The mathematics and physics of radiation dose planning using X-rays

1990 ◽  
pp. 41-55 ◽  
Author(s):  
A. M. Cormack ◽  
E. T. Quinto
Keyword(s):  
Radiation Dose ◽  
X Rays ◽  
Dose Planning ◽  
Mathematics And Physics

scholarly journals Optimization of X-ray Investigations in Dentistry Using Optical Coherence Tomography

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4554
Author(s):  
Ralph-Alexandru Erdelyi ◽  
Virgil-Florin Duma ◽  
Cosmin Sinescu ◽  
George Mihai Dobre ◽  
Adrian Bradu ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Radiation Dose ◽  
Imaging Techniques ◽  
Image Resolution ◽  
Optical Coherence ◽  
X Rays ◽  
High Quality ◽  
X Ray

The most common imaging technique for dental diagnoses and treatment monitoring is X-ray imaging, which evolved from the first intraoral radiographs to high-quality three-dimensional (3D) Cone Beam Computed Tomography (CBCT). Other imaging techniques have shown potential, such as Optical Coherence Tomography (OCT). We have recently reported on the boundaries of these two types of techniques, regarding. the dental fields where each one is more appropriate or where they should be both used. The aim of the present study is to explore the unique capabilities of the OCT technique to optimize X-ray units imaging (i.e., in terms of image resolution, radiation dose, or contrast). Two types of commercially available and widely used X-ray units are considered. To adjust their parameters, a protocol is developed to employ OCT images of dental conditions that are documented on high (i.e., less than 10 μm) resolution OCT images (both B-scans/cross sections and 3D reconstructions) but are hardly identified on the 200 to 75 μm resolution panoramic or CBCT radiographs. The optimized calibration of the X-ray unit includes choosing appropriate values for the anode voltage and current intensity of the X-ray tube, as well as the patient’s positioning, in order to reach the highest possible X-rays resolution at a radiation dose that is safe for the patient. The optimization protocol is developed in vitro on OCT images of extracted teeth and is further applied in vivo for each type of dental investigation. Optimized radiographic results are compared with un-optimized previously performed radiographs. Also, we show that OCT can permit a rigorous comparison between two (types of) X-ray units. In conclusion, high-quality dental images are possible using low radiation doses if an optimized protocol, developed using OCT, is applied for each type of dental investigation. Also, there are situations when the X-ray technology has drawbacks for dental diagnosis or treatment assessment. In such situations, OCT proves capable to provide qualitative images.

scholarly journals Radiation dose from common radiological investigations and cumulative exposure in children with cystic fibrosis: an observational study from a single UK centre

BMJ Open ◽  
2017 ◽  
Vol 7 (8) ◽  
pp. e017548 ◽  
Author(s):  
Rebecca Ward ◽  
William D Carroll ◽  
Paula Cunningham ◽  
Sheng-Ang Ho ◽  
Mary Jones ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Radiation Dose ◽  
Radiation Exposure ◽  
Cumulative Exposure ◽  
X Rays ◽  
Modern Equipment ◽  
Increased Risk ◽  
Risk Of Malignancy ◽  
The Mean ◽  
Cumulative Radiation Exposure

ObjectivesCumulative radiation exposure is associated with increased risk of malignancy. This is important in cystic fibrosis (CF) as frequent imaging is required to monitor disease progression and diagnose complications. Previous estimates of cumulative radiation are outdated as the imaging was performed on older equipment likely to deliver higher radiation. Our objectives were to determine the radiation dose delivered to children during common radiological investigations using modern equipment and to identify the number of such investigations performed in a cohort of children with CF to calculate their cumulative radiation exposure.Design, setting and participantsData including age at investigation and radiation exposure measured as estimated effective dose (EED) were collected on 2827 radiological studies performed on children at one UK paediatric centre. These were combined with the details of all radiological investigations performed on 65 children with CF attending the same centre to enable calculation of each child’s cumulative radiation exposure.ResultsThe mean EED for the common radiological investigations varied according to age. The range was 0.01–0.02 mSv for chest X-rays, 0.03–0.11 mSv for abdominal X-rays, 0.57–1.69 mSv for CT chest, 2.9–3.9 mSv for abdominal and pelvic CT, 0.20–0.21 mSv for sinus CT and 0.15–0.52 mSv for fluoroscopy-guided procedures. The mean EED was three to five times higher for helical compared with axial chest CT scans. The mean annual cumulative EED for our cohort of children with CF was 0.15 mSv/year with an estimated cumulative paediatric lifetime EED (0–18 years) of 3.5 mSv.ConclusionsThis study provides up-to-date estimations of the radiation exposure when using common radiological investigations. These doses and the estimates of cumulative radiation exposure in children with CF are lower than previously reported. This reflects the reduced EED associated with modern equipment and the use of age-specific scanning protocols.

scholarly journals An in vitro of radiation dose enhancement using gold nanorods and plasmonic photothermal therapy

2021 ◽  
Author(s):  
Daniel DiCenzo DiCenzo
Keyword(s):  
Radiation Dose ◽  
Ionizing Radiation ◽  
Gold Nanorods ◽  
Near Infrared ◽  
Infrared Light ◽  
Nuclear Localization Sequence ◽  
X Rays ◽  
Dose Enhancement ◽  
Near Infrared Light ◽  
Pc3 Cells

Gold nanoparticles (GNP) have been shown to highly absorb ionizing radiation compared to tissue. GNPs have also been shown to be high absorbers of non-ionizing radiation with a peak absorbance at a wavelength dependent on their shape and size. This study investigated radiation dose enhancement in PC3 cells when in the presence of gold nanorods (NR) and near infrared light (IR). The PC3 cells were incubated with either PEGylated NRs (PNR) or anti prostate stem cell antigen antibody with nuclear localization sequence peptide conjugated NRs (AbNR). They were exposed to near infrared light at a wavelength of 810 nm to achieve a temperature of 42 ºC to 43 ºC for 60 minutes. They were also exposed to 160 kVp x-rays. It was found that both targeted and non-targeted GNPs when exposed to radiation and near infrared light synergistically enhanced radiation dose. It was also found that AbNRs provide greater dose enhancement than PNRs.

The quality factor of x-rays/gamma rays as one is realistic?

2012 ◽  
Vol 11 (3) ◽  
pp. 195-197 ◽  
Author(s):  
Syed F. Akber
Keyword(s):  
Radiation Dose ◽  
Energy Range ◽  
Quality Factor ◽  
Gamma Rays ◽  
Specific Energy ◽  
Biological Systems ◽  
X Rays ◽  
Radiation Quality ◽  
Cell Cycles ◽  
The Mean

AbstractThe quality factor for x-rays, gamma rays and electrons assigned as one need to be revised. It is observed that as the energy decreases, mean lethal radiation dose (Do)decreases as well and become more potent. It is therefore proposed that radiation quality in biological systems should be assessed in the mitotic phase of the cell cycles. Furthermore, based on the mean lethal radiation dose within specific energy range, an appropriate quality factor of x-rays, gamma rays and electrons should be assigned.

RADIATION DOSE EFFECTS IN RELATION TO OBSTETRIC X-RAYS AND CHILDHOOD CANCERS

The Lancet ◽  
1970 ◽  
Vol 295 (7658) ◽  
pp. 1185-1188 ◽  
Author(s):  
Alice Stewart ◽  
G.W Kneale
Keyword(s):  
Radiation Dose ◽  
X Rays ◽  
Childhood Cancers ◽  
Dose Effects

Thermal stability of some radiation damage products in X-irradiated NaClO3

1979 ◽  
Vol 57 (2) ◽  
pp. 128-131 ◽  
Author(s):  
V. S. Sivasankar ◽  
P. W. Whippey
Keyword(s):  
Thermal Stability ◽  
Electron Spin Resonance ◽  
Radiation Dose ◽  
Optical Absorption ◽  
Radiation Damage ◽  
Sodium Chlorate ◽  
X Rays ◽  
Optical Absorption Spectra ◽  
Spin Resonance ◽  
Thermal Stability Of

Single crystals of sodium chlorate have been exposed to X-rays, at 77 K. Thermoluminescence glow curves of the irradiated crystals have been recorded from 77 to 400 K. Optical absorption spectra and electron spin resonance spectra of the crystals subjected to radiation damage have also been recorded as a function of radiation dose, and at different stages of thermal annealing between 77 and 400 K. Using the optical and ESR data, the glow peaks at 173, 185, and 249 K have been identified as due to O2− in the vicinity of ClO3, ClO3, itself, and O2− adjacent to ClO2, respectively. The trapping parameters for these centers have been determined.

scholarly journals Feasibility Of Radiation Dose Planning Guided Surgical Resection In Spinal Tumours

2021 ◽  
Author(s):  
Raphael Y. Jakubovic
Keyword(s):  
Spinal Cord ◽  
Radiation Dose ◽  
Treatment Planning ◽  
Surgical Resection ◽  
Ultrasound Imaging ◽  
High Frequency ◽  
Radiation Treatment ◽  
Radiation Treatment Planning ◽  
Spinal Tumours ◽  
Dose Planning

The objective of high dose stereotactic radiotherapy regardless of application is to treat the malignancy while minimizing the radiation dose to the surrounding healthy tissue. In the context of spinal tumours this paradigm is difficult since the rigid dose tolerance of the spinal cord precludes optimal dose coverage of the epidural disease. To achieve adequate coverage spine separation surgery is performed, increasing the distance from the spinal cord to the malignancy and facilitating adequate radiation treatment planning. This approach has been validated with delivery of maximum tolerable dose and local control rates over 90%. The objective of this dissertation is to establish the feasibility of intraoperative, dose guided, spine separation surgery. In the current clinical context, spine separation surgery is performed prior to radiation treatment planning and contours are placed based on postoperative resected tumour volumes. The extent of surgical resection is not dictated by the dosimetric constraints of the spinal cord and relies solely on the clinical expertise of the operating neurosurgeon. Further, though a skilled surgeon can perform precise tumour debulking with or without the aid of millimetre resolution neuronavigation devices, determination of surgical debulking progress with accuracy comparable to treatment delivery cannot be recognized without intraoperative imaging. To achieve this goal, we introduced pre-surgical dosimetric planning with tracked high frequency micro-ultrasound imaging into the operating theatre to inform the surgeon of the surgical progress while considering the dosimetric objectives. In this dissertation, we assessed the dosimetric advantage of spine separation surgery on a millimetre by millimetre basis in a retrospective simulation study. Feasibility of intraoperative navigation with submillimetre resolution was established by quantifying the application accuracy of surgical navigation in the context of cranial and spinal surgery. Accuracy quantification was performed, assessing our revolutionary optical topographical imaging system and benchmarked versus existing commercially available neuronavigation systems. Finally, to establish feasibility of radiation dose planning guided surgical resection we integrated a high frequency micro-ultrasound system into the operating theater during spine separation surgery. Thus, by implementing sub-millimetre high frequency micro-ultrasound imaging and neuronavigation, incremental gains towards establishing the feasibility of in traoperative dose planning by iteratively updating the extent of tumour resection were recognized.

Interaction of ionizing radiations with matter

2015 ◽  
Author(s):  
Colin J Martin
Keyword(s):  
Radiation Dose ◽  
Scattered Radiation ◽  
Final Section ◽  
Radioactive Decay ◽  
Photoelectric Effect ◽  
X Rays ◽  
X Ray ◽  
Radiation Fields ◽  
Ionizing Radiations ◽  
Radiology Image

Interactions of ionizing radiations with matter are fundamental to the practice of radiation protection. They determine the magnitude and distribution of doses in tissues, the performance of detectors and imaging devices, and the attenuating properties of shielding materials. This chapter describes briefly the processes of radioactive decay and the properties of the various particles emitted, and then goes on to consider the interactions of radiation with matter. Electron interactions with metals result in bremsstrahlung and characteristic X-rays that form the basis of X-ray production. The interaction mechanisms of X-rays with tissue, particularly the photoelectric effect and Compton scattering, are inherent in the process of radiology image formation. Understanding the physics behind X-ray interactions so that scattered radiation can be taken into account is crucial in designing methods for accurately measuring radiation dose parameters. The final section deals with the dose related variables involved in measurement of radiation fields.

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