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Physics in Medicine and Biology Aug 2023. In conventional radiotherapy, a single treatment plan is generated pre-treatment, and delivered in daily fractions. In this study, we propose to generate different...
. In conventional radiotherapy, a single treatment plan is generated pre-treatment, and delivered in daily fractions. In this study, we propose to generate different treatment plans for all fractions ('Per-fraction' planning) to reduce cumulative organs at risk (OAR) doses. Per-fraction planning was compared to the 'Conventional' single-plan approach for non-coplanar 4 × 9.5 Gy prostate stereotactic body radiation therapy (SBRT).. An in-house application for fully automated, non-coplanar multi-criterial treatment planning with integrated beam angle and fluence optimization was used for plan generations. For the Conventional approach, a single 12-beam non-coplanar IMRT plan with individualized beam angles was generated for each of the 20 included patients. In Per-fraction planning, four fraction plans were generated for each patient. For each fraction, a different set of patient-specific 12-beam configurations could be automatically selected. Per-fraction plans were sequentially generated by adding dose to already generated fraction plan(s). For each fraction, the cumulative- and fraction dose were simultaneously optimized, allowing some minor constraint violations in fraction doses, but not in cumulative.. In the Per-fraction approach, on average 32.9 ± 3.1 [29;39] unique beams per patient were used. PTV doses in the separate Per-fraction plans were acceptable and highly similar to those in Conventional plans, while also fulfilling all OAR hard constraints. When comparing total cumulative doses, Per-fraction planning showed improved bladder sparing for all patients with reductions in Dmean of 22.6% (= 0.0001) and in D1cc of 2.0% (= 0.0001), reductions in patient volumes receiving 30% and 50% of the prescribed dose of 54.7% and 6.3%, respectively, and a 3.1% lower rectum Dmean (= 0.007). Rectum D1cc was 4.1% higher (= 0.0001) and Urethra dose was similar.. In this proof-of-concept paper, Per-fraction planning resulted in several dose improvements in healthy tissues compared to the Conventional single-plan approach, for similar PTV dose. By keeping the number of beams per fraction the same as in Conventional planning, reported dosimetric improvements could be obtained without increase in fraction durations. Further research is needed to explore the full potential of the Per-fraction planning approach.
Topics: Male; Humans; Radiotherapy Planning, Computer-Assisted; Radiosurgery; Radiotherapy Dosage; Radiotherapy, Intensity-Modulated; Radiometry; Organs at Risk
PubMed: 37524087
DOI: 10.1088/1361-6560/acec27 -
Cureus Oct 2023Interpretation of imaging modalities depends on robust normal reference limits. Ethnicity is an essential determinant of cardiac chamber sizes. Though few studies from...
BACKGROUND AND AIM
Interpretation of imaging modalities depends on robust normal reference limits. Ethnicity is an essential determinant of cardiac chamber sizes. Though few studies from India have focused on this research, it has yet to include the Kashmiri population. We aimed to study normal echocardiographic values of healthy Kashmiri adults and compare them with Western and Indian studies.
METHODS
It was a prospective observational study on healthy adults of Kashmir Valley. A comprehensive echocardiographic analysis following standardized protocols was performed.
RESULTS
A total of 2245 study participants were analyzed. The mean age was 32.52±11.55 years. There were 1100 (49%) males. Males had higher absolute left ventricular volumes and mass, left atrial volumes, right ventricular diameter, and aortic size, while females had higher absolute left ventricular ejection fraction and early and late diastolic mitral inflow velocities. Males had higher indexed left ventricular end-systolic volume, while females had higher indexed left ventricular end diastole diameter, aorta diameter, right ventricle, and left and right atrial sizes. Left ventricular mass and diastolic parameters were significantly associated with age. Compared with the American Society of Echocardiography/European Association of Cardiovascular Imaging, absolute values of left ventricle size, volumes, mass, right ventricle size, aortic size, and left and right atrial size were higher than those in our study. Our study population had a higher left ventricle ejection fraction. Among indexed parameters, left ventricle volumes, left ventricle systolic diameter, aortic annulus, and left and right atrial volumes were still significantly higher in Western data. While comparing with Indian data, we noted significant regional differences.
CONCLUSION
We provide normal reference values for our local population. We noted significant differences with Western as well as other Indian populations. Our study highlights the need for developing ethnic-specific reference values of various echocardiographic measurements.
PubMed: 38022041
DOI: 10.7759/cureus.47449 -
HardwareX Sep 2023Preparative liquid chromatography is a technique for separating complex samples or isolating pure compounds from complex extracts. It involves eluting samples through a...
Preparative liquid chromatography is a technique for separating complex samples or isolating pure compounds from complex extracts. It involves eluting samples through a packed column and selectively collecting or isolating the separated bands in a sequence of fractions. Depending on the column length and the sample complexity, a large number of fractions may be obtained, making fraction collection a laborious and time-consuming process. Manual fraction collection is also tedious, error-prone, less reproducible, and susceptible to contamination. Several commercial and lab-made solutions are available for automated fraction collection, but most systems do not synchronize with the instrument detector and collect fractions at fixed volumes or time intervals. We have assembled a low-cost Arduino-based smart fraction collector that can record the signal from the UV-vis detector of the chromatography instrument and enable the automated selective collection of the targeted bands. The system consists of a robot equipped with position sensors and a 3-way solenoid valve that switches the column effluent between the waste or collection positions. By proper programming, an Arduino board records the detector response and actuates the solenoid valve, the position sensors, and the stepper motors to collect the target chromatographic bands.
PubMed: 37600064
DOI: 10.1016/j.ohx.2023.e00462 -
La Radiologia Medica Aug 2023Reirradiation (reRT) of local recurrent/second primary tumors of the head and neck represents a potential curative treatment for patients not candidate to a salvage... (Review)
Review
INTRODUCTION
Reirradiation (reRT) of local recurrent/second primary tumors of the head and neck represents a potential curative treatment for patients not candidate to a salvage surgery. Aim of the present study is to summarize literature data on modern radiation techniques and fractionations used in this setting of patients.
MATERIALS AND METHODS
A narrative review of the literature was conducted on three topics: (1) target volume delineation (2) reRT dose and techniques and (3) ongoing studies. Patients treated with postoperative reRT and palliative intent were not considered for the current analysis.
RESULTS
Recommendations on the target volume contouring have been reported. 3D-Conformal Radiotherapy, Intensity Modulated Radiotherapy, Stereotactic body Radiotherapy Intraoperative Radiotherapy, Brachytherapy and Charged Particles have been analyzed in terms of indication and fractionation in the field of reRT. Ongoing studies on the topic have been reported for IMRT and Charged Particles. Moreover, according to literature data a stepwise approach has been proposed aiming to provide a useful tool to select patients candidate to a curative reRT in daily clinical practice. Two clinical cases were also provided for its application.
CONCLUSION
Different radiation techniques and fractionations can be used for a second course of radiotherapy in patients with recurrent/second primary tumor of head and neck region. Tumor characteristics as well as radiobiological considerations should be take into account to define the best reRT approach.
Topics: Humans; Squamous Cell Carcinoma of Head and Neck; Re-Irradiation; Dose Fractionation, Radiation; Radiotherapy, Intensity-Modulated; Radiotherapy Dosage; Neoplasm Recurrence, Local; Head and Neck Neoplasms
PubMed: 37415056
DOI: 10.1007/s11547-023-01671-0 -
World Journal of Clinical Cases Jun 2024Paragangliomas (PG) are rare neoplasms of neuroendocrine origin that tend to be highly vascularized, slow-growing, and usually sporadic. To date, common treatment...
BACKGROUND
Paragangliomas (PG) are rare neoplasms of neuroendocrine origin that tend to be highly vascularized, slow-growing, and usually sporadic. To date, common treatment options are surgical resection (SR), with or without radiation therapy (RT), and a watch-and-wait approach.
AIM
To evaluate the local control and effectiveness of exclusive fractionated stereotactic RT (FSRT) treatment in unresectable PG (uPG).
METHODS
We retrospectively evaluated patients with uPG (medically inoperable or refused SR) treated with FSRT with a Cyberknife System (Accuray Incorporated, Sunnyvale, California). Toxicity and initial efficacy were evaluated.
RESULTS
From May 2009 to January 2023, 6 patients with a median age of 68 (range 20-84) were treated with FSRT. The median delivered dose was 21 Gy (range 20-30 Gy) at a median isodose line of 75.5% (range 70%-76%) in 4 fractions (range 3-5 fractions). The median volume was 13.6 mL (range 12.4-65.24 mL). The median cumulative biological effective dose and equivalent dose in 2-Gy fractions were 70 Gy and 37.10 Gy respectively. Site of origin involved were the timpa-nojugular glomus (4/6), temporal bone, and cervical spine. In 1 of the 6 patients, the follow-up was insufficient; 5 of 6 patients showed a 5-year overall survival and 5-year progression-free survival of 100%. We observed negligible toxicities during and after RT. The majority of patients showed stable symptoms during follow-up. Only 1 patient developed spine metastases.
CONCLUSION
Our preliminary results on this small cohort of patients suggest that FSRT could be an effective and safe alternative to SR.
PubMed: 38899289
DOI: 10.12998/wjcc.v12.i16.2729 -
Perfusion Apr 2024Patients with primary mitral regurgitation (MR) usually remain asymptomatic for a long time due to compensatory mechanisms and an adequate treatment could be delayed....
INTRODUCTION
Patients with primary mitral regurgitation (MR) usually remain asymptomatic for a long time due to compensatory mechanisms and an adequate treatment could be delayed. Stress echocardiography and speckle-tracking analysis could help to evaluate impaired left atrium (LA) function before the manifestation of clinically significant myocardial changes in asymptomatic patients with primary MR and preserved left ventricular (LV) ejection fraction (EF).
METHODS
This study prospectively enrolled 91 patients with preserved LV EF (≥60%) at rest, of which 60 patients had moderate-to-severe MR and 31 were healthy controls. Rest and stress (bicycle ergometry) echocardiography and speckle-tracking offline analysis were performed.
RESULTS
In MR group LA volume indices were higher at rest and during stress, while LA reservoir, conduit, and contractile fractions were decreased ( < .005). LA deformation parameters at rest were similar in both groups. During maximum stress LA conduit, contractile fractions and reservoir strain were lower ( < .05) in patients with MR. Indices of LA volume were related to SPAP at rest and during stress. Higher NT-proBNP concentrations was associated with higher LA volume indices, decreased contractile and reservoir functions during peak stress ( < .05). LA volume indices, LA EF, and filling index at rest could predict exercise-induced pulmonary hypertension (EIPH) ( < .05).
CONCLUSIONS
In patients with primary MR and preserved LV EF, LA parameters are related to SPAP and NT-pro-BNP concentration. LA volume indices, LA EF and LA filling index are predictors of EIPH.
PubMed: 38687977
DOI: 10.1177/02676591241251441 -
Cureus Aug 2023Stereotactic ablative radiotherapy (SABR) is a possible treatment option for patients who develop recurrence within or at the edge of a previously irradiated... (Review)
Review
Stereotactic ablative radiotherapy (SABR) is a possible treatment option for patients who develop recurrence within or at the edge of a previously irradiated volume. Robotic stereotactic radiotherapy is the result of technological advances in robotic precision, real-time imaging, non-invasive, highly customizable treatment plan, and delivery with sub-millimeter accuracy. This article reviews the radiobiologic, technical, and clinical aspects of robotic-based SABR re-irradiation for various anatomical sites. An extensive literature search was performed to identify articles on the utilization of robotic stereotactic radiotherapy for patients undergoing re-irradiation. The reported prescription dose and fractionation data along with outcomes such as overall survival, local control rates, and toxicities were qualitatively reviewed. The findings consistently indicate that re-irradiation using robotic SABR provides encouraging survival rates with minimal toxicity in the clinical setting of various anatomical sites delivered using locally non-invasive means where other treatment options are scarce.
PubMed: 37719625
DOI: 10.7759/cureus.43500 -
Physics in Medicine and Biology Apr 2024. Radio-opaque markers are recommended for image-guided radiotherapy in liver stereotactic ablative radiotherapy (SABR), but their implantation is invasive. We evaluate...
. Radio-opaque markers are recommended for image-guided radiotherapy in liver stereotactic ablative radiotherapy (SABR), but their implantation is invasive. We evaluate in thisstudy the feasibility of cone-beam computed tomography-guided stereotactic online-adaptive radiotherapy (CBCT-STAR) to propagate the target volumes without implanting radio-opaque markers and assess its consequence on the margin that should be used in that context.. An emulator of a CBCT-STAR-dedicated treatment planning system was used to generate plans for 32 liver SABR patients. Three target volume propagation strategies were compared, analysing the volume difference between the GTVand the GTV, the vector lengths between their centres of mass (), and the 95th percentile of the Hausdorff distance between these two volumes (HD95). These propagation strategies were: (1) structure-guided deformable registration with deformable GTV propagation; (2) rigid registration with rigid GTV propagation; and (3) image-guided deformable registration with rigid GTV propagation. Adaptive margin calculation integrated propagation errors, while interfraction position errors were removed. Scheduled plans (Plan) and daily-adapted plans (Plan) were compared for each treatment fraction.The image-guided deformable registration with rigid GTV propagation was the best propagation strategy regarding to(mean: 4.3 +/- 2.1 mm), HD95 (mean 4.8 +/- 3.2 mm) and volume preservation between GTVand GTV. This resulted in a planning target volume (PTV) margin increase (+69.1% in volume on average). Online adaptation (Plan) reduced the violation rate of the most important dose constraints ('priority 1 constraints', 4.2 versus 0.9%, respectively;< 0.001) and even improved target volume coverage compared to non-adaptive plans (Plan).. Markerless CBCT-STAR for liver tumours is feasible using Image-guided deformable registration with rigid GTV propagation. Despite the cost in terms of PTV volumes, daily adaptation reduces constraints violation and restores target volumes coverage.
Topics: Humans; Feasibility Studies; Radiosurgery; Radiotherapy Planning, Computer-Assisted; Cone-Beam Computed Tomography; Radiotherapy, Image-Guided; Liver; Liver Neoplasms
PubMed: 38565128
DOI: 10.1088/1361-6560/ad39a1 -
Physics and Imaging in Radiation... Jan 2024Daily online treatment plan adaptation requires a fast workflow and planning process. Current online planning consists of adaptation of a predefined reference plan,...
BACKGROUND AND PURPOSE
Daily online treatment plan adaptation requires a fast workflow and planning process. Current online planning consists of adaptation of a predefined reference plan, which might be suboptimal in cases of large anatomic changes. The aim of this study was to investigate plan quality differences between the current online re-planning approach and a complete re-optimization.
MATERIAL AND METHODS
Magnetic resonance linear accelerator reference plans for ten prostate cancer patients were automatically generated using particle swarm optimization (PSO). Adapted plans were created for each fraction using (1) the current re-planning approach and (2) full PSO re-optimization and evaluated overall compliance with institutional dose-volume criteria compared to (3) clinically delivered fractions. Relative volume differences between reference and daily anatomy were assessed for planning target volumes (PTV60, PTV57.6), rectum and bladder and correlated with dose-volume results.
RESULTS
The PSO approach showed significantly higher adherence to dose-volume criteria than the reference approach and clinical fractions (p < 0.001). In 74 % of PSO plans at most one criterion failed compared to 56 % in the reference approach and 41 % in clinical plans. A fair correlation between PTV60 D98% and relative bladder volume change was observed for the reference approach. Bladder volume reductions larger than 50 % compared to the reference plan recurrently decreased PTV60 D98% below 56 Gy.
CONCLUSION
Complete re-optimization maintained target coverage and organs at risk sparing even after large anatomic variations. Re-planning based on daily magnetic resonance imaging was sufficient for small variations, while large variations led to decreasing target coverage and organ-at-risk sparing.
PubMed: 38298884
DOI: 10.1016/j.phro.2024.100534 -
Academic Radiology Jun 2024The pericoronary fat attenuation index (FAI) values around plaques may reveal the relationship between periplaque vascular inflammation and different plaque component...
RATIONALE AND OBJECTIVES
The pericoronary fat attenuation index (FAI) values around plaques may reveal the relationship between periplaque vascular inflammation and different plaque component volume fractions. We aimed to evaluate the potential associations between periplaque FAI values and plaque component volume fractions.
MATERIALS AND METHODS
496 patients (1078 lesions) with coronary artery disease, who underwent computed tomography angiography (CCTA) between September 2022 and August 2023, were analyzed retrospectively. Each lesion was characterized and the plaque component volume fractions and periplaque FAI values were measured. Multiple linear regression, weighted quantile sum (WQS) regression, and quantile g-computation (Qgcomp) were used to explore the relationship between plaque component volume fractions and the risk of elevated periplaque FAI values.
RESULTS
After adjusting for clinical characteristics, multiple linear regression identified that lipid components volume fraction (β = 0.162, P < 0.001) were independent risk factors for elevated periplaque FAI values whereas calcified components volume fraction (β = -0.066, P = 0.025) were independent protective factors. The WQS regression models indicated an increase in the overall confounding effect of the adjusted lipid indices and plaque composition volume fraction on the risk of elevated periplaque FAI values (P = 0.004). Qgcomp analysis indicated lipid component volume fraction and calcified component volume fraction was positively and negatively correlated with elevated plaque FAI values, respectively (all P < 0.05).
CONCLUSIONS
Periplaque FAI values quantified by CCTA were strongly correlated with lipid and calcification component volume fractions.
PubMed: 38852002
DOI: 10.1016/j.acra.2024.05.001