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Is the in vivo dosimetry with the OneDosePlusTM system able to detect intra-fraction motion? A retrospective analysis of in vivo data from breast and prostate patients.

Falco MD, D'Andrea M, Bosco AL, Rebuzzi M, Ponti E, Tolu B, Tortorelli G, Barbarino R, Di Murro L, Santoni R - Radiat Oncol (2012)

Bottom Line: The ATs have been found to be very similar (5.0% for TPS1 and 4.5% for TPS2).From statistical data analysis, the system has been found not sensitive enough to reveal displacements smaller than 1 cm (within two standard deviations).Splitting data into medial and lateral field, two patients have been found to move during all these sessions; the others, instead, moved only in the second part of the treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, Tor Vergata University General Hospital, V.le Oxford 81, 00133, Rome, Italy. mdanielafalco@hotmail.com

ABSTRACT

Background: The OneDosePlusTM system, based on MOSFET solid-state radiation detectors and a handheld dosimetry reader, has been used to evaluate intra-fraction movements of patients with breast and prostate cancer.

Methods: An Action Threshold (AT), defined as the maximum acceptable discrepancy between measured dose and dose calculated with the Treatment Planning System (TPS) (for each field) has been determined from phantom data. To investigate the sensitivity of the system to direction of the patient movements, fixed displacements have been simulated in phantom. The AT has been used as an indicator to establish if patients move during a treatment session, after having verified the set-up with 2D and/or 3D images. Phantom tests have been performed matching different linear accelerators and two TPSs (TPS1 and TPS2).

Results: The ATs have been found to be very similar (5.0% for TPS1 and 4.5% for TPS2). From statistical data analysis, the system has been found not sensitive enough to reveal displacements smaller than 1 cm (within two standard deviations). The ATs applied to in vivo treatments showed that among the twenty five patients treated for breast cancer, only four of them moved during each measurement session. Splitting data into medial and lateral field, two patients have been found to move during all these sessions; the others, instead, moved only in the second part of the treatment. Patients with prostate cancer have behaved better than patients with breast cancer. Only two out of twenty five moved in each measurement session.

Conclusions: The method described in the paper, easily implemented in the clinical practice, combines all the advantages of in vivo procedures using the OneDosePlusTM system with the possibility of detecting intra-fraction patient movements.

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Related in: MedlinePlus

Breast treatment with the Elekta Precise. Average discrepancy using TPS1 and a 2D verification system, for the lateral field along the entire treatment course.
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Figure 6: Breast treatment with the Elekta Precise. Average discrepancy using TPS1 and a 2D verification system, for the lateral field along the entire treatment course.

Mentions: Figure4 shows the data for twenty five patients with breast cancer and TPS1. The mean discrepancy was −1.4% with a SD of 3.8%. These values were averaged on both fields (medial and lateral) and along the entire treatment. To investigate if the patients moved during both fields or only during the last field of the treatment session, data were also split into medial and lateral field only. Figures 5 and6 show the average discrepancy for the medial and the lateral field, respectively. In these plots, the mean discrepancy was −2.2% with a SD of 3.0%, and 0.9% with a SD of 5.1% for the medial and the lateral field, respectively. The lateral field show a wider data dispersion with respect to the medial one. In the figures, red dots mark the Δ values exceeding AT1.


Is the in vivo dosimetry with the OneDosePlusTM system able to detect intra-fraction motion? A retrospective analysis of in vivo data from breast and prostate patients.

Falco MD, D'Andrea M, Bosco AL, Rebuzzi M, Ponti E, Tolu B, Tortorelli G, Barbarino R, Di Murro L, Santoni R - Radiat Oncol (2012)

Breast treatment with the Elekta Precise. Average discrepancy using TPS1 and a 2D verification system, for the lateral field along the entire treatment course.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3526469&req=5

Figure 6: Breast treatment with the Elekta Precise. Average discrepancy using TPS1 and a 2D verification system, for the lateral field along the entire treatment course.
Mentions: Figure4 shows the data for twenty five patients with breast cancer and TPS1. The mean discrepancy was −1.4% with a SD of 3.8%. These values were averaged on both fields (medial and lateral) and along the entire treatment. To investigate if the patients moved during both fields or only during the last field of the treatment session, data were also split into medial and lateral field only. Figures 5 and6 show the average discrepancy for the medial and the lateral field, respectively. In these plots, the mean discrepancy was −2.2% with a SD of 3.0%, and 0.9% with a SD of 5.1% for the medial and the lateral field, respectively. The lateral field show a wider data dispersion with respect to the medial one. In the figures, red dots mark the Δ values exceeding AT1.

Bottom Line: The ATs have been found to be very similar (5.0% for TPS1 and 4.5% for TPS2).From statistical data analysis, the system has been found not sensitive enough to reveal displacements smaller than 1 cm (within two standard deviations).Splitting data into medial and lateral field, two patients have been found to move during all these sessions; the others, instead, moved only in the second part of the treatment.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Diagnostic Imaging, Molecular Imaging, Interventional Radiology and Radiotherapy, Tor Vergata University General Hospital, V.le Oxford 81, 00133, Rome, Italy. mdanielafalco@hotmail.com

ABSTRACT

Background: The OneDosePlusTM system, based on MOSFET solid-state radiation detectors and a handheld dosimetry reader, has been used to evaluate intra-fraction movements of patients with breast and prostate cancer.

Methods: An Action Threshold (AT), defined as the maximum acceptable discrepancy between measured dose and dose calculated with the Treatment Planning System (TPS) (for each field) has been determined from phantom data. To investigate the sensitivity of the system to direction of the patient movements, fixed displacements have been simulated in phantom. The AT has been used as an indicator to establish if patients move during a treatment session, after having verified the set-up with 2D and/or 3D images. Phantom tests have been performed matching different linear accelerators and two TPSs (TPS1 and TPS2).

Results: The ATs have been found to be very similar (5.0% for TPS1 and 4.5% for TPS2). From statistical data analysis, the system has been found not sensitive enough to reveal displacements smaller than 1 cm (within two standard deviations). The ATs applied to in vivo treatments showed that among the twenty five patients treated for breast cancer, only four of them moved during each measurement session. Splitting data into medial and lateral field, two patients have been found to move during all these sessions; the others, instead, moved only in the second part of the treatment. Patients with prostate cancer have behaved better than patients with breast cancer. Only two out of twenty five moved in each measurement session.

Conclusions: The method described in the paper, easily implemented in the clinical practice, combines all the advantages of in vivo procedures using the OneDosePlusTM system with the possibility of detecting intra-fraction patient movements.

Show MeSH
Related in: MedlinePlus