IGRT. IGRT can increase the accuracy by locating the target volume before and during the treatment.

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Agatha Peters
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1 DERYA ÇÖNE RADIOTHERAPY THERAPIST ACIBADEM KOZYATAGI HOSPITAL RADIATION ONCOLOGY DEPARTMENT IGRT IGRT (image-guided radiation therapy) is a technique that reduces geometric uncertainties by considering the set-up errors and organ movements

radiation therapy) is a technique that reduces geometric

2 IGRT IGRT can increase the accuracy by locating the target volume before and during the treatment. IGRT provides detailed anatomical information about the irradiated region, reduces the differences between planning and treatment and ensures correct set-up (minimal set-up errors) Off line On line Real time Re -calculation Plan adaptation

IGRT provides detailed anatomical information about the irradiated region, reduces

3 Tools kv, MV Diaphragm, lung, bone (density differences) Implanted markers: gold and skin markers, metal clips Optical detectors CBCT Soft tissue differences Set-up accuracy Immobilisation Watching, invigilate Training Image evaluation Set-up correction Adaptive treatment strategies

Soft tissue differences Set-up accuracy Immobilisation Watching,

4 INTRODUCTION Dose increase; Better tumor control Risks of complications increase. IMRT More conformal dose distribution Increasing the dose to target structure while reducing the dose to adjacent normal structures. IGRT is essential for IMRT High dose gradient makes IGRT more important for IMRT Small set-up errors cause big dose differences Treatment should be applied as planned

Prostate IGRT Gold marker inserted prostate can be evaluated by comparing images from Mega-voltage or Kilo-voltage systems with reference images obtained from treatment planning systems.

5 Prostate IGRT Gold marker inserted prostate can be evaluated by comparing images from Mega-voltage or Kilo-voltage systems with reference images obtained from treatment planning systems. CBCT gives information related to both prostate and OAR volumes such as rectum and bladder. Rectum and bladder are hollow organs therefore daily filling differences are important for tumor control and side effects. Dose delivered to the prostate and OAR can be important for the planned dose. DAILY DOSE RECALCULATION Langen et al., Phys Med Biol, 50: , Gy 2 Gy per fx Margins: 6 mm Post 4 mm Daily MVCT Alignment on markers Rectal daily DVHs from recalculation on daily MV CTs Treatment Plan DVH Daily DVHs

Rectum and bladder are hollow organs therefore daily filling differences are important for tumor control and side effects.

6 Our in-house protocol for set-up correction for prostate cancer patients requires: kv-cbct (Cone Beam Computerized Tomography based kv) before treatment Physicians evaluate the CBCT on the 1 st fraction, afterwards it is evaluated by RTTs and correct set-up errors < 5 mm and inform physicians if the correction is > 5 mm CBCT is taken for the first 5 fractions, and once a week for the rest of the treatment

$correction is > 5 mm CBCT is taken for the first 5 fractions, and once a week for the rest of the$

7 Diet SET UP Rectal- Bladder Filling Simulation and treatment can be arranged to be at the same time of the day. below-knee pillow The use of pillows and ankle stabilizer ankle stabilizer PURPOSE In this study, we aimed to determine the feasibility of incorporating a teaching intervention on soft tissue anatomy match of cone beam CT (CBCT) to radiation therapist s (RTT) training and its contribution to RTT skills.

below-knee pillow The use of pillows and ankle stabilizer ankle stabilizer PURPOSE In this study, we

8 MATERIALS Twenty CBCT images of 6 prostate cancer patients were used in this study. Patients were treated in the supine position with knee-foot stabilizer and with full bladders. MATERIALS CBCT images were obtained with gantry starting at and making a turn in approximately 60 seconds. Images, in 2.5-mm slice intervals and 15 cm length, were taken by using a half fan-bow tie filter.

MATERIALS CBCT images were obtained with gantry starting at 180 0 and making a 360 0 turn in

9 MATERIALS The participants attended a training on prostate anatomy and radiology which consisted of seminars and practical training lectured by a diagnostic radiologist. Training Prostate apex evaluation Seminal vesicles

seminars and practical training lectured by a

10 CBCT The ability to view 3-D CT image of the target and normal tissues Assesment according to the soft tissue and prostate Total set-up time including CBCT acquisition and evaluation ~12-15 minutes MATERIALS On Clinac DHX-OBI(Varian-On Board Imaging ), pretreatment CBCT images were aligned with treatment planning CT scans manually and off-line by 4 RTTs. Planning CT and CBCT images were also aligned by a radiation oncologist, and results were accepted as "reference value" (RV) for each patient. RTTs were asked to repeat the CBCT match for evaluation after training.

aligned with treatment planning CT scans manually and off-line by 4 RTTs.

11 Planning CT- CBCT Planning CT- CBCT

12 MATERIALS Vertical, lateral, and longitudinal vectors were calculated according to the set-up corrections of each RTT for all CBCTs. These values were compared with the RV and differences between pre-training were obtained, Alignment times were measured for pre and post training and contribution of teaching intervention on set-up correction time was evaluated. MATERIALS RTTs were asked to complete a survey to assess the training s efficiency.

These values were compared with the RV and differences between pre-training were obtained, Alignment times were

13 DIFFERENCES BETWEEN RV AND PRE-TRAINING, POST-TRAINING RESULTS Contribution of training on set-up correction was found significant for 3 of the RTTs, while significance was limited for 1 RTT. Set-up corrections were found to be improved by 75%, 65%, 60% and 45%. Alignment times improved for 2 RTTs while remained stable for the other 2.

14 RESULTS Survey assessment showed the training was useful to refresh the knowledge of anatomy and radiology of prostate and contributed to the identification of apex. CONCLUSIONS Image guided radiation therapy applications and the use of CBCT for set-up verification provides more accurate treatment. Our study shows that incorporating a teaching intervention in RTTs refresher courses is feasible and is useful for optimal evaluation.

CONCLUSIONS Image guided radiation therapy applications and the use of CBCT for set-up verification provides

15 THANK YOU...

Radiation Protection in Radiotherapy

Radiation Protection in Radiotherapy Albert Lisbona Medical Physics Department CLCC Nantes Atlantique 44805 Saint-Herblain France [email protected] Radiation therapy The lecture is oriented to