography-reconstructed images. This retrospective study divided 40 patients who had undergone preoperative CRT (50-60 Gy in 25 fractions) followed by surgical resection into two groups: the response group (Grades II, III and IV, evaluated from surgical specimens) and the nonresponse group (Grades Ia and Ib). The computed tomography number [in Hounsfield units (HUs)] and iodine concentration (IC) were measured at the locations of the aorta, PC and pancreatic parenchyma (PP) in the contrast-enhanced 4D dual-energy computed tomography images. Logistic regression analysis was performed to identify predictors of histopathological response. Univariate analysis did not reveal a significant relation between any parameter and patient characteristics or dosimetric parameters of the treatment plan. The HU and IC values in PP and the differences in HU and IC between the PP and PC (ΔHU and ΔIC, respectively) were significant predictors for distinguishing the response (n = 24) and nonresponse (n = 16) groups (P < 0.05). The IC in PP and ΔIC had a higher area under curve values [0.797 (95% confidence interval, 0.659-0.935) and 0.789 (0.650-0.928), respectively] than HU in PP and ΔHU [0.734 (0.580-0.889) and 0.721 (0.562-0.881), respectively]. The IC value could potentially be used for predicting the histopathological response in patients who have undergone preoperative CRT.
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Iodo , Neoplasias Pancreáticas , Humanos , Estudos Retrospectivos , Meios de Contraste , Tomografia Computadorizada por Raios X/métodos , Neoplasias Pancreáticas/diagnóstico por imagem , Neoplasias Pancreáticas/terapia , Quimiorradioterapia/métodos , Neoplasias PancreáticasRESUMO
Currently, treatment planning systems (TPSs) that can compute the intensities of intensity-modulated carbon-ion therapy (IMCT) using scanned carbon-ion beams are limited. In the present study, the computational efficacy of the newly designed IMCT algorithms was analyzed for the first time based on the mixed beam model with respect to the physical and biological doses; moreover, the validity and effectiveness of the robust radiobiological optimization were verified. A dose calculation engine was independently generated to validate a clinical dose determined in the TPS. A biological assay was performed using the HSGc-C5 cell line to validate the calculated surviving fraction (SF). Both spot control (SC) and voxel-wise worst-case scenario (WC) algorithms were employed for robust radiobiological optimization followed by their application in a Radiation Therapy Oncology Group benchmark phantom under homogeneous and heterogeneous conditions and a clinical case for range and position errors. Importantly, for the first time, both SC and WC algorithms were implemented in the integrated TPS platform that can compute the intensities of IMCT using scanned carbon-ion beams for robust radiobiological optimization. For assessing the robustness, the difference between the maximum and minimum values of a dose-volume histogram index in the examined error scenarios was considered as a robustness index. The relative biological effectiveness (RBE) determined by the independent dose calculation engine exhibited a -0.6% difference compared with the RBE defined by the TPS at the isocenter, whereas the measured and the calculated SF were similar. Regardless of the objects, compared with the conventional IMCT, the robust radiobiological optimization enhanced the sensitivity of the examined error scenarios by up to 19% for the robustness index. The computational efficacy of the novel IMCT algorithms was verified according to the mixed beam model with respect to the physical and biological doses. The robust radiobiological optimizations lowered the impact of range and position uncertainties considerably in the examined scenarios. The robustness of the WC algorithm was more enhanced compared with that of the SC algorithm. Nevertheless, the SC algorithm can be used as an alternative to the WC IMCT algorithm with respect to the computational cost.
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Radioterapia com Íons Pesados , Terapia com Prótons , Radioterapia de Intensidade Modulada , Radioterapia de Intensidade Modulada/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia com Íons Pesados/métodos , Algoritmos , Carbono/uso terapêutico , Dosagem Radioterapêutica , Terapia com Prótons/métodosRESUMO
BACKGROUND/AIM: Angiosarcoma of the scalp (AS) is a rare tumor that has often been treated by total scalp irradiation (TSI). TSI has technical and dosimetric challenges. This study aimed to compare the dosimetric performance of helical tomotherapy (HT) plans with that of HyperArc (HA) plans for TSI in AS. PATIENTS AND METHODS: A planning study was conducted for 11 patients with AS (70 Gy/35 fr). HT and HA planning was performed using TomoHDA and TrueBeam Edge systems, respectively. The performance of three different plans were compared: HT, HA, and HA with half-field beams (HF-HA). The dose distribution and dosimetric parameters for each plan were evaluated. RESULTS: All constraint parameters for the target and organs at risk (OARs) met the goals within acceptable limits for the three techniques. The HA and HF-HA plans provided significantly lower mean brain dose (12.46±2.48 Gy and 8.02±1.48 Gy) than did the HT plan (17.59±3.47 Gy). The doses receiving 0.1 cc of the volume for brainstem and chiasm were significantly lower in the HA and HF-HA plans than those in the HT plan. The HA and HF-HA plans provided a shorter beam-on time (155±3 s and 181±14 s) than did the HT plan (962±221 s). CONCLUSION: The HA plan provided significantly better OARs sparing than the HT plan for TSI in AS and had an advantage to using half-field beams.
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Hemangiossarcoma , Radioterapia de Intensidade Modulada , Humanos , Radioterapia de Intensidade Modulada/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Dosagem Radioterapêutica , Couro Cabeludo , Hemangiossarcoma/radioterapia , Órgãos em Risco/efeitos da radiaçãoRESUMO
This study aimed to compare dosimetric parameters for targets and organs at risk (OARs) between volumetric modulated arc therapy (VMAT) and automated VMAT (HyperArc, HA) plans in stereotactic radiotherapy for patients with cervical metastatic spine tumors. VMAT plans were generated for 11 metastases using the simultaneous integrated boost technique to deliver 35 to 40 and 20 to 25 Gy for high dose and elective dose planning target volume (PTVHD and PTVED), respectively. The HA plans were retrospectively generated using 1 coplanar and 2 noncoplanar arcs. Subsequently, the doses to the targets and OARs were compared. The HA plans provided significantly higher (p < 0.05) Dmin (77.4 ± 13.1%), D99% (89.3 ± 8.9%), and D98% (92.5 ± 7.7%) for gross tumor volume (GTV) than those of the VMAT plans (73.4 ± 12.2%, 84.2 ± 9.6 and 87.3 ± 8.8% for Dmin, D99% and D98%, respectively). In addition, D99% and D98% for PTVHD were significantly higher in the HA plans, whereas dosimetric parameters were comparable between the HA and VMAT plans for PTVED. The Dmax values for the brachial plexus, esophagus, and spinal cord were comparable, and no significant difference was observed in the Dmean for the larynx, pharyngeal constrictor, thyroid, parotid grand (left and right), and Submandibular gland (left and right). The HA plans provided significantly higher target coverage of GTV and PTVHD, with a comparable dose for OARs with VMAT plans. The results of this study may contribute to the improvement of local control in clinical practice.
RESUMO
To compare the dosimetric parameters of automated noncoplanar volumetric modulated arc therapy plans using single-isocentric (SIC) and multi-isocentric (MIC) techniques for patients with two brain metastases (BMs) in stereotactic irradiation and to evaluate the robustness of rotational errors. The SIC and MIC plans were retrospectively generated (35 Gy/five fractions) for 58 patients. Subsequently, a receiver operating characteristic curve analysis between the tumor surface distance (TSD) and V25Gy was performed to determine the thresholds for the brain tissue. The SIC and MIC plans were recalculated based on the rotational images to evaluate the dosimetric impact of rotational error. The MIC plans showed better brain tissue sparing for TSD > 6.6 cm. The SIC plans provided a significantly better conformity index for TSD ≤ 6.6 cm, while significantly lower gradient index was obtained (3.22 ± 0.56vs. 3.30 ± 0.57, p < 0.05) in the MIC plans with TSD > 6.6 cm. For organs at risk (OARs) (brainstem, chiasm, lens, optic nerves, and retinas), D0.1 cc was significantly lower (p < 0.05) in the MIC plans than in the SIC plans. The prescription dose could be delivered (D99%) to the gross tumor volume (GTV) for patients with TSD ≤ 6.6 cm when the rotational error was < 1°, whereas 31% of the D99% of GTV fell below the prescription dose with TSD > 6.6 cm. MIC plans can be an optimal approach for reducing doses to OARs and providing robustness against rotational errors in BMs with TSD > 6.6 cm.
Assuntos
Neoplasias Encefálicas , Radiocirurgia , Radioterapia de Intensidade Modulada , Humanos , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Estudos Retrospectivos , Planejamento da Radioterapia Assistida por Computador/métodos , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/patologia , Órgãos em Risco , Radiocirurgia/métodosRESUMO
To compare dosimetric parameters for the hippocampus, organs at risk (OARs), and targets of volumetric modulated arc therapy (VMAT), noncoplanar VMAT (NC-VMAT), and HyperArc (HA) plans in patients undergoing postoperative radiotherapy for primary brain tumors. For 20 patients, HA plans were generated to deliver 40.05 to 60 Gy for the planning target volume (PTV). In addition, doses for the hippocampus and OARs were minimized. The VMAT and NC-VMAT plans were retrospectively generated using the same optimization parameters as those in the HA plans. For the hippocampus, the equivalent dose to be administered in 2 Gy fractions (EQD2) was calculated assuming α/ßâ¯=â¯2. Dosimetric parameters for the PTV, hippocampus, and OARs in the VMAT, NC-VMAT, and HA plans were compared. For PTV, the HA plans provided significantly lower Dmax and D1% than the VMAT and NC-VMAT plans (p < 0.05), whereas the D99% and Dmin were significantly higher (p < 0.05). For the contralateral hippocampus, the dosimetric parameters in the HA plans (8.1 ± 9.6, 6.5 ± 7.2, 5.6 ± 5.8, and 4.8 ± 4.7 Gy for D20%, D40%, D60% and D80%, respectively) were significantly smaller (p < 0.05) than those in the VMAT and NC-VMAT plans. Except for the optic chiasm, the Dmax in the HA plans (brainstem, lens, optic nerves, and retinas) was the smallest (p < 0.05). In addition, the doses in the HA plans for the brain and skin were the smallest (p < 0.05) among the 3 plans. HA planning, instead of coplanar and noncoplanar VMAT, significantly reduces the dosage to which the contralateral hippocampus as well as other OARs are exposed without compromising on target coverage.
Assuntos
Neoplasias Encefálicas , Radioterapia de Intensidade Modulada , Humanos , Dosagem Radioterapêutica , Redução da Medicação , Estudos Retrospectivos , Planejamento da Radioterapia Assistida por Computador , Radioterapia de Intensidade Modulada/efeitos adversos , Órgãos em Risco , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/cirurgia , HipocampoRESUMO
Pancreatic cancer is one of the most aggressive cancers and the seventh leading cause of cancer-associated death in the world. Radiation is performed as an adjuvant therapy as well as anti-cancer drugs. Because cancer stem-like cells (CSCs) are considered to be radioresistant and cause recurrence and metastasis, understanding their properties is required for the development of novel therapeutic strategies. To investigate the CSC properties of pancreatic cancer cells, we used a pancreatic CSC model, degron (++) cells, which have low proteasome activity. Degron (++) cells displayed radioresistance in comparison with control cells. Using Ribonucleic acid (RNA) sequencing, we successfully identified KRT13 as a candidate gene responsible for radioresistance. Knockdown of KRT13 sensitized the degron (++) cells to radiation. Furthermore, a database search revealed that KRT13 is upregulated in pancreatic cancer cell lines and that high expression of KRT13 is associated with poorer prognosis. These results indicate that a combination therapy of KRT13 knockdown and radiation could hold therapeutic promise in pancreatic cancer.