- Lindsay Tremethick added an answer:What materials in accelerator?...........Yes Hanno quite correct, my apologies, I didn't add that "head of linac" actually means primary collimator.Following
- Daniel Robert Franklin added an answer:LINACS?T lead.Tungsten is actually not that expensive... about $35/kg in bulk quantities. I'm not sure how sanctions affect its availability in Iran. The cost in medical applications is usually more a result of the difficulty of machining it. There are some soft and flexible polymer-tungsten powder composites which are available for shielding applications, but they probably don't make a very good collimator.
Your best option is therefore probably lead, possibly alloyed with antimony (about 1-5%) to make it harder and stronger. If you're trying to do microbeams or some very fine geometry it will be challenging to accurately machine or cut it; for large beam geometries I think it should be OK.Following
- Serge Grabtchak added an answer:I'm looking for data on spectrally-resolved optical properties (absorption and scatering coefficients etc) of porcine muscles.I'd appreciate any references on the subject. Range: 650-900 nmThis publication contains our recent data on optical absorption and scattering properties of bulk porcine muscles, Longissimus dorsi (the loin) and Psoas major (the tenderloin):
- Closed account added an answer:Does anyone know a setup to generate 10 Volume per average respiratory motion in MRI?I am using MRI symphony TIM Siemens.The lungs, esophagus, liver, pancreas, breast, prostate, and kidneys, among other organs, are known to move with breathing. The degradation of image quality due to this motion and subsequent effects on radiotherapy dose planning and delivery have prompted medical physicists and clinicians to study the motion using a variety of imaging modalities.Following
- Alan Futivić added an answer:How do you react to the recent publication from Australia in the BMJ that indicates an increase in cancers arising from paediatric CT scans?The publication can be accessed in the link below. This is how the publication is summarised in an ESR Newsletter: This cancer risk assessment in an Australian study cohort showed that overall cancer incidence was 24% higher for children and adolescents exposed to low dose ionising radiation from computed tomography (CT) than for patients who were not exposed. Australian Medicare records from 1985–2005 were analysed for this study, and although radiation doses from current CT scans are likely to be lower, a slight increase in cancer risk due to exposure is still possible.Exactly. We need to know at least roughly what we want to prove with examination. Then we can do a search in the patient's best interests. Optimal protocol with less radiation.
- Andrew Chicco added an answer:How do I measure Organ doses by gamma counter?I have measured Counts from a γ-counter for different organs (lungs, liver, spleen, stomach, brain, kidney and heart) after 3.5 hours of intravenous injection with 80 MBq initial dose of Technetium labeled with Glycol Chitosan Palmitoylated quaternary ammonium (GCPQ). Now I want to convert these counts in to organ injected doses. Please can any person guide me how to do this?Hi Rafique,
As mentioned above you do require the activity within each of the different organs at several points in time (i.e. you need to have data from several rabbits, each sacrificed at these times).
There is a very good book published by Dr. Michael Stabin: "Fundamentals of Nuclear Medicine Dosimetry" (Springer, 2008). It has several case studies included (i.e. fuly worked examples), and also discusses the issues involved in translating animal dosimetry to human. I most thoroughly recommend it.
There is also freely available MIRD Pamphlet 16 (published by the Society of Nuclear Medicine, available online), which discusses the experimental design for what you are attempting to do (please correct me if I am wrong).
- Jean Rene Grezes added an answer:Can somebody suggest a source of tabulated spectral data of absorption coefficients for myoglobin and oxy-myoglobin?-Dear Serge,
thank you for fast answer but there isin my answer no confusion
I clicked your link but it is a "slight shoddy" link . WHY??
- the author gives some details as follows:
Tabulated Molar Extinction Coefficient for Hemoglobin in Water
These values for the molar extinction coefficient e in [cm-1/(moles/liter)] were compiled by Scott Prahl using data from
W. B. Gratzer, Med. Res. Council Labs, Holly Hill, London
N. Kollias, Wellman Laboratories, Harvard Medical School, Boston
To convert this data to absorbance A, multiply by the molar concentration and the pathlength. For example, if x is the number of grams per liter and a 1 cm cuvette is being used, then the absorbance is given by
(e) [(1/cm)/(moles/liter)] (x) [g/liter] (1) [cm]
A = ---------------------------------------------------
using 64,500 as the gram molecular weight of hemoglobin.
To convert this data to absorption coefficient in (cm-1), multiply by the molar concentration and 2.303,
µa = (2.303) e (x g/liter)/(64,500 g Hb/mole)
where x is the number of grams per liter. A typical value of x for whole blood is x=150 g Hb/liter.
but there is no details about the quality of water (bidist. water p.e.) and the 1 cm cuvette is without quality and kind of cuvette (p.e. quartz, glass ....) and cut off of water.
No infos about the used spectrometer (single , dual or arrays). Very important !
- No infos about the purity of hemoglobin (and its kind) and about the analysis prior to weight for the wished concentration. The presence of impurities or water will give a wrong concentration e.g. A and later e (epsilon)
- If you find such tabulated data for myoglobin and derivative(s), please control the source and quality and infos about purity.
- Please note that most investiagationsabout myoglobin and der. were done in buffer in the past.
you cannot compare values in water and in buffer either for hemo or myoglobin.
- Sundaram Thangavelu added an answer:Kindly tell me the equation for calculating the volume of pear precisely?Volume of a pear is required for me to use in a research. Kindly help us to find the volume of a group of pears.We have generated 90 pear-shaped volumes (cancer tissue volumes) in patient 3D CT images for treatment using radiation. We have measured the length, width and thickness of each pear and tabulated and this data is what we need to use to find an equation for finding the volume. We need to find an equation to find the volume of a pear based on inputting length, width or thickness of these 90 pear volumes. We intent to use such a equation for generating pear-shaped treatment volume by inputting length or width or thickness. Kindly help us.Following
- John Houghton added an answer:Stable isotopes. As far as they are stable?In the course of professional work 1999 - 2012 the project «Star dust» SSH&H the first generation has been realised. The received result following: there is a substance, cardinally braking process of ageing of human physiology and in parallel, giving positive dynamics of treatment and knocking over of some illnesses, including heavy. In the course of researches of pharmacological dynamics the result has been received, that in an investigated substance there is no active component and molecular reactions are not observed at application by its person. Low-energy nuclear reaction safe for the person was observed only.
The further researches spent on the basis of nuclear institutes, have allowed to consider additional development of the project: medical and technical.
To discussion the technical direction is offered.
Proceeding, from a working hypothesis follows, that there is a number of stable isotopes entering low-energy nuclear interaction with radioisotopes of the air and water environment. In other words low-energy reaction is possible at ordinary fluctuation of air.
- Alawiah Ariffin added an answer:Does the shape of dosimeter influences the position of TL main peak?Should I get the same peak position if i use TLD-100 chip shape and TLD-100 rod shape?Thanks Anuj for sharing the paper...Following
- Abhijit Mandal asked a question:Can someone advise on the use of an implantable biocompatible in vivo dosimeter?I have found some articles on DVS Dosimetry system from Sicel technologies and am seeking to learn more.Following
- Michael Dada added an answer:Is it possible to introduce magnetic flux density (B) in the radiative transfer equation?i like to quantify the magnetic field (B) from the fluence rate from radiative transport equation. Since light is an electromagnetic wave, i guess there should be a place for B(x,t).Thanks Dr. Patyk. Your response is very insightful indeed!Following
- Peer Koltermann added an answer:Could anyone suggest a reasonable dose range for calculating gamma pass rate in radiation therapy?When we evaluate the difference between the measured and calculated dose distribution values, gamma index can serve as a good quantitative method. But what is the reasonable dose range when we calculate the pass rage? Generally, for clinic radiation therapy, dose range 60%-100% is what we are concerned with, right? So we can just calculate the dose range from 60% to 100%? I asked another medical physicist, but he said there is no exact answer for this question. Could anyone give me a suggestion? Thank you very much.Just some general thoughts added: As said above the gamma index is not a fixed equation. Vendors "adapt" the gamma pass rate as their devices need it. There are many ways to name a gamma index. So you can not even compare 2 gamma pass rate without lots of background information. Sayings like "we just treat with pass rates above 98%" don't give you any information, it just sounds nice.
We are working on common "baselines" so medical physicists can compare worldwide exactly for this reason.Following
- Peer Koltermann added an answer:Can anyone recommend a medical physics expert willing to travel to London, UK?We have a DXA scanner than requires a MPE to approve any protocols before we can commence testing. If anyone could suggest a MPE near London that would be much appreciated.we work with medical physicists worldwide. Email to email@example.com and we can help.Following
- Samuel Ojo added an answer:How can I find a good fiber-optical thermocouple?I need a good thermometer for measuring temperature of nanoparticles and mouse skin in a AC magnetic field. I need the available models with moderate price for temperature range: 25-70 centigrade degreeI will suggest the use of small diameter optical fibre (SDOF) as we once developed a novel method for measuring light intensity at different temperature. This can measure up to 180 degree celcius. This probably allay the fear of high costs you raised as the diameter of SDOF ranges between 12-20 microns.Following
- Martins Piksis added an answer:Does anyone know the average life span of Varian Clinac's klystron tube?Klystron tube damageThanks, Marcel!Following
- Toutaoui Abdelkader added an answer:Simulation dataI have written a simulation program for 6 and 18 MV Varian Linac for MCNP code. I'm sure of the geometry but I have two questions:
1- The profiles in deptyh 5, 10, 15cm don't fit on the musearment data. Can anyone guid me for some hits (phys, cut, prdmp, dbcn or other factors) to reduce variance.
2- When using the SSW for output, the results are not same the primary data. Are these differences okay?generally in MC simulation of Linac, the influencing parameter on the PDDs is the initial electron beam (hitting the target) energy, but for the beam profiles it's important to select and adequate focal spot sizeFollowing
- Vinod Nelson added an answer:How can I measure modulation transfer function (MTF) from catphan phantom?I would like to measure MTF in CBCT images.Hi Witold, Thanks for info on IQWorks, I used it and works fine, needed to modify some parameters on the ED number analysis module. CT AutoLiteQA was never able to find the 'bead' to carry out MTF determination but with IQWorks you can locate the 'bead' yourself and run the test.Following
- Sajjad Ahmed Memon added an answer:Can a Cobalt treatment machine (Theratron 1000) be used to sterilize bacterial media or fresh meat-extract to feed sterile larvae?Would like to use a gamma treatment machine after-hours to sterilize biologic products.Cobalt treatment machines have low dose rates as compared to irradiators used for sterlization as the activity of these sterilzers is about ten times or more than regular treatment units.Following
- Faezeh Rahmani added an answer:Calculating structural shielding of exposure rooms of radiation facilitiesIs there any Computer Software for the calculation of Structural shielding of Exposure rooms of radiation facilities? We have a software but we want improvementIf you want to simulate deep prenetration and radiation streaming problem in 3D, MCNP is the best tool, but only deep penetration in one wall without acattering, Microshield can help youFollowing
- Piero Chiarelli added an answer:Articles on cosmology and life sciences?I am interested by some connections between cosmology, gravity etc with life sciences, biophysics or whatever. I will be appreciative if you can give me some initial starting points with articles, textbooks etc dedicated to my interests.Second paperFollowing
- Lindsay Tremethick added an answer:Simulation dataHi every body. I'm writing monte carlo program for Varian Unit. I need wedge composition for varian 2100 CD. thanksUnfortunately I think Nahid Chegeni is "between a rock and a hard place". I am guessing (although I could be wrong) that the sanctions laws within the US would restrict exactly what information Varian would provided. As far as I can tell Varian has received licences to "export" however I think they are on a case by case basis and I don't know whether one of those licences may be broad enough to just distribute information to another party. I know that Varian has had its wrist slapped for unlicenced distribution of software "OFAC alleged that Varian acted without an OFAC license or outside the scope of its license by exporting U.S. origin software without a license."Following
- Hassaan Alkhatib added an answer:Qa of mlc ?icru 83 application in tpsi need how to make Quality assurance of Elketa MLC machine ? also how to apply ICRU 83 in IMRT plan to get good result . Can any body help?i think the two references above are great suggestions we have used them both as bases in our QA program and if you need more detailed information just let me knowFollowing
- Clemens Grassberger added an answer:Is Coulomb scattering included in elastic cross sections provided by ICRU report 63?In our research group, we are performing dedicated Monte Carlo simulations of proton therapy beams. We are currently implementing nuclear interactions. There are two types of nuclear reactions. Inelastic, where the proton is "absorbed" and many secondaries are generated (protons, neutrons, alphas...). Elastic, when the target nucleus is not excited and the proton is deviated and loses energy.
Nuclear elastic scattering occurs through nuclear forces. However, the dominant processes are electromagnetic interactions. In electromagnetic interactions, there is also an elastic component that comes from the interaction of the incident proton with the coulomb field of the nucleus. It is well described by the Rutherford cross-section.
So the question is: in ICRU 63 cross section tables for elastic cross sections, is the rutherford cross section included?Following
- Mushtaq Ahmad added an answer:Looking for guidance on the selection,use, calibration, and quality assurance of radionuclide calibrators used in nuclear medicine?"This American Association of Physicists in Medicine (AAPM) Report No. 181 is designed to provide guidance on the selection, use, calibration, and quality assurance of radionuclide calibrators for use in nuclear medicine for the quantification of the activity of known radionuclides.Quality assurance for radioactivity measurement in nuclear medicine. Technical reports series no. 454, international atomic energy agency, vienna, 2006 should fulfil the purpose. It can be downloaded from iaea publications website.Following
- Ken Tanaka added an answer:Where can I get equipment to measure subtle electric currents of the human body?I want to get it from India. I need to measure microamps and microvolts.ryodoraku device