Evolution of Head and Neck Treatment Using Protons Mayank Amin, M.Sc,CMD
Facility Layout Gantry Room 3 Fixed Beams Room 4 HEBT Gantry Room 2 Gantry Room 1 Synchrotron Linac Treatment Planning Imaging Area Reception Waiting Room Treatment Rooms 1. Passive Scattering 2. Passive Scattering 3. Spot Beam Scanning 4. Passive Scattering a. Large Field 2 b. Eye Treatment
Is Proton an option for Head and Neck Cancers? What we are dealing with? How we deal with? Evolution of H & N Cancer Treatment from 3D-IMRT-Proton Therapy Why Protons? Treatment options Simulation Treatment devices Clinical Examples QOL after Proton Therapy Summery
What we are dealing with? Eye Paranasal Sinuses -BOS Maxillary Sinus Nasopharynx Oropharynx -BOT, Tonsil Oral Cavity Ipsilateral Treatment - Parotid Gland Larynx Thyroid Gland Unknown Primary
What we are dealing with? Involvement of lymph nodes from level I to V RP RP I A/B II III IV
How we deal with? Surgery Radiation Therapy Chemotherapy- Stage III-IV, Inoperable tumors, salvage therapy Combination
Evolution of H & N CA TX Conventional Nasopharynx 1990 2000
Benefits of IMRT 2000 2012 Courtesy of Matt Palmer
Intensity Modulated Radiation Therapy (IMRT) Parotid Gland
Disadvantages of IMRT 2000 2012 Rosenthal et al. IJROBP 2008
Why Protons for H & N Cancers? Protons are attractive to radiotherapy due to their physical dose distribution Proton beam has the ability to stop at a defined range and further conforms to the distal side of the target in three dimensions. Thus less normal tissue is being irradiated The RBE of proton is 10-15% more effective than X-Rays (RBE=1.1) Escalate dose to the tumor, increase tumor control Treatment of recurrence disease Reduce side effects, improve quality of life
A single photon beam, Higher entrance and exit dose. A single proton beam, Lower entrance dose and no exit dose
How we use PROTONS? Proton specific Simulation Passive scattering system Spot scanning system ( SFO and MFO) -IMPT
Proton Technique Selection Passive Scattered Protons (PSPT) vs. Scanning Pencil Beam (IMPT)? Tumor Depth Shallow- PSPT Tumor Shape Simple- PSPT Concave or Complex- IMPT Tumor Location Wrapping around critical structure- IMPT Simultaneous Integrated Boost IMPT
Passive Scattered Protons (PSPT) Distal Coverage- Compensator Tumor Coverage- Range Modulator Wheel (SOBP) Lateral Coverage- Brass Aperture Compensator Range Modulator Wheel Aperture
Passive Scattering - 3D planning Hardware RMW, 2 nd Scatter, aperture & compensator Proton stops but there is range uncertainty 3D planning difficult to conform complex target volumes no simultaneous boost
Conclusion Passive Scattering Treatment planning and delivery Inadequate compared to IMRT Patch-through fields results in higher uncertainties and dose inhomogeneties - Programmatic efforts should be directed toward single and multiple scanning beam delivery Simple and/or ipsilateral targets can be treated successfully
Active(Spot) Scanning Logistics - No hardware required Pencil beam (spot) Can treat entire head & neck target with one plan Can conform proximal dose to target Adaptive planning possible Simultaneous boost
The Pencil Beam Scanning Mode Goitein et al. Physics Today 2002
Depth Dose
Discrete Spot Scanning A target is divided into many layers A layer is divided into many spots Spots are irradiated one by one Range modulation Proton Beam Scanning Magnets E change Layer Target Spot
Spot Scanning Pedroni, PSI
SFO vs. MFO SFO Open Field for simpler volume Each field is optimized to deliver uniform dose to target Less sensitive to uncertainties Integrated boost is possible with both techniques MFO Patch Field for complex volume Multiple field required to cover target More sensitive to uncertainties Robustness of MFO is important QA is significantly more demanding
IMPT vs. IMXT Delivery IMPT Spot & Layer Delivery IMXT Beam MLC Delivery CP MU %Wt (IMPT) the weight of each spot is optimized using an inverse planning process. All the layers make up a 3D dose distribution. (IMXT) Segments are created for each beam with individual beam lets. The dose through each segment creates a 2D fluence. All beam fluences make the 3D dose dist.
Conclusions Proton plan optimization utilizes optimization techniques that are similar to photons Comparisons PSPT optimization similar to 3D-CRT IMPT optimization similar to IMRT Protons has the unique ability to treat with fewer beams and has lower integral dose Question? For some cases, if proton plan and photon plan are similar but the integral dose (Doses < 30 Gy) is significantly less with protons, then shouldn t the proton plan inherently be a better treatment plan for the patient?
Simulation Treatment position must be reproducible Must provide adequate level of patient comfort Patient immobilization devices must be proton-friendly Special considerations-presence of high Z material Current photon therapy immobilization devices can be used for proton therapy with little or no modification
Head & Neck table extension Head rest & holder Bite block Thermoplastic mask Treatment Devices
Head & Neck Cancers Complex target volumes and many normal tissues: Most target volumes have concave shape Different volumes requiring different doses Different dose limits for critical structures IMRT has been very successful We are our own competitors Proton Specific issues: Metal artifacts increase range uncertainty
Lt Maxilla
Base of Tongue
Lacrimal Gland
RT PAROTID GLAND
Unknown Primary
Unknown Primary Rt Parotid: 18 Gy Lt Parotid: 22 Gy
Unknown Primary Spinal Cord: 114 cgy Oral cavity: 22 Gy Brainstem: 40 cgy
Lt Tonsil
Lt Cheek
Rt Salivary Gland
Ipsilateral Neck IMRT Plan Proton Plan
Sinus Proton IMRT
Nasopharynx IMPT vs. IMRT
Nasopharynx IMPT vs. IMRT
Nasopharynx IMPT vs. IMRT
Acute Side Effects - Localized Skin Changes (erythema or darkening of the skin, dry & moist desquamation) Mucositis (oral, throat, esophageal sores) Xerostomia (dry mouth) Thick, ropey oral secretions Dysphagia (difficulty swallowing) Odynophagia (painful swallowing) Laryngitis (inflammation/edema of the larynx resulting in hoarseness)
BENEFITS of IMPT Less dose to Brain Stem Less dose to Spinal cord Less dose to Chochleas Less dose to Oral cavity Less dose to Salivary glands Less dose to normal brain Less dose to normal tissue and skin
QOL- Potential advantages Maintain taste, hearing, speech, Swallowing, Maintain Salivary function Decreased nausea and vomiting Concurrent chemotherapy Decrease oral pain and less narcotics Less mucositis Decrease feeding tubes Less constipation
Question? Are we delivering what we planned to? Why we are unable to deliver what we planned? How do we know what is being delivered? How can we improve? Yes, We do have answers Adaptive Planning is the answer
Question? Are we delivering what we planned May be Not - In house research in 2007 showed that even IMRT treatment delivered higher dose to parotid glands than planned* - Why we are unable to deliver what we planned? -Major cause of dose discrepancy is set up error and weight loss- common for IMRT & IMPT - Use of BB s for the patient alignment to treatment iso had higher dose to parotid glands than using C-2 vertebra for bony alignment * PAROTID GLAND DOSE IN INTENSITY-MODULATED RADIOTHERAPY FOR HEAD AND NECK CANCER: IS WHAT YOU PLAN WHAT YOU GET?- JENNIFER C. O DANIEL, PH.D.,* Int. J. Radiation Oncology Biol. Phys., Vol. 69, No. 4, pp. 1290 1296, 2007
SET UP ERROR and WEIGHT LOSS Verification Plan 8.4.11
SET UP ERROR and WEIGHT LOSS Verification Plan 8.4.11
Question? How do we know what is being delivered? -10 H & N patients were scanned weekly during treatment and verification plan were generated- 5 to 6 plans per patient - The original TP (Day 0) was compared to the summated VRFN TP (VRFN_Sum) on the original CT - Comparison between two is the estimation of dose difference between planned and delivered dose
Dose Distribution APRVD PLAN 7.1.11 vs. Verification Plan 8.4.11
Dose Distribution Verification Plan 8.17.11
Adaptive planning Adaptive planning means replaning of radiation treatment plan during the course of the treatment and implementing for rest of the treatment as needed The adaptive plans replaced each vrfn plan and adpt sum plan was compared with original plan -Dose to CTV1,CTV2,CTV3 and all critical structures were collected and compared statistically Our research found that based on amount of weight loss, 3 rd or 4 th week is the best time to use adaptive plan to treat for rest of the course
Immobilization Devices Original Mask
New Immobilization Devices
New Immobilization Devices
Custom made Immobilization Devices
Custom made Immobilization Devices
Immobilization Devices Old- blue head rest New uniform density mold
Answers How did we improve? - The new device has much less daily shift than previously used devices - Takes approximately 30 minutes at simulator for fabrication Weight loss - Dr Frank has started special nutrition counseling program for H & N patients - All patients knows the importance of not loosing the weight
Summary Proton IMPT has significant potential for improving QOL for H & N CA patients Both SFO and MFO plans are robust and does not need adaptive planning for Unilateral H & N Targets MFO treatment of bilateral disease with weight loss more than 10 Lb. warns for adaptive plan As we move forward, new devices and procedures are being developed and used Communication and team work between nursing, dietitian, dosimetry, therapy and physics is vital Never forget that treatment success relies on treatment set-up Yes, Proton is an option for H & N Cancers
Acknowledgement Dr Steven Frank Matt Palmer Shane Ikner Chuck Merrifield Our Dosimetry team Our Physics team Our Sim tech
Thank you Questions? mvamin@mdanderson.org