Nuclear Physics - a Blessing to Mankind: Recent Advances in Radiation Therapies for Cancer Ruprecht...

Nuclear Physics - a Blessing to Nuclear Physics - a Blessing to Mankind:Mankind:

Recent Advances in Radiation Recent Advances in Radiation Therapies for CancerTherapies for Cancer

Ruprecht MachleidtRuprecht MachleidtDepartment of Physics, University of IdahoDepartment of Physics, University of Idaho

Renfrew Colloquium Sept. 10, 2013

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Radiation Therapies Renfrew Colloquium

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OutlineOutline

• Cancer factsCancer facts• How does radiation therapy work?How does radiation therapy work?• Passage of radiation through Passage of radiation through

mattermatter• Differences between electron, Differences between electron,

photon and proton/heavy ion photon and proton/heavy ion radiationsradiations

• The Bragg peak and its use in The Bragg peak and its use in cancer therapycancer therapy

• Proton/heavy ion facilitiesProton/heavy ion facilities• ConclusionsConclusions

Cancer factsCancer facts

• Cancer is the second largest killer.Cancer is the second largest killer.

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Cancer factsCancer facts

• Cancer is the second largest killer.Cancer is the second largest killer.• How to fight cancer: detect it (early!) How to fight cancer: detect it (early!)

and erase it.and erase it.• One way of detection: Imaging (CT, One way of detection: Imaging (CT,

MRI, PET, …)MRI, PET, …)• Erasing cancer: Erasing cancer:

Surgery, chemo (both are invasive), Surgery, chemo (both are invasive),

Radiation (non-invasive, involved in Radiation (non-invasive, involved in 50% of cancer treatments)50% of cancer treatments)

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How does radiation therapy How does radiation therapy work?work?

• Radiation causes ionization.Radiation causes ionization.

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How does radiation therapy How does radiation therapy work?work?

• Radiation causes ionization.Radiation causes ionization.• Most ionization occurs on water Most ionization occurs on water

(80% of our body)(80% of our body)• Generates free radicals, e.g., OH*, Generates free radicals, e.g., OH*,

chemically extremely reactive.chemically extremely reactive.• Radicals react with other Radicals react with other

molecules, disrupting and disabling molecules, disrupting and disabling them, e.g., DNA.them, e.g., DNA.

• Cell with damaged DNA can Cell with damaged DNA can continue to live, but continue to live, but dies at next dies at next cell divisioncell division..

Healthy cells Healthy cells versusversus cancer cancer cellscells

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Healthy cells Healthy cells versusversus cancer cancer cellscells

under radiationunder radiation

• Healthy cells are able to repair Healthy cells are able to repair themselves.themselves.

• Cancer cells less able, and they Cancer cells less able, and they divide more often (recall: cell-death divide more often (recall: cell-death occurs upon cell division).occurs upon cell division).

• Thus, more damage is done to Thus, more damage is done to cancer cells.cancer cells.

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““FractionationFractionation””

• Total dose: 80 Gray (Gy)Total dose: 80 Gray (Gy)• This is broken up into 40 portions: This is broken up into 40 portions:

2 Gy per portion2 Gy per portion• 5 portions per week (weekend free, 5 portions per week (weekend free,

healthy cells can recover)healthy cells can recover)• Total radiation treatment: 8 weeks.Total radiation treatment: 8 weeks.• Fractionation enhances the survival Fractionation enhances the survival

of the healthy cells.of the healthy cells.

Example:

Goal of all cancer Goal of all cancer therapiestherapies

• Do lethal damage to the cancer Do lethal damage to the cancer (tumor).(tumor).

• Do minimal damage to healthy Do minimal damage to healthy tissue.tissue.

• Not so easy!Not so easy!• What radiation is best suited to What radiation is best suited to

reach the above goal?reach the above goal?

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What radiations are there?And what are the differences?

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Passage of Passage of radiation radiation through through matter:matter: Energy Energy

depositiodeposition n

Photons

Heavy Ions

Bragg Peak

Electrons

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Differences in the energy Differences in the energy depositionsdepositions

• Electrons:Electrons: small depth, small depth, ““superficialsuperficial””. . The light electrons bounce off heavy The light electrons bounce off heavy atoms: chaotic zigzag path. The electrons atoms: chaotic zigzag path. The electrons are not getting anywhere.are not getting anywhere.

• Photons:Photons: Exponential fall-off, like light Exponential fall-off, like light passing through milky/foggy glass.passing through milky/foggy glass.

• Protons and heavy ions:Protons and heavy ions: They have They have a mass; so they stop after losing their a mass; so they stop after losing their kinetic energy. Shortly before stopping, kinetic energy. Shortly before stopping, they do maximum ionization: Bragg peak.they do maximum ionization: Bragg peak.

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Medical applications in Medical applications in cancer treatmentcancer treatment

• Electrons: Skin cancer (Electrons: Skin cancer (““superficialsuperficial””))• Photons (X-ray): deeper lying tumorsPhotons (X-ray): deeper lying tumors• Protons and heavy ions: deeper lying Protons and heavy ions: deeper lying

tumorstumors

What’s the difference between

photons and protons?

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PHOTONS

Tumor

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PHOTONS

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PROTONS

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PROTONS more energy

Deeper lying Tumor

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PHOTONS

PRO-TONS

“Bragg Peak”

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PHOTONS

PROTONS more energy

“Bragg Peak”

Reducing the disadvantage of photons: Reducing the disadvantage of photons: ““Multi-Multi-fieldfield””

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• Further refinements: Intensity Modulated Radiation Therapy (IMRT): Five or more fields with different intensities.

• But the same is done with protons and then multi-field is even more effective, because you start from a better beam: Intensity Modulated Proton Therapy (IMPT).

Shaping the proton beam for 3D Shaping the proton beam for 3D conformal irradiation of the tumorconformal irradiation of the tumor

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Comparison Protons - Photons Comparison Protons - Photons for a brain tumorfor a brain tumor

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Comparing different treatment protocols for prostate cancer

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Some HistorySome History1905 W. H. Bragg and R. Kleeman, University

of Adelaide, discover the “Bragg Peak” using alpha particles from radium; Phil. Mag. 10, 318 (1905).

1946 R. R. Wilson proposes medical use of protons; Radiology 47, 487 (1946).

1954 First human treated at Berkeley.

1961 Harvard starts proton therapy (9000 patients treated by 2003).

1988-90 First hospital-based proton accelerator (synchrotron) built at Loma Linda University Medical Center, S. California.

2012 16,000-th proton patient treated at Loma Linda; 39 proton centers world-wide; more than 96,000 patients treated world-wide.

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Loma Linda

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The Proton Center at Loma Linda

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The proton beam treatment room (gantry) from the patients view

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In contrast: a photon treatment “center”

The costThe cost

• Proton facilities are expensive, Proton facilities are expensive, but when run efficiently [16 but when run efficiently [16 hours per day (two shifts), 64 hours per day (two shifts), 64 patients per treatment room per patients per treatment room per day, 3 rooms: 192 patients per day, 3 rooms: 192 patients per day], the cost per patients gets day], the cost per patients gets within a factor of two to photon within a factor of two to photon (X-ray, (X-ray, ““conventionalconventional””) radiation ) radiation therapy.therapy.

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The cost: exampleThe cost: example• Proton therapy: ≈$60,000Proton therapy: ≈$60,000• Photon (X-ray, Photon (X-ray, ““conventionalconventional””): ):

≈$30,000≈$30,000• BUT:BUT: you have to add the follow-up you have to add the follow-up

cost. With large side effects, there are cost. With large side effects, there are large follow-up costs. $5,000 follow-up large follow-up costs. $5,000 follow-up costs per year (for a photon case with costs per year (for a photon case with severe side effects) generates costs of severe side effects) generates costs of $50,000 in 10 years, $100,000 in 20 $50,000 in 10 years, $100,000 in 20 years, …years, …

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Some useful linksSome useful links

• www.protons.com• www.proton-therapy.orgwww.proton-therapy.org• www.protonbob.comwww.protonbob.com

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Conclusions Conclusions

• Nuclear physics saves lives every day.Nuclear physics saves lives every day.• Radiation treatment using beams of heavy charged Radiation treatment using beams of heavy charged

particles (protons, ions) allows to focus on localized particles (protons, ions) allows to focus on localized tumors due to the Bragg peak, thus, dramatically tumors due to the Bragg peak, thus, dramatically reducing negative side effects.reducing negative side effects.

• It is the preferred method for the removal of tumors that It is the preferred method for the removal of tumors that are difficult to reach by surgery (scull base, back of the are difficult to reach by surgery (scull base, back of the eye) or where surgery has typically large side effects eye) or where surgery has typically large side effects (prostate cancer).(prostate cancer).

• Proton therapy has been used for 50 years and is well Proton therapy has been used for 50 years and is well tested with long-term (10y) follow-up studies. It is not tested with long-term (10y) follow-up studies. It is not experimental.experimental.

• Medicare and most (but not all!) health insurances pay Medicare and most (but not all!) health insurances pay nowadays for proton therapy.nowadays for proton therapy.

• However your doctor may have never heard about proton However your doctor may have never heard about proton therapy or thinks that it is something very weird and therapy or thinks that it is something very weird and untested.untested.

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