Measurement of the Chamber Correction Factor k ch for Absorbed Dose to Water in Superficial Radiotherapy X-rays

JIANG Pengxuan; ZHAO Rui; YANG Zhijun; ZHANG Jian; WU Jinjie; BAO Junxia; DING Weicheng

doi:10.3969/j.issn.1000-1158.2026.01.16

PDF(3772 KB)

Acta Metrologica Sinica ›› 2026, Vol. 47 ›› Issue (1) : 132-140. DOI: 10.3969/j.issn.1000-1158.2026.01.16

Measurement of the Chamber Correction Factor k _ch for Absorbed Dose to Water in Superficial Radiotherapy X-rays

JIANG Pengxuan ¹^,² ,
ZHAO Rui ² ,
YANG Zhijun ² ,
ZHANG Jian ² ,
WU Jinjie ² ,
BAO Junxia ¹^,² ,
DING Weicheng ¹

Author information +

History +

Abstract

The purpose of this study is to investigate the methodology for determining the chamber correction factor k _ch and to calculate absorbed dose to water in superficial X-rays radiotherapy accurately. Under superficial X-ray radiotherapy reference radiation qualities with tungsten alloy collimators of varying apertures， this study analyzed the ratio of readings measured in air versus on the surface of a PMMA phantom measured by plane-parallel ionization chambers， PTW23342 and PTW23344. Backscatter factors were determined through Monte Carlo simulations， and the variations of the chamber correction factor k _chwith half value layers （HVLs） and radiation beam sizes were measured. Under the four reference radiation qualities （SRT-50a， SRT-50b， SRT-70 and SRT-100）， with an SSD （source to skin distance） of 0.45 m and radiation beam sizes of 3.0~7.2 cm. For the PTW23342 plane-parallel ionization chamber： the ratio of readings measured in air to those on the PMMA phantom surface with ranges from 0.870 0 to 0.991 3. The measured results of correction factor k _ch are within 1.046~1.094. For the PTW23344 plane-parallel ionization chamber： the ratio of readings measured in air to those on the PMMA phantom surface ranges from 0.901 4 to 0.992 4. The measured correction factor k _ch are within 1.053~1.108.

Key words

ionizing radiation metrology / superficial X-rays radiotherapy / chamber correction factor k _ch / plane-parallel ionization chamber / absorbed dose to water

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

JIANG Pengxuan , ZHAO Rui , YANG Zhijun , et al . Measurement of the Chamber Correction Factor k _ch for Absorbed Dose to Water in Superficial Radiotherapy X-rays[J]. Acta Metrologica Sinica. 2026, 47(1): 132-140 https://doi.org/10.3969/j.issn.1000-1158.2026.01.16

References

List( Publishing order | Descend order by publishing year | Descend order by cited within ) Chart analysis

[1]	陈大卫，尚士洁，于金明. 重新认识放射治疗在肿瘤综合治疗中的作用［J］. 中国科学基金， 2025， 39（1）： 34-49. CHEN D W， SHANG S J， YU J M. Re-evaluating the Role of Radiotherapy in Comprehensive Cancer Treatment［J］. Bulletin of National Natural Science Foundation of China， 2025， 39（1）： 34-49. Cited in this article [1]

[2]	张慧，刘君怡，陶莉，等. 皮肤病变的浅层放射治疗技术进展［J］. 中国医疗设备， 2024， 39（11）： 143-148. ZHANG H， LIU J Y， TAO L， et al. Current Advances in Superficial Radiotherapy for Skin Lesions［J］. China Medical Divices， 2024， 39（11）： 143-148. Cited in this article [1]

[3]	HILL R， HEALY B， HOLLOWAY L， et al. Advances in kilovoltage X-ray beam dosimetry［J］. Physics in Medicine and Biology， 2014， 59（6）： R183–R231. Cited in this article [1]

[4]	夏云，王兵，徐斌. 手术切除联合术后放射疗法治疗瘢痕疙瘩［J］. 中华实用诊断与治疗杂志，2008（11）： 860-861. XIA Y， WANG B， XU B. Surgical resection combined with postoperative radiotherapy for keloid treatment［J］. Journal of Chinese Practical Diagnosis and Therapy， 2008（11）： 860-861.

[5]	HAN H W， GADE A， CECI FM.， et al. Superficial radiation therapy for nonmelanoma skin cancer： A review［J］. Dermatological Reviews，2022（3）：409-417. Cited in this article [1]

[6]	MUSOLINO S V. Absorbed dose determination in external beam radiotherapy： an international code of practice for dosimetry based on standards of absorbed dose to water； technical reports series No. 398［J］. Health Physics， 2001， 81（5）： 39-40. Cited in this article [3]

[7]

KLEVENHAGEN

S C

， AUKETT

R J

， HARRISON

R M

，et al. The IPEMB Code of Practice for the determination of absorbed dose for X-rays below 300 kV generating potential （0.035mm Al-4 mm Cu HVL； 10-300 kV generating potential）［J］. Physics in Medicine and Biology， 1996， 41（12）： 2606-2625.

Cited in this article [3]

[8]	IPE N E， ROSSER K E， MORETT C J， et al. Air kerma calibration factors and chamber correction values for PTW soft X-ray， NACP and Roos ionization chambers at very low X-ray energies［J］. Physics in Medicine and Biology， 2001， 46（8）： 2108-2110. Cited in this article [2]

[9]	PERRIN B A， WHITEHURST P， COOPER P， et al. The measurement of k _ch factors for application with the IPEMB very low energy dosimetry protocol［J］. Physics in Medicine & Biology， 2001， 46（7）： 1985-1995. Cited in this article [5]

[10]	AUKETT R J， BURNS J E， GREENER A G， et al. Addendum to the IPEMB code of practice for the determination of absorbed dose for x-rays below 300 kV generating potential （0.035 mm Al–4 mm Cu HVL）［J］. Physics in Medicine and Biology， 2005， 50（12）： 2739-2748. Cited in this article [1]

[11]	包俊霞，赵瑞，汤显强，等. SRT-100浅层 X 射线治疗系统辐射能谱的模拟研究［J］. 计量学报， 2024， 45（8）： 1236-1241. BAO J X， ZHAO R， TANG X Q， et al. Simulation Study of Radiation Energy Spectrum of SRT-100 Superficial X-ray Therapy System［J］. Acta Metrologica Sinica， 2024， 45（8）： 1236-1241. Cited in this article [2]

[12]	周振杰，任世伟，吴金杰，等. 10~50 kV X射线水吸收剂量的测量与研究［J］. 核技术， 2016， 39（12）： 110-114. ZHOU Z J， REN S W， WU J J， et al. Study and measurement of the water absorbed dose in 10~50 kV X-ray［J］. Nuclear Techniques， 2016， 39（12）： 110-114. Cited in this article [1]

[13]	KNIGHT R T. Absorbed dose conversion factors for therapeutic kilovoltage and megavoltage X-ray beams calculated by the Monte Carlo method［J］. Medical Physics， 1997， 24（2）： 336. Cited in this article [1]

[14]	ASPRADAKIS M M， BUCHILLIER T， KOHLER T， et al. SSRMP Recommendations No 9： Reference dosimetry in low and medium energy X-ray beams［J］. Zeitschrift für Medizinische Physik， 2023， 33（4）： 601-617. Cited in this article [1]

[15]	杜海燕，吴金杰，廖振宇，等. X射线半值层测量方法的研究［J］. 计量学报， 2016， 37（6A）： 29-33. DU H Y， WU J J， LIAO Z Y， et al. Study of X-ray Half-value-layer Measurement Methods［J］. Acta Metrologica Sinica， 2016， 37（6A）： 29-33. Cited in this article [1]

[16]	SOUSA LACERDA M A， SILVA T A， OLIVEIRA A H. The methodology for evaluating half-value layer and its influence on the diagnostic radiology［J］. Radiologia Brasileira， 2007， 40（5）： 331-336. Cited in this article [1]

[17]	GROSSWENDT B. Dependence of the photon backscatter factor for water on source-to-phantom distance and irradiation field size［J］. Physics in Medicine & Biology， 1990， 35（9）： 1233-1245. Cited in this article [2]

[18]	ANDREO P. Data for the dosimetry of low-and medium-energy kV X-rays［J］. Physics in Medicine & Biology， 2019， 64（20）： 1-19. Cited in this article [3]

[19]	ROGERS D W O， Kawrakow I. Monte Carlo calculated correction factors for primary standards of air kerma［J］. Medical Physics， 2003， 30（4）： 521-532. Cited in this article [1]

[20]	鲁平周，吴金杰，李梦宇，等. 低能X射线水吸收剂量测量的散射辐射研究［J］. 核技术， 2022， 45（4）： 31-38. LU P Z， WU J J， LI M Y， et al. Study on scatter of low energy X-ray absorbed dose towater measurement ［J］. Nuclear Techniques， 2022， 45（4）： 31-38. Cited in this article [1]

[21]	樊松，吴金杰，余继利，等. 治疗水平电离室刻度因子不确定度评定［J］. 核电子学与探测技术， 2017， 37（8）： 792-796. FAN S， WU J J， YU J L， et al. Uncertainty Evaluation for the Calibration Factor of Therapeutic Ionization Chamber［J］. Nuclear Electronics ＆ Detection Technology， 2017， 37（8）： 792-796. Cited in this article [1]