جستجوی مقالات مرتبط با کلیدواژه « brachytherapy » در نشریات گروه « پزشکی »

Radiomic feature reproducibility assessment is critical in radiomics‑based image biomarker discovery. This study aims to evaluate the impact of preprocessing parameters on the reproducibility of magnetic resonance image (MRI) radiomic features extracted from gross tumor volume (GTV) and high‑risk clinical tumor volume (HR‑CTV) in cervical cancer (CC) patients.

This study included 99 patients with pathologically confirmed cervical cancer who underwent an MRI prior to receiving brachytherapy. The GTV and HR‑CTV were delineated on T2‑weighted MRI and inputted into 3D Slicer for radiomic analysis. Before feature extraction, all images were preprocessed to a combination of several parameters of Laplacian of Gaussian (1 and 2), resampling (0.5 and 1), and bin width (5, 10, 25, and 50). The reproducibility of radiomic features was analyzed using the intra‑class correlation coefficient (ICC).

Almost all shapes and first‑order features had ICC values > 0.95. Most second‑order texture features were not reproducible (ICC < 0.95) in GTV and HR‑CTV. Furthermore, 20% of all neighboring gray‑tone difference matrix texture features had ICC > 0.90 in both GTV and HR‑CTV.

The results presented here showed that MRI radiomic features are vulnerable to changes in preprocessing, and this issue must be understood and applied before any clinical decision‑making. Features with ICC > 0.90 were considered the most reproducible features. Shape and first‑order radiomic features were the most reproducible features in both GTV and HR‑CTV. Our results also showed that GTV and HR‑CTV radiomic features had similar changes against preprocessing sets.

Tongue Squamous Cell Carcinoma (TSCC) is one of the most consequential oral Squamous Cell Carcinomas (SCC) worldwide. 

This retrospective cross-sectional study was conducted on 29 TSCC patients treated with High Dose Rate Brachytherapy (HDR-BT) with or without External Beam Radiotherapy (EBRT) between 2017-2020. Patients without distant metastasis at the time of treatment and at least one year after completion of brachytherapy were included. 

One-year Overall Survival (OS), Disease-Free Survival (DFS), and Local Control Rate (LCR) were 82.8, 79.3, and 100%, respectively. 6 patients (20.7%) had distant metastasis, of which 5 (17.2%) died. Local recurrence was not observed in any patients, and only one (3.4%) regional recurrence occurred. The most common late toxicity of HDR-BT was dry mouth (79.2%) and dysarthria (66.7%). There were no severe and life-threatening complications (grades 3 and 4) during one year. Also, 79.2% of the patients had good functional performance. One-year OS, the significant difference between the two groups of HDR-BT with and without EBRT (p=0.055).

Our findings indicated that the HDR-BT increases the OS of TSCC patients more than EBRT without developing grade 3-4 AEs and metastasis. We showed that the mean 3.2 ±0.7 Gy of HDR-BT has more OS compared to EBRT.

The BEBIG Portio multi-channel applicator provides better target dose coverage and sparing organs-at-risk compared to a single-channel cylinder. However, artifacts and distortions of Portio in magnetic resonance images (MRI) have not yet been reported.

We aimed to quantify the artifacts and distortions in its 1.5-Tesla MR images before clinical use.

In this experimental study, we employed a gelatin-filled phantom to conduct our measurements. T2-weighted (T2W) images were examined for artifacts and distortions. Computed tomography (CT) images were used as a reference to assess image distortions. Artifact severity was measured by recording the full-width-at-half-maximum (FWHM) image pixel values at various positions along the length of the applicator/channels. CT and MRI-based applicator reconstruction accuracy were then compared, and signal-to-noise ratio (SNR) and contrast were also determined for the applicator images.

The applicator distortion level for the Portio applicator was less than the image spatial resolution (0.5±0.5 pixels). The average FWHM for the tandem applicator images was 5.23±0.39 mm, while it was 3.21±0.37 mm for all channels (compared to their actual diameters of 5.0 mm and 3.0 mm, respectively). The average applicator reconstruction difference between CT and MR images was 0.75±0.30 mm overall source dwell positions. The image SNR and contrast were both acceptable. 

These findings indicate that the Portio applicator has a satisfactory low level of artifacts and image distortions in 1.5-Tesla, T2W images. It may, therefore, be a promising option for MRI-guided multi-channel vaginal brachytherapy.

Percutaneous vertebroplasty employs bone cement for injecting into the fractured vertebral body (VB) caused by spinal metastases. Radioactive bone cement and also brachytherapy seeds have been utilized to suppress the tumor growth in the VB.
This study aims to investigate the dose distributions of low-energy brachytherapy seeds, and to compare them to those of radioactive bone cement, by Monte Carlo simulation.
In this simulation study, nine CT scan images were imported in Geant4. For the simulation of brachytherapy, I-125, Cs-131, or Pd-103 seeds were positioned in the VB, and for the simulation of vertebroplasty, the VB was filled by a radioactive cement loaded by P-32, Ho-166, Y-90, or Sm-153 radioisotopes. The dose-volume histograms of the VB, and the spinal cord (SC) were obtained after segmentation, considering that the reference dose is the minimum dose covered 95% of the VB.
The SC sparing was improved by using beta-emitting cement because of their steep gradient dose distribution. I-125 seeds and Y-90 radioisotope showed better VB coverage for brachytherapy and vertebroplasty techniques, respectively. Pd-103 seeds and P-32 radioisotope showed better SC sparing for brachytherapy and vertebroplasty, respectively. The minimum mean doses that covered 100% of the VB were 62.0%, 56.5%, and 45.0% for I-125, Cs-131, and Pd-103 seeds, and 28.3%, 28.6%, 32.9%, and 17.7%, for P-32, Ho-166, Y-90, and Sm-153 sources, respectively. 
I-125 and Cs-131 seeds may be useful for large tumors filling the entire VB, and also for the extended tumors invading multiple vertebrae. Beta-emitting bone cement is recommended for tumors located near the SC.

Ophthalmic brachytherapy using radioactive plaques is an effective technique for the treatment of uveal melanoma. Ru-106 eye plaques are considered as interesting issue due to their steep gradient dose. The pre-planning evaluation of dosimetric parameters is essential for the treatment planning system.
The current study aims at providing dose distributions of six Ru-106 eye plaques (CCA, CCB, CGD, CIB, COB and COD) using radiochromic EBT3 film, Geant4 Monte Carlo toolkit and the treatment planning software (Plaque Simulator).
In this experimental study, an in-house phantom was employed for depth dose measurements with EBT3 films. Also, Geant4.10.5 scoring mesh was implemented to obtain the 2D dose distribution of the plaques. The results were compared with Plaque Simulator software and the manufacturer’s (BEBIG) data. The gamma index criterion (3%/3 mm) was used to evaluate dose distributions obtained by the film measurements and Geant4 simulation.
A good agreement was achieved between simulation and experimental results. Gamma index passing rate was 94.2%, 89.3%, 88.2%, 82.2%, 92.2% and 90.1% for CCA, CCB, CGD, CIB, COB and COD plaques, respectively. Absolute dose rate (mGy/min) obtained by EBT3 film at the depth of 2 mm was 79.4 mGy/min, 81.0 mGy/min, 78.6 mGy/min, 62.2 mGy/min, 75.2 mGy/min and 81.2 mGy/min for CCA, CCB, CGD, CIB, COB and COD plaques, respectively.  
The measured dose distributions and lateral dose profiles may be utilized in the treatment planning system to cover clinical volumes such as the clinical target volume and the gross tumor volume.

Our aims were to prepare microspheres labelled with radioactive astatine as brachytherapy seeds and to confirm the antitumor ability of these microspheres.

Chitosan-collagen composite microspheres (CCMs) were synthesized through an emulsification crosslink reaction and radiolabelled with 211At using the chloramine-T method. Radiation stability was assessed in both phosphate-buffered saline and blood serum. The in vivo distribution and therapeutic effects were evaluated in BALB/c nude mice with implanted tumours.

CCMs showed ideal morphological characteristics (diameter of 7.5-15 μm) and acceptable radiation stability (73.99% in PBS and 72.56% in serum after 16 hours). The in vivo biodistribution analysis demonstrated that 211At-CCMs were highly localized in tumour tissue. The therapeutic efficacy of 211At-CCMs when intratumorally injected into a cervical tumour model was assessed. Fourteen days after a single-dose treatment with 211At-CCMs, significantly retarded tumour volume growth was observed.

211At-CCM brachytherapy has the potential to provide an alternative solution for tumour treatment.

In partial-breast irradiation (PBI), an accurate target volume delineation based on the lumpectomy cavity (LC) has been reported to remain difficult due to uncertain LC identification. However, the impact of accurate LC delineation on the planning target volume (PTV) has not been investigated.

Between September 2018 and April 2020, 159 patients receiving perioperative PBI with multicather-interstitial brachytherapy were evaluated. While LC delineation using implanted catheters as fiducial markers was used as a reference, conventional LC was virtually delineated on computed tomography with clips. PTV1-cm margin and PTV2-cm margin, which means 1cm and 2cm expansion from LC, were developed and assumed for brachytherapy and externalbeam PBI, respectively. The target accuracy and the impact of the delineation accuracy of LC on PTVs were evaluated. The geographic miss index (GMI) and normal tissue index (NTI) were used as accuracy indices and were defined as the percentage of under- and overestimating volume, respectively.

The PTV1-cm margin and PTV2-cm margin were significantly larger than the reference volume, 57.9cm3 vs. 37.9cm3 (P<0.001) and 113.2cm3 vs. 93.8cm3 (P<0.001), respectively. The GMI and NTI of LC were 27.3% and 41.2%, respectively. Although the GMI in the PTV1-cm margin and PTV2-cm margin was significantly reduced to 9.8% (P<0.0001) and 9.9% (P<0.0001), respectively, the NTI was not significantly improved in the PTV1-cm margin, which was 41.8% (P=0.60) but was improved in PTV2-cm margin, which was 23.1% (P<0.0001).

The GMI in PTV1-cm margin was reduced to be as low as PTV2-cm margin. Although PTV2-cm margin was associated with lower NTI, the absolute volume was almost double with PTV1-cm margin. Although further research is required, brachytherapy-based PBI may be a reasonable option to achieve tumor control and cosmesis using the conventional delineation method.

The dose prescription point in high dose rate (HDR) intracavitory brachytherapy (ICBT) of cervical cancer is Manchester point A but the localization of this point has a wider variation. To minimize these variations, the American Brachytherapy Society (ABS) introduced a new definition of point A and named it as point H. In this study, these two points have been compared in terms of dosimetric parameters. Twenty HDR ICBT of cervical cancer patients were retrospectively evaluated with Manchester point A and ABS point H. Target volume covered by prescribed dose (TV), dose to 2cc (D2cc) of the bladder and rectum were noted for both points. Statistical analysis using a two-tailed paired t-test was performed to compare dosimetric parameters of both the points of prescription. The maximum value, minimum value, and mean ± standard deviation along with the p value have been noted. On average, point H was 4.0mm ± 6.4mm shifted (superior/inferior) from point A, along the tandem direction. The average TV when the prescription was done at point H (TVH) was 33.7cc ± 10.1cc which was higher than the average TV when the prescription was done at point A (TVA) of 33.3cc ± 9.4 cc.D2cc increased from 63% ± 23% to 68% ± 24% for the rectum and 52% ± 18% to 56% ± 20% for the bladder when the prescription point changed from A to H. As observed, average TV, D2cc of the bladder, and rectum were higher in the case of point H prescription plan (PH) as compared with point A prescription plan (PA). The dose difference between PH and PA was found to be statistically significant, so careful consideration is needed to implementation of new point H in clinical practice.

Conventional optimization techniques are based on the planning approach in which positions and weights are varied to generate the desired dose distribution. Inverse planning simulated annealing (IPSA) is an advanced optimization method developed to automatically determine a suitable combination of positions to design an acceptable plan.  In this study, three optimization techniques namely IPSA, graphical optimization (GROPT), and geometrical optimization (GOPT) methods are compared in high-dose-rate interstitial brachytherapy of cervical carcinoma. In this retrospective study, twenty computed tomography (CT) data sets of 10 cervical cancer patients treated with Martinez Universal Perineal Interstitial Template-based interstitial brachytherapy were studied. The treatment plans generated were optimized using the IPSA, and GOPT methods. The prescribed dose was 24 Gy in 4 fractions. Plans produced using IPSA, GrOPT, and GOPT techniques were analyzed for comparison of dosimetric parameters, including target coverage, homogeneity, conformity, and organs at risk (OAR) doses.  V100 values for IPSA, GrOPT and GOPT plans were 95.81±2.33%, 93.12±2.76% and 88.90±4.95%, respectively. The mean D90 values for the IPSA, GrOPT, and GOPT plans were 6.45±0.15 Gy, 6.12±0.21 Gy, and 5.85±0.57 Gy, respectively. Significantly lower doses of OAR were in the IPSA plans that were more homogeneous (HI=0.66). Conformity was comparatively higher in IPSA-based plans (CI=0.75).   IPSA plans were superior and resulted in better target coverage, homogeneity, conformity, and minimal OAR doses.

The incidence of secondary bladder cancer after treatment for localized prostate cancer (PCa) remains unclear. In this study, PCa cases treated with brachytherapy (BT) were evaluated to assess the incidence of a sec-ond malignancy of bladder cancer in a Japanese cohort.

Overall, 969 patients treated with BT at our hospital between July 2006 and January 2019 were included in the study cohort. The incidence and predictors of secondary bladder cancer were also assessed.

The incidence of secondary bladder cancer was 1.5% (n = 14). Of the seven factors (age, pretreatment PSA, Gleason score, cTNM stage, prostate volume, total activity, and combined external beam), prostate volume and total activity showed significant differences between the cohorts with and without secondary bladder cancer (P = .03 and P = .001, respectively). Upon comparison of the seven parameters for the 969 patients treated with BT, we found that only the total activity factor was affected by the incidence of secondary bladder cancer in the multivariate analysis (P = .007).

The incidence of secondary bladder cancer was evaluated after BT for PCa. Total activity was asso-ciated with the incidence of secondary bladder cancer in Japanese patients who received BT

Multi-catheter interstitial brachytherapy (MIB) is one kind of accelerated partial breast irradiation, which applied only to local target breast tissue for patients with breast cancer. The objective of this case report was to report the therapeutic effect of interstitial brachytherapy for treating advanced breast cancer with multiple complications.

The patient was a 64-year-old woman with diagnosed stage IV breast cancer and multiple complications that included primary liver cancer, post-hepatitis cirrhosis, and hypertension. In October 2016, the patient was treated with chemoembolization for liver cancer, and chemotherapy and targeted molecular therapy in a series for advanced breast cancer at Jilin Province Cancer Hospital before admission to Second Hospital of Jilin University. The tumor in her right breast was about 13.0 cm × 11.0 cm, and the surface was red, swollen, and ulcerated. As the patient was not suitable for surgery and intolerant to further chemotherapy the tumor was treated with interstitial brachytherapy. The brachytherapy was performed once a week, overall three times as doses of 28 Gy in 3 fractions. She was then treated by external radiotherapy with a dose of 50 Gy in 25 fractions. The treatment was ended in December 2016. During the follow-up in January 2017, the original breast mass had necrosed and shrank. No overt bleeding or exudation was found. The patient has survived until now.

For this patient with advanced breast cancer and multiple complications, interstitial brachytherapy was an effective treatment.

Auditing the treatment planning system (TPS) software for a radiotherapy unit is of paramount importance in any radiation therapy department. A Plexiglas phantom was proposed to measure the ionization of 60Co high dose rate (HDR) source and compare dose points in the planning system for auditing and verifying TPS.

Auditing was performed using a Plexiglas phantom in an end‑to‑end test, and relative dose points were detected by a farmer‑type ionization chamber and compared with the relative dose of similar points in TPS. The audit results were determined as pass optimal level (<3.3%), pass action level (between 3.3% and 5%), and out of tolerance (>5%).

The comparison of the collected data revealed that 80% of the measured values were ≤5% in the pass level, and 20% of the points were out of tolerance (between 5% and 6.99%).

This study documented the appropriateness of the dosimetry audit test and this phantom design for the HDR brachytherapy TPS.

In developing countries, treatment of cervical cancer with metastasis to the spinal cord is generally associated with failure and reduced patient survival due to the lack of appropriate facilities. Oncologists are using a variety of methods to prolong patient survival. In the present study, we aimed to estimate the three- and five-year disease-free survival of patients with cervical cancer and spinal cord metastasis, treated with external radiotherapy + brachytherapy (i.e., internal radiotherapy.

This descriptive cross-sectional study was performed over a period of ten years (2010-20) in the brachytherapy ward of Shahid Madani Hospital (Tabriz, Iran). Overall, 200 patients with cervical cancer and spinal cord metastasis who were candidates for external radiotherapy + brachytherapy were recruited by the census sampling method. The variables that were likely to affect survival were recorded and analyzed using the Koch survival test and relevant descriptive and inferential statistics in SPSS version 23 software.

The patients’ overall survival was 43.12 ± 1.44 months; 78 patients (39%) survived until the end of the third year, and 49 (24.5%) lived till the end of the fifth year. Also, the pathological diagnosis (P = 0.013- P = 0.015), disease stage (P = 0.014- P = 0.018), the length of the treatment area (P = 0.026- P = 0.044), and undergoing chemotherapy (P = 0.001- P = 0.002) were significantly associated with the survival of the patients who completed the treatment course.

Chemotherapy, advanced disease, and greater length of the treatment area reduced three- and five-year survival in the patients with cervical cancer and spinal cord metastasis who underwent brachytherapy.

Soft tissue sarcoma (STS) is a wide group of solid tumors with specific features originating from mesenchymaltissue. Radiotherapy (RT) and chemotherapy have been widely applied in the treatment of these tumors to enhance surgical outcomes. This study was performed aiming to compare the results of postoperative brachytherapy (BRT) versus RTin patients who underwent surgical resection of extremity STSs.

In a prospective study from 2011 to 2015, 166 patients with extremity STSwho underwent surgical resection were included. All visible tumors, scars, and drain sites, if present during the surgery, were resected. A number of 79 patients received adjuvant RT, and 87 patients underwent BRT after surgical resection.

In patients who were treated through RT, the two-year local control was 90% in comparison with 87% for those treated through BRT (P > 0.050). The total radiation dose was 3869 ± 370 and 3048 ± 465 in the patients who underwent RT and in the BRT group (P < 0.001), respectively. The number of radiation sessions in the RT group and BRT group was respectively 27.3 ± 4.5 and 5.8 ± 2.0 (P = 0.001).

Not only BRT can lead to similar local control and survival in comparison with the conventional adjuvant RT, but it can also decrease the total dose and number of radiation sessions in patients with STS of the extremity, which is a high grade, in individuals who underwent surgical resection.

Stereotactic brachytherapy (SBT) is an appropriate method that has been used for brain tumors and metastases treatment for more than 40 years for many patients in the world. Also, Iodine-125 brachytherapy has been utilized in brain tumors for interstitial brachytherapy treatment since 1979. Even though the physical and biological feathers make these implants particularly attractive for minimal invasive treatment.

In this paper, monte carlo simulation have been applied by the Gate code with 20 (MBq) activity for an iodine seed design for the low-grade glioma tumors treatment. Dosimetry feathers of this source were defined by the updated TG-43U1 recommendations. The absorbed dose distribution around the seed was calculated using the Gate code in liquid water.

Results show, the ideal condition for brachytherapy are for tumors smaller than 4 (cm). As the larger tumor size, the absorption dose at the border of tumor and healthy tissue will be decreased and the implantation time for seeds will increase.

Placing an iodine-125 source inside the tumor is not sufficient due to the non-uniform dose distribution in the tumor and the length of treatment time. Using four iodine-125 sources eliminates the tumor, and also, a uniform dose distribution is created in the tumor and the implantation time will be reduced, respectively.

To investigate the difference between CT-guided three‑dimensional brachytherapy using insertion needles and Fletcher applicator brachytherapy.

Ninety-three patients with cervical squamous cell carcinoma were included. Insertion needle or Fletcher applicators were used depending on tumor conditions. The target volume, target and organs at risk (OAR) dose, and treatment-related complications, in patients receiving the different brachytherapy techniques were compared.

The mean volume of the high-risk clinical target volume (HR-CTV) and intermediate-risk clinical target volume (IR-CTV) in the Fletcher applicator group were smaller compared with the insertion needle group (P<0.05). The mean values of D90 per fraction of the HR-CTV and IR-CTV in the Fletcher applicator group were 101 cGy and 60 cGy lower, respectively, compared with the insertion needle group (P<0.05). The mean bladder and rectum D0.1cm3 per fraction, the mean sigmoid and small intestine D2cm3 per fraction were statistically different between two groups( all P<0.05), the remaining dosimetric parameters were no significant differences (P>0.05). Following dose normalization, with the exception of the mean normalized sigmoid D0.1cm3 per fraction for the received by the OAR in the Fletcher applicator group and the insertion needle group were significantly different (P<0.05). There was no serious complication in the brachytherapy of two types applicators.

Brachytherapy using insertion needles enables the treatment of larger target volumes with higher target doses when compared with conventional Fletcher applicator brachytherapy. In addition, the doses received by the OAR are lower, indicating that it is a safe and effective technique that warrants wide adoption.

The study aimed to assess the effectiveness of the dosimetric parameters of organs-at-risks (OARs) and target coverage in optimized plans compared to non-optimised plans normalized at point A.
This retrospective study examined 21 patients with cervical cancer in stages II and III, who had undergone a high dose rate (HDR) ICBT following external beam radiotherapy(EBRT).In this study, two treatment plans were created for each case using computed tomography (CT) images. Normalization at point A was performed in the non-optimised plans, and 90% of the high-risk clinical target volume (HR-CTV) was to receive the prescribed dose in the optimised plans. Dose-volume histograms (DVH) were used to compare D5cc, D2cc, D1cc, and D0.1cc (minimum doses received by the most irradiated volumes of5cc, 2cc, 1cc and 0.1cc, respectively) for OARs as well as the D90%, D50%, D98%, D100%, and D95% coverage of HR-CTV between the non-optimised and optimised plans. Statistical analysis was performed using Wilcoxon signed rank test.
The HR-CTV coverage improved in 80% of the patients. In the optimised plans, the rectum and bladder doses decreased by 8.75% and 9.85%, as compared to the non-optimised plans normalized at point A, respectively. In the sigmoid and bowel cases, there were dose drops by 8.95% and 9.75%, in the optimised plans, respectively.
Target coverage and OAR sparing were more satisfactory in the optimised plans than the non-optimised plans normalized at point A.

The most frequent primary ocular malignancy in the western world is the uveal melanoma. While it mainly affects Caucasians, it is extremely uncommon among non-Caucasians. Continuous improvement in therapies for local treatment has allowed sparing of the eye, although this approach apparently does not improve survival. The present review aimed to explain different radiotherapy (RT) methods and compare the pros and cons of each method, along with the main complications that may be encountered in the treatment of uveal melanoma.

Relevant papers published between September 2009 and January 2021 were retrieved, reviewed, and screened. Four databases, including PubMed, MEDLINE, Google Scholar, and GeneCards, were searched for this purpose.

Forty-one relevant articles were identified. Based on the selected papers, we highlighted the advantages and disadvantages of the different RT methods that have allowed sparing of the eye, even though they have not, as yet, improved survival. We listed a detailed comparison between therapies that allow an educated choice among the different available RT methods.

The choice of uveal melanoma management is determined by the location of the tumor and volume of the extraocular extent. At present, there is no gold standard for the management of all ocular melanomas, and each case should be approached individually. Therefore, classification is a valuable prognostic tool. Many cases in cT3-4 classification categories are treated by primary enucleation and conservative treatment follow-up, while in cT2 and most cT1 classifications (i.e., 3.1–6.0-mm tumor thickness), several forms of RT are used.