TBI treatment planning using the ADAC Pinnacle Treatment Planning System

The aim of this work is to establish if the new CT‐based total body irradiation (TBI) planning techniques used at University College London Hospital (UCLH) and Royal Free Hospital (RFH) are comparable to the previous technique at the Middlesex Hospital (MXH) by analyzing predicted and measured diode results. TBI aims to deliver a homogeneous dose to the entire body, typically using extended SSD fields with beam modulation to limit doses to organs at risk. In vivo dosimetry is used to verify the accuracy of delivered doses. In 2005, when the Middlesex Hospital was decommissioned and merged with UCLH, both UCLH and the RFH introduced updated CT‐planned TBI techniques, based on the old MXH technique. More CT slices and in vivo measurement points were used by both; UCLH introduced a beam modulation technique using MLC segments, while RFH updated to a combination of lead compensators and bolus. Semiconductor diodes were used to measure entrance and exit doses in several anatomical locations along the entire body. Diode results from both centers for over five years of treatments were analyzed and compared to the previous MXH technique for accuracy and precision of delivered doses. The most stable location was the field center with standard deviations of 4.1% (MXH), 3.7% (UCLH), and 1.7% (RFH). The least stable position was the ankles. Mean variation with fraction number was within 1.5% for all three techniques. In vivo dosimetry can be used to verify complex modulated CT‐planned TBI, and demonstrate improvements and limitations in techniques. The results show that the new UCLH technique is no worse than the previous MXH one and comparable to the current RFH technique.PACS numbers: 87.55.Qr, 87.56.N‐

Section: Discussionmentioning

confidence: 81%

“…More recently, treatment planning using computed tomography (CT) scans of the patient have been introduced, using either in‐house (9) or commercial software 10 , 11 , 12 , 13 , 14 . CT data allow accurate estimation of organ‐at‐risk doses such as the lung, which usually limits the maximum tolerable dose.…”

Section: Introductionmentioning

confidence: 99%

In vivo dosimetry for total body irradiation: five‐year results and technique comparison

Patel

Warry

Eaton

et al. 2014

“…In the last decade, however, a number of studies have demonstrated the use of commercially available treatment planning systems for TBI dose distribution calculations. ( 1 – 5 ) These studies were based on either standard or modified models using data acquired under TBI conditions (i.e. at extended SSD).…”

Section: Introductionmentioning

confidence: 99%

Validation of the Eclipse AAA algorithm at extended SSD

Hussain

Villarreal-Barajas

Brown

et al. 2010

The accuracy of dose calculations at extended SSD is of significant importance in the dosimetric planning of total body irradiation (TBI). In a first step toward the implementation of electronic, multi‐leaf collimator compensation for dose inhomogeneities and surface contour in TBI, we have evaluated the ability of the Eclipse AAA to accurately predict dose distributions in water at extended SSD. For this purpose, we use the Eclipse AAA algorithm, commissioned with machine‐specific beam data for a 6 MV photon beam, at standard SSD (100 cm). The model was then used for dose distribution calculations at extended SSD (179.5 cm). Two sets of measurements were acquired for a 6 MV beam (from a Varian linear accelerator) in a water tank at extended SSD: i) open beam for 5 × 5, 10 × 10, 20 × 20 and 40×40 cm2 field sizes (defined at 179.5 cm SSD), and ii) identical field sizes but with a 1.3 cm thick acrylic spoiler placed 10 cm above the water surface. Dose profiles were acquired at 5 cm, 10 cm and 20 cm depths. Dose distributions for the two setups were calculated using the AAA algorithm in Eclipse. Confidence limits for comparisons between measured and calculated absolute depth dose curves and normalized dose profiles were determined as suggested by Venselaar et al. The confidence limits were within 2% and 2 mm for both setups. Extended SSD calculations were also performed using Eclipse AAA, commissioned with Varian Golden beam data at standard SSD. No significant difference between the custom commissioned and Golden Eclipse AAA was observed. In conclusion, Eclipse AAA commissioned at standard SSD can be used to accurately predict dose distributions in water at extended SSD for 6 MV open beams.PACS numbers: 87.53.Kn, 87.55.D‐, 87.55.de, 87.56.ng

“…This technique, along with chemotherapy, is most often utilized to treat myeloid and lymphoid disease by providing conditioning for bone marrow transplant (2) . Radiation results in immunosuppression and also eradicates a modest number of radiosensitive tumor cells, clearing the host marrow to allow repopulation with donor marrow cells (3) .…”

Section: Introductionmentioning

confidence: 99%

“…Other studies have explored this subject utilizing the AAA and ADAC Pinnacle (Philips Healthcare, Andover, MA) albeit at much shorter SSDs of less than 180 cm 2 , 13 . This study is unique in that two commissioned dose calculation algorithms are compared to measurements at an extended SSD of 400 cm.…”

Section: Introductionmentioning

confidence: 99%

Going the distance: validation of Acuros and AAA at an extended SSD of 400 cm

Lamichhane

Patel

Studenski

2016

Accurate dose calculation and treatment delivery is essential for total body irradiation (TBI). In an effort to verify the accuracy of TBI dose calculation at our institution, we evaluated both the Varian Eclipse AAA and Acuros algorithms to predict dose distributions at an extended source‐to‐surface distance (SSD) of 400 cm. Measurements were compared to calculated values for a 6 MV beam in physical and virtual phantoms at 400 cm SSD using open beams for both 5×5 and 40×40 cm2 field sizes. Inline and crossline profiles were acquired at equivalent depths of 5 cm, 10 cm, and 20 cm. Depth‐dose curves were acquired using EBT2 film and an ion chamber for both field sizes. Finally, a RANDO phantom was used to simulate an actual TBI treatment. At this extended SSD, care must be taken using the planning system as there is good relative agreement between measured and calculated profiles for both algorithms, but there are deviations in terms of the absolute dose. Acuros has better agreement than AAA in the penumbra region.PACS number(s): 87.55.kd