Paediatric patients have a higher average risk of developing cancer compared with adults receiving the same dose. The longer life expectancy in children allows more time for any harmful effects of radiation to manifest, and developing organs and tissues are more sensitive to the effects of radiation. This publication aims to provide guiding principles of radiological protection for referring clinicians and clinical staff performing diagnostic imaging and interventional procedures for paediatric patients. It begins with a brief description of the basic concepts of radiological protection, followed by the general aspects of radiological protection, including principles of justification and optimisation. Guidelines and suggestions for radiological protection in specific modalities - radiography and fluoroscopy, interventional radiology, and computed tomography - are subsequently covered in depth. The report concludes with a summary and recommendations. The importance of rigorous justification of radiological procedures is emphasised for every procedure involving ionising radiation, and the use of imaging modalities that are non-ionising should always be considered. The basic aim of optimisation of radiological protection is to adjust imaging parameters and institute protective measures such that the required image is obtained with the lowest possible dose of radiation, and that net benefit is maximised to maintain sufficient quality for diagnostic interpretation. Special consideration should be given to the availability of dose reduction measures when purchasing new imaging equipment for paediatric use. One of the unique aspects of paediatric imaging is with regards to the wide range in patient size (and weight), therefore requiring special attention to optimisation and modification of equipment, technique, and imaging parameters. Examples of good radiographic and fluoroscopic technique include attention to patient positioning, field size and adequate collimation, use of protective shielding, optimisation of exposure factors, use of pulsed fluoroscopy, limiting fluoroscopy time, etc. Major paediatric interventional procedures should be performed by experienced paediatric interventional operators, and a second, specific level of training in radiological protection is desirable (in some countries, this is mandatory). For computed tomography, dose reduction should be optimised by the adjustment of scan parameters (such as mA, kVp, and pitch) according to patient weight or age, region scanned, and study indication (e.g. images with greater noise should be accepted if they are of sufficient diagnostic quality). Other strategies include restricting multiphase examination protocols, avoiding overlapping of scan regions, and only scanning the area in question. Up-to-date dose reduction technology such as tube current modulation, organ-based dose modulation, auto kV technology, and iterative reconstruction should be utilised when appropriate. It is anticipated that this publication will assist institutions in encouraging the standardisation of procedures, and that it may help increase awareness and ultimately improve practices for the benefit of patients.

https://journals.sagepub.com/doi/pdf/10.1016/j.icrp.2012.10.001

ICRP Publication 121: Radiological Protection in Paediatric Diagnostic and Interventional Radiology

https://www.zora.uzh.ch/id/eprint/181192/1/2018_05_02_Manuscript2_ECCO_ESGAR-DiagnosticsGL_c4-5.pdf

Ecco-esgar guideline for diagnostic assessment in ibd part 2: Ibd scores and general principles and technical aspects

Purpose: We investigated whether detection of ctDNA after resection of colorectal cancer identifies the patients with the highest risk of relapse and, furthermore, whether longitudinal ctDNA analysis allows early detection of relapse and informs about response to intervention.Experimental Design: In this longitudinal cohort study, we used massively parallel sequencing to identify somatic mutations and used these as ctDNA markers to detect minimal residual disease and to monitor changes in tumor burden during a 3-year follow-up period.Results: A total of 45 patients and 371 plasma samples were included. Longitudinal samples from 27 patients revealed ctDNA postoperatively in all relapsing patients (n = 14), but not in any of the nonrelapsing patients. ctDNA detected relapse with an average lead time of 9.4 months compared with CT imaging. Of 21 patients treated for localized disease, six had ctDNA detected within 3 months after surgery. All six later relapsed compared with four of the remaining patients [HR, 37.7; 95% confidence interval (CI), 4.2-335.5; P < 0.001]. The ability of a 3-month ctDNA analysis to predict relapse was confirmed in 23 liver metastasis patients (HR 4.9; 95% CI, 1.5-15.7; P = 0.007). Changes in ctDNA levels induced by relapse intervention (n = 19) showed good agreement with changes in tumor volume (κ = 0.41; Spearman ρ = 0.4).Conclusions: Postoperative ctDNA detection provides evidence of residual disease and identifies patients at very high risk of relapse. Longitudinal surveillance enables early detection of relapse and informs about response to intervention. These observations have implications for the postoperative management of colorectal cancer patients. Clin Cancer Res; 23(18); 5437-45. ©2017 AACR.

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Clinical Implications of Monitoring Circulating Tumor DNA in Patients with Colorectal Cancer

OBJECTIVE. Our purpose was to evaluate the utility of CT urography performed using a split contrast bolus that yields synchronous nephrographic and excretory phase enhancement.MATERIALS AND METHODS. Five hundred consecutive patients referred for evaluation of possible urinary tract abnormalities (327 for painless hematuria) underwent CT urography with unenhanced scanning of the abdomen and pelvis and scanning during concurrent nephrographic and excretory phase enhancement produced by administration of a split contrast bolus. The enhanced abdomen scan was obtained with abdominal compression; the enhanced pelvis scan was obtained after release of compression. Findings from axial sections and coronal maximum intensity projections were correlated with clinical follow-up and, as available, with laboratory and other imaging studies including cystoscopy, ureteroscopy, urine cytology, surgery, and pathology. Follow-up management for each patient was determined by the clinical judgment of the referring physician.R...

https://www.ajronline.org/doi/pdfplus/10.2214/AJR.07.2288

Split-bolus MDCT urography with synchronous nephrographic and excretory phase enhancement.

Since its introduction in the 1970s, computed tomography (CT) has revolutionized diagnostic decision-making. One of the major concerns associated with the widespread use of CT is the associated increased radiation exposure incurred by patients. The link between ionizing radiation and the subsequent development of neoplasia has been largely based on extrapolating data from studies of survivors of the atomic bombs dropped in Japan in 1945 and on assessments of the increased relative risk of neoplasia in those occupationally exposed to radiation within the nuclear industry. However, the association between exposure to low-dose radiation from diagnostic imaging examinations and oncogenesis remains unclear. With improved technology, significant advances have already been achieved with regards to radiation dose reduction. There are several dose optimization strategies available that may be readily employed including omitting unnecessary images at the ends of acquired series, minimizing the number of phases acquired, and the use of automated exposure control as opposed to fixed tube current techniques. In addition, new image reconstruction techniques that reduce radiation dose have been developed in recent years with promising results. These techniques use iterative reconstruction algorithms to attain diagnostic quality images with reduced image noise at lower radiation doses.

Computed tomography and patient risk: Facts, perceptions and uncertainties

The present study results demonstrated that thin-section CT can be performed in pediatric patients at an effective dose of 0.14 mSv, a dose that approaches that of 1.5 frontal and lateral radiographs.

Development of low-dose protocols for thin-section CT assessment of cystic fibrosis in pediatric patients.

OBJECTIVE. The purpose of this study was to compare FDG PET/CT and contrast-enhanced 64-MDCT of the chest, abdomen, and pelvis in the detection of tumor recurrence in patients with colorectal cancer and an elevated level of carcinoembryonic antigen (CEA).MATERIALS AND METHODS. A retrospective analysis included 50 patients (31 men, 19 women; mean age, 61 years; range, 28–89 years) with 55 clinical events of elevated or increasing CEA level who underwent FDG PET/CT and MDCT for suspected tumor recurrence.RESULTS. Recurrent or metastatic disease was found in 36 of 55 events (65.5%) of elevated CEA. Fifty-four of 61 tumor sites suspected as tumor recurrence with any imaging technique were found to be local recurrence or metastatic colorectal cancer at final analysis. The other seven sites were one separate malignant tumor (small lymphocytic lymphoma) and six benign lesions. Diagnosis was based on histopathologic findings (n = 27) or clinical and imaging findings (n = 35) during a median follow-up period of 12...

https://www.ajronline.org/doi/pdf/10.2214/AJR.09.3205

Assessment of Tumor Recurrence in Patients With Colorectal Cancer and Elevated Carcinoembryonic Antigen Level: FDG PET/CT Versus Contrast-Enhanced 64-MDCT of the Chest and Abdomen

https://www.ajronline.org/doi/pdfplus/10.2214/AJR.09.4181

Imaging of Hematuria

Despite the proliferation of guidelines that comment on the issue, this article demonstrates that there is a striking dearth of robust evidence and prospective studies, in particular, regarding the appropriate use of radiologic imaging in patients with irritable bowel syndrome.

Role of Radiologic Imaging in Irritable Bowel Syndrome: Evidence-based Review

In clinical radiology, there are numerous examples of new techniques that were initially enthusiastically promoted and then subsequently abandoned when early promise was not realized in routine patient care. Appropriateness of new or established interventional radiology techniques to specific clinical conditions must be determined from clinical experience, from communication with experts in the field and/or careful review of available medical literature, and on an individual patient basis by means of review of clinical notes and diagnostic imaging studies. For patients with liver neoplasms, regional techniques such as radiofrequency ablation (RFA) have been developed and are now the subject of ongoing research. This article decribes the utilization of Evidence-Based Practice (EBP) techniques as a means of deciding the appropriateness of percutaneous RFA in treating colorectal liver metastases (CLM).

Sean E. McSweeney

Papers

Development of low-dose protocols for thin-section CT assessment of cystic fibrosis in pediatric patients.

Assessment of Tumor Recurrence in Patients With Colorectal Cancer and Elevated Carcinoembryonic Antigen Level: FDG PET/CT Versus Contrast-Enhanced 64-MDCT of the Chest and Abdomen

Imaging of Hematuria

Role of Radiologic Imaging in Irritable Bowel Syndrome: Evidence-based Review

Which patients will benefit from percutaneous radiofrequency ablation of colorectal liver metastases? Critically appraised topic.