A Copper Shield for the Reduction of X-γ True Coincidence Summing in Gamma-ray Spectrometry

Byun, Jong-In The Korean Association for Radiation Protection 2018 방사선방어학회지 Vol.43 No.4

Background: Gamma-ray detectors having a thin window of a material with low atomic number can increase the true coincidence summing effects for radionuclides emitting X-rays or gamma-rays. This effect can make efficiency calibration or spectrum analysis more complicated. In this study, a Cu shield was tested as an X-ray filter to neglect the true coincidence summing effect by X-rays and gamma-rays in gamma-ray spectrometry, in order to simplify gamma-ray energy spectrum analysis. Materials and Methods: A Cu shield was designed and applied to an n-type high-purity germanium detector having an $X-{\gamma}$ summing effect during efficiency calibration. This was tested using a commercial, certified mixed gamma-ray source. The feasibility of a Cu shield was evaluated by comparing efficiency calibration results with and without the shield. Results and Discussion: In this study, the thickness of a Cu shield needed to avoid true coincidence summing effects due to $X-{\gamma}$ was tested and determined to be 1 mm, considering the detection efficiency desired for higher energy. As a result, the accuracy of the detection efficiency calibration was improved by more than 13% by reducing $X-{\gamma}$ summing. Conclusion: The $X-{\gamma}$ summing effect should be considered, along with ${\gamma}-{\gamma}$ summing, when a detection efficiency calibration is implemented and appropriate shielding material can be useful for simplifying analysis of the gamma-ray energy spectra.

68Ga-DOTATOC PET/CT에서 Prompt Gamma Correction을 적용한 SUV의 평가

윤석환 한국방사선학회 2018 한국방사선학회 논문지 Vol.12 No.1

68Ga was eluted from a 68Ge/68Ga radionuclide generator. 68Ga decays into 68Zn, with a half life=67.8min. The decay is 88.9 % by β+ and 11.1 % by EC. The main β+ decay (87.7 %) is to the ground level of 68Zn and it is a pure positron emission branch. A small fraction decays β+ (1.2 %) into an excited level of 68Zn, which promptly decays into the ground level with a γ (1.077 Mev). This can constitute prompt gamma contamination in the PET data, if the 1.077 Mev γ has a scatter interaction in the patient, and generates a lower energy γ in coincidence with the positron annihilation pair. The purpose of this study was to evaluate standardized uptake value(SUV) before and after applying prompt gamma rays correction on 68Ga-DOTATOC PET/CT image. Fifty patient underwent PET/CT 1 hour after injection of the 68Ga-DOTATOC. The SUVmax and SUVmean of lesions and normal tissues (Pituitary, Lung, Liver, Spleen, Kidney, Intestine) were evaluated before and after applying prompt gamma correction on 68Ga-DOTATOC PET/CT image. Additionally, the SUVmax of each lesions and SUVmean of the soft tissues were measured on images. and target to background ratios (TBR) were calculated as quantitative indices. Among 15 patients, 25 of lesions (Pancreas, Liver, Thoracic Spine, Brain) with increased uptake on 68Ga-DOTATOC PET/CT image. SUVmax and SUVmean were increased in lesion site and normal tissue after prompt gamma rays correction. TBR was 51.51 ± 49.28 and 55.50 ± 53.12 before and after prompt gamma rays correction, respectively. (p<0.0001) 68Ga 방사성 핵종은 68Ge/68Ga 제너레이터에서 생산되는 양전자 방출핵종으로서 PET 검사에 이용되는 방사성 핵종이다. 68Ga은 67.8분의 반감기를 가지고 88.9 %의 β+ 붕괴와 11.1 %의 전자포획으로 68Zn으로 붕괴된다. β+ 붕괴 과정에서 87.7 %는 기저상태의 68Zn로 붕괴되며, 1.2 %는 여기상태의 68Zn로 붕괴된다. 여기상태의 68Zn은 1.077 Mev의 γ선을 방출하며 기저상태의 68Zn가 된다. 이때 방출되는 1.077 Mev의 γ선을 Prompt Gamma라 하며, Prompt Gamma-ray가 환자와 상호작용하게 되면 저에너지 γ선의 산란선이 발생되게 되는데 이 산란선이 PET의 동시계수 회로에 검출되어 질 수 있다. 이 연구의 목적은 68Ga을 이용하는 PET검사 중 신경내분비 종양진단에 사용되는 68Ga-DOTATOC PET/CT영상에 Prompt Gamma-ray 보정 전 후의 표준섭취계수(SUV)를 평가해 보고자 하였다. 68Ga-DOTATOC PET/CT를 시행한 15명의 환자에 대해서 병변부위(Pancreas, Liver, Thoracic Spine, Brain)와 정상으로 섭취되는 조직(Pituitary, Lung, Liver, Spleen, Kidney, Intestine)의 SUVmax와 SUVmean을 비교하였으며, 임상영상의 정량적 평가를 위해 Target to Background Ratio(TBR)을 산출하여 비교하였다. Prompt Gamma-ray 보정 후 Thoracic Spine을 제외한 병변부위와 Pituitary를 제외한 정상조직에서 SUVmax, SUVmean은 높은 값을 나타내었으며, TBR은 Prompt Gamma-ray 보정 전 후 각각 51.51±49.28, 55.50±53.12로 보정 후 높은 값을 나타냈다. (p<0.0001)

⁶⁸Ga-DOTATOC PET/CT에서 Prompt Gamma Correction을 적용한 SUV의 평가

윤석환 ( Seok Hwan Yoon ) 한국방사선학회 2018 한국방사선학회 논문지 Vol.12 No.1

⁶⁸Ga 방사성 핵종은 ⁶⁸Ge/⁶⁸Ga 제너레이터에서 생산되는 양전자 방출핵종으로서 PET 검사에 이용되는 방사성 핵종이다. ⁶⁸Ga은 67.8분의 반감기를 가지고 88.9 %의 β+ 붕괴와 11.1 %의 전자포획으로 ⁶⁸Zn으로 붕괴된다. β⁺ 붕괴 과정에서 87.7 %는 기저상태의 ⁶⁸Zn로 붕괴되며, 1.2 %는 여기상태의 ⁶⁸Zn로 붕괴된다. 여기상태의 ⁶⁸Zn은 1.077 Mev의 γ선을 방출하며 기저상태의 ⁶⁸Zn가 된다. 이때 방출되는 1.077 Mev의 γ선을 Prompt Gamma라 하며, Prompt Gamma-ray가 환자와 상호작용하게 되면 저에너지 γ선의 산란선이 발생되게 되는데 이 산란선이 PET의 동시계수 회로에 검출되어 질 수 있다. 이 연구의 목적은 ⁶⁸Ga을 이용하는 PET검사 중 신경내분비 종양진단에 사용되는 ⁶⁸Ga-DOTATOC PET/CT영상에 Prompt Gamma-ray 보정 전 후의 표준섭취계수(SUV)를 평가해 보고자 하였다. ⁶⁸Ga-DOTATOC PET/CT를 시행한 15명의 환자에 대해서 병변부위(Pancreas, Liver, Thoracic Spine, Brain)와 정상으로 섭취되는 조직(Pituitary, Lung, Liver, Spleen, Kidney, Intestine)의 SUVmax와 SUVmean을 비교하였으며, 임상영상의 정량적 평가를 위해 Target to Background Ratio(TBR)을 산출하여 비교하였다. Prompt Gamma-ray 보정 후 Thoracic Spine을 제외한 병변부위와 Pituitary를 제외한 정상조직에서 SUVmax, SUVmean은 높은 값을 나타내었으며, TBR은 Prompt Gamma-ray 보정 전 후 각각 51.51±49.28, 55.50±53.12 로 보정 후 높은 값을 나타냈다. (p<0.0001) ⁶⁸Ga was eluted from a ⁶⁸Ge/⁶⁸Ga radionuclide generator. 68Ga decays into 68Zn, with a half life=67.8min. The decay is 88.9 % by β+ and 11.1 % by EC. The main β+ decay (87.7 %) is to the ground level of ⁶⁸Zn and it is a pure positron emission branch. A small fraction decays β+ (1.2 %) into an excited level of ⁶⁸Zn, which promptly decays into the ground level with a γ (1.077 Mev). This can constitute prompt gamma contamination in the PET data, if the 1.077 Mev γ has a scatter interaction in the patient, and generates a lower energy γ in coincidence with the positron annihilation pair. The purpose of this study was to evaluate standardized uptake value(SUV) before and after applying prompt gamma rays correction on ⁶⁸Ga-DOTATOC PET/CT image. Fifty patient underwent PET/CT 1 hour after injection of the ⁶⁸Ga-DOTATOC. The SUVmax and SUVmean of lesions and normal tissues (Pituitary, Lung, Liver, Spleen, Kidney, Intestine) were evaluated before and after applying prompt gamma correction on 68Ga-DOTATOC PET/CT image. Additionally, the SUVmax of each lesions and SUVmean of the soft tissues were measured on images. and target to background ratios (TBR) were calculated as quantitative indices. Among 15 patients, 25 of lesions (Pancreas, Liver, Thoracic Spine, Brain) with increased uptake on ⁶⁸Ga-DOTATOC PET/CT image. SUVmax and SUVmean were increased in lesion site and normal tissue after prompt gamma rays correction. TBR was 51.51 ± 49.28 and 55.50 ± 53.12 before and after prompt gamma rays correction, respectively. (p<0.0001)

Performance Study of Gamma-ray Imager Using Gridded Collimator for Near-Field Imaging

J. H. Ha,김남영 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The performance of a gamma-ray imager was investigated that consists of one pair of gridded-collimators and non-position sensitive NaI(Tl) detector. A gamma-ray imager with rotation collimators do not require the position-sensitive detector in order to search for the position of gamma-ray sources. Such gamma-ray imager of simple operation has the use-values for constant surveillance in the restricted area at a radioactive facility. A modulation pattern which is produced by rotation collimators contains the information necessary to reconstruct the position of gamma-ray source. Hence a reconstruction algorithm must be applied to the experimental data with an ideal function of modulation pattern. A reconstructed images from a ^(133)Ba gamma-ray source has been obtained by using a simple back-projection algorithm. The reconstructed image which have nothing to do with energy selection shows the correspondence the location of gamma-ray source. The ideal image resolution is about 1.4˚ but the experimental image resolution shows about 2.5˚ FWHM. And also because the gridded collimator has a symmetrical structure and the ideal modulation function is completely identical to every half-rotation of the collimator, the mirror image is reconstructed on the image plane. The present gamma-ray imager is enough to obtain a rough location rather then a precise location of gamma-ray. Consequently, the method of rotation collimator has the possibility of getting an image without a position-sensitive detector.

기내$\gamma$-선 처리에 의한 감(Diospyros kaki Thunb.) 돌연변이 유기

고갑천 한국식물생명공학회 2000 식물생명공학회지 Vol.27 No.2

This study was carried out to know the optimum dose of gamma-ray for the induction of mutation in vitro and the characteristics of the mutants induced by gamma-ray in persimmon (Diospyros kaki Thunb.). The LD50 (50% lethal dose) for in vitro shoots of the cultivar, Nishimurawase was between 1 krad and 2 krad and about 1 krad for the cultivar, Ichikikeijiro. As the dose of gamma-ray increased, the length of shoots decreased and necrosis of buds increased. For the cultivar, Nishmurawase, 37.5∼58.3% shoots rooted and the rooting rate and the number of roots per shoot was low in high gamma-ray. The irradiated young plants which were grown in the growth cabinet for 6 weeks were shorter in shoot length and had more branches than non-irradiated plants. The survival rate of irradiated plants grown in the green house for 3 months was 33%, while 77% for control plants. 감 돌연변이 획득을 위해 기내배양 신초에 ${\gamma}$-선을 조사하여 변이유기를 위한 적정 선량, ${\gamma}$-선 조사 식물체의 기내 발근 및 생육 특성을 조사한 결과는 다음과 같다. 감 돌연변이 유기를 위한 적정한 조사 선량 (LD$_{50}$)은 서촌조생 품종에서 1 krad와 2 krad사이이었고, 일목계차랑 품종은 1 krad이었다. ${\gamma}$-선을 조사한 신초를 1차,2차, 3차에 걸쳐 계대배양하는 각 기간의 기내 생육상태를 보면 ${\gamma}$-선량이 증가할수록 기내에서 생장한 신초의 길이가 감소하였으며, 신초의 정아가 가장 장애를 많이 받았다. 서촌조생 품종에서 신초의 37.5~58.3% 정도가 발근되었고 발근율은 2 krad 처리에서는 가장 낮았다. ${\gamma}$-선 조사선량이 높아지면 발근율과 뿌리의 발생수가 줄어들었다. 순화한 뒤 6주 동안 생장상에서 생육한 ${\gamma}$-선 조사 개체는 무처리 개체의 묘고가 6.0 cm인데 비해 2krad 처리개체는 평균 묘고는 2.6 cm에 불과하였다. 또한 발생한 가지의 수도 무처리에서는 1.0개인데 비해 2krad에서는 1.8 개로 많았다. 온실 생육시에서 ${\gamma}$-선 처리선량이 높았던 개체는 처리되지 않았거나 낮았던 개체에 비해 묘고가 작고 분지수가 많았으며, 생육상태도 부진하여 생육 중에 33%정도만 생존하고 나머지는 고사하였다.다.

방사선 조사 마우스에서 오가피의 면역활성 효과

김계엽,정현우,김경윤,Kim, Gye-Yeop,Jeong, Hyun-Woo,Kim, Kyung-Yoon 대한동의생리학회 2006 동의생리병리학회지 Vol.20 No.6

This experimental study was carried out to investigate the immunostimulating effect of Acanthopanax, as Oriental rhizomata herbs, on jejunal survival, endogenous spleen colony formation, apoptosis in jejunal crypt cells and lipid peroxidation in the liver of mice following Gamma-ray irradiation. The subject of this study includes 72 mice which were divided into each 7 groups. Acanthopanax experiment groups were Acanthopanax. Gamma-ray(lOGy), Acanthopanax. Gamma-ray(3Gy), Acanthopnax. Gamma-ray(1Gy), Gamma-ray control(1OGy), Gamma-ray control(3Gy), Gamma-ray control(1Gy), Normal groups. The results of this study were as follows : Treatment with Acanthopanax showed significantly increased(p<0.05) on the cell death apoptosis in crypt, intestine crypts survival of intestine in mice following low-dose(1Gy) Gamma-ray radiation. And that significantly increased(p<0.05) on jejunal crypt survival and reduced(p<0.05) on lipid peroxidation in mice following high-dose(1OGy) Gamma-ray radiation. The above results suggest that Acathopanax were immunostimulating effectively reduced Gamma-ray irradiation.

Evaluation of Standardized Uptake Value applying Prompt Gamma Correction on 68Ga-DOTATOC PET/CT Image

Seok Hwan Yoon 한국방사선학회 2018 한국방사선학회 논문지 Vol.12 No.1

68Ga 방사성 핵종은 68Ge/68Ga 제너레이터에서 생산되는 양전자 방출핵종으로서 PET 검사에 이용되는 방사성 핵종이다. 68Ga은 67.8분의 반감기를 가지고 88.9 %의 β+ 붕괴와 11.1 %의 전자포획으로 68Zn으로 붕괴된다. β+ 붕괴 과정에서 87.7 %는 기저상태의 68Zn로 붕괴되며, 1.2 %는 여기상태의 68Zn로 붕괴된다. 여기상태의 68Zn은 1.077 Mev의 γ선을 방출하며 기저상태의 68Zn가 된다. 이때 방출되는 1.077 Mev의 γ선을 Prompt Gamma라 하며, Prompt Gamma-ray가 환자와 상호작용하게 되면 저에너지 γ선의 산란선이 발생되게 되는데 이 산란선이 PET의 동시계수 회로에 검출되어 질 수 있다. 이 연구의 목적은 68Ga을 이용하는 PET검사 중 신경내분비 종양진단에 사용되는 68Ga-DOTATOC PET/CT영상에 Prompt Gamma-ray 보정 전 후의 표준섭취계수(SUV)를 평가해 보고자 하였다. 68Ga-DOTATOC PET/CT를 시행한 15명의 환자에 대해서 병변부위(Pancreas, Liver, Thoracic Spine, Brain)와 정상으로 섭취되는 조직(Pituitary, Lung, Liver, Spleen, Kidney, Intestine)의 SUVmax와 SUVmean을 비교하였으며, 임상영상의 정량적 평가를 위해 Target to Background Ratio(TBR)을 산출하여 비교하였다. Prompt Gamma-ray 보정 후 Thoracic Spine을 제외한 병변부위와 Pituitary를 제외한 정상조직에서 SUVmax, SUVmean은 높은 값을 나타내었으며, TBR은 Prompt Gamma-ray 보정 전 후 각각 51.51±49.28, 55.50±53.12로 보정 후 높은 값을 나타냈다. (p<0.0001) 68Ga was eluted from a 68Ge/68Ga radionuclide generator. 68Ga decays into 68Zn, with a half life=67.8min. The decay is 88.9 % by β+ and 11.1 % by EC. The main β+ decay (87.7 %) is to the ground level of 68Zn and it is a pure positron emission branch. A small fraction decays β+ (1.2 %) into an excited level of 68Zn, which promptly decays into the ground level with a γ (1.077 Mev). This can constitute prompt gamma contamination in the PET data, if the 1.077 Mev γ has a scatter interaction in the patient, and generates a lower energy γ in coincidence with the positron annihilation pair. The purpose of this study was to evaluate standardized uptake value(SUV) before and after applying prompt gamma rays correction on 68Ga-DOTATOC PET/CT image. Fifty patient underwent PET/CT 1 hour after injection of the 68Ga-DOTATOC. The SUVmax and SUVmean of lesions and normal tissues (Pituitary, Lung, Liver, Spleen, Kidney, Intestine) were evaluated before and after applying prompt gamma correction on 68Ga-DOTATOC PET/CT image. Additionally, the SUVmax of each lesions and SUVmean of the soft tissues were measured on images. and target to background ratios (TBR) were calculated as quantitative indices. Among 15 patients, 25 of lesions (Pancreas, Liver, Thoracic Spine, Brain) with increased uptake on 68Ga-DOTATOC PET/CT image. SUVmax and SUVmean were increased in lesion site and normal tissue after prompt gamma rays correction. TBR was 51.51 ± 49.28 and 55.50 ± 53.12 before and after prompt gamma rays correction, respectively. (p<0.0001)

100-MeV 양성자 빔을 이용하여 169Tm(p,3n)167Yb 반응에 의해 생성된 167Yb 방사성동위원소에서 방출되는 감마선 스펙트럼 비교 연구

이삼열 한국방사선학회 2022 한국방사선학회 논문지 Vol.16 No.7

The measurement of branching ratio of 167Yb radioactive isotopes from gamma-ray spectrum of 169Tm(p,3n)167Yb reaction were performed by using a 100-MeV proton linear accelerator of the Korea Multi-purpose Accelerator Complex (KOMAC). The 167Yb isotope has a half-life of 17.5 minutes and decays to 169Tm. The gamma rays generated from the 167Yb isotope were measured using an HPGe detector gamma ray spectroscopy system. The energy calibration of the detector and the efficiency measurement of the detector were determined using a standard source. The gamma rays of known main energy (62.9, 106.2, 113.3, 143.5 and 176.3 keV) were measured. On the other hand, information about the intensity of the generated gamma rays is very inaccurate. Therefore, in this study, the decay strength of the main gamma rays was accurately measured. Overall, it was different from the previously known results, and in particular, it was found that the intensity of the main decay gamma ray, such as the 113.3 and 106.2 keV gamma ray, was overestimated, and it was found that the gamma ray, such as 62.9, 116.7 and 143.5 keV was underestimated. The present results are considered to be important information in the fields of nuclear fusion, astrophysics and nuclear physics in the future. 양성자과학연구단의 100-MeV 양성자선형가속기의 양성자를 사용하여 천연 169Tm과 핵반응을 일으켜 167Yb 방사성동위원소를 생성하였다. 생성된 동위원소는 17.5분의 반감기를 가지며 167Tm로 붕괴한다. 이때 발생하는 감마선을 HPGe 검출시스템을 사용하여 측정하였다. 검출기의 에너지 교정 및 검출기의 효율 측정은 표준선원을 사용하여 결정하였다. 기존에 알려진 Table of Isotopes의 주요 감마선 에너지는 모두 측정되었다. 한편, 현재까지 알려진 발생되는 감마선의 강도에 대한 정보는 매우 부정확한 상황이다. 따라서 본 연구를 통하여 주요 감마선에 대한 붕괴 강도를 정확하게 측정하였다. 전체적으로 기존에 알려져 있던 결과들과 상이한 차이를 보였으며 특히 113.3 및 106.2 keV 감마선 같은 주 붕괴 감마선의 강도들이 과대평가 되었다는 사실을 알게 되었고 62.9, 116.7 및 143.56 keV의 감마선 들은 과소평가 된 감마선들임을 알게 되었다. 본 연구의 결과는 핵융합 연구, 천체 물리학 및 핵물리 분야에 있어서 중요한 정보가 될 것으로 생각된다.

Development of Virtual Gamma-Ray Energy Spectrum Simulator Program for Training

Yoomi Choi,Young-Yong Ji,Sungyeop Joung,Eunjoong Lee 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

Gamma spectrometry is one of the main analysis methods used to obtain information about unknown radioactive materials. In gamma-ray energy spectrometry, even for the same gamma-ray spectrum, the analysis results may be slightly different depending on the skill of the analyst. Therefore, it is important to increase the proficiency of the analyst in order to derive accurate analysis results. This paper describes the development of the virtual spectrum simulator program for gamma spectrometry training. This simulator program consists of an instructor module and trainee module program based on an integrated server, in which the instructor transmits a virtual spectrum of arbitrarily specified measurement conditions to the students, allowing each student to submit analysis results. It can reproduce a virtual gamma-ray energy spectrum based on virtual reality and augmented reality technique and includes analysis function for the spectrum, allowing users to experience realistic measurement and analysis online. The virtual gamma-ray energy spectrum DB program manages a database including theoretical data obtained by Monte Carlo simulation and actual measured data, which are the basis for creating a virtual spectrum. The currently developed database contains data on HPGe laboratory measurement as well as in-situ measurements (ground surface, decommissioned facility wall, radiowaste drum) of portable HPGe detectors, LaBr3(Ce) detector and NaI detector. The analysis function can be applied not only to the virtual spectrum, but also to the input measured spectrum. The parameters of the peak analysis algorithm are customizable so that even low-resolution spectra can be properly analyzed. The validity of the database and analysis algorithm was verified by comparing with the results derived by the existing analysis programs. In the future, the application of various in-situ gamma spectrometers will be implemented to improve the profiling of the depth distribution of deposited nuclides through dose rate assessment, and the applicability of the completed simulator in actual in-situ gamma spectrometry will be verified.

Gamma rays as an effective tool for removing undesirable color without adverse changes in biological activities of red beet extracts

Lee, Seung Sik,Lee, Eun Mi,Hong, Sung Hyun,Bai, Hyoung-Woo,Lee, In Chul,Chung, Byung Yeoup Elsevier 2012 Radiation physics and chemistry Vol.81 No.8

<P><B>Abstract</B></P><P>The ethanolic extracts of red beet (<I>Beta vulgaris</I> L.) hairy root were used to investigate the removal of color and improvement of biological activity for enhanced industrial applications. The extracts were exposed to gamma rays ranging from 2.5 to 30kGy. The red beet hairy root is composed of two major red-colorants, betanin and isobetanin. Gamma ray radiation at 5kGy remarkably reduced the levels of the major colorants by 94% and the reddish color was eliminated by doses greater than 10kGy. Color removal was likely due to the gamma ray radiolysis of ethanol. Although details on the mechanism responsible for the decay of the chromophore have not been entirely determined, our results suggest that the free radicals that are produced during this process are capable of destroying the chromophore group in isobetanin, thus bleaching the substrate solution. In spite of the degradation of the major colorants, the biological activities of constituents of the extract such as DPPH radical scavenging and tyrosinase inhibition were negligibly affected by the gamma ray radiation up to 20kGy. The antioxidant activity was 92.7% in control samples and 90.0–92.0% in irradiated samples (2.5–20kGy), and a slight decrease to 87.5% was observed for gamma ray radiation at 30kGy. In addition, tyrosinase inhibition activity has also the same pattern; the activity is slightly increased from 50.7% of control to 49.1–52.8% of irradiated samples (2.5–20kGy) with a 46.8% at 30kGy.</P> <P><B>Highlights</B></P><P>► Gamma ray radiation at 5kGy remarkably reduced the levels of the major colorants. ► The reddish color was eliminated by doses greater than 10kGy. ► The biological activities of constituents of the extract were negligibly affected by the gamma ray.</P>