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Characterization of a MOSkin detector for in vivo skin dose measurements during interventional radiology procedures

Safari MJ, Wong JH, Ng KH, Jong WL, Cutajar DL, Rosenfeld AB

Med Phys, 2015 May;42(5):2550-8.
PMID: 25979047 DOI: 10.1118/1.4918576

The MOSkin is a MOSFET detector designed especially for skin dose measurements. This detector has been characterized for various factors affecting its response for megavoltage photon beams and has been used for patient dose measurements during radiotherapy procedures. However, the characteristics of this detector in kilovoltage photon beams and low dose ranges have not been studied. The purpose of this study was to characterize the MOSkin detector to determine its suitability for in vivo entrance skin dose measurements during interventional radiology procedures.

Matched MeSH terms: Radiology, Interventional/methods*
ASSESSMENT ON THE INTERCHANGEABILITY OF PERSONAL EFFECTIVE DOSE ALGORITHMS IN FLUOROSCOPY-GUIDED INTERVENTIONS USING BLAND-ALTMAN ANALYSIS

Bohari A, Hashim S, Ghoshal SK, Mohd Mustafa SN

Radiat Prot Dosimetry, 2019 Dec 31;186(4):462-468.
PMID: 31329977 DOI: 10.1093/rpd/ncz051

Long exposure to radiation from fluoroscopy-guided interventions (FGIs) can be detrimental to both patients and radiologists. The effective doses received by the interventional radiology staff after performing 230 FGIs in a year were assessed by using double dosimetry and five various algorithms. The Shapiro-Wilk test revealed normally-distributed data (p < 0.01), while the significant correlation coefficients between the effective doses ranged between 0.88 and 1.00. As for the Bland-Altman analysis, both Niklason and Boetticher algorithms strongly supported the absence of statistical significance between the estimated effective doses. This portrays that the occupational doses received by the interventional radiology staff during FGIs fall within the acceptable limit regardless of the varied algorithms applied. In short, the Niklason and Boetticher algorithms appeared to be the more interchangeable ones for effective evaluation of doses. This is in view of their strong mutual correlations and excellent agreement.

Matched MeSH terms: Radiology, Interventional/methods*
Influence of exposure and geometric parameters on absorbed doses associated with common neuro-interventional procedures

Safari MJ, Wong JHD, Jong WL, Thorpe N, Cutajar D, Rosenfeld A, et al.

Phys Med, 2017 Mar;35:66-72.
PMID: 28256398 DOI: 10.1016/j.ejmp.2017.02.002

PURPOSE: The purpose of this study was to investigate the effects of routine exposure parameters on patient's dose during neuro-interventional radiology procedures.
METHODS: We scrutinized the routine radiological exposure parameters during 58 clinical neuro-interventional procedures such as, exposure direction, magnification, frame rate, and distance between image receptor to patient's body and evaluate their effects on patient's dose using an anthropomorphic phantom. Radiation dose received by the occipital region, ears and eyes of the phantom were measured using MOSkin detectors.
RESULTS: DSA imaging technique is a major contributor to patient's dose (80.9%) even though they are used sparingly (5.3% of total frame number). The occipital region of the brain received high dose largely from the frontal tube constantly placed under couch (73.7% of the total KAP). When rotating the frontal tube away from under the couch, the radiation dose to the occipital reduced by 40%. The use of magnification modes could increase radiation dose by 94%. Changing the image receptor to the phantom surface distance from 10 to 40cm doubled the radiation dose received by the patient's skin at the occipital region.
CONCLUSION: Our findings provided important insights into the contribution of selected fluoroscopic exposure parameters and their impact on patient's dose during neuro-interventional radiology procedures. This study showed that the DSA imaging technique contributed to the highest patient's dose and judicial use of exposure parameters might assist interventional radiologists in effective skin and eye lens dose reduction for patients undergoing neuro-interventional procedures.

Matched MeSH terms: Radiology, Interventional/methods*
Fulltext Towards precision medicine: from quantitative imaging to radiomics

Acharya UR, Hagiwara Y, Sudarshan VK, Chan WY, Ng KH

J Zhejiang Univ Sci B, 2018 1 9;19(1):6-24.
PMID: 29308604 DOI: 10.1631/jzus.B1700260

Radiology (imaging) and imaging-guided interventions, which provide multi-parametric morphologic and functional information, are playing an increasingly significant role in precision medicine. Radiologists are trained to understand the imaging phenotypes, transcribe those observations (phenotypes) to correlate with underlying diseases and to characterize the images. However, in order to understand and characterize the molecular phenotype (to obtain genomic information) of solid heterogeneous tumours, the advanced sequencing of those tissues using biopsy is required. Thus, radiologists image the tissues from various views and angles in order to have the complete image phenotypes, thereby acquiring a huge amount of data. Deriving meaningful details from all these radiological data becomes challenging and raises the big data issues. Therefore, interest in the application of radiomics has been growing in recent years as it has the potential to provide significant interpretive and predictive information for decision support. Radiomics is a combination of conventional computer-aided diagnosis, deep learning methods, and human skills, and thus can be used for quantitative characterization of tumour phenotypes. This paper discusses the overview of radiomics workflow, the results of various radiomics-based studies conducted using various radiological images such as computed tomography (CT), magnetic resonance imaging (MRI), and positron-emission tomography (PET), the challenges we are facing, and the potential contribution of radiomics towards precision medicine.

Matched MeSH terms: Radiology, Interventional/methods*
Fulltext Antegrade repositioning of Memokath stent in malignant ureteroileal anastomotic stricture

Ng KL, Nawawi O, Lim BK, Htun TH, Dublin N, Razack AH

Asian J Surg, 2017 Apr;40(2):171-174.
PMID: 24210538 DOI: 10.1016/j.asjsur.2013.09.012

Ureteric strictures are common and can be due to benign or malignant causes. Various surgical treatments can be used from minimally invasive endoscopic retrograde JJ stent insertion, balloon dilatation, ureterolithotomy, to open surgical exploration and repair. Memokath 051 stent is a metallic stent designed for long-term ureteral stenting in the management of ureteral strictures. The insertion of this device is usually a straightforward procedure performed endoscopically in a retrograde fashion via cystoscopy. However, this procedure can be difficult in complicated scenarios when the bladder has been removed with neoureteral reimplantations or high-grade strictures. Here, we report a case of Memokath stent insertion complicated by placement difficulties in a lady with ileal conduit due to previous ovarian cancer complicated by vesicovaginal fistula, who presented with malignant stricture of the ureteroileal anastomosis. We describe a simple yet effective antegrade technique to precisely reposition the malpositioned Memokath stent, along with illustrations.

Matched MeSH terms: Radiology, Interventional/methods*