Análise da viabilidade de simulações com feixes de prótons de 100, 150, 200 e 250 MeV em alvos heterogêneos

In the recent years, the use of proton beams in radiotherapy has been an outstanding progress (SMITH, 2006). Up to now, computed tomography (CT) is a prerequisite for treatment planning in this kind of therapy because it provides the electron density distribution required for calculation of dose and the interval of doses. However, the use of CT images for proton treatment planning ignores fundamental differences in physical interaction processes between photons and protons and is, therefore, potentially inaccurate (SADROZINSKI, 2004). Proton CT (pCT) can in principle directly measure the density distribution needed in a patient for the dose distribution (SCHULTE, et al, 2004). One important problem that should be solved is the implementation of image reconstruction algorithms. In this sense, it is necessary to know how the presence of materials with different density and composition interfere in the energy deposition by ionization and coulomb excitation, during its trajectory. The study was conducted in two stages, was used in both the program SRIM (The Stopping and Range of Ions in Matter) to perform simulations of the interaction of proton beams with pencil beam type. In the first step we used the energies in the range of 100-250 MeV (ZIEGLER, 1999). The targets were set to 50 mm in length for the beam of 100 MeV, due to its interaction with the target, and short-range, and 70 mm for 150, 200 and 250 MeV The target was composed of liquid water and a layer of 6 mm cortical bone (ICRP). It were made 9 simulations varying the position of the heterogeneity of 5 mm. In the second step the energy of 250 MeV was taken out from the simulations, due to its greater energy and less interaction. The targets were diminished to 50 mm thick to standardize the simulations. The layer of bone was divided into two equal parts and both were put in the ends of the target... (Complete abstract click electronic access below)

Jerry Burns, UM 150-pound football team, 1948

[cropped from team photo]

University of Michigan 150-pound football team, 1948

Top Row: Dick Bodycomb, Gus Eaton, Bud Marshall, Tony Cybulski, Herb Taggart, Bob Kash, Burl Selden (ass't coach), Cliff Keen (coach).

Third Row: Gene Kiddon, Gordon Smith, Vaughn Lowther, Jim Coleman, Larry Shaw, James Johnson, Frank Whitehouse, Gene Freed, Everet Knapp, George Sipp, Stan Emerling.

Second Row: Bill Clark, James Richter, Jack Keller, Dave Bradbury Fred Koehn, Hyman Berman, Bill Parshall, Bill Connoly, M. Richard Fleishman, Frank Murphy, Jim Briskin, Leon Hinz.

Bottom Row: John Wilcox, Prentice Ryan, Ed Morey, Jim Costa, Barry Breakey, Jere Ogle, Jim Armelagos, Don O'Connell, Jerry Burns, John Picard, James Sakai, Ted Karmazin.

1947 150 Pound Football team, UM Football

Top Row (left to right): ? Nelson*, Aram Nahabedian*, Robert Hicks, George Strong, Bradshaw McKee, James Costa, John Olson, George Sipp, Gene Kiddon, Don O'Connell, Doug Wicks.

Third Row: Barry Breakey, Ross Marshall, Byron Parshall, George Bradley, Herbert Hurell, Leon Hinz, Eugene Freed, James Smith, William Clark, Meryl Englander, Edwin Morey, Edward Rosatti.

Second: Dave Bradbury, James Sakai, Russell Buster, Robert Rodgers, assistant coach George Allen, captain, Charlie Ketterer, head coach Cliff Keen, Dick Mandeville*,? Singer*, Frank Whitehouse,

Bottom Row: John Wilcox*, Larry Shaw, ? Schnider*,? Budick*, Stanley Emerling*

*Did not earn 150 pound letter

Letterwinners not pictured: John Allred