Purpose: This study aimed to compare the dose characteristics of the volumetric modulated arc therapy (VMAT) and dynamic conformal arc (DCA) techniques for metastatic brain tumor treatment using various indices to evaluate the quality of the plan and provide insights into the clinical implications of each approach. Methods: Twelve patients with single metastatic brain tumors treated with VMAT were retrospectively analyzed. For comparison with DCA, identical geometric parameters (excluding multileaf collimators) were applied. Dose coverage, normal tissue sparing, and treatment efficiencywere evaluated using indices such as CILIM98 , CIICRU , CIRTOG , QCRTOG , CISALT , HTCISALT , and CIPADDIC .These indices were statistically assessed to evaluate the differences between VMAT and DCA. Results: VMAT was superior to DCA in most indices for both small and large planning targetvolumes (PTVs). DCA plans for large PTVs showed a higher V12Gy , exceeding 10 mL and failing tomeet the recommended criteria (<10 mL). However, DCA required nearly half the monitor units(MUs) of VMAT, resulting in shorter treatment times. All indices, except for QCRTOG , demonstratedsignificant differences between VMAT and DCA. Conclusions Careful consideration is necessary for larger PTVs when deciding a plan becauseDCA can occasionally result in V12Gy of a brain minus PTV >10 mL. Conversely, DCA provides theadvantage of shorter treatment times because of its lower MU. This study highlights the importance of using a combination of indices to comprehensively assess treatment plan quality.

Purpose: This study aimed to compare the dose characteristics of the volumetric modulated arc therapy (VMAT) and dynamic conformal arc (DCA) techniques for metastatic brain tumor treatment using various indices to evaluate the quality of the plan and provide insights into the clinical implications of each approach. Methods: Twelve patients with single metastatic brain tumors treated with VMAT were retrospectively analyzed. For comparison with DCA, identical geometric parameters (excluding multileaf collimators) were applied. Dose coverage, normal tissue sparing, and treatment efficiencywere evaluated using indices such as CILIM98 , CIICRU , CIRTOG , QCRTOG , CISALT , HTCISALT , and CIPADDIC .These indices were statistically assessed to evaluate the differences between VMAT and DCA. Results: VMAT was superior to DCA in most indices for both small and large planning targetvolumes (PTVs). DCA plans for large PTVs showed a higher V12Gy , exceeding 10 mL and failing tomeet the recommended criteria (<10 mL). However, DCA required nearly half the monitor units(MUs) of VMAT, resulting in shorter treatment times. All indices, except for QCRTOG , demonstratedsignificant differences between VMAT and DCA. Conclusions Careful consideration is necessary for larger PTVs when deciding a plan becauseDCA can occasionally result in V12Gy of a brain minus PTV >10 mL. Conversely, DCA provides theadvantage of shorter treatment times because of its lower MU. This study highlights the importance of using a combination of indices to comprehensively assess treatment plan quality.

Purpose: This study aimed to compare the dose characteristics of the volumetric modulated arc therapy (VMAT) and dynamic conformal arc (DCA) techniques for metastatic brain tumor treatment using various indices to evaluate the quality of the plan and provide insights into the clinical implications of each approach. Methods: Twelve patients with single metastatic brain tumors treated with VMAT were retrospectively analyzed. For comparison with DCA, identical geometric parameters (excluding multileaf collimators) were applied. Dose coverage, normal tissue sparing, and treatment efficiencywere evaluated using indices such as CILIM98 , CIICRU , CIRTOG , QCRTOG , CISALT , HTCISALT , and CIPADDIC .These indices were statistically assessed to evaluate the differences between VMAT and DCA. Results: VMAT was superior to DCA in most indices for both small and large planning targetvolumes (PTVs). DCA plans for large PTVs showed a higher V12Gy , exceeding 10 mL and failing tomeet the recommended criteria (<10 mL). However, DCA required nearly half the monitor units(MUs) of VMAT, resulting in shorter treatment times. All indices, except for QCRTOG , demonstratedsignificant differences between VMAT and DCA. Conclusions Careful consideration is necessary for larger PTVs when deciding a plan becauseDCA can occasionally result in V12Gy of a brain minus PTV >10 mL. Conversely, DCA provides theadvantage of shorter treatment times because of its lower MU. This study highlights the importance of using a combination of indices to comprehensively assess treatment plan quality.

Purpose: This study aimed to compare the dose characteristics of the volumetric modulated arc therapy (VMAT) and dynamic conformal arc (DCA) techniques for metastatic brain tumor treatment using various indices to evaluate the quality of the plan and provide insights into the clinical implications of each approach. Methods: Twelve patients with single metastatic brain tumors treated with VMAT were retrospectively analyzed. For comparison with DCA, identical geometric parameters (excluding multileaf collimators) were applied. Dose coverage, normal tissue sparing, and treatment efficiencywere evaluated using indices such as CILIM98 , CIICRU , CIRTOG , QCRTOG , CISALT , HTCISALT , and CIPADDIC .These indices were statistically assessed to evaluate the differences between VMAT and DCA. Results: VMAT was superior to DCA in most indices for both small and large planning targetvolumes (PTVs). DCA plans for large PTVs showed a higher V12Gy , exceeding 10 mL and failing tomeet the recommended criteria (<10 mL). However, DCA required nearly half the monitor units(MUs) of VMAT, resulting in shorter treatment times. All indices, except for QCRTOG , demonstratedsignificant differences between VMAT and DCA. Conclusions Careful consideration is necessary for larger PTVs when deciding a plan becauseDCA can occasionally result in V12Gy of a brain minus PTV >10 mL. Conversely, DCA provides theadvantage of shorter treatment times because of its lower MU. This study highlights the importance of using a combination of indices to comprehensively assess treatment plan quality.

Purpose: This study aimed to compare the dose characteristics of the volumetric modulated arc therapy (VMAT) and dynamic conformal arc (DCA) techniques for metastatic brain tumor treatment using various indices to evaluate the quality of the plan and provide insights into the clinical implications of each approach. Methods: Twelve patients with single metastatic brain tumors treated with VMAT were retrospectively analyzed. For comparison with DCA, identical geometric parameters (excluding multileaf collimators) were applied. Dose coverage, normal tissue sparing, and treatment efficiencywere evaluated using indices such as CILIM98 , CIICRU , CIRTOG , QCRTOG , CISALT , HTCISALT , and CIPADDIC .These indices were statistically assessed to evaluate the differences between VMAT and DCA. Results: VMAT was superior to DCA in most indices for both small and large planning targetvolumes (PTVs). DCA plans for large PTVs showed a higher V12Gy , exceeding 10 mL and failing tomeet the recommended criteria (<10 mL). However, DCA required nearly half the monitor units(MUs) of VMAT, resulting in shorter treatment times. All indices, except for QCRTOG , demonstratedsignificant differences between VMAT and DCA. Conclusions Careful consideration is necessary for larger PTVs when deciding a plan becauseDCA can occasionally result in V12Gy of a brain minus PTV >10 mL. Conversely, DCA provides theadvantage of shorter treatment times because of its lower MU. This study highlights the importance of using a combination of indices to comprehensively assess treatment plan quality.

PURPOSE: To see the gross tumor volume (GTV) dependency according to the phase selection and reconstruction methods, we measured and analyzed the changes of tumor volume and motion at each phase in 20 cases with lung cancer patients who underwent image-guided radiotherapy. MATERIALS AND METHODS: We retrospectively analyzed four-dimensional computed tomography (4D-CT) images in 20 cases of 19 patients who underwent image-guided radiotherapy. The 4D-CT images were reconstructed by the maximum intensity projection (MIP) and the minimum intensity projection (Min-IP) method after sorting phase as 40%–60%, 30%–70%, and 0%–90%. We analyzed the relationship between the range of motion and the change of GTV according to the reconstruction method. RESULTS: The motion ranges of GTVs are statistically significant only for the tumor motion in craniocaudal direction. The discrepancies of GTV volume and motion between MIP and Min-IP increased rapidly as the wider ranges of duty cycles are selected. CONCLUSION: As narrow as possible duty cycle such as 40%–60% and MIP reconstruction was suitable for lung cancer if the respiration was stable. Selecting the reconstruction methods and duty cycle is important for small size and for large motion range tumors.
Four-Dimensional Computed Tomography* ; Humans ; Lung Neoplasms* ; Lung* ; Methods* ; Radiotherapy, Image-Guided ; Range of Motion, Articular ; Respiration ; Retrospective Studies ; Tumor Burden*

PURPOSE: To see the gross tumor volume (GTV) dependency according to the phase selection and reconstruction methods, we measured and analyzed the changes of tumor volume and motion at each phase in 20 cases with lung cancer patients who underwent image-guided radiotherapy. MATERIALS AND METHODS: We retrospectively analyzed four-dimensional computed tomography (4D-CT) images in 20 cases of 19 patients who underwent image-guided radiotherapy. The 4D-CT images were reconstructed by the maximum intensity projection (MIP) and the minimum intensity projection (Min-IP) method after sorting phase as 40%–60%, 30%–70%, and 0%–90%. We analyzed the relationship between the range of motion and the change of GTV according to the reconstruction method. RESULTS: The motion ranges of GTVs are statistically significant only for the tumor motion in craniocaudal direction. The discrepancies of GTV volume and motion between MIP and Min-IP increased rapidly as the wider ranges of duty cycles are selected. CONCLUSION: As narrow as possible duty cycle such as 40%–60% and MIP reconstruction was suitable for lung cancer if the respiration was stable. Selecting the reconstruction methods and duty cycle is important for small size and for large motion range tumors.
Four-Dimensional Computed Tomography* ; Humans ; Lung Neoplasms* ; Lung* ; Methods* ; Radiotherapy, Image-Guided ; Range of Motion, Articular ; Respiration ; Retrospective Studies ; Tumor Burden*

The purpose of this study was to measure curvature contour skin dose using radiochromic film and TLD for a conventional open field. We also attempted to quantify the degradation of skin sparing associated with use of immobilization devices for high energy photon beams and to calculate the skin dose with a help of Monte Carlo (MC) simulation. To simulate head-and-neck and shoulder treatment, a cylindrical solid water phantom 11 cm in diameter was irradiated with 6 MV x-rays using 40x40 cm2 field at 100 cm source axis distance (SAD) to the center of the phantom. Aquaplastic mesh mask was placed on the surface of the cylindrical phantom that mimicked relevant clinical situations. The skin dose profile was obtained by taking measurements from 0degrees to 360degrees around the circumference of the cylindrical phantom. The skin doses obtained from radiochromic film were found to be 47% of the maximum dose of D(max) at the 0degrees beam entry position and 61% at the 90degrees oblique beam position without the mask. Using the mask (1.5 mm), the skin dose received was 59% at 0degrees incidence and 78% at 80degrees incidence. Skin dose results were also gathered using thin thermoluminescent dosimeters (TLD). With the mask, the skin dose was 66% at 0degrees incidence and 80% at 80degrees incidence. This method with the mask revealed the similar pattern as film measurement. For the treatments of the head-and-neck and shoulder regions in which immobilization mask was used, skin doses at around tangential angle were nearly the same as the prescription dose. When a sloping skin contour is encountered, skin doses may be abated using thinner and more perforated immoblization devices which should still maintain immoblization.
Axis, Cervical Vertebra ; Carboxymethylcellulose Sodium ; Immobilization ; Incidence ; Masks ; Prescriptions ; Shoulder ; Skin ; Water

PURPOSE: To compare audio-only biofeedback to conventional audiovisual biofeedback for regulating patients' respiration during four-dimensional radiotherapy, limiting damage to healthy surrounding tissues caused by organ movement. MATERIALS AND METHODS: Six healthy volunteers were assisted by audiovisual or audio-only biofeedback systems to regulate their respirations. Volunteers breathed through a mask developed for this study by following computer-generated guiding curves displayed on a screen, combined with instructional sounds. They then performed breathing following instructional sounds only. The guiding signals and the volunteers' respiratory signals were logged at 20 samples per second. RESULTS: The standard deviations between the guiding and respiratory curves for the audiovisual and audio-only biofeedback systems were 21.55% and 23.19%, respectively; the average correlation coefficients were 0.9778 and 0.9756, respectively. The regularities between audiovisual and audio-only biofeedback for six volunteers' respirations were same statistically from the paired t-test. CONCLUSION: The difference between the audiovisual and audio-only biofeedback methods was not significant. Audio-only biofeedback has many advantages, as patients do not require a mask and can quickly adapt to this method in the clinic.
Biofeedback, Psychology* ; Feedback, Sensory ; Healthy Volunteers ; Humans ; Masks ; Radiotherapy* ; Respiration* ; Volunteers

We evaluated the overall setup accuracy for the On-Board Imager (OBI, Varian Medical Systems Inc., Palo Alto, CA, USA), with attention to the laser, the gantry, and operator performance. We let experienced technicians place the marker block on the couch using a lock bar system, with alignment to the isocenter of the laser, every morning. A pair of radiographic images of the marker block was acquired at 0degrees and 270degrees angles to the kV arm to correct the position using a 2D/2D matching technique. Once the desired match was achieved, the couch was moved remotely to correct the setup error and the parameters were saved. The average for the vertical and the longitudinal displacements were 0.65 mm and 0.66 mm, and 0.01 mm for the lateral displacement. The average for the vertical and longitudinal displacements were statistically significant at the 0.05 level (p value=0.000 for both), while the p value for the lateral direction was 0.829. These results show that the tendencies to displacement in vertical and longitudinal directions occur through systematic error, while systematic error was not found in the lateral displacement. This daily overall evaluation is practical and easy to find the systematic and random errors in the setup system; however, a daily QA for laser and OBI alignment is still needed to minimize the systematic error in aligning patients.
Arm ; Displacement (Psychology) ; Humans ; Hypogonadism ; Linear Energy Transfer ; Mitochondrial Diseases ; Ophthalmoplegia