• The Journal of Korean Society for Radiation Therapy
• /
• v.26 no.1
• /
• pp.115-126
• /
• 2014

Purpose : Depending on a variety of therapeutic areas using MVCT(Megavoltage computed tomography) intra-and interfraction is to evaluate changes in patient position. Materials and Methods : In this study, head and neck, thorax, liver, and prostate tumor patients, 48 people with a full course of treatment for patients with various MVCT scan was performed. Average 60 per patient MVCT images were acquired and analyzed. Results : Interfraction error thorax and abdomen, and pelvis in the longitudinal difference was more than 3 mm. Intrafraction to see a change after the end of treatment MVCT taken, and the results confirmed Intrafraction 2 mm in motion around the longitudinal difference. In addition, due to changes in the movement before and after treatment, Inter-and Intrafraction difference was found. Conclusion : In the present study, the Head and Neck, Thorax, liver, prostate cancer in patients with inter-and intrafraction changes and target the appropriate fixtures to complete the outline of the margin would be helpful is considered.

• The Journal of Korean Society for Radiation Therapy
• /
• v.26 no.1
• /
• pp.69-76
• /
• 2014

Purpose : To evaluate the changes of the motion of abdominal cavity between interfraction and intrafraction by using abdominal compression for reducing abdominal motion. Materials and Methods : 60 MVCT images were obtained before and after tomotherapy from 10 prostate cancer patients over the whole radiotherapy period. Shift values ( X -lateral Y -longitudinal Z -vertical and Roll ) were measured and from it, the correlation of between interfraction set up change and intrafraction target motion was analyzed when applying abdominal compression. Results : The motion changes of interfraction were X-average $0.65{\pm}2.32mm$, Y-average $1.41{\pm}4.83mm$, Z-average $0.73{\pm}0.52mm$ and Roll-average $0.96{\pm}0.21mm$. The motion changes of intrafraction were X-average $0.15{\pm}0.44mm$, Y-average $0.13{\pm}0.44mm$, Z-average $0.24{\pm}0.64mm$ and Roll-average $0.1{\pm}0.9mm$. The average PTV maximum dose difference was minimum for 10% phase and maximum for 70% phase. The average Spain cord maximum dose difference was minimum for 0% phase and maximum for 50% phase. The average difference of $V_{20}$, $V_{10}$, $V_5$ of Lung show bo certain trend. Conclusion : Abdominal compression can minimize the motion of internal organs and patients. So it is considered to be able to get more ideal dose volume without damage of normal structures from generating margin in small in producing PTV.

• Progress in Medical Physics
• /
• v.26 no.4
• /
• pp.286-293
• /
• 2015

The purpose of this study was to evaluate the set up accuracy using stereotactic body frame and frameless immobilizer for lung stereotactic body radiation therapy (SBRT). For total 40 lung cancer patients treated by SBRT, 20 patients using stereotactic body frame and other 20 patients using frameless immobilizer were separately enrolled in each group. The setup errors of each group depending on the immobilization methods were compared and analyzed. All patients received the dose of 48~60 Gy for 4 or 5 fractions. Before each treatment, a patient was first localized to the treatment isocenter using room lasers, and further aligned with a series of image guidance procedures; orthogonal kV radiographs, cone-beam CT, orthogonal fluoroscopy. The couch shifts during these procedures were recorded and analyzed for systematic and random errors of each group. Student t-test was performed to evaluate significant difference depending on the immobilization methods. The setup reproducibility was further analyzed using F-test with the random errors excluding the systematic setup errors. In addition, the ITV-PTV margin for each group was calculated. The setup errors for SBF were $0.05{\pm}0.25cm$ in vertical direction, $0.20{\pm}0.38cm$ in longitudinal direction, and $0.02{\pm}0.30cm$ in lateral direction, respectively. However the setup errors for frameless immobilizer showed a significant increase of $-0.24{\pm}0.25cm$ in vertical direction while similar results of $0.06{\pm}0.34cm$, $-0.02{\pm}0.25cm$ in longitudinal and lateral directions. ITV-PTV margins for SBF were 0.67 cm (vertical), 0.99 cm (longitudinal), and 0.83 cm (lateral), respectively. On the other hand, ITV-PTV margins for Frameless immobilizer were 0.75 cm (vertical), 0.96 cm (longitudinal), and 0.72 cm (lateral), indicating less than 1 mm difference for all directions. In conclusion, stereotactic body frame improves reproducibility of patient setup, resulted in 0.1~0.2 cm in both vertical and longitudinal directions. However the improvements are not substantial in clinic considering the effort and time consumption required for SBF setup.