SAM Question Set:
Session title: Monte Carlo for Photon Treatment Planning; CV/SP and other Modern
Algorithms; Monte Carlo for Electron Planning
AAPM Spring Meeting 2014
Indrin J. Chetty, Joanna Cygler and Moyed Miften
1. Which of the following regarding the condensed history technique is true?
(a) It is used for the single-scatter (analog) transport of photons.
(b) It is used for the single-scatter (analog) transport of electrons.
(c) It is based on the observation that the majority of electron interactions lead to very large
changes in the electron energy and/or direction.
(d) It is based on the observation that the majority of electron interactions lead to very small
changes in the electron energy and/or direction.
(e) It applies to neither photons nor electrons.
Answer: D
REF: M.J. Berger, "Monte Carlo calculations of the penetration and diffusion of fast charged
particles", in Methods in Computational Physics, Vol. 1, edited by S. Fernbach B. Alder, M.
Rothenberg (Academic Press, New York, 1963).
2. An MC simulation, run with 1 million (1 M) histories produces an uncertainty in average dose of
4%. If we want the uncertainty to be 1%, how many histories should be run (assuming all other
factors are equal)?
(a) 1 M
(b) 2 M
(c) 4 M
(d) 8 M
(e) 16 M
Answer: E
REF: I.J. Chetty, B. Curran, J. E. Cygler, et al., "Report of the AAPM Task Group No. 105: issues
associated with clinical implementation of Monte Carlo-based photon and electron external beam
treatment planning", Med Phys 34 (12), 4818-53 (2007).
3. Which of the following regarding dose-to-water (Dw) and dose-to-medium (Dm) in the MV energy
range is true?
(a)
(b)
(c)
(d)
(e)
Dw and Dm are equivalent for all tissues.
Dm is always higher than Dw for all tissues.
Dw and Dm differ by greater than 10% for soft bone material.
Dw and Dm differ by a few percent for lung tissue.
Dw and Dm differ by less than 10% for cortical bone material.
Answer: D
REF: J.V. Siebers, P.J. Keall, A.E. Nahum, R. Mohan, " Converting absorbed dose to medium to
absorbed dose to water for Monte Carlo based photon beam dose calculations", Phys Med Biol 45,
983–995 (2000).
4. In Superposition dose calculations with tissue inhomogeneites, the density scaling theorem does
account for
(a) Incident photons.
(b) Scattered photon transport.
(c) Primary electron transport.
(d) Electron contamination.
(e) Scattered photons from treatment head.
Answer: B
REF: 1. Papanikolaou et al, AAPM TG-85 report, “TISSUE INHOMOGENEITY CORRECTIONS FOR
MEGAVOLTAGE PHOTON BEAMS”, Med. Phys. Publishing, www.aapm.org (2004).
2. J. E. O’Connor, “The variation of scattered x-rays with density in an irradiated body,” Phys. Med.
Biol. 1:352–369 (1957).
5.
(a)
(b)
(c)
(d)
(e)
The surface dose from electron contamination in clinical photon beam therapy
Decreases with increasing field size.
Decreases with decreasing SSD.
Increases with increasing beam energy.
Decreases with wedges.
Constant for all treatment setups.
Answer: C
REF: 1. R. Sjögren and M. Karlson, “Electron contamination in clinical high energy photon
beams,” Med. Phys. 23, 1873–1881 (1996).
2. T. Zhu and J. Palta, “Electron contamination in 8 and 18 MV photon beams,” Med. Phys. 25, 1219 (1998).
6.
(a)
(b)
(c)
(d)
(e)
The accuracy of deterministic dose calculation algorithms, such as AcurosXB, depend on
Number of simulated particles.
Material properties.
Material to water scaled densities.
Discretization in space, energy, and angle.
Interaction cross section.
Answer: D
REF: 1. O. Vassiliev, T. Wareing, J. McGhee, et al, “Validation of a new grid-based Boltzmann
equation solver for dose calculation in radiotherapy with photon beams,” Phys. Med. Biol. 55, 581598, (2010).
2. T. Han, JK Mikell, M. Salehpour, et al, “Dosimetric comparison of Acuros XB deterministic
radiation transport method with Monte Carlo and model-based convolution methods in
heterogeneous media,” Med. Phys. 38, 2651-2664 (2011).
7. The Eclipse treatment planning system uses the following algorithm for Monte Carlo dose
calculation for electron beams:
(a)
XVMC
(b)
VMC++
(c)
Macro Monte Carlo
(d)
MCNP
Answer: C
REF: 1. H. Neuenschwander and E.J. Born “A Macro Monte Carlo method for electron beam dose
calculations”, Phys. Med. Biol. 37 107 – 125 (1992).
2. Neuenschwander H, Mackie T R and Reckwerdt P J “MMC - a high-performance Monte
Carlo code for electron beam treatment planning”, Phys. Med. Biol. 40 543–74 (1995).
3. I.J. Chetty, B. Curran, J. E. Cygler, et al., "Report of the AAPM Task Group No. 105: issues
associated with clinical implementation of Monte Carlo-based photon and electron external
beam treatment planning", Med Phys 34 (12), 4818-53 (2007).
8. For the same calculation volume, Monte Carlo calculation time is not affected by:
(a) number of histories
(b) desired statistical uncertainty
(c) voxel size for a given statistical uncertainty
(d) anatomical site
Answer: D
REF: 1. I.J. Chetty, B. Curran, J. E. Cygler, et al., "Report of the AAPM Task Group No. 105: issues
associated with clinical implementation of Monte Carlo-based photon and electron external
beam treatment planning", Med Phys 34 (12), 4818-53 (2007).
2. Cygler, J.E, and Ding, G.X., Electrons: Clinical Considerations and Applications “in Monte
Carlo Techniques in Radiation Therapy, ISBN-10: 1466507926, Taylor & Francis (CRC
Press INC ) Boca Raton, p 155-166, (2013)
9. Dose-to-medium and dose-to-water calculations for electron beams give the most different
results in
(a) fat
(b) lung
(c) hard bone
(d) muscle
Answer: C
REF: 1. G.X. Ding, et al, ” First macro Monte Carlo based commercial dose calculation module for
electron beam treatment planning—new issues for clinical consideration, Phys.Med. Biol. 51,
2781-2799, (2006)
2. I.J. Chetty, B. Curran, J. E. Cygler, et al., "Report of the AAPM Task Group No. 105:
issues associated with clinical implementation of Monte Carlo-based photon and electron
external beam treatment planning", Med Phys 34 (12), 4818-53 (2007)
10. Calculation of a typical dose distribution with clinically useful statistical uncertainties of 2% from
an 18 MeV electron beam by a commercial Monte Carlo treatment planning systems takes:
a. minutes
b. hours
c. days
d. weeks
Answer: A
REF: 1. I.J. Chetty, B. Curran, J. E. Cygler, et al., "Report of the AAPM Task Group No. 105: issues
associated with clinical implementation of Monte Carlo-based photon and electron external
beam treatment planning", Med Phys 34 (12), 4818-53 (2007).
2. J.E. Cygler, and G.X. Ding, “Electrons: Clinical Considerations and Applications “in Monte
Carlo Techniques in Radiation Therapy, ISBN-10: 1466507926, Taylor & Francis (CRC
Press INC) Boca Raton, p 155-166, (2013)