Dataset Information

Effect of contrast medium on treatment modalities planned with different photon beam energies: a planning study.

ABSTRACT:

Background

Routinely, patient's planning scans are acquired after administration of iodinized contrast media but they will be treated in the absence of that. Similarly, high energy photons have a better penetrating power, while low energy photons will result in tighter dose distribution and negligible neutron contamination. The aim of the study was to investigate a suitable photon beam energy in the presence of intravenous contrast medium.

Materials and methods

An indigenously made original-contrast (OC) phantom was mentioned as virtual-contrast (VC) and virtual-without-contrast (VWC) phantom were generated by assigning the Hounsfield Units (HU) to different structures. Intensity-modulated (IMRT) and volumetric-modulated-arc (VMAT) plans were generated as per criteria of the TG-119 protocol.

Results

It was observed that the maximum dose to the spinal cord was better with 6 mega-voltage (MV) in IMRT. The coverage of Prostate PTV (PR PTV) was similar with all the photon energies and was comparable with TG-119, except for original-contrast (OC) phantom using the VMAT technique. Homogeneity-index (HI) was comparatively better for VMAT plans.

Conclusion

The contrast CT images lower the dose to targets. IMRT or VMAT plans, generated on such CT images will be delivered with higher doses than evaluated. However, the overdose remains non-significant.

SUBMITTER: Bhushan M

PROVIDER: S-EPMC8575357 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Publications

Effect of contrast medium on treatment modalities planned with different photon beam energies: a planning study.

Bhushan Manindra M Tripathi Deepak D Yadav Girigesh G Kumar Lalit L Dewan Abhinav A Tandon Sarthak S Kumar Gourav G Wahi Inderjit Kaur IK Gairola Munish M

Reports of practical oncology and radiotherapy : journal of Greatpoland Cancer Center in Poznan and Polish Society of Radiation Oncology 20210930 5

<h4>Background</h4>Routinely, patient's planning scans are acquired after administration of iodinized contrast media but they will be treated in the absence of that. Similarly, high energy photons have a better penetrating power, while low energy photons will result in tighter dose distribution and negligible neutron contamination. The aim of the study was to investigate a suitable photon beam energy in the presence of intravenous contrast medium.<h4>Materials and methods</h4>An indigenously mad ...[more]

PMID: 34760305

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Project description:ObjectiveTo evaluate the image quality of an ultra-low contrast medium and radiation dose CT pulmonary angiography (CTPA) protocol for the diagnosis of acute pulmonary embolism using a clinical photon-counting detector (PCD) CT system and compare its performance to a dual-energy-(DE)-CTPA protocol on a conventional energy-integrating detector (EID) CT system.MethodsSixty-four patients either underwent CTPA with the novel scan protocol on the PCD-CT scanner (32 patients, 25 mL, CTDIvol 2.5 mGy·cm) or conventional DE-CTPA on a third-generation dual-source EID-CT (32 patients, 50 mL, CTDIvol 5.1 mGy·cm). Pulmonary artery CT attenuation, signal-to-noise ratio, and contrast-to-noise-ratio were assessed as objective criteria of image quality, while subjective ratings of four radiologists were compared at 60 keV using virtual monoenergetic imaging and polychromatic standard reconstructions. Interrater reliability was determined by means of the intraclass correlation coefficient (ICC). Effective dose was compared between patient cohorts.ResultsSubjective image quality was deemed superior by all four reviewers for 60-keV PCD scans (excellent or good ratings in 93.8% of PCD vs. 84.4% of 60 keV EID scans, ICC = 0.72). No examinations on either system were considered "non-diagnostic." Objective image quality parameters were significantly higher in the EID group (mostly p < 0.001), both in the polychromatic reconstructions and at 60 keV. The ED (1.4 vs. 3.3 mSv) was significantly lower in the PCD cohort (p < 0.001).ConclusionsPCD-CTPA allows for considerable reduction of contrast medium and radiation dose in the diagnosis of acute pulmonary embolism, while maintaining good to excellent image quality compared to conventional EID-CTPA.Clinical relevance statementClinical PCD-CT allows for spectral assessment of pulmonary vasculature with high scan speed, which is beneficial in patients with suspected pulmonary embolism, frequently presenting with dyspnea. Simultaneously PCD-CT enables substantial reduction of contrast medium and radiation dose.Key points• The clinical photon-counting detector CT scanner used in this study allows for high-pitch multi-energy acquisitions. • Photon-counting computed tomography allows for considerable reduction of contrast medium and radiation dose in the diagnosis of acute pulmonary embolism. • Subjective image quality was rated best for 60-keV photon-counting scans.

Project description:BackgroundAge-related remodelling has the potential to affect the microvascular response to hyperemic stimuli. However, its precise effects on the vasodilatory response to adenosine and contrast medium, as well as its influence on fractional flow reserve (FFR) and contrast fractional flow reserve (cFFR), have not been previously investigated. We investigate the impact of age on these indices.MethodsWe extrapolated data from the post-revascularization optimization and physiological evaluation of intermediate lesions using fractional flow reserve (PROPHET-FFR) and The Multi-center Evaluation of the Accuracy of the Contrast MEdium INduced Pd/Pa RaTiO in Predicting (MEMENTO) studies. Only lesions with a relevant vasodilatory response to adenosine and contrast medium were considered of interest. A total of 2080 patients, accounting for 2294 pressure recordings were available for analysis. The cohort was stratified into three age terciles. Age-dependent correlations with FFR, cFFR, distal pressure/aortic pressure (Pd/Pa) and instantaneous wave-free ratio (iFR) were calculated. The vasodilatory response was calculated in 1619 lesions (with both FFR and cFFR) as the difference between resting and hyperaemic pressure ratios and correlated with aging. The prevalence of FFR-cFFR discordance was assessed.ResultsAge correlated positively to FFR (r = 0.062, p = 0.006), but not with cFFR (r = 0.024, p = 0.298), Pd/Pa (r = -0.015, p = 0.481) and iFR (r = -0.026, p = 0.648). The hyperemic response to adenosine (r = -0.102, p ≤ 0.0001) and to contrast medium (r = -0.076, p = 0.0023) showed a negative correlation with age. When adjusted for potential confounders, adenosine induced hyperaemia was negatively associated with age (p = 0.04 vs p = 0.08 for cFFR). Discordance decreased across age terciles (14.64% vs 12.72% vs 10.12%, p = 0.032).ConclusionsAs compared to adenosine, contrast induced hyperaemia appeared to be less affected by age. cFFR may be considered a more stable and reproducible tool to assess epicardial stenosis in elderly patients.Clinical trial registrationPROPHET-FFR STUDY, Clinicaltrials.gov (NCT05056662).

Dataset Information

Effect of contrast medium on treatment modalities planned with different photon beam energies: a planning study.

Background

Materials and methods

Results

Conclusion

Publications

Effect of contrast medium on treatment modalities planned with different photon beam energies: a planning study.

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