Multi-lumen Breast Brachytherapy in Patients With 5 mm or Less Balloon Surface-Skin Distance (BSD)...
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OR45 Presentation Time: 9:20 AM Monte Carlo Verification of a CT/MR Ovoid Model Used by a Grid-Based Boltzmann Solver in a Commercial Treatment Planning System Justin Mikell, BS, Firas Mourtada, PhD. University of Texas M.D. Anderson Cancer Center, Houston, TX. Purpose: A commercial TPS is available that accounts for patient boundaries, applicator materials, and tissue heterogeneities. A library of HDR brachytherapy applicators is included with the TPS. The purpose of this work is to verify the geometric and dosimetric properties for a CT/ MR compatible ovoid. Materials and Methods: A model of the ovoid was constructed using the MCNPX visual editor. The Monte Carlo (MC) model was based on CAD drawings (part #:AL07334001 v1.0) obtained from the vendor and independent measurement of the ovoid structure from CT images. The ovoid model was then placed in a 30 cm diameter sphere of water. Materials in the ovoid include Titanium tubing, an Acetal cap, and dry air. The commercial TPS BrachyVision v8.8 with grid-based Boltzmann solver (GBBS) Acuros v1.3.1 was used in this work. MC simulations for a single source centered in the ovoid were performed using MCNPX v2.6. A MC model of the VS2000 192 Ir HDR source was taken from our previously benchmarked MC model of this source. A source cable length of 1 mm was chosen to match the cable length modeled in the GBBS. The absorbed dose was approximated by collisional kerma. Cross sections were based on MCPLIB04. A rectangular mesh tally 150 2 1 with 2 mm isotropic voxels was setup for both the xz and xy plane. 6.5 10 8 histories were simulated (1s ! 0.5%). A virtual sphere of water was created in IDL and imported as a DICOM CT into the TPS. The right-side (diameter52.5 cm) FSD CT/MR compatible ovoid was placed at the center of the sphere. The dose grid was set to 2 mm isotropic for 150 3 voxels. The GBBS calculation was done using the CT option. Both MC and GBBS output were converted to Gy/U to allow comparisons. Geometric and dosimetric differences between the two models were reported. Results: The MC ovoid model included the Titanium set screw and an air pocket on the back of the Acetal cap where the Titanium ovoid tubing enters, while the library applicator model used for GBBS does not account for these structures. The hole for the screw and air pocket are visible in Fig 1a. Other dimensions of the ovoid were in good agreement. The ratio of GBBS/MC dose predictions are shown in Fig 1. The white dashed line (r53.25 cm) shows the physical location of the profile shown in Fig 1b. At q5180 the profile is 2 cm from the ovoid surface where disease would usually be present. Points 1 & 8 in Fig 1b: GBBS models Acetal whereas MC includes a Ti screw. Point 2 in Fig 1b: These are artificial differences below the display range due to the Ti ovoid arm. The MC conversion to Gy/U assumed all materials were water. Point 3 in Fig 1b: GBBS is less than MC due to Acetal in place of air. Point 4 in Fig 1b: Good agreement is found here because differences would be attributed to Ti tubing, not air. Point 5 in Fig 1b: The difference is due to the Acetal (GBBS) and air (MC). Agreement between GBBS and MC is within 2% for the clinical disease region from point 6 to 7 in Fig 1b. Conclusions: The GBBS ovoid model has simplified the actual ovoid geometry as it does not include the Titanium set screw or the air pocket in the Acetal cap. Differences due to these can exceed 4% relative to MC for a single source, but the dosimetric impact is found in areas that might not have clinical impact. However, the GBBS dose prediction around this ovoid model agrees within 2% of MC throughout the assumed disease location. BREAST Saturday April 16, 2011 11:00 AMe12:30 PM OR46 Presentation Time: 11:00 AM Multi-lumen Breast Brachytherapy in Patients With 5 mm or Less Balloon Surface-Skin Distance (BSD) Using the ConturaÔ Brachytherapy Catheter Daniel Reed, DO, Chris Biggs, MD, PhD, Terry Lee, MD, Kevin Rogers, MS, Frank Rafie, MS. Radiation Oncology, Arizona Center for Cancer Care, Peoria, AZ. Purpose: To evaluate the toxicity of multi-lumen breast brachytherapy in patients with 5 mm or less balloon surface-skin distance (BSD) treated with the ConturaÔ catheter. Materials and Methods: From September, 2008 through February, 2010 a total of 411 patients with early stage breast cancer (stages 0, I, IIA) were treated with multi-lumen HDR brachytherapy for definitive APBI using the ConturaÔ brachytherapy catheter. Of those patients 92 had a balloon surface-skin distance (BSD) of 5 mm or less, and had at least 6 months clinical followup. All patients were status post breast conserving surgery and met the ABS APBI guidelines for treatment eligibility. All patients received 34 Gy in ten fractions bid over 5 days, with the maximum skin dose restricted to 145% of the prescribed dose or less. Varian Brachyvision was used for 3-D conformal HDR treatment planning. CT image evaluation and DVH analyses was performed to investigate and compare the PTV_EVAL (cc) defined as a 1 cm expansion from the anterior surface of the device modified to 5 mm from the skin surface and not extending into the chest wall; BSD (mm) defined as the distance from the closest point on the balloon to the closet point on the skin surface; maximum skin dose (% and cGy); the volume of breast tissue (cc) receiving 150% and 200% of the prescription dose (V150, V200). Patient toxicity was evaluated at one week, one month and 6 months following brachytherapy including; skin reaction (RTOG Acute Radiation Morbidity Scoring Criteria), pigmentation, telangiectasia, pain, fat necrosis, symptomatic seroma. Results: The mean BSD was 3.7 mm, with a range of 1e5 mm. The mean maximum skin dose was 4508 cGy. The mean V150 was 21 cc and the V200 was 4.7 cc. The mean PTV_EVALV90 was 93.7 %. 49 % of patients had skin reaction, including at 1 week; 47 % Grade 1, 0% Grade 2 or 3. At 1 month; 31% Grade 1, 14% Grade 2 and 0% Grade 3. At 6 months; 2% Grade 1, 2% Grade 2 and 0% Grade 3. 6.5 % developed pigmentation changes (hypo or hyper). 5.4% developed telangiectasias, 9.7% reported pain. No patients had fat necrosis, and 15.2 % had a symptomatic seroma. 1 patient had wound dehiscence (maxium skin dose 4195 cGy, 123.4% of prescribed dose) at 1 week which was healed following closure at the 1 month followup. Patients that experienced toxicity had no difference in BSD (3.6 vs 3.9 mm) or in the maximum skin dose (132.6 % vs. 132.6 %) compared to those that did not experience toxicity. Conclusions: Breast brachytherapy in patients with 5 mm or less BSD (balloon surface-skin distance) has acceptable toxicity with proper planning using the ConturaÔ multi-lumen catheter. Careful attention to maximum skin dose must be used, and we recommend not exceeding 145 % (4930 cGy) of the prescribed dose. OR47 Presentation Time: 11:10 AM Interstitial High-Dose-Rate Brachytherapy for Early Stage Breast Cancer: Median 6-Year Followup of 273 Cases Using Multi-catheter Technique Rufus J. Mark, MD, Paul J. Anderson, MD, Robin S. Akins, MD, Murali Nair, PhD. Radiation Oncology, Joe Arrington Cancer Center, Lubbock, TX. Purpose: External Beam Radiation Therapy (EBRT) has been the standard of care for breast conservation radiation therapy. Recent data indicate that S36 Abstracts / Brachytherapy 10 (2011) S14eS101
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Transcript of Multi-lumen Breast Brachytherapy in Patients With 5 mm or Less Balloon Surface-Skin Distance (BSD)...
S36 Abstracts / Brachytherapy 10 (2011) S14eS101
OR45 Presentation Time: 9:20 AM
Monte Carlo Verification of a CT/MR Ovoid Model Used by
a Grid-Based Boltzmann Solver in a Commercial Treatment
Planning System
Justin Mikell, BS, Firas Mourtada, PhD. University of Texas M.D.
Anderson Cancer Center, Houston, TX.
Purpose: A commercial TPS is available that accounts for patientboundaries, applicator materials, and tissue heterogeneities. A library ofHDR brachytherapy applicators is included with the TPS. The purpose ofthis work is to verify the geometric and dosimetric properties for a CT/MR compatible ovoid.Materials and Methods: A model of the ovoid was constructed using theMCNPX visual editor. The Monte Carlo (MC) model was based on CADdrawings (part #:AL07334001 v1.0) obtained from the vendor andindependent measurement of the ovoid structure from CT images. Theovoid model was then placed in a 30 cm diameter sphere of water.Materials in the ovoid include Titanium tubing, an Acetal cap, and dry air.The commercial TPS BrachyVision v8.8 with grid-based Boltzmannsolver (GBBS) Acuros v1.3.1 was used in this work. MC simulations fora single source centered in the ovoid were performed using MCNPX v2.6.A MC model of the VS2000 192Ir HDR source was taken from ourpreviously benchmarked MC model of this source. A source cable lengthof 1 mm was chosen to match the cable length modeled in the GBBS. Theabsorbed dose was approximated by collisional kerma. Cross sectionswere based on MCPLIB04. A rectangular mesh tally 1502 � 1 with 2 mmisotropic voxels was setup for both the xz and xy plane. 6.5 � 108 historieswere simulated (1s!0.5%). A virtual sphere of water was created in IDLand imported as a DICOM CT into the TPS. The right-side (diameter52.5cm) FSD CT/MR compatible ovoid was placed at the center of the sphere.The dose grid was set to 2 mm isotropic for 1503 voxels. The GBBScalculation was done using the CT option. Both MC and GBBS outputwere converted to Gy/U to allow comparisons. Geometric and dosimetricdifferences between the two models were reported.Results: The MC ovoid model included the Titanium set screw and an airpocket on the back of the Acetal cap where the Titanium ovoid tubingenters, while the library applicator model used for GBBS does notaccount for these structures. The hole for the screw and air pocket arevisible in Fig 1a. Other dimensions of the ovoid were in good agreement.The ratio of GBBS/MC dose predictions are shown in Fig 1. The whitedashed line (r53.25 cm) shows the physical location of the profile shownin Fig 1b. At q5180� the profile is 2 cm from the ovoid surface wheredisease would usually be present. Points 1 & 8 in Fig 1b: GBBS modelsAcetal whereas MC includes a Ti screw. Point 2 in Fig 1b: These areartificial differences below the display range due to the Ti ovoid arm. TheMC conversion to Gy/U assumed all materials were water. Point 3 in Fig1b: GBBS is less than MC due to Acetal in place of air. Point 4 in Fig 1b:Good agreement is found here because differences would be attributed toTi tubing, not air. Point 5 in Fig 1b: The difference is due to the Acetal(GBBS) and air (MC). Agreement between GBBS and MC is within 2%for the clinical disease region from point 6 to 7 in Fig 1b.
Conclusions: The GBBS ovoid model has simplified the actual ovoidgeometry as it does not include the Titanium set screw or the air pocket inthe Acetal cap. Differences due to these can exceed� 4% relative to MC fora single source, but the dosimetric impact is found in areas that might nothave clinical impact. However, the GBBS dose prediction around this ovoidmodel agrees within 2% of MC throughout the assumed disease location.
BREAST
Saturday April 16, 2011
11:00 AMe12:30 PM
OR46 Presentation Time: 11:00 AM
Multi-lumen Breast Brachytherapy in Patients With 5 mm or Less
Balloon Surface-Skin Distance (BSD) Using the Contura�Brachytherapy Catheter
Daniel Reed, DO, Chris Biggs, MD, PhD, Terry Lee, MD, Kevin Rogers,
MS, Frank Rafie, MS. Radiation Oncology, Arizona Center for Cancer
Care, Peoria, AZ.
Purpose: To evaluate the toxicity of multi-lumen breast brachytherapy inpatients with 5 mm or less balloon surface-skin distance (BSD) treatedwith the Contura� catheter.Materials and Methods: From September, 2008 through February, 2010a total of 411 patients with early stage breast cancer (stages 0, I, IIA)were treated with multi-lumen HDR brachytherapy for definitive APBIusing the Contura� brachytherapy catheter. Of those patients 92 hada balloon surface-skin distance (BSD) of 5 mm or less, and had at least 6months clinical followup. All patients were status post breast conservingsurgery and met the ABS APBI guidelines for treatment eligibility. Allpatients received 34 Gy in ten fractions bid over 5 days, with themaximum skin dose restricted to 145% of the prescribed dose or less.Varian Brachyvision was used for 3-D conformal HDR treatmentplanning. CT image evaluation and DVH analyses was performed toinvestigate and compare the PTV_EVAL (cc) defined as a 1 cm expansionfrom the anterior surface of the device modified to 5 mm from the skinsurface and not extending into the chest wall; BSD (mm) defined as thedistance from the closest point on the balloon to the closet point on theskin surface; maximum skin dose (% and cGy); the volume of breasttissue (cc) receiving 150% and 200% of the prescription dose (V150,V200). Patient toxicity was evaluated at one week, one month and 6months following brachytherapy including; skin reaction (RTOG AcuteRadiation Morbidity Scoring Criteria), pigmentation, telangiectasia, pain,fat necrosis, symptomatic seroma.Results: The mean BSD was 3.7 mm, with a range of 1e5 mm. The meanmaximum skin dose was 4508 cGy. The mean V150 was 21 cc and the V200was 4.7 cc. The mean PTV_EVALV90 was 93.7 %. 49 % of patients hadskin reaction, including at 1 week; 47 % Grade 1, 0% Grade 2 or 3. At 1month; 31% Grade 1, 14% Grade 2 and 0% Grade 3. At 6 months; 2%Grade 1, 2% Grade 2 and 0% Grade 3. 6.5 % developed pigmentationchanges (hypo or hyper). 5.4% developed telangiectasias, 9.7% reportedpain. No patients had fat necrosis, and 15.2 % had a symptomatic seroma.1 patient had wound dehiscence (maxium skin dose 4195 cGy, 123.4% ofprescribed dose) at 1 week which was healed following closure at the 1month followup. Patients that experienced toxicity had no difference inBSD (3.6 vs 3.9 mm) or in the maximum skin dose (132.6 % vs. 132.6%) compared to those that did not experience toxicity.Conclusions: Breast brachytherapy in patients with 5 mm or less BSD(balloon surface-skin distance) has acceptable toxicity with properplanning using the Contura� multi-lumen catheter. Careful attention tomaximum skin dose must be used, and we recommend not exceeding 145% (4930 cGy) of the prescribed dose.
OR47 Presentation Time: 11:10 AM
Interstitial High-Dose-Rate Brachytherapy for Early Stage Breast
Cancer: Median 6-Year Followup of 273 Cases Using Multi-catheter
Technique
Rufus J. Mark, MD, Paul J. Anderson, MD, Robin S. Akins, MD, Murali
Nair, PhD. Radiation Oncology, Joe Arrington Cancer Center, Lubbock,
TX.
Purpose: External Beam Radiation Therapy (EBRT) has been the standardof care for breast conservation radiation therapy. Recent data indicate that
