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T OTAL M ARROW I RRADIATION WITH H ELICAL T OMOTHERAPY ALONG THE ENTIRE P ATIENT ’ S A XIS : A P LANNING T ECHNIQUE TO M ERGE H ELICAL D OSE D ISTRIBUTIONS.

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Presentation on theme: "T OTAL M ARROW I RRADIATION WITH H ELICAL T OMOTHERAPY ALONG THE ENTIRE P ATIENT ’ S A XIS : A P LANNING T ECHNIQUE TO M ERGE H ELICAL D OSE D ISTRIBUTIONS."— Presentation transcript:

1 T OTAL M ARROW I RRADIATION WITH H ELICAL T OMOTHERAPY ALONG THE ENTIRE P ATIENT ’ S A XIS : A P LANNING T ECHNIQUE TO M ERGE H ELICAL D OSE D ISTRIBUTIONS PRODUCING U NIFORM D OSE IN THE J UNCTION R EGION M. Zeverino, S. Agostinelli, G. Taccini, F. Cavagnetto, S. Garelli, M. Gusinu, S. Vagge, S. Barra, R. Corvò National Institute for Cancer Research Genova- ITALY

2 O UTLINES TMI rationale and its potential over TBI treatments TMI treatment technical issues Patient selection and treatment approach The strategy to overcome limits and delivery a “Full TOMO” treatment Dose junction manipulation Treatment delivery QA M. Zeverino ASTRO 2010, San Diego

3 O UTLINES TMI rationale and its potential over TBI treatments TMI treatment technical issues Patient selection and treatment approach The strategy to overcome limits and delivery a “Full TOMO” treatment Dose junction manipulation Treatment delivery QA M. Zeverino ASTRO 2010, San Diego

4 TMI RATIONALE Leukemia relapse (LR) cause of failure after allogeneic stem cell trasplantation LR first cause of death for patient with advanced hematologic diseases Total Body Irradiation (TBI) dose escalation may reduce LR ratio but is associated with higher toxicity TMI has the potential to fulfill a dose escalation protocol and reduce the dose delivered to the organs at risks M. Zeverino ASTRO 2010, San Diego

5 D OSE V OLUME H ISTOGRAMS TBI VS TMI Typical TBI Dose Volume Histogram vs. TBITMI TMI – H&N TMI – Trunk Entire target STILL receives full dose Critical Organ receives LESS dose 9 entries in PubMed for TMI with HT: Hui SK et al. Feasibility study of helical tomotherapy for total body or total marrow irradiation. Med Phys Wong JY et al. Image-guided total-marrow irradiation using helical tomotherapy in patients with multiple myeloma and acute leukemia undergoing hematopoietic cell transplantation. IJROBP 2009 M. Zeverino ASTRO 2010, San Diego

6 O UTLINES TMI rationale and its potential over TBI treatments TMI treatment technical issues Patient selection and treatment approach The strategy to overcome limits and delivery a “Full TOMO” treatment Dose junction manipulation Treatment delivery QA M. Zeverino ASTRO 2010, San Diego

7 H OW TO DEAL WITH THE COUCH Y LIMIT ? Maximum couch travel ability of about 160 cm Treatment has to be split in two segments: Upper body TMI (UTMI) Lower body TMI (LTMI) Two different treatment approaches: To treat lower limbs with LINAC Extended SSD AP/PA technique 4 fixed fields (minimum) with at least 2 junctions in addition To treat lower limbs with TOMO FFS oriented Single junction A method for matching fields should be used M. Zeverino ASTRO 2010, San Diego

8 O UTLINES TMI rationale and its potential over TBI treatments TMI treatment technical issues Patient selection and treatment approach The strategy to overcome limits and delivery a “Full TOMO” treatment Dose junction manipulation Treatment delivery QA M. Zeverino ASTRO 2010, San Diego

9 P ATIENT SELECTION 15 patients (10 M, 5 F) from 07/2009 to 06/2010 Median age 35 y (range 18 y – 55 y) 10 patients with acute myeloid leukemia (AML) 5 in relapse status 5 in second remission 5 patients with acute lymphoid leukemia (ALL) 3 in relapse status 1 in second remission 1 in third remission M. Zeverino ASTRO 2010, San Diego

10 T REATMENT IST TBI + TMI Day 1Day 2 TBI 2 Gy (x2) Day 3Day 4 TBI 2 Gy (x2) TBI 2 Gy (x2) +++ TMI 2 Gy (x1) = TBI + TMI 14 Gy time

11 O UTLINES TMI rationale and its potential over TBI treatments TMI treatment technical issues Patient selection and treatment approach The strategy to overcome limits and delivery a “Full TOMO” treatment Dose junction manipulation Treatment delivery QA M. Zeverino ESTRO 2010, Barcelona

12 M ATCHING UTMI AND LTMI CT DATA SETS Upper body HFS oriented (from vertex to knees) Lower body FFS oriented (lower limbs including knees) Two CT scans – Whole body CT = lower body images are mirrored and properly matched with upper body images – Lower limbs CT = original images of lower body Two CT data sets M. Zeverino ESTRO 2010, Barcelona

13 LTMI planned on the lower limbs CT data set 2 Generation of a “twin” LTMI plan on the whole body CT data set 3 UTMI planned on the whole body CT data set with PTV going from vertex to knees 1 M ATCHING UTMI AND LTMI T REATMENT PLANNING H&N Trunk M. Zeverino ASTRO 2010, San Diego

14 LTMI easy to plan (rounded PTV, no OARs) LTMI plan features: Fixed number (50) of iterations allowed No changes of dose constraint during optimization Plan saved as protocol LTMI protocol was loaded on the whole body CT data set providing identity between structures tLTMI dose distribution was then calculated with the same fixed number of iterations DVH comparison to assess dose identity “Modified” γ index (1 % dose/ 1% volume) Plans are defined twins only if for >99% of points γ<1 Method Evaluation T WIN LTMI PLAN G ENERATION M. Zeverino ASTRO 2010, San Diego

15 F ULL H ELICAL TMI D OSE D ISTRIBUTION Finally UTMI and tLTMI plans can be summed on the same CT data set M. Zeverino ASTRO 2010, San Diego

16 O UTLINES TMI rationale and its potential over TBI treatments TMI treatment technical issues Patient selection and treatment approach The strategy to overcome limits and delivery a “Full TOMO” treatment Dose junction manipulation Treatment delivery QA M. Zeverino ASTRO 2010, San Diego

17 P RODUCING UNIFORM DOSE IN THE JUNCTION REGION A couple of transition volumes were used to improve dose uniformity in the abutment region for UTMI, LTMI and tLTMI plans by replacing the PTV segments PTV Stop replaced the last two segments for UTMI and the first two segments for LTMI PTV Trans replaced the two PTV segments preceding and following PTV Stop for UTMI and LTMI, respectively Optimization tips: PTV Stop is a RAR (zero dose requested) PTV Trans is a PTV (acting as a dose modulator) UTMI LTMI M. Zeverino ASTRO 2010, San Diego

18 J UNCTION DOSE EVALUATION Overall 3D dose distribution allows to evaluate calculated dose in the abutment region by means of: DVH Dose profile Our policy allows maximum dose inhomogeneity of ± 10% of prescribed dose. Otherwise LTMI is replanned acting on the dose constraints of both PTV Stop and PTV Trans M. Zeverino ASTRO 2010, San Diego

19 J UNCTION D OSE E VALUATION : T OMO VS L INAC TOMO LINAC Static fields dose junction region TMI dose junction region Regions of < 50 % of prescribed dose “Full TOMO” TMI features: Easy to deliver (quick setup, no patient shifts) More conformal (sparing of lower limbs vessels) M. Zeverino ASTRO 2010, San Diego

20 J UNCTION D OSE E VALUATION : T OMO VS L INAC TOMO LINAC Static fields dose junction region TMI dose junction region Regions of < 50 % of prescribed dose “Full TOMO” TMI features: Easy to deliver (quick setup, no patient shifts) More conformal (sparing of lower limbs vessels) M. Zeverino ASTRO 2010, San Diego

21 J UNCTION D OSE H OMOGENEITY : T OMO VS L INAC “Full TOMO” junction - 2% Dmin +8% Dmax M. Zeverino ASTRO 2010, San Diego

22 J UNCTION D OSE H OMOGENEITY : T OMO VS L INAC TOMO – Linac junction (NO GAP) - 14% Dmin +10% Dmax M. Zeverino ASTRO 2010, San Diego

23 J UNCTION D OSE H OMOGENEITY : T OMO VS L INAC TOMO – Linac junction (5 mm GAP) - 28% Dmin +3% Dmax M. Zeverino ASTRO 2010, San Diego

24 J UNCTION D OSE H OMOGENEITY : T OMO VS L INAC TOMO – Linac junction (5 mm OVERLAP) - 10% Dmin +34% Dmax M. Zeverino ASTRO 2010, San Diego

25 J UNCTION D OSE H OMOGENEITY : T OMO VS L INAC Junction Dmin (% of target dose) Dmax (% of target dose) Dose Inhomogeneity Full TOMO-2 %+8%10% TOMO – Linac (NO GAP) -14%+10%24% TOMO – Linac (5 mm GAP) -28%+3%31% TOMO – Linac (5 mm OVERLAP) -10%+34%44% 1.Inverse planning allows to obtain a more uniform dose distribution in the overlapping area 2.Target over- or under-dosage can be easily avoided 3.These are calculated values! 4.MV/kVCT registration process will affect dose uniformity in the overlapping area M. Zeverino ASTRO 2010, San Diego

26 J UNCTION D OSE H OMOGENEITY RESULTS Structure Mean D5 (cGy) Mean D95 (cGy) Dmean (cGy) HI PTV STOP 211 (201 – 218) 194 (189 – 201) 203 (196 – 210) 0.08 (0.05 – 0.13) PTV TRANS 212 (203 – 218) 187 (182 – 191) 200 (195 – 209) 0.13 (0.07 – 0.18) M. Zeverino ASTRO 2010, San Diego

27 O UTLINES TMI rationale and its potential over TBI treatments TMI treatment technical issues Patient selection and treatment approach The strategy to overcome limits and delivery a “Full TOMO” treatment Dose junction manipulation Treatment delivery QA M. Zeverino ASTRO 2010, San Diego

28 P LAN V ERIFICATION Dose point verification A1SL ion chamber & Cheese Phantom Target sites (i.e. bone marrow) 3% ∆D 2D dose verification GafChromic EBT/EBT2 Anthropomorphic phantom (head and chest) Lung equivalent tissue slabs γ (3%/3mm) M. Zeverino ASTRO 2010, San Diego

29 MV- K V REGISTRATION Results from the first 8 treated patients: Treatment setup (TS) = Observed Shift – Averaged Shift < 4 mm If 4 mm < TS < 6 mm, physician review and evaluation If TS > 6 mm, patient repositioning M. Zeverino ASTRO 2010, San Diego

30 I N VIVO DOSIMETRY In vivo dosimetry = assessing the accuracy of dose delivered in the field junction Gafchromic EBT2 Two stripes of approximately 10 cm long and 2 cm wide Placed on the skin according to the tattoo individuating the junction MOSFET 5 detectors placed on the skin 1 cm apart in the long direction according to the tattoo individuating the junction M. Zeverino ASTRO 2010, San Diego

31 S OME NUMBERS … Organ Median Dose reduction Standard Deviation Brain 45,5%4,6% Left Parotid 30,3%11,5% Right Parotid 29,6%10,3% Oral Mucosa 35,8%9,2% Larynx 56,4%4,9% Thyroid 43,3%9,6% Left Lung 44,3%2,7% Right Lung 47,5%4,3% Heart 45,1%2,1% Liver 47,0%4,1% Left Kidney 56,8%5,2% Right Kidney 60,5%2,1% Bowel 52,2%3,4% Male Gonads 80,7%12,3% PTV ValueMean (%)Range (%) D9593,391,9 - 94,2 D9095,794,1 - 96,7 D5102,9101, ,8 MFTime (min) UTMI (FW 5 & pitch 0.287) mean 1,4920,5 range 1,33- 1,8317,5 - 23,5 LTMI (FW 5 & pitch 0.287) mean 1,89,0 range 1,73 - 2,006,1 - 12,6 Legenda: D95 = dose received by 95 % of PTV volume D90 = dose received by 90 % of PTV volume D5 = dose received by 5 % of PTV volume Considerations: Organ sparing is achievable in terms of median dose reduction (i.e. dose delivered to 50% of organ volume) Small organs are penalized because of technical parameters of treatment Optimal PTV coverage and homogeneity Mean overall beam-on time < 30 min M. Zeverino ASTRO 2010, San Diego

32 R EMARKS AND CONCLUSIONS Full helical dose distribution is true as long as dose identity between LTMI and tLTMI exists Different solutions can be adopted for producing uniform dose in the junction through inverse planning In vivo dosimetry is mandatory to assess the dosimetric impact of the patient shifts on the junction Patient alignment process may cause over- or under-dosage to PTV. Split the treatment at the knees (= lack of bone marrow) On a total of 17 patients underwent TMI with HT (first patient July 2009), 11 were treated using the presented technique Treatments well tolerated (1 severe nausea episode) Short median FU (7 months). 12/17 patients are currently alive in CR M. Zeverino ASTRO 2010, San Diego


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