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Exploiting the machine log files for VMAT and IMRT treatment verification
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Abstracts/Physica Medica 32 (2016) e1–e70
A.58 EXPLOITING THE MACHINE LOG FILES FOR VMAT AND IMRT TREATMENT VERIFICATION V. D’Errico *,a, A. Sarnelli a, D. Bianchini a, E. Menghi a, E. Mezzenga a, F. Marcocci a, L. Strigari b, M. Benassi a. a Medical Physics Department, IRCCS Istituto Scientifico Romagnolo per lo Studio e la Cura dei tumori, Meldola, Italy; b Laboratory of Medical Physics and Expert Systems, National Cancer Institute Regina Elena, Roma, Italy Introduction: The rotational-volumetric treatments are more complex than the traditional IMRT; as more degrees of freedom are involved during treatment delivery, a greater potential for delivery errors is associated to the treatment section. Investigation and improvements of QA methods are mandatory to avoid that potential errors are masked. Materials and methods: A tool to capture the machine parameters stored in the log file is developed and implemented. All the machine parameters are compared with the planned ones in order to quantify delivery errors. A new treatment plan including all the parameters extracted from the machine log file output is the input for Pinnacle 9.10 and is used for the re-calculation of the dose distribution. The re-calculated dose distribution is the actual delivered dose distribution. Action levels based on DVH analysis and radiobiological quantities are proposed to evaluate the goodness of the delivered dose. Five left breast treatments and five prostate treatments are considered. The deviations between calculated dose distribution and the delivered one were evaluated. The comparison included evaluations of DVHs and radiobiological quantities. Results: For the targets the discrepancy between the calculated and delivered dose distributions is less than 2%; the largest deviations occur in correspondence of the highest dose. The discrepancy between the TCP values is less than 5%. For the organs of interest near the targets, the discrepancy between the dose distributions could reach 10%, while the discrepancy between the NTCP values is less than 5%. The histograms of the planned and delivered machine parameters are within the tolerances expected. Conclusions: The machine log file analysis allows to verify that machine parameters are consistent as planned. DVH analysis and radiobiological quantities are a promising tool to evaluate the goodness of a treatment and overcomes the limitations of the gamma index analysis. http://dx.doi.org/10.1016/j.ejmp.2016.01.062
A.59 WEB-INTERFACED MONTE CARLO SIMULATION FOR QUALITY ASSURANCE IN RADIATION THERAPY F. Dalmasso *,a, F. Bourhaleb a,b,c, G. Russo c, N. Franza d, S. Spoto c, A. Attili a. a Istituto Nazionale di Fisica Nucleare, Torino, Italy; b Università degli Studi, Torino, Italy; c Internet Simulation Evaluation Envision (I-SEE), Torino, Italy; d DosimETrICA, Nocera Inferiore, Italy Introduction: The increasing complexity of radiotherapy equipment (e.g. IMRT) requires increasing accuracy in QA procedures. The system used to verify the adherence between planned and delivered dose should be independent of the treatment planning system. Monte Carlo (MC) algorithms are the reference choice. They allow computing the dose taking into account patient heterogeneities and dosimetric effects generated by multi-leaf collimators (MLCs). In line with these motivations, we developed a MCbased tool for dosimetric purposes and the independent verification of planned dose distributions. Materials and methods: The tool is built exploiting the Geant4 MC simulation package. Any LINAC can be modelled, provided that the manufacturer discloses its specifications. The simulation is performed in two stages. First, the phase space above the secondary collimator is derived simulating the traversal of the patient-independent part of the LINAC head. Then, the radiation field generated from the phase space is propagated through the secondary collimators, the MLCs and into the patient, where the dose distribution is scored. We run the simulations on a cluster, implementing an automatic way to distribute the computations of events, monitor their progress and gather the outputs. We provide the user with a remote web-based interface that eases the management of the workflow and the inspection of the results. Results: We tested the tool simulating the Varian Clinac iX machine. For different energies and field sizes, the simulations and measurements in water
agreed to within 1.0% for percentage depth doses and 2.0% for dose profiles. We then simulated a daily QA irradiation of a homogeneous phantom and obtained that more than 90% of the points passed the 3%/3 mm γ-index criterion. Conclusions: Our MC tool provides a way to independently verify planned dose distributions. The use of a web interface makes MC distributed computations accessible to clinical users and allows one to run the computations and inspect the results from any location. http://dx.doi.org/10.1016/j.ejmp.2016.01.063 A.60 A SIMPLIFIED INTENSITY-MODULATED RADIOTHERAPY TECHNIQUE FOR THE BREAST TO REDUCE POSTERIOR PART OF THE AXILLA IRRADIATION R. Di Benedetto *, C. Guida, D. Barzaghi, O. Cristiano, M. Elmo, S. Ancona, A. Buonavita, A. Iacobelli, V. Lampognara, D. Spiniello, C. Iervolino. Radiotherapy Department, A.O. S.G. Moscati, Avellino, Italy Introduction: The breast irradiation with conventional technique (CN-C) poses a clinical difficulty in treating pendulous breast in patients with unfavorable anatomy of chest, causing an overdosage of posterior part of the axilla. The aims of the study are to implement and to quantify the benefits of a simplified IMRT technique using a set of beams with optimal orientations (SI-O). Materials and methods: The patients included in the study were 55 consecutive patients in which the distance (d), calculated from the posterior entrance of the lateral tangent beam to the target, was greater than 3.5 cm on axial slices during the CT simulation. SI-O plan is an extension of CN-C plan that uses the same tangent pair of beams but with additional segments oriented on the CTV geometry. The additional lateral tangent beam is split into two segments (s-C and s-D). The segment s-D, parallel to lateral tangent beam, is generated on the BEV view closing the collimator Y2 on the portion of the target identified as the portion with a 95% isodose’s distribution compliant to CTV. s-C is generated in the same way on BEV, closing the collimator Y1 on the portion of the target identified as the portion with overdosage on the posterior part of the patient’s axilla. It has a different angle (about 13°) of lateral tangent. The overlap between s-C and s-D has been done so that no hot spot is caused. Results: Although we reached equal dosimetric and geometric index in the comparison of the treatment plans, we found a significant difference for CIRTOG (p < 0.05). The average CI is 1.38 ± 0.03 vs 1.45 ± 0.03 for the SI-O and CN-C plans, respectively. Conclusions: Using the SI-O technique, we have a significant sparing of the posterior part of the axilla in patients with a particular breast anatomy. The SI-O technique ensures a better CI with equal potential damage induced on OARs, such as heart, lung, and contralateral breast. http://dx.doi.org/10.1016/j.ejmp.2016.01.064 A.61 RADIOTHERAPY IN ASSOCIATION WITH HYPERTHERMIA: OUTCOME AND TOXICITY IN THE TREATMENT OF SUPERFICIAL RECURRENT/METASTATIC TUMORS A. Di Dia *,a, E. Garibaldi b, E. Delmastro b, G. Belli b, M. Gatti b, G. Cattari b, A. Salatino b, S. Squintu b, A. Miranti a, M. Poli a, P. Gabriele b, M. Stasi a. a Medical Physics, FPO-IRCCS, Candiolo Cancer Institute, Candiolo, TO, Italy; b Radiotherapy Department, FPO-IRCCS, Candiolo Cancer Institute, Candiolo, TO, Italy Introduction: The aim of this work is to evaluate the outcome/toxicity of radiotherapy-hyperthermia (RT-HT) in the treatment of superficial recurrent/ metastatic tumors. Materials and methods: Twenty-nine patients (mean [range]: 69 years [49– 93], 17 breast carcinoma, 5 head and neck cancer, 2 malignant melanoma, 2 sarcomas, 1 uterine adenocarcinoma, 1 hepatocarcinoma, 1 squamous skin cancer) were evaluated. Patients underwent radiotherapy treatment using 3D-conformal radiotherapy (10/29) or helical tomotherapy (19/29). External beam radiotherapy was delivered (1.8–5 Gy, 6–27 fractions, total dose 20–57.5 Gy (mean dose: 41 Gy). Hyperthermia is performed with an electromagnetic superficial applicator operating at the frequency of 434 MHz. HT session was delivered once/twice weekly (mean[range]: 5[1–9] sessions), 1 hour after radiotherapy. Average (Tmean), maximum (Tmax) and
Abstracts/Physica Medica 32 (2016) e1–e70
A.58 EXPLOITING THE MACHINE LOG FILES FOR VMAT AND IMRT TREATMENT VERIFICATION V. D’Errico *,a, A. Sarnelli a, D. Bianchini a, E. Menghi a, E. Mezzenga a, F. Marcocci a, L. Strigari b, M. Benassi a. a Medical Physics Department, IRCCS Istituto Scientifico Romagnolo per lo Studio e la Cura dei tumori, Meldola, Italy; b Laboratory of Medical Physics and Expert Systems, National Cancer Institute Regina Elena, Roma, Italy Introduction: The rotational-volumetric treatments are more complex than the traditional IMRT; as more degrees of freedom are involved during treatment delivery, a greater potential for delivery errors is associated to the treatment section. Investigation and improvements of QA methods are mandatory to avoid that potential errors are masked. Materials and methods: A tool to capture the machine parameters stored in the log file is developed and implemented. All the machine parameters are compared with the planned ones in order to quantify delivery errors. A new treatment plan including all the parameters extracted from the machine log file output is the input for Pinnacle 9.10 and is used for the re-calculation of the dose distribution. The re-calculated dose distribution is the actual delivered dose distribution. Action levels based on DVH analysis and radiobiological quantities are proposed to evaluate the goodness of the delivered dose. Five left breast treatments and five prostate treatments are considered. The deviations between calculated dose distribution and the delivered one were evaluated. The comparison included evaluations of DVHs and radiobiological quantities. Results: For the targets the discrepancy between the calculated and delivered dose distributions is less than 2%; the largest deviations occur in correspondence of the highest dose. The discrepancy between the TCP values is less than 5%. For the organs of interest near the targets, the discrepancy between the dose distributions could reach 10%, while the discrepancy between the NTCP values is less than 5%. The histograms of the planned and delivered machine parameters are within the tolerances expected. Conclusions: The machine log file analysis allows to verify that machine parameters are consistent as planned. DVH analysis and radiobiological quantities are a promising tool to evaluate the goodness of a treatment and overcomes the limitations of the gamma index analysis. http://dx.doi.org/10.1016/j.ejmp.2016.01.062
A.59 WEB-INTERFACED MONTE CARLO SIMULATION FOR QUALITY ASSURANCE IN RADIATION THERAPY F. Dalmasso *,a, F. Bourhaleb a,b,c, G. Russo c, N. Franza d, S. Spoto c, A. Attili a. a Istituto Nazionale di Fisica Nucleare, Torino, Italy; b Università degli Studi, Torino, Italy; c Internet Simulation Evaluation Envision (I-SEE), Torino, Italy; d DosimETrICA, Nocera Inferiore, Italy Introduction: The increasing complexity of radiotherapy equipment (e.g. IMRT) requires increasing accuracy in QA procedures. The system used to verify the adherence between planned and delivered dose should be independent of the treatment planning system. Monte Carlo (MC) algorithms are the reference choice. They allow computing the dose taking into account patient heterogeneities and dosimetric effects generated by multi-leaf collimators (MLCs). In line with these motivations, we developed a MCbased tool for dosimetric purposes and the independent verification of planned dose distributions. Materials and methods: The tool is built exploiting the Geant4 MC simulation package. Any LINAC can be modelled, provided that the manufacturer discloses its specifications. The simulation is performed in two stages. First, the phase space above the secondary collimator is derived simulating the traversal of the patient-independent part of the LINAC head. Then, the radiation field generated from the phase space is propagated through the secondary collimators, the MLCs and into the patient, where the dose distribution is scored. We run the simulations on a cluster, implementing an automatic way to distribute the computations of events, monitor their progress and gather the outputs. We provide the user with a remote web-based interface that eases the management of the workflow and the inspection of the results. Results: We tested the tool simulating the Varian Clinac iX machine. For different energies and field sizes, the simulations and measurements in water
agreed to within 1.0% for percentage depth doses and 2.0% for dose profiles. We then simulated a daily QA irradiation of a homogeneous phantom and obtained that more than 90% of the points passed the 3%/3 mm γ-index criterion. Conclusions: Our MC tool provides a way to independently verify planned dose distributions. The use of a web interface makes MC distributed computations accessible to clinical users and allows one to run the computations and inspect the results from any location. http://dx.doi.org/10.1016/j.ejmp.2016.01.063 A.60 A SIMPLIFIED INTENSITY-MODULATED RADIOTHERAPY TECHNIQUE FOR THE BREAST TO REDUCE POSTERIOR PART OF THE AXILLA IRRADIATION R. Di Benedetto *, C. Guida, D. Barzaghi, O. Cristiano, M. Elmo, S. Ancona, A. Buonavita, A. Iacobelli, V. Lampognara, D. Spiniello, C. Iervolino. Radiotherapy Department, A.O. S.G. Moscati, Avellino, Italy Introduction: The breast irradiation with conventional technique (CN-C) poses a clinical difficulty in treating pendulous breast in patients with unfavorable anatomy of chest, causing an overdosage of posterior part of the axilla. The aims of the study are to implement and to quantify the benefits of a simplified IMRT technique using a set of beams with optimal orientations (SI-O). Materials and methods: The patients included in the study were 55 consecutive patients in which the distance (d), calculated from the posterior entrance of the lateral tangent beam to the target, was greater than 3.5 cm on axial slices during the CT simulation. SI-O plan is an extension of CN-C plan that uses the same tangent pair of beams but with additional segments oriented on the CTV geometry. The additional lateral tangent beam is split into two segments (s-C and s-D). The segment s-D, parallel to lateral tangent beam, is generated on the BEV view closing the collimator Y2 on the portion of the target identified as the portion with a 95% isodose’s distribution compliant to CTV. s-C is generated in the same way on BEV, closing the collimator Y1 on the portion of the target identified as the portion with overdosage on the posterior part of the patient’s axilla. It has a different angle (about 13°) of lateral tangent. The overlap between s-C and s-D has been done so that no hot spot is caused. Results: Although we reached equal dosimetric and geometric index in the comparison of the treatment plans, we found a significant difference for CIRTOG (p < 0.05). The average CI is 1.38 ± 0.03 vs 1.45 ± 0.03 for the SI-O and CN-C plans, respectively. Conclusions: Using the SI-O technique, we have a significant sparing of the posterior part of the axilla in patients with a particular breast anatomy. The SI-O technique ensures a better CI with equal potential damage induced on OARs, such as heart, lung, and contralateral breast. http://dx.doi.org/10.1016/j.ejmp.2016.01.064 A.61 RADIOTHERAPY IN ASSOCIATION WITH HYPERTHERMIA: OUTCOME AND TOXICITY IN THE TREATMENT OF SUPERFICIAL RECURRENT/METASTATIC TUMORS A. Di Dia *,a, E. Garibaldi b, E. Delmastro b, G. Belli b, M. Gatti b, G. Cattari b, A. Salatino b, S. Squintu b, A. Miranti a, M. Poli a, P. Gabriele b, M. Stasi a. a Medical Physics, FPO-IRCCS, Candiolo Cancer Institute, Candiolo, TO, Italy; b Radiotherapy Department, FPO-IRCCS, Candiolo Cancer Institute, Candiolo, TO, Italy Introduction: The aim of this work is to evaluate the outcome/toxicity of radiotherapy-hyperthermia (RT-HT) in the treatment of superficial recurrent/ metastatic tumors. Materials and methods: Twenty-nine patients (mean [range]: 69 years [49– 93], 17 breast carcinoma, 5 head and neck cancer, 2 malignant melanoma, 2 sarcomas, 1 uterine adenocarcinoma, 1 hepatocarcinoma, 1 squamous skin cancer) were evaluated. Patients underwent radiotherapy treatment using 3D-conformal radiotherapy (10/29) or helical tomotherapy (19/29). External beam radiotherapy was delivered (1.8–5 Gy, 6–27 fractions, total dose 20–57.5 Gy (mean dose: 41 Gy). Hyperthermia is performed with an electromagnetic superficial applicator operating at the frequency of 434 MHz. HT session was delivered once/twice weekly (mean[range]: 5[1–9] sessions), 1 hour after radiotherapy. Average (Tmean), maximum (Tmax) and