Design and construction of the 1st proton CT scanner

Coutrakon, G.; Bashkirov, V.; Hurley, Ford; Johnson, Rucker C.; Rykalin, V.; Sadrozinski, H. F-W.; Schulte, R.

doi:10.1063/1.4802343

Cited by 11 publications

(13 citation statements)

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“…The Phase I scanner consisted of four position‐sensitive detector modules to infer proton path and a segmented CsI (Tl) crystal calorimeter as a residual energy‐range detector (RERD). With this scanner and earlier conceptual studies using Monte Carlo simulations encouraging results were reported, indicating that an RSP accuracy of better than 1% may be possible . In 2011, LLU, UCSC, and California State University, San Bernardino (CSUSB), started the development of the next generation phase II pCT scanner.…”

Section: Introductionmentioning

confidence: 85%

“…With this scanner and earlier conceptual studies using Monte Carlo simulations encouraging results were reported, indicating that an RSP accuracy of better than 1% may be possible. [9][10][11][12][13][14][15][16][17][18][19] In 2011, LLU, UCSC, and California State University, San Bernardino (CSUSB), started the development of the next generation phase II pCT scanner. The system, completed in 2011, is capable of imaging phantom heads and QA phantoms with protons of a nominal energy of 200 MeV.…”

Section: Introductionmentioning

confidence: 99%

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The effect of beam purity and scanner complexity on proton CT accuracy

et al. 2017

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Purpose To determine the dependence of the accuracy in reconstruction of relative stopping power (RSP) with proton computerized tomography (pCT) scans on the purity of the proton beam and the technological complexity of the pCT scanner using standard phantoms and a digital representation of a pediatric patient. Methods The Monte Carlo method was applied to simulate the pCT scanner, using both a pure proton beam (uniform 200 MeV mono-energetic, parallel beam) and the Northwestern Medicine Chicago Proton Center (NMCPC) clinical beam in uniform scanning mode. The accuracy of the simulation was validated with measurements performed at NMCPC including reconstructed RSP images obtained with a preclinical prototype pCT scanner. The pCT scanner energy detector was then simulated in three configurations of increasing complexity: an ideal totally absorbing detector, a single stage detector and a multi-stage detector. A set of 15 cm diameter water cylinders containing either water alone or inserts of different material, size, and position were simulated at 90 projection angles (4° steps) for the pure and clinical proton beams and the three pCT configurations. A pCT image of the head of a detailed digital pediatric phantom was also reconstructed from the simulated pCT scan with the prototype detector. Results The RSP error increased for all configurations for insert sizes under 7.5 mm in radius, with a sharp increase below 5 mm in radius, attributed to a limit in spatial resolution. The highest accuracy achievable using the current pCT calibration step-phantom and reconstruction algorithm, calculated for the ideal case of a pure beam with totally absorbing energy detector, was 1.3% error in RSP for inserts of 5 mm radius or more, 0.7 mm in range for the 2.5 mm radius inserts, or better. When the highest complexity of the scanner geometry was introduced, some artifacts arose in the reconstructed images, particularly in the center of the phantom. Replacing the step-phantom used for calibration with a wedge phantom led to RSP accuracy close to the ideal case, with no significant dependence of RSP error on insert location or material. The accuracy with the multi-stage detector and NMCPC beam for the cylindrical phantoms was 2.2% in RSP error for inserts of 5 mm radius or more, 0.7 mm in range for the 2.5 mm radius inserts, or better. The pCT scan of the pediatric phantom resulted in mean RSP values within 1.3% of the reference RSP, with a range error under 1 mm, except in exceptional situations of parallel incidence on a boundary between low and high density. Conclusions The pCT imaging technique proved to be a precise and accurate imaging tool, rivalling the current x-rays based techniques, with the advantage of being directly sensitive to proton stopping power rather than photon interaction coefficients. Measured and simulated pCT images were obtained from a wobbled proton beam for the first time. Since the in-silico results are expected to accurately represent the prototype pCT, upcoming measurements using the wedge p...

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Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

The effect of beam purity and scanner complexity on proton CT accuracy

et al. 2017

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“…Replacing X‐ray planning CT with proton CT (pCT) planning CT simulations with individual proton tracking during the scan has been proposed as a low‐dose method to reduce this planning uncertainty; pretreatment pCT would also provide a method for pretreatment verification of correct patient setup and RSP distribution. This method is currently in the preclinical stage of its development …”

Section: Introductionmentioning

confidence: 99%

Accuracy of low‐dose proton CT image registration for pretreatment alignment verification in reference to planning proton CT

Cassetta

Piersimoni

Riboldi

et al. 2019

J Applied Clin Med Phys

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Purpose Proton CT (pCT) has the ability to reduce inherent uncertainties in proton treatment by directly measuring the relative proton stopping power with respect to water, thereby avoiding the uncertain conversion of X‐ray CT Hounsfield unit to relative stopping power and the deleterious effect of X‐ ray CT artifacts. The purpose of this work was to further evaluate the potential of pCT for pretreatment positioning using experimental pCT data of a head phantom. Methods The performance of a 3D image registration algorithm was tested with pCT reconstructions of a pediatric head phantom. A planning pCT simulation scan of the phantom was obtained with 200 MeV protons and reconstructed with a 3D filtered back projection (FBP) algorithm followed by iterative reconstruction and a representative pretreatment pCT scan was reconstructed with FBP only to save reconstruction time. The pretreatment pCT scan was rigidly transformed by prescribing random errors with six degrees of freedom or deformed by the deformation field derived from a head and neck cancer patient to the pretreatment pCT reconstruction, respectively. After applying the rigid or deformable image registration algorithm to retrieve the original pCT image before transformation, the accuracy of the registration was assessed. To simulate very low‐dose imaging for patient setup, the proton CT images were reconstructed with 100%, 50%, 25%, and 12.5% of the total number of histories of the original planning pCT simulation scan, respectively. Results The residual errors in image registration were lower than 1 mm and 1° of magnitude regardless of the anatomic directions and imaging dose. The mean residual errors ranges found for rigid image registration were from −0.29 ± 0.09 to 0.51 ± 0.50 mm for translations and from −0.05 ± 0.13 to 0.08 ± 0.08 degrees for rotations. The percentages of sub‐millimetric errors found, for deformable image registration, were between 63.5% and 100%. Conclusion This experimental head phantom study demonstrated the potential of low‐dose pCT imaging for 3D image registration. Further work is needed to confirm the value pCT for pretreatment image‐guided proton therapy.

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“…To image adult patients requires an entrance energy somewhat higher than the 250 MeV needed for treatment -330 MeV being a common specification due to the need to measure the residual energy accurately enough in a calorimeter -and some accelerator designs (such as for example the ProTom synchrotron design [155]) address the need for these energies. Gantries must of course be able to handle both treatment and imaging if techniques such as pCT are to be taken toward clinical use from the present point of technical demonstration [149]. Hand in hand with improved imaging to support proton therapy must be the development of improved calculation methods, and a rapidly-developing area is the much greater use of Monte Carlo techniques in codes such as GEANT4 [42,156].…”

Section: Imaging With Acceleratorsmentioning

confidence: 99%

“…Many such measurements (somewhat less than a billion [149]) of individual proton energy loss with trajectory may be combined to create a proton computed tomograph (pCT) [150][151][152][153][154]. To image adult patients requires an entrance energy somewhat higher than the 250 MeV needed for treatment -330 MeV being a common specification due to the need to measure the residual energy accurately enough in a calorimeter -and some accelerator designs (such as for example the ProTom synchrotron design [155]) address the need for these energies.…”

Section: Imaging With Acceleratorsmentioning

confidence: 99%

Hadron accelerators for radiotherapy

Owen

Mackay

Peach

et al. 2014

Contemporary Physics

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Over the last twenty years the treatment of cancer with protons and light nuclei such as carbon ions has moved from being the preserve of research laboratories into widespread clinical use. A number of choices now exist for the creation and delivery of these particles, key amongst these being the adoption of pencil beam scanning using a rotating gantry; attention is now being given to what technologies will enable cheaper and more effective treatment in the future. In this article the physics and engineering used in these hadron therapy facilities is presented, and the research areas likely to lead to substantive improvements. The wider use of superconducting magnets is an emerging trend, whilst further ahead novel high-gradient acceleration techniques may enable much smaller treatment systems. Imaging techniques to improve the accuracy of treatment plans must also be developed hand-in-hand with future sources of particles, a notable example of which is proton computed tomography.

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Design and construction of the 1st proton CT scanner

Cited by 11 publications

References 0 publications

The effect of beam purity and scanner complexity on proton CT accuracy

The effect of beam purity and scanner complexity on proton CT accuracy

Accuracy of low‐dose proton CT image registration for pretreatment alignment verification in reference to planning proton CT

Hadron accelerators for radiotherapy

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