Senin, 03 Agustus 2009

Ph.D. Abstract from Medical Physics 

Medical Physics is the scientific journal of the American Association of Physicists in Medicine
William R. Hendee, Editor
Departments of Radiology, Radiation Oncology, Biophysics, Community and Public Health, Medical College of Wisconsin
One Physics Ellipse College Park, Maryland 20740 

301-209-3352

Ph.D. Abstracts submitted to Medical Physics
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Dari Teknik Fisika UGM


Tujuan Program Sarjana Ekstensi Kerjasama Departemen Kesehatan adalah untuk meningkatkan derajat akademik dan keilmuan tenaga ahli instrumentasi medik dan teknologi fisika medik dari D-III menjadi S-1 Sarjana Tek-nik, sehingga memiliki kualitas pengetahuan, daya anali-sis, dan keterampilan yang matang dalam bidangnya.
  1. Untuk bidang Instrumentasi Medik:
    1. Perancangan peralatan instrumentasi medik;
    2. Pengembangan dan modifikasi peralatan medik yang telah tersedia;
    3. Pemeliharaan peralatan medik; dan
    4. Perbaikan (trouble shooting) peralatan medik.
  2. Untuk bidang Teknologi Fisika Medik:
    1. Perencanaan terapi radiasi (treatment planning);
    2. Penguasaan teknologi berbagai peralatan radiologi, radioterapi, dan perangkat penunjangnya;
    3. Asas-asas proteksi radiasi serta kesehatan dan keselamatan kerja; dan
    4. Penelitian dan pengembangan yang mendukung proses transfer teknologi fisika medik.
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Sabtu, 25 Juli 2009

Neuropharmacology (Arip Nurahman)

Neuropharmacology:

The study of drugs specifically employed to affect the nervous system Several drugs used for the treatment of extra-neural pathology may have an effect on the Nervous system

The effects of a drug can be considered at different levels:
•Molecular
•Cellular
•Behavioral

As the complexity of the system increases it becomes more difficult to predict the effects of a drug


Neuropharmacology is concerned with drug-induced changes in the functioning of cells in the nervous system.[1]. Within the discipline of neuropharmacology there are two branches, behavioral and molecular.

Neuropharmacology is that branch of neuroscience,which deals with the study of drug-induced changes in the functioning of cells in the nervous system.

Neuropharmacology is concerned with the study of the neurochemical interactions of neuropeptides, neurohormones, neuromodulators, enzymes, secondary messenger systems of the central nervous system, co-transporters, ion channels, receptor proteins, and more.

Neuropsychopharmacology, the branch of neuropharmacology interested in the biological basis of mind, is an especially active area of neuropharmacology research.

References

  1. ^ Meyer, J. S. and Quenzer, L. S. (2004). Psychopharmacology: Drugs, the Brain and Behavior. Sinauer Associates. ISBN 0-87-893534-7

See also



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Kamis, 18 Juni 2009

Tomotherapy (Arip Nurahman)

Tomotherapy describes a type of radiation therapy in which the radiation is delivered slice-by-slice, hence the use of the Greek prefix "tomo", which means "slice". This method of delivery radiation differs from other forms of external beam radiation therapy in which the entire tumor volume is irradiated at one time.

History

The first implementation of tomotherapy was the Corvus system developed by Nomos Corporation.[1] This was the first commercial system for planning and delivering intensity modulated radiation therapy (IMRT). The original system was designed solely for use in the brain and incorporated a rigid skull-based fixation system to prevent patient motion between the delivery of each slice of radiation. It was not long before many users eschewed the fixation system and applied the technique to tumors in many different parts of the body.

TomoTherapy, or Helical TomoTherapy, is a form of CT Guided IMRT or Intensity Modulated Radiation Therapy, which is a relatively new type of radiation therapy delivery system. The system was developed at the University of Wisconsin-Madison by professor Thomas Rockwell Mackie, Ph.D. and by freelance scientist Tomohiro Muta. A small megavoltage x-ray source was mounted in a similar fashion to a CT x-ray source, and the geometry provided the opportunity to provide CT images of the body in the treatment setup position. Although original plans were to include kilovoltage CT imaging, current models use megavoltage energies. With this combination, the unit was one of the first devices capable of providing modern image-guided radiation therapy (IGRT). The first patients were treated in 2002, at the University of Wisconsin under the guidance of Professor Minesh Mehta, M.D., under the auspices of an NIH-funded Program Project Grant.


External links

(Arip Nurahman)

Case Studies

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TomoTherapy® SBRT for non-small cell carcinoma

The TomoTherapy® Hi·Art® system delivers precise and effective stereotactic body radiation therapy for inoperable non-small cell lung carcinoma. Read more

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TomoTherapy® Clinical Flexibility

The TomoTherapy® Hi·Art® treatment system's sophisticated delivery method allows tremendous planning flexibility and lessens the need for planning trade-offs between target coverage and critical structure avoidance. Read more

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TomoTherapy® CTrue™ Adaptive Lung Case

This clinical case study demonstrates how the TomoTherapy® Hi·Art® treatment system's CTrue™ technology provides true dose guidance. Only TomoTherapy's daily 3D imaging reveals anatomical changes and their dosimetric impact at every fraction. Read more

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Treating squamous cell carcinoma

An 85-year-old man with squamous cell carcinoma was facing surgical removal of his upper left jaw, eye, and socket. TomoTherapy radiation treatment spared his vision and restored his quality of life. Read more

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TomoTherapy® Treatment Plan for Prostate Cancer

This simulated treatment plan demonstrates how the TomoTherapy® Hi·Art® treatment system can be used to focus the radiation dose on the target area of the prostate, while avoiding sensitive structures close by. Read more

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TomoTherapy® Treatment Plan for Multiple Metastases

This simulated treatment plan demonstrates how the TomoTherapy® Hi·Art® system can be used to treat multiple lesions without the need to change isocenters. Read more

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TomoTherapy® Treatment Plan for Scalp Carcinoma

This clinical case study demonstrates the TomoTherapy® Hi·Art® system's ability to treat a large, irregular lesion on the scalp in lieu of electron therapy. Read more

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TomoTherapy® SBRT for Lung Metastasis

This clinical case study demonstrates the TomoTherapy® Hi·Art® system's ability to deliver stereotactic body radiation therapy (SBRT), in which very high doses are delivered to a precisely-defined target volume in a single or a few treatment fractions. A high degree of conformality and targeting accuracy are of paramount importance. Read more

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TomoTherapy® Planned Adaptive™ Case

This clinical case study demonstrates the TomoTherapy® Hi·Art® treatment system's Planned Adaptive™ feature, which the clinician can use to evaluate how changes in anatomy and patient positioning impact the delivered dose. Read more


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Proton therapy (Arip Nurahman)

Proton therapy is a type of particle therapy which uses a beam of protons to irradiate diseased tissue, most often in the treatment of cancer.

Description

Proton therapy is a type of external beam radiotherapy. It works by aiming energetic ionizing particles (in this case, protons accelerated with a particle accelerator) onto the target tumor.[1][2] These particles damage the DNA of cells, ultimately causing their death. Cancerous cells, because of their high rate of division and their reduced ability to repair damaged DNA, are particularly vulnerable to attack on their DNA.

Due to their relatively large mass, protons do not scatter much in the tissue; the beam does not broaden much and stays focused on the tumor shape without much damage to surrounding tissue. All protons of a given energy have a certain range; no proton penetrates beyond that distance. Furthermore, the dose delivered to tissue is maximum just over the last few millimeters of the particle’s range; this maximum is called the Bragg peak.[3] This depth depends on the energy to which the particles were accelerated by the proton accelerator, which can be adjusted to the maximum rating of the accelerator (typically 70 to 250 MeV). It is therefore possible to focus the cell damage due to the proton beam at the very depth in the tissues where the tumor is situated; tissues situated before the Bragg peak receive only a reduced dose, and tissues situated after the peak receive none.[4]


Comparison with conventional x-ray radiotherapy

The dose from protons to tissue is maximum just over the last few millimeters of the particle’s range, quite different from electrons or x rays.
Irradiation of nasopharyngeal carcinoma by photon therapy (left) and proton therapy (right).

The figure on the left shows how beams of electrons, x rays or protons of different energies (expressed in MeV) penetrate human tissue. Electrons have a short range and are therefore only of interest close to the skin. Bremsstrahlung x rays penetrate more deeply, but the dose absorbed by the tissue then shows the typical exponential decay with increasing thickness. For protons, on the other hand, the dose increases with increasing thickness up to the Bragg peak that occurs near the end of the particle's range.

The treatment method is of interest because of its ability to accurately target and kill tumors, both near the surface and deep seated within the body, while minimizing damage to the surrounding tissue.[2] For this reason, it is favored for treating certain kinds of tumors where conventional X-ray radiotherapy would damage surrounding radio-sensitive tissues to an unacceptable level.[2][14] This is of particular importance in the case of pediatric patients where long term side effects such as residual occurrence of secondary tumors resulting from the overall radiation dose to the body are of great concern. Because of the lower dose to healthy tissue protons have less severe side-effects than conventional radiation therapy[15].

One area where proton therapy has had considerable success is in treating choroidal malignant melanomas, a type of eye cancer for which the only known treatment was enucleation (removal of the eye). Today, proton therapy is one of the techniques that are capable of treating this tumor without mutilation. Proton therapy is used on cancers that have not yet spread.[16]

Proton beam radiation therapy has also had remarkable success in the treatment of many other types of cancer, including brain and spinal tumors, as well as prostate cancer. Some researchers have suggested that antiprotons may be even more effective at killing cancer cells than their proton counterparts. So far, only initial research with cell cultures has been performed.[17]

Present Proton Therapy Centers


2005 image of the control panel of the synchrocyclotron at the Orsay proton therapy center

Proton therapy needs heavy equipment.[2] For instance, the Orsay proton therapy center, in France, (see figure) uses a synchrocyclotron weighing 900 tons in total. Such equipment was formerly only available within centers studying particle physics. In the case of the Orsay installation, the treatment machine was converted from particle research usage to medical usage.

Presently (end of 2008), there are proton therapy centers in Canada, China, England, France, Germany, Italy, Japan (5 centers), Korea, Russia, South Africa, Sweden, Switzerland, and USA (6 centers), altogether 26 installations, and over 60000 patients have been treated so far.[18]

Proton therapy for ocular tumors is a special case since this treatment requires only a comparably low energy (about 70 MeV). In the United Kingdom, it is currently only available at the Clatterbridge Centre for Oncology in Bebington on the Wirral, Merseyside. In China, the only proton therapy machine is located in the Wanjie Proton Therapy Center in Zibo, Shandong. In the USA, it is available in Sacramento, California at the University of California, Davis, the UC Davis Proton Facility which is operated exclusively by the UC San Francisco Department of Radiation Oncology. Since 2004, the Midwest Proton Radiotherapy Institute at Indiana University, and, in 2006, the University of Texas M. D. Anderson Cancer Center in Houston TX, and the University of Florida Proton Therapy Institutein Jacksonville, FL[19].

With over 5000 patients, the largest number of ocular tumors have been treated since 1984 at the Paul Scherrer Institute in Switzerland[13].

Im March, 2009, patient treatment has begun at the first commercial proton therapy center of Europe, the Rinecker Proton Therapy Center (RPTC)[20] in Munich, Germany.

Future proton centers

The Particle Therapy Co-Operative Group[13] keeps a list of planned therapy facilities which is updated continually. At present (March 2009), it lists 21 projects in various stages of progress, from all over the world (see below).

Future centers in the United States

There are several new centers in the advanced planning stage within the U. S., most requiring an investment of $120 million to $200 million.

Future centers in other countries

Future technical development

One hindrance to universal use of the proton in cancer treatment is the size and cost of the cyclotron or synchrotron equipment necessary. Several industrial teams are working on development of comparatively small cyclotron or synchrotron systems to deliver the proton therapy to patients[21]. When perfected, an even more rapid expansion of proton facilities should almost immediately occur. The St. Louis, Missouri facility, and the two Florida hospitals mentioned above are each planning to use one of these systems.

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A gamma knife (or Leksell gamma knife) Arip Nurahman




Gamma knife

NRC graphic of the Leksell Gamma Knife.

A gamma knife (or Leksell gamma knife) is a device used to treat brain tumors with a high dose of radiation therapy in one day. The device was invented by Lars Leksell, a Swedish neurosurgeon, in 1967 at the Karolinska Institute in Sweden.

The gamma knife device contains 201 cobalt-60 sources of approximately 30 curies (1.1 TBq) each, placed in a circular array in a heavily shielded assembly. The device aims gamma radiation through a target point in the patient's brain. The patient wears a specialized helmet that is surgically fixed to their skull so that the brain tumor remains stationary at target point of the gamma rays. An ablative dose of radiation is thereby sent through the tumor in one treatment session, while surrounding brain tissues are relatively spared.


See also

Gallery

Leksell Gamma Knife

Gamma Knife Perfexion



External links

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Brachytherapy (Arip Nurahman)

Brachytherapy (from the Greek brachy, meaning "short"), also known as sealed source radiotherapy or endocurietherapy, is a form of radiotherapy where a radioactive source is placed inside or next to the area requiring treatment. Brachytherapy is commonly used to treat localized prostate cancer[1][2], cervical cancer [1] and cancers of the head and neck.[3] Brachytherapy to prevent restenosis after stenting associated with coronary angioplasty has been proven safe and effective in clinicals trials, such the START and START 40/20 Trials.

External links


Types

Brachytherapy exists in numerous forms:

  • Mold brachytherapy. Superficial tumours can be treated using sealed sources placed close to the skin. Dosimetry is often performed with reference to the Manchester system; a rule-based approach designed to ensure that the dose to all parts of the target volume is within 10% of the prescription dose.
  • Strontium plaque, used for very superficial lesions less than 1 mm thick. The plaque is a hollow, thin silver casing that encloses a radioactive strontium-90 powdered salt. The beta (electron) particles produced from strontium's radioactive decay have a very shallow penetration. Typically the Sr-90 plaque is placed on the bed of a resected pterygium. A stat dose of around 10-12 Gy is delivered by timing the contact. As the electrons only penetrate a few mm of air, radiation protection issues are slightly less but very different from other radiation sources. Cleaning the plaques that are placed on the eye sclera is required but must be gentle because the silver casing is thin and easily damaged. Strontium belongs to the same chemical class as calcium, i.e., an alkaline earth metal, and so will co-locate in the bone if any strontium salt makes contact with the eye and is absorbed. Operators can prevent exposure to the beta rays by facing the applicator away from their bodies.
  • Interstitial brachytherapy. Here the sources are inserted into tissue. The first treatments of this kind used needles containing radium-226, arranged according to the Manchester system, but modern methods tend to use iridium-192 wire. Iridium wire can be arranged either using the Manchester or the Paris system; the latter was designed specifically to take advantage of the new nuclide. This also includes the removal of small lung cancers through wedge resection followed by placement of a brachymesh device, consisting of absorbable suture containing iodine-125 seeds to reduce the risk of recurrence. LDR prostate brachytherapy treats prostate cancer using iodine-125 or palladium-103 seeds . This latter treatment type differs from other interstitial treatments as the sources are left in the prostate permanently, rather than being removed after the intended treatment time. For details of the gamma emitters please see commonly used gamma emitting isotopes.
  • Intracavitary brachytherapy places the sources inside a pre-existing body cavity. The most common applications of this method are gynaecological in nature,[2] although it can also be performed on the nasopharynx.
  • Intravascular brachytherapy places a catheter inside the vasculature through which sources are sent and returned. The most common application of this method is the treatment of coronary in-stent restenosis, although the therapy has also been investigated for use in the treatment of peripheral vasculature stenoses and also considered for the treatment of atrial fibrillation. Although a few systems have been used successfully for intravascular brachytherapy, the only device currently available is the Novoste Beta-Cath System from Best Vascular, Inc. which uses beta-emitting sources of Sr/Y-90.
  • Electronic brachytherapy places a miniature low energy (<>

(Arip Nurahman)

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Cyberknife (Arip Nurahman)

The CyberKnife is a frameless robotic radiosurgery system invented by John R. Adler, a Stanford University Professor of Neurosurgery and Radiation Oncology. The two main elements of the CyberKnife are (1) the radiation produced from a small linear particle accelerator and (2) a robotic arm which allows the energy to be directed at any part of the body from any direction.

The CyberKnife system is a method of delivering radiotherapy, with the intention of targeting treatment more accurately than standard radiotherapy.[1] It is not widely available, although the number of centres offering the treatment around the world has grown in recent years to over 150, particularly centered in the USA, Japan, the Far East, India and Europe - the first UK CyberKnife was opened at The Harley Street Clinic [1] in February 2009.

The CyberKnife system is sold by the company Accuray, located in Sunnyvale, California. The CyberKnife system is used for treating benign tumors, malignant tumors and other medical conditions.[2][3]

The main features of the CyberKnife system, shown on a Fanuc robot



Robotic Mounting

The first is the fact that the radiation source is mounted on a precisely controlled industrial robot. The original CyberKnife used a Japanese Fanuc robot[4], however the more modern systems use a German KUKA KR 240.[5] Mounted on the Robot is a compact X-band linac that produces 6MV X-ray radiation. The linac is capable of delivering approximately 600 cGy of radiation each minute - a new 800 cGy / minute model was announced at ASTRO[6][7] 2007.

The radiation is collimated using fixed tungsten collimators (also referred to as “cones”) which produce circular radiation fields. At present the radiation field sizes are: 5, 7.5, 10, 12.5, 15, 20, 25, 30, 35, 40, 50 and 60 mm. ASTRO 2007 also saw the launch of the IRIS[7] variable-aperture collimator which uses two offset banks of six prismatic tungsten segments to form a blurred dodecagon field that is almost circular.

The IRIS replicates the fixed collimator sizes without the need for exchanging the fixed collimators. Mounting the radiation source on the robot allows complete freedom to position the radiation within a space about the patient. The robotic mounting allows very fast repositioning of the source, which enables the system to deliver radiation from many different directions in a feasibly short treatment time.

(Arip Nurahman)

External links

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Fisika dan Sepak Bola

Bucky Ball



In 1996, the Nobel Prize in Chemistry was awarded to three chemists for their discovery of a carbon molecule known as the "buckyball". The buckyball was named after the famed architect R.Buckminster Fuller whose unique structures called Geodesic Domes resembled soccer balls.

Mathematically, the buckball (and the soccer ball) is an Archimedean Solid called a "truncated icosahedron" - a polygon with 60 vertices and 32 faces, 12 of which are pentagons (5-sided objects) and 20 of which are hexagons (6-sided objects).

In 1999, buckyballs were found trapped inside a 4.6-billion-year-old meteorite that landed in Mexico three decades ago.
Recently, groups of buckballs have been used to fight cancer.


bernouilli



Consider a free kick taken by the great Brazilian World Cup player, Roberto Carlos. The ball is kicked the ball with high speed (70 mph) with a high spin (10 rev/sec).

At first, airflow past the rocketing ball has low-drag and high turbulance. However, about 10 m along its trajectory (just as it shoots wide of a wall of poised defenders) the ball slows enough for it to enter into a smooth-airflow (laminar) phase. This create an ever increasing degree of drag, which in turns brings the Bernouilli principle (and a hefty sideways force, or "lift") into play, dramatically curving the ball past the goalie into the net. GOAL!!


NIELS BOHR
(soccer player, physicist)


Niels Bohr


Niels Bohr was a renowned soccer player as a student but he is best known for the investigations of atomic structure and for work on radiation, which won him the 1922 Nobel Prize for physics.
Einstein expressed grave doubts about Bohr's interpretation of Quantum Theory. Bohr and Einstein spent many hours in deep discussion, but Bohr's view prevailed.
Bohr's other major contributions include his theoretical description of the periodic table of elements, his theory of the atomic nucleus being a compound structure, and his understanding of uranium fission.


HOW A PHYSICIST'S BRAIN WORKS













When a soccer ball is kicked, it is compressed. Assuming the ball is struck through its center, the amount of compression depends mostly on the pressure in the ball, initial velocity of the ball and the speed of the foot striking the ball with the mass of the leg and the mass of the ball being two additional variables but, these last two do not vary much.

What does a physicist ask him/herself?

  • How much compression takes place for a reasonable set of parameters?
  • How long in time is the ball incontact with the foot?
  • How far do the foot and ball travel while they are in contact?
  • What makes the ball spin? Is it striking the ball off center, or is it a movement of the foot away from a path through the ball's center during the period of contact, or both?
A ROBOTIC KICK

robo-leg



Members of the Field Robotics Center of Carnegie Mellon University have been involved in the design and building of an experimental soccer- ball kicking robot for a large sports-shoe company in order to perform unbiased and repeatable experiments to improve upon shoe and soccer-ball designs.
The leg was designed to approximate as close as possible the human kinematics and dynamics during the action of kicking a soccer ball. The purpose was to provide a consistent test-bed to remove the statistical variance associated with human testing and thus provide objective comparison criteria to judge and drive the design of new soccer-shoe prototypes.

HE DID THE MATH FOR YOU! Leonhard Euler


Leonhard Euler was one of top mathematicians of the eighteenth century and the greatest mathematician to come out of Switzerland. He made numerous contributions to almost every mathematics field and was the most prolific mathematics writer of all time. It was said that "Euler calculated without apparent effort, as men breathe...." He was dubbed "Analysis Incarnate" by his peers for his incredible ability.
Euler's polyhedral formula states that, for any simply connected polyhedron, the number of faces (F) minus the number of edges (E) plus the number of vertices (V) is always equal to 2, or stated mathematically: F - E + V2
For a soccer ball, which has the shape of a truncated icosahedron with 32 faces, 90 edges, and 60 vertices: 32 - 90 + 602

HOW HIGH WAS THAT GOAL KICK? goal kick

Suppose a goal kick is booted 36 feet into the air. When it finally comes down, it bounces up off the grass 12 feet. The formula for the coefficient of restitution (c) is coefficient of restitution, where h=the bounce height and H=the drop height.
The coefficient of restitution is a measure of the elasticity of the collision between the ball and the ground. Elasticity is a measure of how much bounce there is, or in other words, how much of the kinetic energy of the colliding objects before the collision remains as kinetic energy of the objects after the collision.
A perfectly elastic collision has a coefficient of restitution of 1. Example: two diamonds bouncing off each other. A perfectly plastic, or inelastic, collision has c=0. Example: two lumps of clay that don't bounce at all, but stick together. So the coefficient of restitution will always be between zero and one.
In the above example, c=0.58. If the ball had bounced up only 6 feet, the coefficient of restitution would have been 0.41
How do you think the height of the grass, moisture, and temperature might affect the coefficient of restitution?

sumber:

http://physics-of-sport.net/
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