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Title: SU-F-T-442: Dose Distribution Comparison for Post-Laryngectomy Stoma Area Between Conventional AP and VMAT Plans with Or Without Bolus

Abstract

Purpose: To compare dose distributions of conventional AP vs. VMAT treatment plans with or without bolus around post-laryngectomy stoma. Methods: Radiation dose coverage for post-laryngectomy stoma was analyzed using a set of real-case CT-simulation images. After meticulous contouring of the catheter cuff, stoma lumen, peri-stoma skin and subclinical tumor bed at the larynx, the resulting dosimetry plans were analyzed with or without a 5 mm bolus placement. Wet gauze was used to minimize the effect of any air gap. Four plans were generated: AP superclavicular (SCV) plan with or without bolus, and VMAT plan with or without bolus. A dose of 60Gy in 30 fractions was prescribed at 3 cm depth for AP SCV plan, and to 95% of the PTV volume for VMAT plan. Results: For the conventional AP SCV plan, the peri-stoma skin dose is sensitive to bolus placement as well as air gap compensation by wetted gauze (V95% of 20.7%, 33.0% and 94.8% for no bolus, bolus without and with air gap compensation, respectively). For stoma lumen, the dose drops off rapidly in depth. The catheter cuff may have certain dose-buildup effect, but air gap around it and under the bolus placed can pose a more seriousmore » problem. The dose distributions of the two VMAT plans are moderately different for peri-stoma skin (V95% of 95.0% with bolus and air gap compensation, and 82.3% without bolus), but nearly identical for stoma lumen (V95% of 91.5% and 92.0%, respectively). VMAT allows beamlets with different angles of incidence that helped achieve such dose distribution around the stoma even without bolus placement. Conclusion: Overall, the dose coverage around the stoma in the VMAT plan is better than the conventional AP SCV plan. To achieve optimal dose distribution, it is still recommended to place physical bolus and reduce the air gaps.« less

Authors:
 [1]; ;  [2];  [3];  [4];  [2];  [1];  [3];  [1];  [3];  [3]
  1. University of California, Los Angeles, Los Angeles, CA (United States)
  2. VA Long Beach Healthcare System, Long Beach, CA (United States)
  3. (United States)
  4. VA Greater Los Angeles Healthcare System, Los Angeles, CA (United States)
Publication Date:
OSTI Identifier:
22649033
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; LARYNGECTOMY; RADIATION DOSE DISTRIBUTIONS; RADIOTHERAPY; SKIN

Citation Formats

Lee, B, Zhang, J, Cho-Lim, J, University of California, Irvine, Orange, CA, Leu, M, Inouye, W, Lorentz, W, VA Greater Los Angeles Healthcare System, Los Angeles, CA, Lee, S, VA Long Beach Healthcare System, Long Beach, CA, and VA Greater Los Angeles Healthcare System, Los Angeles, CA. SU-F-T-442: Dose Distribution Comparison for Post-Laryngectomy Stoma Area Between Conventional AP and VMAT Plans with Or Without Bolus. United States: N. p., 2016. Web. doi:10.1118/1.4956627.
Lee, B, Zhang, J, Cho-Lim, J, University of California, Irvine, Orange, CA, Leu, M, Inouye, W, Lorentz, W, VA Greater Los Angeles Healthcare System, Los Angeles, CA, Lee, S, VA Long Beach Healthcare System, Long Beach, CA, & VA Greater Los Angeles Healthcare System, Los Angeles, CA. SU-F-T-442: Dose Distribution Comparison for Post-Laryngectomy Stoma Area Between Conventional AP and VMAT Plans with Or Without Bolus. United States. doi:10.1118/1.4956627.
Lee, B, Zhang, J, Cho-Lim, J, University of California, Irvine, Orange, CA, Leu, M, Inouye, W, Lorentz, W, VA Greater Los Angeles Healthcare System, Los Angeles, CA, Lee, S, VA Long Beach Healthcare System, Long Beach, CA, and VA Greater Los Angeles Healthcare System, Los Angeles, CA. 2016. "SU-F-T-442: Dose Distribution Comparison for Post-Laryngectomy Stoma Area Between Conventional AP and VMAT Plans with Or Without Bolus". United States. doi:10.1118/1.4956627.
@article{osti_22649033,
title = {SU-F-T-442: Dose Distribution Comparison for Post-Laryngectomy Stoma Area Between Conventional AP and VMAT Plans with Or Without Bolus},
author = {Lee, B and Zhang, J and Cho-Lim, J and University of California, Irvine, Orange, CA and Leu, M and Inouye, W and Lorentz, W and VA Greater Los Angeles Healthcare System, Los Angeles, CA and Lee, S and VA Long Beach Healthcare System, Long Beach, CA and VA Greater Los Angeles Healthcare System, Los Angeles, CA},
abstractNote = {Purpose: To compare dose distributions of conventional AP vs. VMAT treatment plans with or without bolus around post-laryngectomy stoma. Methods: Radiation dose coverage for post-laryngectomy stoma was analyzed using a set of real-case CT-simulation images. After meticulous contouring of the catheter cuff, stoma lumen, peri-stoma skin and subclinical tumor bed at the larynx, the resulting dosimetry plans were analyzed with or without a 5 mm bolus placement. Wet gauze was used to minimize the effect of any air gap. Four plans were generated: AP superclavicular (SCV) plan with or without bolus, and VMAT plan with or without bolus. A dose of 60Gy in 30 fractions was prescribed at 3 cm depth for AP SCV plan, and to 95% of the PTV volume for VMAT plan. Results: For the conventional AP SCV plan, the peri-stoma skin dose is sensitive to bolus placement as well as air gap compensation by wetted gauze (V95% of 20.7%, 33.0% and 94.8% for no bolus, bolus without and with air gap compensation, respectively). For stoma lumen, the dose drops off rapidly in depth. The catheter cuff may have certain dose-buildup effect, but air gap around it and under the bolus placed can pose a more serious problem. The dose distributions of the two VMAT plans are moderately different for peri-stoma skin (V95% of 95.0% with bolus and air gap compensation, and 82.3% without bolus), but nearly identical for stoma lumen (V95% of 91.5% and 92.0%, respectively). VMAT allows beamlets with different angles of incidence that helped achieve such dose distribution around the stoma even without bolus placement. Conclusion: Overall, the dose coverage around the stoma in the VMAT plan is better than the conventional AP SCV plan. To achieve optimal dose distribution, it is still recommended to place physical bolus and reduce the air gaps.},
doi = {10.1118/1.4956627},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = 2016,
month = 6
}
  • Purpose: This study compared the rectal dose-volume consistency, equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) in prostate intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). Methods: For forty prostate IMRT and fifty VMAT patients treated using the same dose prescription (78 Gy/39 fraction) and dose-volume criteria in inverse planning optimization, the rectal EUD and NTCP were calculated for each patient. The rectal dose-volume consistency, showing the variability of dose-volume histogram (DVH) among patients, was defined and calculated based on the deviation between the mean and corresponding rectal DVH. Results: From both the prostate IMRT andmore » VMAT plans, the rectal EUD and NTCP were found decreasing with the rectal volume. The decrease rates for the IMRT plans (EUD = 0.47 × 10{sup −3} Gy cm{sup −3} and NTCP = 3.94 × 10{sup −2} % cm{sup −3}) were higher than those for the VMAT (EUD = 0.28 × 10{sup −3} Gy cm{sup −3} and NTCP = 2.61 × 10{sup −2} % cm{sup −3}). In addition, the dependences of the rectal EUD and NTCP on the dose-volume consistency were found very similar between the prostate IMRT and VMAT plans. This shows that both delivery techniques have similar variations of the rectal EUD and NTCP on the dose-volume consistency. Conclusion: Dependences of the dose-volume consistency on the rectal EUD and NTCP were compared between the prostate IMRT and VMAT plans. It is concluded that both rectal EUD and NTCP decreased with an increase of the rectal volume. The variation rates of the rectal EUD and NTCP on the rectal volume were higher for the IMRT plans than VMAT. However, variations of the rectal dose-volume consistency on the rectal EUD and NTCP were found not significant for both delivery techniques.« less
  • Purpose: The target volume for Whole Breast Irradiation (WBI) is dictated by location of tumor mass, breast tissue distribution, and involvement of lymph nodes. Dose coverage and Organs at Risk (OARs) sparing can be difficult to achieve in patients with unfavorable thoracic geometries. For these cases, inverse-planned and 3D-conformal prone treatments can be alternatives to traditional supine 3D-conformal plans. A dosimetric comparison can determine which of these techniques achieve optimal target coverage while sparing OARs. Methods: This study included simulation datasets for 8 patients, 5 of whom were simulated in both supine and prone positions. Positioning devices included breast boardsmore » and Vaclok bags for the supine position, and prone breast boards for the prone position. WBI 3-D conformal plans were created for patients simulated in both positions. Additional VMAT and IMRT WBI plans were made for all patients in the supine position. Results: Prone and supine 3D conformal plans had comparable PTV coverage. Prone 3D conformal plans received a significant 50% decrease to V20, V10, V5 and V30% for the ipsilateral lung in contrast to the supine plans. The heart also experienced a 10% decrease in maximum dose in the prone position, and V20, V10, V5 and V2 had significantly lower values than the supine plan. Supine IMRT and VMAT breast plans obtained comparable PTV coverage. The heart experienced a 10% decrease in maximum dose with inverse modulated plans when compared to the supine 3D conformal plan, while V20, V10, V5 and V2 showed higher values with inverse modulated plans than with supine 3D conformal plans. Conclusion: Prone 3D-conformal, and supine inverse planned treatments were generally superior in sparing OARs to supine plans with comparable PTV coverage. IMRT and VMAT plans offer sparing of OARs from high dose regions with an increase of irradiated volume in the low dose regions.« less
  • Cutaneous involvement by Kaposi's sarcoma (KS) is frequently diffuse, requiring large field irradiation. Selective tissue compensation techniques, accomplished with either a 1.5 cm bolus cast or water bath phantom, are compared. Dosimetric determinations were performed using 6 MVX with bone heterogeneity corrections. Application of 1.5 cm bolus effectively eliminated dose buildup and provided tissue compensation equivalent to water bath phantom technique. Treatment of other cutaneous malignancies, such as angiosarcoma, requiring higher total doses, should be accompanied by dosimetric evaluation, because cutaneous and midline dose inhomogeneity may result in a significant total dose differential over the target volume. Application of 1.5more » cm bolus improved accuracy in treatment positioning, eliminated concerns regarding infection control in AIDS-related KS, and provided dose homogeneity comparable to the more standard water bath phantom technique.« less
  • Purpose: We compare the efficacy and toxicity among the 3 major modalities available used to treat high-risk prostate cancer (HRCaP). Methods and Materials: From 1996 to 2012, 2557 HRCaP patients were treated: 734 received external beam radiation therapy (EBRT) with or without androgen deprivation therapy (ADT), 515 received low-dose-rate prostate brachytherapy (LDR) with or without ADT, and 1308 received radical prostatectomy (RP) with or without EBRT. Biochemical relapse-free survival (bRFS), clinical relapse-free survival (cRFS), and prostate cancer–specific mortality (PCSM) were assessed. Toxicity was assessed using the Common Terminology Criteria for Adverse Events, version 4.03. The log-rank test compared bRFS andmore » cRFS among the modalities, and Cox regression identified factors associated with bRFS and cRFS. Gray's test compared differences in late toxicity and PSCM among the modalities. Competing risk regression identified factors associated with PCSM. Results: The median follow-up time and age were 63.5 months and 65 years, respectively. The bRFS at 5 and 10 years, respectively, was 74% and 53% for EBRT, 74% and 52% for LDR, and 65% and 47% for RP (P=.0001). The cRFS at 5 and 10 years, respectively, was 85% and 73% for EBRT, 90% and 76% for LDR, and 89% and 75% for RP (P=.121). The PCSM at 5 and 10 years, respectively, was 5.3% and 11.2% for EBRT, 3.2% and 3.6% for LDR, and 2.8% and 6.8% for RP (P=.0004). The 10-year cumulative incidence of ≥grade 3 genitourinary toxicity was 8.1% for EBRT, 7.2% for LDR, and 16.4% for RP (P<.0001). The 10-year cumulative incidence of ≥grade 3 gastrointestinal toxicity was 4.6% for EBRT, 1.1% for LDR, and 1.0% for RP (P<.0001). Conclusion: HRCaP treated with EBRT, LDR, or RP yields efficacy showing better bRFS for LDR and EBRT relative to RP, equivalence for cRFS, and a PCSM advantage of LDR and RP over EBRT. The toxicity is lowest for LDR.« less