Secondary Neutrons in Proton and Ion Therapy - MELODI neutrons in proton... · Liliana Stolarczyk, Secondary Neutrons in Proton and Ion Therapy Peak around 0.6 MeV in the energy spectra

Secondary Neutrons

in Proton and Ion Therapy

L. Stolarczyk Institute of Nuclear Physics PAN, Poland

on behalf of

WG9 EURADOS

Liliana Stolarczyk, Secondary Neutrons in Proton and Ion Therapy

Acknowledgments

EURADOS Workig Group 9

Roger Harrison

Jean Marc Bordy

Carles Domingo

Francesco d’Errico

Jad Farah

Angela Di Fulvio

Željka Knežević

Saveta Miljanić

Pawel Olko


Controversy around secondary

radiation doses in radiotherapy

Source: Eric J. Hall, ‘Intensity-modulated radiation therapy, protons, and the risk of second cancers,’ Int. J. Rad. Onc. Biol. Phys. 65 (2006) 1-7.


Controversy around secondary

radiation doses in radiotherapy

Source: Eric J. Hall, ‘Intensity-modulated radiation therapy, protons, and the risk of second cancers,’ Int. J. Rad. Onc. Biol. Phys. 65 (2006) 1-7.

“Does it make any sense to spend over $100

million on a proton facility, with the aim

to reduce doses to normal tissues, and then

to bathe the patient with a total body dose

of neutrons (…)?”

Hall, Technol. in Ca. Res. Treat., 2007,6,31-34


Research projects and groups working

on secondary radiation

Allegro Group

Andante Group

Eurados WG9

IRSN

PSI

University of Texas MD Anderson Cancer Center

Massachusetts General Hospital

University of Wollongong

Many more …


Aim of presentation

Epidemiological

risk

assessment

Dosimetry

data

Probability

of

secondary

cancer


Aim of presentation

Epidemiological

risk

assessment

Dosimetry

data

Probability

of

secondary

cancer


Plan

Principles of conventional and hadron therapy

Secondary radiation in radiotherapy

Secondary radiation in conventional and conformal radiotherapy

Neutrons in proton radiotherapy

Passive beam delivery

Active scanning

Neutrons in carbon radiotherapy

Comparison of dosimetric studies on secondary radiation

Conclusion


Plan






Active scanning



Conclusion


Depth – dose distribution

in radiotherapy


Advantages

of hadron radiotherapy

Relatively low entrance

dose (plateau)

Maximum dose at depth

(Bragg peak)

Rapid distal dose

fall-off

Energy modulation

(Spread-Out Bragg

Peak)

Relative biological

effectiveness RBE of

protons and carbon ions


Techniques of beam modulation - passive


Techniques of beam modulation - active

Source: http://radmed.web.psi.ch/asm/gantry/scan/n_scan.html


Dose distribution

Clinical point of view

The dose to 90% of the cochlea was reduced from 101% with standard

photons, to 33% with IMRT, and to 2% with protons

The treatment of posterior fossa

Source: Greco C. Current Status of Radiotherapy With Proton and Light Ion Beams. American CANCER society April 1, 2007 / Volume 109 / Number 7


Plan






Active scanning



Conclusion



Generated in treatment nozzle

and patient body

X – rays: scattered X – rays,

secondary gamma radiation,

photoneutrons

Hadron therapy: neutrons,

charged particles, prompt

gamma radiation, characteristic

X rays, bremssthralung

radiation and residual radiation

from radioactivation

Low dose region


Interactions of neutrons in tissue

Thermal neutrons

Neutron capture by nitrogen 14N(n,p)14C, Etr = 0.62 MeV

Neutron capture by hydrogen 1H(n,γ)2H, Eγ= 2.2 MeV

Intermediate and fast neutrons

Elastic scattering

2)(

2

na

natr

MM

MMEE


Methods of neutron dosimetry

in secondary radiation field

Passive detectors

Track detectors

Bubble detectors

Activation foils

TLDs with 6Li and 7Li

Semiconductor detectors

Active detectors

Rem counters

TEPC

Recombination chambers

Bonner spheres

Monte Carlo simutations

Court

esy o

f A

. D

i F

ulv

io

Courtesy of T. Horwacik


Secondary doses in radiotherapy

Secondary dose

Target dose

Dose Equivalent

Ambient dose equivalent

µSv (µGy)

Gy

target secondary doses


Plan






Active scanning



Conclusion


EURADOS WG9 experiments

in conventional RT (scattered X-rays)

Passive dosimeters for X – rays measurements

outside the target volume

Source: Stolarczyk, PhD thesis, 2012

30 x 30 x 60 cm


Comparison of out-of-field X –rays doses for

prostate treatment

Source: Stolarczyk, PhD thesis, 2012


in conventional RT (scattered X-rays)

0.6 ÷ 1.1 mSv/Gy


Peak around 0.6 MeV

in the energy spectra

outside the target

Photoneutrons for

photon energy as low

as 6 MV

Neutron dose in IMRT

higher than in

conformal

radiotherapy

Neutron spectrum measured with RDNS

Source: Di Fulvio, A., Clinical simulations of prostate radiotherapy using

BOMAB-like phantoms: Results for neutrons, Radiat. Measurements, 2013,

available online


in conventional RT (neutrons)


Total neutron dose equivalent

for prostate treatments


in conventional RT

TOMO

IMRT

VMAT

Peak around 0.6 MeV in

the energy spectra outside

the target

Photoneutrons for photon

energy as low as 6 MV

Beryllium neutron separation

energy 1.66 MeV


higher than in conformal

radiotherapy



available online


Dose equivalent profiles for prostate treatment

measured by SDD and PADC


in conventional RT

Peak around 0.6 MeV

in the energy spectra

outside the target

Photoneutrons for

photon energy as low

as 6 MV


higher than in

conformal

radiotherapy



available online

3 ÷ 20 µSv/Gy


Plan





Active scanning



Conclusion


Main sources of out-of-field doses

in passive scattering proton RT

shifts the range of the

proton beam spreads out the Bragg peak

across the depth of the target volume

conforms the dose distribution to

the shape of the tumour

IFJ PAN proton facility


The decrease of neutron doses

with distance from the field edge

Source: Wroe, A., 2007 Out-of-field dose equivalents delivered by

proton therapy of prostate cancer. Med. Phys. 34, 3449–56

Dosimetric studies on neutron doses


0.3 mSv/Gy


The increase of neutron dose equivalent

with the energy of primary proton beam

Source: Mesoloras, G., et al., 2006. Neutron scattered dose

equivalent to a fetus from proton radiotherapy of the mother. Med.

Phys. 33, 2479–90




Source:L. Stolarczyk, PhD thesis, 2012

The increase of neutron dose with modulation

for low energy proton beams



Modulation depth m’


Source: Zheng, Y., 2007. Monte Carlo study of neutron dose

equivalent during passive scattering proton therapy. Phys. Med. Biol.

52, 4481-4496

The increase of neutron dose equivalent

with modulation for high energy proton beams



Modulation depth m’



The decrease of neutron ambient dose

equivalent with aperture size

for small fields



IFJ PAN Cyclotron Center




Phys. 33, 2479–90

The decrease of neutron dose equivalent

with aperture size for large fields



Source: http://www.nytimes.com/2007/12/26/business/26proton.html?_r=0




Phys. 33, 2479–90

Neutron dose equivalent variation

with air gap



Source: Paganetti H., et al., 2005. Proton Beam Radiotherapy- The

State of the Art


Beam collimation

Shielding around

treatment room

Patient shielding inside

therapy room

Using an optimized

pre-collimator/collimator


Minimization of the undesired dose to the

patient in passive scattering proton RT


Beam collimation

Shielding around

treatment room

Patient shielding inside

therapy room

Using an optimized

pre-collimator/collimator

hybrid plastic-metal collimator

+

patient-specific collimators

Source: Brenner, D.,2009. Reduction of the secondary neutron dose in

passively scattered proton radiotherapy, using an optimized pre-

collimator/collimator, Phys. Med. Biol. 54, 6065–6078

Minimization of the undesired dose to the

patient in passive scattering proton RT


Plan


Secondary radiation in conventional and conformal

radiotherapy


Passive beam delivery mode

Active scanning



Conclusion


Smaller irradiated high-dose volume

Ideally: no scattering devices in the treatment nozzle or patient apertures and compensators

Reality: possibility of use of range shifter and patient collimator

The majority of the secondary neutrons generated in the patient body


in scanning proton RT


Source: Schneider U., 2002 Secondary neutron dose during proton

therapy using spot scanning Int. J. Radiat. Oncol. Biol. Phys. 53244–51





0.015 mSv/Gy


Source: S. Dowdell, PhD thesis, 2011



Neutron doses equivalent at different lateral distences from the field edge


Source: S. Dowdell, PhD thesis, 2011



Neutron doses equivalent at different lateral distences from the field edge

0.013 mSv/Gy


Source: R. Kaderka, PhD thesis, 2011



Fluence of secondary thermal neutrons

measured with TLDs




TL signal for the TLD 600

in all irradiation techniques



Plan



radiotherapy



Active scanning



Conclusion


Sharper dose fall-off than protons close to the target

The dose far out-of-field of carbon ions higher than for protons

Increasing peripheral dose with increasing incident energy

Increasing out-of-field dose with the field size (one order of magnitude for a 300 MeV/u carbon beam with field sizes of 5x5 and 10x10cm2)



in carbon RT



in carbon RT

TL signal for the TLD 600

in all irradiation techniques



Source: Yonai, S., Matsufuji, N., Kanai, T., et. al., 2008. Measurement

of neutron ambient dose equivalent in passive carbon-ion and proton

radiotherapies. Med. Phys. 35, 4782 - 4792


in carbon RT



0.6 ÷ 0.95 mSv/Gy


Plan



radiotherapy



Active scanning


Comparison of dosimetric studies on secondary

radiation

Conclusion


Comparison of dosimetric studies

on secondary radiation (prostate treatment)

Treatment

technique

Dose equivalent

per target dose [mSv/Gy]

Passive proton RT 0.3 Wroe, 2008

Scanning proton RT 0.015 Schneider, 2002

Passive carbon RT 0.60 ÷ 0.95 Yonai, 2008

Scanning carbon RT 0.06 ÷ 0.08 Yonai, 2013

CRT 18 MV 1.7 Kry, 2005

IMRT (6 MV ÷ 18 MV)

0.6 ÷ 8.1

Kry, 2005

Miljanic, 2012

Di Fulvio, 2012

TOMO 6MV 0.9 Miljanic, 2012

Di Fulvio, 2012

VMAT 6 MV 0.7 Miljanic, 2012

Di Fulvio, 2012


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Treatment technique Effective dose [mSv]

Passive proton RT 187 Newhauser, 2009

Passive proton RT

(eye treatment) 0.2 Stolarczyk, 2011

Scanning proton RT 89 Newhauser, 2009

Scanning carbon RT 195 Schardt, 2006

CRT 18 MV 230 Kry, 2005

IMRT (6 MV ÷ 18 MV) 260 ÷ 630 Kry, 2005






Treatment technique Effective dose [mSv]

Passive proton RT 187 Newhauser, 2009

Passive proton RT

(eye treatment) 0.2 Stolarczyk, 2011

Scanning proton RT 89 Newhauser, 2009

Scanning carbon RT 195 Schardt, 2006

CRT 18 MV 230 Kry, 2005

IMRT (6 MV ÷ 18 MV) 260 ÷ 630 Kry, 2005




Conclusions

‘Does it make any sense to spend over $100 million

on a proton facility, with the aim to reduce doses to

normal tissues, and then to bathe the patient with a

total body dose of neutrons (…)?’

Hall, Technol. in Ca. Res. Treat., 2007,6,31-34

‘While we agree that proton therapy represents

a major advance, we differ with Hall’s other key

statements and inferences’

Newhauser, Phys. Med. Biol., 2009,54,2277–2291


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Secondary Neutrons in Proton and Ion Therapy - MELODI neutrons in proton... · Liliana Stolarczyk, Secondary Neutrons in Proton and Ion Therapy Peak around 0.6 MeV in the energy spectra