Spatially resolved measurement of wideband prompt gamma-ray emission toward on-line monitor for the future proton therapy

Koide, A.; Kataoka, J.; Taya, T.; Iwamoto, Yasuhiro; Sueoka, Koki; Mochizuki, Seibu; Arimoto, M.; Inaniwa, Taku

doi:10.1016/j.nima.2017.10.020

Cited by 3 publications

(7 citation statements)

References 16 publications

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“…As noted above, the 4.4 MeV gamma ray line consists of 4438 keV from 12 C * and 4444 keV from 11 B * , but the former cross section is two orders of magnitude larger, hence only that of 4438 keV is plotted in the figure. Also note that the 511 keV gamma rays can be emitted from various positron emitters, such as 15 O, 13 N, and 11 C, but emission from 15 O is dominant during proton irradiation 44 . Clearly, the energy threshold for a major nuclear reaction that emit 4.4 MeV lines, 12 C(p,p) 12 C * , is much lower than other nuclear reaction channels; approximately 6 MeV as compared to 14 MeV for 16 O(p,x) 15 O that emit 511 keV, and 25 MeV for 12 C(p,x) 10 B * that emit 718 keV gamma rays.…”

Section: Discussionmentioning

confidence: 99%

“…Note that the very broad structures most clearly seen in the PMMA spectra between 3 MeV and 5 MeV (shown as a thick green line), is the combination of prompt gamma rays emitted from 12 C * (4438 keV) and 11 B * (4444 keV) and their single or double escape peaks. In contrast, the only prominent line in the off-beam spectrum is the 511 keV annihilation line from a positron emitter like 15 O. As noted above, these 511 keV gamma rays are being widely used for offline monitoring in proton therapy.…”

Section: Prompt Gamma-ray Spectramentioning

confidence: 99%

“…The typical range of clinical proton beam is approximately 25 cm in both water and PMMA, whereas the range is 3.5 cm for 70 MeV protons. Therefore, if we place the 3D-PSCC 20 cm from the proton beam axis, it would be difficult to quantitatively compare with the proton dose distribution, even with the obtained spatial distribution of 4.4 MeV image 15 . Therefore, we used eight 5 mm thick PMMA slab phantoms that were placed 20 mm apart.…”

Section: Setup For Imaging 44 Mev Gamma Raysmentioning

confidence: 99%

“…Despite such difficulties, however, imaging of 1−10 MeV gamma rays may provide fruitful scientific/technical outputs because most nuclear gamma ray lines are narrowly concentrated in this particular energy band. For example, in proton therapy, incident protons interact with atoms in the patient's body, and then promptly emit nuclear gamma rays, such as 4.4 MeV lines from 12 C * and 11 B * , and the 6.2 MeV line from 15 O * 11-15 . These gamma rays are supposed to be a new tool for online monitoring of dose delivery and/or proton range verification [16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

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Precision imaging of 4.4 MeV gamma rays using a 3-D position sensitive Compton camera

Koide

Kataoka

Masuda

et al. 2018

Sci Rep

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Imaging of nuclear gamma-ray lines in the 1–10 MeV range is far from being established in both medical and physical applications. In proton therapy, 4.4 MeV gamma rays are emitted from the excited nucleus of either 12C* or 11B* and are considered good indicators of dose delivery and/or range verification. Further, in gamma-ray astronomy, 4.4 MeV gamma rays are produced by cosmic ray interactions in the interstellar medium, and can thus be used to probe nucleothynthesis in the universe. In this paper, we present a high-precision image of 4.4 MeV gamma rays taken by newly developed 3-D position sensitive Compton camera (3D-PSCC). To mimic the situation in proton therapy, we first irradiated water, PMMA and Ca(OH)2 with a 70 MeV proton beam, then we identified various nuclear lines with the HPGe detector. The 4.4 MeV gamma rays constitute a broad peak, including single and double escape peaks. Thus, by setting an energy window of 3D-PSCC from 3 to 5 MeV, we show that a gamma ray image sharply concentrates near the Bragg peak, as expected from the minimum energy threshold and sharp peak profile in the cross section of 12C(p,p)12C*.

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Section: Discussionmentioning

confidence: 99%

Section: Prompt Gamma-ray Spectramentioning

confidence: 99%

Section: Setup For Imaging 44 Mev Gamma Raysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Precision imaging of 4.4 MeV gamma rays using a 3-D position sensitive Compton camera

Koide

Kataoka

Masuda

et al. 2018

Sci Rep

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“…Future researchers could use this most probable dose as a starting point for dose prescription reduction: We hypothesize that one can use in-room CT for positioning verification and dose recalculation together with dose verification (e.g. prompt gamma-ray emission [ 13 ] or PET autoactivation [ 14 ]) to ensure target coverage and reduce D95 to 55.1 Gy(RBE) rather than the planned value of 57.1 Gy(RBE) in the absence of in-room CT. From these use cases we think the blurred DVH most-probable dose method is an important clinical contribution to evaluate carbon ion treatment of targets with uncorrected interfractional motion.…”

Section: Discussionmentioning

confidence: 99%

Probabilistic dose distribution from interfractional motion in carbon ion radiation therapy for prostate cancer shows rectum sparing with moderate target coverage degradation

2018

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PurposeThis observational study investigates the influence of interfractional motion on clinical target volume (CTV) coverage, planning target volume (PTV) margins, and rectum tissue sparing in carbon ion radiation therapy (CIRT). It reports dose coverage to target structures and organs at risk in the presence of interfractional motion, investigates rectal tissue sparing, and provides recommendations for lowering the rate of toxicity. We also propose probabilistic DVH based on cone-beam computed tomography (CBCT) table shifts from photon therapy for consideration in bone-matching CIRT treatment planning to represent probable dose to our CIRT patient population.MethodsAt Gunma University Hospital intensity-modulated x-ray therapy (IMXT, aka IMRT) prostate cancer patients are positioned on a table which is shifted twice based on CBCT to align bones and then align prostate tissue to isocenter. These shifts thereby contain interfractional motion. A total of 1306 such table shifts from 85 patients were collected. Normal probability distributions were fit to the difference between bone-matching and prostate-matching CBCT-to-planning CT table shifts (i.e. interfractional motion). Between 2011 and 2016 CIRT prostate patients were treated with three beams to PTV1 (lateral-opposing and anterior) one per day for 9 fractions and two beams for a boost PTV2 (lateral-opposing) one per day for 7 fractions for a prescribed total of 57.6 Gy(RBE) as follows: PTV1 extends the prostate contour by 10/10, 5/10, 6/6 mm in the right/left, posterior/anterior, and superior/inferior directions, respectively, and the proximal seminal vesicles contour by 5 mm superiorly and inferiorly, 3 mm right and left. PTV2 reduces PTV1 posteriorly along a straight line to exclude the rectum and reduces the superior and inferior margins by 6 mm. Probable interfractional motion for 40 patients was simulated using each patient’s own beam data as follows: The previously fit normal probability distributions were randomly sampled 2000 times per patient, and the five beams were shifted and summed with the same relative weighting as in the 16-fraction regimen. The resulting dose distribution was then scaled back down by 16/2000 to match the prescribed number of fractions. We then analyzed the resulting doses to contoured structures.ResultsProbable dose to rectum is substantially less than planned: For example, mean+-standard deviation D2% for planned and probable DVH is 51+-1.9 and 45+-2.4, respectively. Cumulative DVH show mean CTV fraction receiving a given probable dose is less than the mean fraction receiving the corresponding planned dose for doses larger than 52 Gy(RBE), up to 19% less at 57.4 Gy(RBE). Our PTV1 margins generally cover 95% of interfractional motion but seminal vesicles and inferior prostate receive less dose than planned due to insufficient PTV2 margins.ConclusionAssuming rigidly shifting interfractional motion around the prostate region and neglecting minor changes in soft tissue stopping power, interfractional motion resulted in target un...

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Multi-modal 3D imaging of radionuclides using multiple hybrid Compton cameras

Omata

Masubuchi

Koshikawa

et al. 2022

Sci Rep

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For radiological diagnosis and radionuclide therapy, X-ray and gamma-ray imaging technologies are essential. Single-photon emission tomography (SPECT) and positron emission tomography (PET) play essential roles in radiological diagnosis, such as the early detection of tumors. Radionuclide therapy is also rapidly developing with the use of these modalities. Nevertheless, a limited number of radioactive tracers are imaged owing to the limitations of the imaging devices. In a previous study, we developed a hybrid Compton camera that conducts simultaneous Compton and pinhole imaging within a single system. In this study, we developed a system that simultaneously realizes three modalities: Compton, pinhole, and PET imaging in 3D space using multiple hybrid Compton cameras. We achieved the simultaneous imaging of Cs-137 (Compton mode targeting 662 keV), Na-22 (PET mode targeting 511 keV), and Am-241 (pinhole mode targeting 60 keV) within the same field of view. In addition, the imaging of Ga-67 and In-111, which are used in various diagnostic scenarios, was conducted. We also verified that the 3D distribution of the At-211 tracer inside a mouse could be imaged using the pinhole mode.

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Spatially resolved measurement of wideband prompt gamma-ray emission toward on-line monitor for the future proton therapy

Cited by 3 publications

References 16 publications

Precision imaging of 4.4 MeV gamma rays using a 3-D position sensitive Compton camera

Precision imaging of 4.4 MeV gamma rays using a 3-D position sensitive Compton camera

Probabilistic dose distribution from interfractional motion in carbon ion radiation therapy for prostate cancer shows rectum sparing with moderate target coverage degradation

Multi-modal 3D imaging of radionuclides using multiple hybrid Compton cameras

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