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Comparative analysis of thermoplastic masks versus vacuum cushions in stereotactic body radiotherapy.

Navarro-Martin A, Cacicedo J, Leaman O, Sancho I, García E, Navarro V, Guedea F - Radiat Oncol (2015)

Bottom Line: TMP resulted in significantly smaller shifts vs.We found that thermoplastic masks offers better reproducibility with significantly less interfractional set up displacement than vacuum cushions.Moreover, radiotherapy technologists rated the TMP system higher.

View Article: PubMed Central - PubMed

Affiliation: Radiation Oncology Department, Hospital Duran i Reynals (ICO) Avda. Gran Via de L'Hospitalet, 199-203 08908 Hospitalet de Llobregat, Barcelona, Spain. anavarro@iconcologia.net.

ABSTRACT

Background: To compare thermoplastic masks (TMP) and vacuum cushion system (VCS) to assess differences in interfraction set up accuracy in patients treated with stereotactic radiotherapy (SBRT) for oligometastatic lung cancer. Secondarily, to survey radiotherapy technologists to assess their satisfaction with the two systems.

Methods: Retrospective study of patients treated with lung SBRT between 2008 to 2012 at our institution. Immobilization was performed for 73 treatment sessions (VCS = 40; TMP = 33). A total of 246 cone-beams were analysed. Patients considered ineligible for surgery with a life expectancy ≥6 months and performance status > 1 were included. Target lesion location was verified by cone beam computed tomography (CBCT) prior to each session, with displacements assessed by CBCT simulation prior to each treatment session. Couch shifts were registered prospectively in vertical, longitudinal, and latero-lateral directions to obtain Kernel coordinates (3D representation). Technologists were surveyed to assess their satisfaction with indexing, positioning, and learning curve of the two systems. Setup displacements were obtained in all patients for each treatment plan and for each session. To assess differences between the immobilization systems, a t-test (Welch) was performed.

Results: Mean displacements for the TMP and VC systems, respectively, were as follows: session one, 0.64 cm vs 1.05 cm (p = 0.0002); session two, 0.49 cm vs 1.02 cm (p < 0.0001), and session three, 0.56 vs 0.97 cm (p = 0.0011). TMP resulted in significantly smaller shifts vs. VCS in all three treatment sessions. Technologists rated the learning curve, set up, and positioning more highly for TMP versus VCS.

Conclusions: Due to the high doses and steep gradients in lung SBRT, accurate and reproducible inter-fraction set up is essential. We found that thermoplastic masks offers better reproducibility with significantly less interfractional set up displacement than vacuum cushions. Moreover, radiotherapy technologists rated the TMP system higher. Taken together, these two findings suggest that TMP may be preferable to VCS. However, more research is needed to determine both inter- and intrafraction error to identify the optimal immobilisation system for use in lung SBRT.

No MeSH data available.


Related in: MedlinePlus

Thermoplastic mask and vacuum cushion system components. Fig. 1a depicts the vacuum cushion system with its components: a: Vacuum Cushion, b: Common Couch, c: Abdominal Compressor. d: Marker Block, e: Arm Support. Fig 1B shows the thermoplastic mask system and its components: a: Thermoplastic Mask, b: Common Couch, c: Abdominal Compressor. d: Marker Block e: Arm support
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Fig1: Thermoplastic mask and vacuum cushion system components. Fig. 1a depicts the vacuum cushion system with its components: a: Vacuum Cushion, b: Common Couch, c: Abdominal Compressor. d: Marker Block, e: Arm Support. Fig 1B shows the thermoplastic mask system and its components: a: Thermoplastic Mask, b: Common Couch, c: Abdominal Compressor. d: Marker Block e: Arm support

Mentions: Patients were immobilized with one of two different immobilization systems (Figs. 1a & b) , as follows: 1) whole body vacuum cushions (VC) (Civco Medical Solutions; Kalona, Indiana, USA) or 2) thermoplastic mask (TMP) system (Lorca Marin S.A., Spain). The VC cushions are custom-formed for positioning accuracy, and become rigid when vacuum is applied. The TMP immobilization system consists of a malleable thermoplastic mask that is fixed to the patient from the head to the upper thorax, while leaving the arms free to place in the fixation system. Our institution initially utilized only the VC system, however, over time we progressively switched to TMP immobilization because we observed unacceptably large set-up errors with the VC system. As Fig. 1 clearly shows, both systems share many of the same components, including the couch, abdominal compressor, marker block, and arm support.Fig. 1


Comparative analysis of thermoplastic masks versus vacuum cushions in stereotactic body radiotherapy.

Navarro-Martin A, Cacicedo J, Leaman O, Sancho I, García E, Navarro V, Guedea F - Radiat Oncol (2015)

Thermoplastic mask and vacuum cushion system components. Fig. 1a depicts the vacuum cushion system with its components: a: Vacuum Cushion, b: Common Couch, c: Abdominal Compressor. d: Marker Block, e: Arm Support. Fig 1B shows the thermoplastic mask system and its components: a: Thermoplastic Mask, b: Common Couch, c: Abdominal Compressor. d: Marker Block e: Arm support
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4554348&req=5

Fig1: Thermoplastic mask and vacuum cushion system components. Fig. 1a depicts the vacuum cushion system with its components: a: Vacuum Cushion, b: Common Couch, c: Abdominal Compressor. d: Marker Block, e: Arm Support. Fig 1B shows the thermoplastic mask system and its components: a: Thermoplastic Mask, b: Common Couch, c: Abdominal Compressor. d: Marker Block e: Arm support
Mentions: Patients were immobilized with one of two different immobilization systems (Figs. 1a & b) , as follows: 1) whole body vacuum cushions (VC) (Civco Medical Solutions; Kalona, Indiana, USA) or 2) thermoplastic mask (TMP) system (Lorca Marin S.A., Spain). The VC cushions are custom-formed for positioning accuracy, and become rigid when vacuum is applied. The TMP immobilization system consists of a malleable thermoplastic mask that is fixed to the patient from the head to the upper thorax, while leaving the arms free to place in the fixation system. Our institution initially utilized only the VC system, however, over time we progressively switched to TMP immobilization because we observed unacceptably large set-up errors with the VC system. As Fig. 1 clearly shows, both systems share many of the same components, including the couch, abdominal compressor, marker block, and arm support.Fig. 1

Bottom Line: TMP resulted in significantly smaller shifts vs.We found that thermoplastic masks offers better reproducibility with significantly less interfractional set up displacement than vacuum cushions.Moreover, radiotherapy technologists rated the TMP system higher.

View Article: PubMed Central - PubMed

Affiliation: Radiation Oncology Department, Hospital Duran i Reynals (ICO) Avda. Gran Via de L'Hospitalet, 199-203 08908 Hospitalet de Llobregat, Barcelona, Spain. anavarro@iconcologia.net.

ABSTRACT

Background: To compare thermoplastic masks (TMP) and vacuum cushion system (VCS) to assess differences in interfraction set up accuracy in patients treated with stereotactic radiotherapy (SBRT) for oligometastatic lung cancer. Secondarily, to survey radiotherapy technologists to assess their satisfaction with the two systems.

Methods: Retrospective study of patients treated with lung SBRT between 2008 to 2012 at our institution. Immobilization was performed for 73 treatment sessions (VCS = 40; TMP = 33). A total of 246 cone-beams were analysed. Patients considered ineligible for surgery with a life expectancy ≥6 months and performance status > 1 were included. Target lesion location was verified by cone beam computed tomography (CBCT) prior to each session, with displacements assessed by CBCT simulation prior to each treatment session. Couch shifts were registered prospectively in vertical, longitudinal, and latero-lateral directions to obtain Kernel coordinates (3D representation). Technologists were surveyed to assess their satisfaction with indexing, positioning, and learning curve of the two systems. Setup displacements were obtained in all patients for each treatment plan and for each session. To assess differences between the immobilization systems, a t-test (Welch) was performed.

Results: Mean displacements for the TMP and VC systems, respectively, were as follows: session one, 0.64 cm vs 1.05 cm (p = 0.0002); session two, 0.49 cm vs 1.02 cm (p < 0.0001), and session three, 0.56 vs 0.97 cm (p = 0.0011). TMP resulted in significantly smaller shifts vs. VCS in all three treatment sessions. Technologists rated the learning curve, set up, and positioning more highly for TMP versus VCS.

Conclusions: Due to the high doses and steep gradients in lung SBRT, accurate and reproducible inter-fraction set up is essential. We found that thermoplastic masks offers better reproducibility with significantly less interfractional set up displacement than vacuum cushions. Moreover, radiotherapy technologists rated the TMP system higher. Taken together, these two findings suggest that TMP may be preferable to VCS. However, more research is needed to determine both inter- and intrafraction error to identify the optimal immobilisation system for use in lung SBRT.

No MeSH data available.


Related in: MedlinePlus