Institute of Nuclear Engineering and Science National Tsing Hua University Institute of Nuclear Engineering and Science National Tsing Hua University BNCT Treatment Planning for Superficial and Deep-Seated Tumors : Experience from Clinical Trial of Recurrent Head and Neck Cancer at THOR C.T. Chang a , L.Y. Yeh a , Y-W H. liu a , L.W. Wang b a Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan, ROC b Department of Oncology Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC June, 2014
Transcript
Institute of Nuclear Engineering and Science National Tsing Hua University
Institute of Nuclear Engineering and Science
National Tsing Hua University
BNCT Treatment Planning for Superficial and Deep-Seated Tumors : Experience from Clinical Trial of RecurrentHead and Neck Cancer at THOR
C.T. Chang a, L.Y. Yeh a, Y-W H. liu a, L.W. Wang b
a Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan, ROC
b Department of Oncology Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
June, 2014
Institute of Nuclear Engineering and Science National Tsing Hua University
Outline
• Purpose
• Material & Method － Calculation tools － Calculation assumptions
• Case discussion － Treatment plannings for different tumor locations ◎ Patient 17 & Patient 16
• Conclusion
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Purpose
• Oral cancer is the fifth of the top ten cancers announced in 2013 by Department of Health in Taiwan
• Currently, there is no effective treatment for recurrence head-and-neck cancer
• Under the collaboration between National Tsing Hua University and Taipei Veterans General Hospital, clinical trial of recurrent head-and-neck cancer using BNCT at Tsing Hua open-pool reactor(THOR) started on August 11, 2010
• Up to January of 2014, 17 patients were treated• This study shows the selection of treatment setup based on
experience on patients with superficial and deep-seated tumors
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Material & Method
Calculation tools•Treatment Planning System THORplan•MCNP 5Boron drug : BPA
Treatment planning assumptions•Reactor power = 1.2MW•Boron-10 in blood = 25ppm•Target tumor dose ： GTV D80 = 20Gy(W)•RBE = 3.2 for neutron = 1 for gamma ray
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• CBE = 3.8 for tumor = 4.9 for mucosa = 2.5 for skin = 1.3 for other normal tissues
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• Patient 17 (1st irradiation)• Tumor volume : 73 cc• The patient is in sitting position during
irradiation• Irradiated at 45 degrees (right and front)• Tumor location (measured from the direction of
irradiation)- tumor center to skin = 2.5 cm- deepest distance to skin = 5.5 cm
Treatment Planning for Superficial tumor
45 〫
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Treatment Planning for Superficial tumor
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• Two conditions (1) Using patient collimator 16-10-1 cm (2) No collimator (direct irradiation)
• Source-to-tumor center distance = 20.5 cm
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Flux(cm-2-s-1)
Flux comparison for superficial tumor treatment
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Flux(cm-2-s-1)
axis (cm)
Using collimator causes fluxes to be higher inside the patient collimator, up to 4.5 cm depth
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Patient 17-1 Direct Irradiation Patient Collimator
• Using collimator : gives higher thermal n fluxes for tissues inside the irradiation field ( +18% for GTV); gives lower thermal n fluxes for tissues outside the irradiation field (-46%, eyeball & brain) . Thermal n flux at mucosa remains about the same
Flux Comparison for Superficial tumor treatment
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(↑ 18%)
(↑ 15%)
(↑ 1%)
(↓ 46%)
(↓ 48%)
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Dose Rate Comparison for Superficial Tumor TreatmentPatient
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Treatment Planning for Patient 17
• Target: GTV D80 = 27 Gy(W)• Boron concentration in blood =25ppm• Reactor power =1.2 MW• Irradiation time = 38.4 minutes
Max. Dose Gy(W)
Dose Limit Gy(W)
Skin 9.81 11
Mucosa 17.77 10
Rt eyeball 2.80 10
Mucosa over dose limit < 10.6 cc
GTV Mean Max. Min.
Gy(W) 37.9 62.1 12.9
• In order to limit the volume of mucosa over 10 Gy(W) less than 10 cc, GTV D80 was set to 27Gy(W) during treatment planning
• The boron concentration in blood was assumed to be 25ppm
• For reactor power of 1.2 MW, the estimated irradiation time was 38 minutes
• Except for mucosa, dose of normal tissues were expected to be within the dose limits
• Volume of mucosa over 10 Gy is < 10 cc
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Final Treatment of Patient 17
• GTV D80 = 26.5 Gy (W) Reactor power = 1.62 MW Boron concentration in blood = 30ppm Irradiation time = 23.4 minutes
Max. Dose Gy(W)
Skin 9.09
Mucosa 17.11
Rt eyeball 2.53
Mucosa over dose limit < 9.5 cc
GTV Mean Max. Min.
Gy(W) 37.3 61.3 12.6
The boron concentration of patient was measured to be 30 ppm.
The treatment was done using reactor power =1.6 MW.
The irradiation time is 23 Minutes.
The GTV D80 is 26.5 Gy (W), very closed to the prescribed dose 27 Gy (W).
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DVH for Patient 17
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• Patient 16 (1st irradiation)
• Tumor volume : 8.2 cc
• Irradiated from left-hand side
• Tumor location
(measured from the direction of irradiation)
- tumor center to skin = 6.5 cm
- deepest distance to skin = 7.7 cm
Treatment Planning for Deep-seated tumor
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• Consider three conditions-- I. Direct irradiation -- II. Patient collimator 10 (long)-10(exit diameter)-1.5 cm (thickness)-- III. Lithium pad 2.5cm thick natural Li2CO3 (size 40*40 cm) + 0.5cm thick enriched Li2CO3 (size 5*5 cm)
• Source to tumor center distance =19 cm
• Source to skin distance = 12.5 cm
Treatment Planning for Deep-seated tumor
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Flux comparison for Deep-seated tumor along the beam direction
Axis (cm)
Flux(cm-2-s-1)For deep-seated tumors, the situation is different.When using collimator, the thermal neutron flux at GTV decrease.
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Patient 16-1 Condition I. Direct irradiation Condition II. Patient Collimator
Flux (cm-2 s-1) Flux (cm-2 s-1)Thermal Epi. Fast Photon Thermal Epi. Fast Photon
• When using collimator, the thermal neutron flux at GTV-D80 decreases by 8%.• Thermal neutron flux of most of the normal tissues change only 1~2%
Flux Comparison for Deep-seated tumor
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• When using collimator, the dose rate at GTV-D80 is lower by 6%, results in longer irrad. time• Dose rates of normal tissues either increases or decreases only slightly.• Therefore, max dose of most of the normal tissues increase. • For deep-seated tumors, using collimator has no benefits
Dose rate Comparison for Deep-seated tumorPatient
16-1Condition I. Direct irradiation(Irradiation time = 35.02 min)
Condition II. Patient Collimator(Irradiation time = 37.34 min)
• The dose rate reduction at GTV-D80 is 29%, the irradiation time is longer.• The dose rate reduction at skin is 32%, therefore the maximum dose of skin is
lower.• Using lithium pad has protection effect for normal tissues
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Final Treatment of Patient 16
• GTV D80 = 19 Gy(W) Reactor power = 1.8 MW Boron concentration in blood =21ppm Irradiation time = 35 minutes
Max. Dose Gy(W)
Skin 14.75
Mucosa 17.11
Lt eyelens 4.81
Skin over dose limit < 2.8 ccMucosa over dose limit < 24 cc
GTV Mean Max. Min.
Gy(W) 22.6 33.2 15.6
Mucosa max.
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Conclusions
• The preferred patient setups are different for tumors at different depth
• For superficial tumors, using patient collimator is better than direct irradiation
• On the other hand, for deep-seated tumors, direct irradiation or attaching lithium pads at beam exit are better choices
• Tumor response of Patient 17 (superficial tumor) is PR, of Patient 16 (deep-seated tumor) is CR
• Minimum dose of GTV of patient 16 is 15.6 Gy (W), higher then patient 17 (12.6 Gy (W)).
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References• H.S. Li, Y-W H. Liu, C.Y. Lee, T.Y Lin, F.Y. Hsu, “Verification of the accuracy
of BNCT treatment planning system THORplan”, Appl. Radiat. Isot. 67 (2009), S122–S125.
• T.Y Lin, Y-W H. Liu, “Development and verification of THORplan—A BNCT treatment planning system for THOR”, Appl. Radiat. Isot. 69 (2011) 1878–1881.
• H.T. Yu, Y-W. H. Liu, T.Y. Lin, L.W. Wang, “BNCT treatment planning of recurrent head-and-neck cancer using THORplan”, Appl. Radiat. Isot. 69 (2011) 1907–1910.
• Ling-Wei Wang, Yi-Wei Chen, Ching-Yin Ho, Yen-Wan Hsueh Liu, Fong-In Chou, Yuan-Hao Liu, Hong-Ming Liu, Jinn-Jer Peir, Shiang-Huei Jiang, Chi-Wei Chang, Ching-Sheng Liu, Shyh-Jen Wang, Pen-Yuan Chu, Sang-Hue Yen, Fractionated BNCT for locally recurrent head and neck cancer: Experience from a phase I/II clinical trial at Tsing Hua Open-Pool Reactor, Appl. Radiat. Isot. (in press)
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Thanks for your attention
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Patient 16-1 Condition I. Direct irradiation
Condition III. Natural lithium pad + Enriched lithium pad
